School of Life Sciences

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Antioxidative and antidiabetic activity and phytochemicals analysis of some selected Sudanese traditional medicinal plants.
(2021) Idris, Almahi Idris Mohamed.; Islam, Shahidul.
This study was conducted to evaluate the antioxidant and anti-diabetic properties of selected traditional Sudanese medicinal plants (Cyperus rotundus, Nauclea latifolia, and Hibiscus sabdariffa) using in vitro, ex vivo, and in silico experimental models. The crude extracts (ethyl acetate, ethanol, and aqueous) were screened in vitro for their antioxidant activities using ferricreducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and nitric oxide radical (NO) scavenging activities, as well as their carbohydrate digesting enzyme inhibitory activities for antidiabetic evaluation. Subsequently, the extracts were subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis to elucidate their possible bioactive compounds. Additionally, ex vivo studies was conducted to investigate their capability to promote muscle glucose uptake and suppress glucose absorption in the intestine as well as to analyze antioxidative effects in iron–induced oxidative stress in hepatic tissue. Molecular docking was carried out to determine the probable enzymes' inhibitory mode of action by ligands identified through GC-MS. This study indicates that these traditional Sudanese medicinal plants have remarkable antioxidant and antidiabetic activities, which may help to ameliorate oxidative stress and diabetes. Therefore, these plants may be considered a natural source of bioactive compounds beneficial for human health, particularly for managing diabetes and oxidative stress-related metabolic disorders.
Antioxidative and antidiabetic activity and phytochemicals, analysis of some selected Sudanese traditional medicinal plants.
(2021) Idris, Almahi Mohamed.; Islam, Shahidul.
This study was conducted to evaluate the antioxidant and anti-diabetic properties of selected traditional Sudanese medicinal plants (Cyperus rotundus, Nauclea latifolia, and Hibiscus sabdariffa) using in vitro, ex vivo, and in silico experimental models. The crude extracts (ethyl acetate, ethanol, and aqueous) were screened in vitro for their antioxidant activities using ferricreducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and nitric oxide radical (NO) scavenging activities, as well as their carbohydrate digesting enzyme inhibitory activities for antidiabetic evaluation. Subsequently, the extracts were subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis to elucidate their possible bioactive compounds. Additionally, ex vivo studies was conducted to investigate their capability to promote muscle glucose uptake and suppress glucose absorption in the intestine as well as to analyze antioxidative effects in iron–induced oxidative stress in hepatic tissue. Molecular docking was carried out to determine the probable enzymes' inhibitory mode of action by ligands identified through GC-MS. This study indicates that these traditional Sudanese medicinal plants have remarkable antioxidant and antidiabetic activities, which may help to ameliorate oxidative stress and diabetes. Therefore, these plants may be considered a natural source of bioactive compounds beneficial for human health, particularly for managing diabetes and oxidative stress-related metabolic disorders.
Comparative antidiabetic effects and mechanisms of actions of five Chinese and South African indigenous teas.
(2020) Xiao, Xin.; Islam, Shahidul.
The present thesis assessed the in vitro, ex vivo and in vivo anti-oxidative and antidiabetic activities of five teas which are widely consumed in China or South Africa. Three of the selected five teas are from South Africa, namely red rooibos (Aspalathus linearis), green rooibos (Aspalathus linearis) and red honeybush (Cyclopia genistoides) tea. The remaining two from China are jasmine green (Camellia sinensis) and zhengshanxiaozhong (ZSXZ) black tea (Camellia sinensis). The different sequential solvent extracts following increasing polarity index (dichloromethane, ethyl acetate, ethanol, and water) and hot water extract of different teas were evaluated at in vitro and ex vivo conditions for their antioxidant properties, inhibitory potentials on α-glucosidase, α-amylase and pancreatic lipase, effects on ameliorating Fe2+- induced oxidative pancreatic or hepatic injury, as well as the glucose absorption inhibition in small intestine and the glucose uptake stimulation in isolated psoas muscle of rats. Possible bioactive components responsible for the activities of the extracts were identified by using Gas Chromatography-Mass Spectrometry (GC-MS) analysis or liquid chromatograph-mass spectrometry (LC-MS) analysis. In vitro and ex vivo tests presented promising antioxidant and antidiabetic activities of these five teas. The red honeybush, jasmine green and green rooibos teas, were further subjected to an in vivo intervention trial in a fructose-streptozotocin (STZ) induced T2D model of Sprague-Dawley rats. Assays were carried out to reveal the effects of these teas on lowering blood glucose level, improving oral glucose tolerance ability, stimulating insulin secretion and hepatic glycogen synthesis and ameliorating some diabetes related parameters such as serum lipid profile, hepatic and renal function tests and calculated insulin resistance (HOMA-IR), β-cell function (HOMA-β) from the blood glucose and serum insulin data. Furthermore, in vivo oxidative stress markers such as reduced glutathione, superoxide dismutase and catalase activity and lipid peroxidation were analysed in harvested organs (liver, kidney, heart and pancreas). The results of in vivo tests demonstrated that high dose of jasmine green tea showing the best activity followed by the high dose of red honeybush tea, low dose of jasmine green tea, high dose of green rooibos tea, low dose of red honeybush tea, when lowest activity was observed for the low dose green rooibos tea. The results of this study indicated promising anti-T2D properties of the above-mentioned teas. However, further clinical trials are needed to ascertain the results of these in vitro, ex vivo and in vivo studies.
Evaluation of the larvicidal potential of Bacillus velezensis strain PHP1601 as a viable biological control agent against selected fly species.
(2024) Ramesar, Danvir Rajesh.; Hunter, Charles Haig.
Flies are one of the most abundant and prevalent insect pests posing a growing threat to various sectors of the economy. In response to this, a study was undertaken to evaluate Bacillus spp. strain PHP1601 as a candidate biocontrol agent against Lucilia cuprina larvae as a proxy for fly species of biocontrol significance. The identity of PHP1601 was confirmed as B. velezensis using MLSA and species-specific PCR. Bioassays demonstrated a larvicidal effect of cell, endospore (102 – 1010 cells/endospores g -1 ) and cell-free supernatant (1 – 30% v w -1 ) treatments on second instar larvae of L. cuprina. Studies were directed to the larvicidal effect of extracellular compounds, namely lipopeptides. Crude lipopeptide extract (CLP) was acquired using organic extraction from Landy broth. Bioassays with CLP extract (5 – 1000 μg g -1 ) resulted in a dose-dependent larvicidal response. Lipopeptides in the CLP extract were purified by TLC and characterised using UPLC ESI-TOF MS. This indicated the presence of iturin, fengycin and surfactin homologues of which, the purified surfactin fraction (Rf 0.91) was the most larvicidal. Bioassays were repeated with commercial surfactin, confirming its larvicidal potency, exhibiting an LC50 of 9.87 μg g -1 at 240 h. Larvae scent choice tests using TSB and MG bioassay medium fermented by PHP1601 showed that resulting VOCs were attractive to fly larvae, which was considered a viable trait of a fly biocontrol agent. CG-MS of the VOCs produced indicated that ketones were the dominant VOC class and, presumably, the major contributor to this larvae attraction effect. Field performance evaluation using pig manure trials demonstrated successful inhibition of several fly species of agricultural and veterinary importance using endospore treatments (105 and 1010 endospores g -1 ) of PHP1601. qPCR and REP-PCR fingerprinting confirmed that PHP1601 could grow in the manure slurries and was amiable to recovery and monitoring. Zebrafish embryo toxicity bioassays of the CLP produced by PHP1601 indicated that they achieved an LC50 of 22.77 µg ml-1, which characterised these metabolites as slightly toxic. Genome mining detected no genes associated with pathogenicity or virulence and presented no apparent pathogenic threat. The investigation demonstrated that B. velezensis PHP1601 is a viable fly biocontrol candidate and constitutes the first report of a B. velezensis antagonist of Brachycera flies.
Genetic analyses of antimicrobial resistance and virulence genes in Enterococcus species isolated from livestock production systems in South Africa.
(2021) Mnguni, Anele Buhle.; Zishiri, Oliver.
Enterococcus species are widely dispersed in the environment this includes soil, water, plants, food and animals. Although Enterococcus constitute mostly as a commensal bacterium; over the past years the bacterium has evolved to cause nosocomial infections. The proliferation of this pathogen is attributed to its ability in successfully transferring antimicrobial and virulence genes using several channels such as mobile genetic elements. This study investigated the prevalence of Enterococcus spp. in small-scale commercial farms in rural South Africa. The dissemination of virulent E. faecium and E. faecalis isolates allied with livestock production in the Eastern Cape and KwaZulu-Natal provinces was investigated. A total of 276 samples randomly sampled from livestock and their associated environments (feed, soil and water) were screened for Enterococcus spp. using selective media and using DNA molecular methods. E. faecalis and E. faecium prevalence was confirmed by the amplification of the tuf and sodA genes. Sixty-one percent of total presumptive isolates were E. faecalis (n=61) and only 8% (n=8) were identified as E. faecium. The presence of virulence determining factors such as asa1, ccf, cylA, esp, gelE and hyl was screened in all samples that tested positive for Enterococcus species. Presumptive E.faecalis and E. faecium isolates were mostly recovered from Amandawe (KZN). E. faecalis isolates harboured the most virulence genes asa1 (25%; n=), ccf (84%; n=), esp(4%;n= ), gelE (69%; n=) and hyl (12%; n= ). Whilst E. faecium isolates only harboured of asa1(12.5%; n=1), ccf (100%; n=8), gelE (75%;n=6 ) and hyl (25%;n=2). The current study also evaluated the antibiotic resistance profiles and their associated genes in these two species. Antibiotic susceptibility profiles of E. faecium and E. faecalis were assessed using Kirby-Bauer disk-diffusion assay as per the CSLI guidelines. Erythromycin had the highest occurrence of resistant isolates in both species with 75% (n=6) and 54.1% (n=33) respectively. Isolates were least resistant to ampicillin, with 0.03% resistance in E. faecalis and 0% in E. faecium. E. faecalis had the highest prevalence of Multi Drug Resistance (MDR), exhibiting phenotypic resistance to macrolides, aminoglycoside, tetracyclines and fluoroquinolones. TET-CIP-ERY was the most observed antibiotic resistance pattern. Furthermore, the isolates were screened for vanA, vanB, vanC1, vanC2/3, aac(6”)-aph(2”) ,ermA and ermB. The resistance genes that amplified in E. faecalis included vanB (8%;n=5), vanC1 (37%;n=23), vanC2/3 (37%; n=23), ermB (96%;n=58), ermA (8%;n=5) and aac(6”)-aph(2”) (1.6%;n=1). The immense dissemination of E. faecalis that has potentially pathogenic virulent determinants is a cause for concern in livestock production systems. In addition, faecal contamination from livestock poses a threat to the dissemination of virulent strains. The study demonstrated that E. faecium and E. Faecalis isolated from livestock and their associated environment were predominantly resistant to macrolides, glycopeptides, tetracyclines and fluroquinolones. In addition to be the first study in South Africa to document the emergence of inducible vanC determinants in Vancomycin Resistant Enterococci isolates.
Identification of arthropods of forensic importance during cold and warm seasons in KwaZulu-Natal Province of South Africa.
(2021) Tembe, Danisile.; Mukaratirwa, Samson.
Forensic entomology is the study and use of insects and other arthropods in forensic investigations associated with death, abuse and neglect of both humans and animals. Although there has been an increased interest in forensic entomology and its application in predicting post-mortem interval (PMI) amongst other issues in many developed countries, the results cannot be extrapolated beyond the countries/regions of study since the arthropods species spectra may vary with region and geographical conditions. The present study aimed to determine the arthropod species of forensic importance found during different stages of decomposition of sheep (Ovis aries) and pig (Sus scrofa domesticus) carrion during the warm and cold season in KwaZulu-Natal province of South Africa. A scoping review was conducted to determine the state of knowledge of forensic entomology research and application in southern Africa. To determine the arthropod species associated with sheep and pig carcass during different stages of decomposition, two medium sized Large-White pigs and two medium sized Merino sheep were humanely killed and used for the cold and warm season. Adult arthropods found on and around the carcasses during different stages of decomposition were collected and identified using combined morphological identification keys and molecular technique based on the mitochondrial gene. The review showed that arthropod species that were found on a decomposing carcass could be useful in the estimation of PMI and provided clues in cases of criminal investigations. The review also confirmed the scarcity of forensic entomology research, and its application in southern Africa. Experimental results from this study showed that dipteran flies from the families Calliphoridae, Muscidae and Sarcophagidae were the first to colonize the sheep and pig carcasses during both warm and cold seasons. These include species of Chrysomya marginalis, Ch. putoria, Ch. albiceps, Ch. chloropyga, Lucilia cuprina, Musca domestica and Sarcophaga calcifera. On the sheep carcasses, Ch. marginalis, Ch. albiceps and M. domestica were the most dominant fly species, contributing 63.2 % of the collected flies in the warm season, and 68.9 % in the cold season. Colonization by coleopterans during the warm season started as early as the fresh stage with Dermestes maculatus, Thanatophilus micans and Onthophagus crassicollis. In the cold season these same beetle species were collected from the bloated stage of the sheep carcass. On the pig carcasses, Ch. marginalis (n = 111), Ch. albiceps (n = 99) and M. domestica (n = 131) were the most abundant species during the warm season. The same species were the most abundant species in the cold season (n = 55), (n = 34) and (n = 81) respectively, although in lower numbers than the warm season. Among the collected Coleoptera species, D. maculatus (n = 112) and N. rufipes (n=62) were the most abundant species found on the carcass during the warm season and the same species were the most abundant species in the cold season (n = 66) and (n = 48) respectively. In the warm season Dermestes maculatus was recorded on the pig carcass during the fresh stage and persisted on the carcass until the last of decomposition. However, in the cold season Dermestes maculatus was first recorded on the carcass during the active stage of decomposition. Molecular analyses confirmed the identification of twelve (12) arthropod taxa collected from both sheep and pig carcasses during the cold season. Results showed that 11/12 arthropod species were common in both sheep and pig carcasses, with exception to Onthophagus sp. and Atherigona soccata species which were unique to sheep and pig carcasses respectively. However, during the warm season, the sheep carcass attracted more (n=13) taxa as compared to the pig carcass. The variation in the arthropod was due to the presence of Onthophagus sp. which was also unique to the sheep carcass during this season. Furthermore, there was an addition of a beetle species Hycleus lunatus, which was collected from both sheep and pig carcasses but unique to the warm season. This study generated important information on the endemic arthropod species that are of forensic importance KwaZulu-Natal province. The arrival time and association of arthropods species with different stages of decomposition during the warm and cold season highlighted their value in estimating the PMI in forensic investigations in the locality of KwaZulu-Natal province. The studied arthropods can potentially be useful in the estimation of PMI and other cases of criminal investigations. The seasonal variations in abundance of both Diptera and Coleoptera in the two seasons seemed to indicate influence of seasons which subsequently influenced temperature. It is recommended that similar studies be conducted at other geographical locations of South Africa with a different ecological system to build a database of dipteran and coleopteran species of forensic importance which are endemic in these areas.
Influence of human-associated tsetse habitat degradation on tsetse fly (Diptera: Glossinidae) populations and prevalence of infection with trypanosomes in North-Eastern Zambia.
(2021) Chilongo, Kallinga.; Mukaratirwa, Samson.
African trypanosomiasis is among the most important parasitic diseases of livestock and humans caused by several species of trypanosomes, and the disease occurs in 36 countries in sub-Saharan Africa. Human African Trypanosomiasis (HAT) causes a considerable public health burden on rural populations, and Animal African Trypanosomiasis (AAT) is an important constraint to livestock production and full utilization of land for agricultural production, such that if not controlled the disease can induce important losses through limiting crop production and access to land, and diminishing income from meat, milk and other livestock products, consequently resulting in poverty. In Zambia, approximately 40% of the country’s land is tsetse-infested and the infestation in the Luangwa valley is among the most important with respect to occurrence of both human and animal trypanosomiais. In affected areas, occurrence of trypanosomiasis in humans and in livestock normally correlates with the prevalence of trypanosome infection in tsetse flies. Laboratory studies have shown that among the major factors that affect such trypanosome infection in tsetse flies, is occurrence of stress in tsetse flies. Occurrence of stress in wild tsetse fly populations is associated with unfavourable environmental conditions for the flies, and this is usually a consequence of tsetse habitat degradation. In many parts of Zambia’s eastern tsetse belt, human-associated degradation of the tsetse habitat has been on the increase over the last decades. This suggests that research to determine the effects of such human-associated tsetse habitat degradation, on tsetse populations and prevalence of trypanosome infection in the tsetse population in the area, could provide some insights into the epidemiology of trypanosomiasis in the area. In this study undertaken in three sites, Mpika, Lundazi and Rufunsa sites, in north-eastern Zambia (in parts of the eastern tsetse belt), the objectives were, to determine and measure (i) variation in size, age and hunger stages in tsetse flies and (ii) variation in prevalence of trypanosome infection in the tsetse flies, with increase in distance away from the edge into the inner parts of tsetse belt, and in relation to the distribution of human settlements; and (iii) to detect, assess and evaluate the contribution and importance of existing agricultural and other forms of ecosystem utilization, to tsetse-habitat degradation in the three sites. Three study sites were selected based on level and pattern of human settlement, i.e. Mpika and Rufunsa sites with human settlement concentrated at or close to the edge of the tsetse belt, and Lundazi site with human settlement evenly distributed from the edge into the innermost parts of the tsetse belt. Samples of two species of tsetse flies found in the sample sites, i.e. Glossina morsitans morsitans and G. pallidipes, were collected and (i) size, age and hunger stage in the tsetse flies were recorded and assessed with reference to distance away from the edge of the tsetse belt; (ii) variation in prevalence of trypanosome infection in the tsetse population in the study sites, with reference to distance away from the edge of the tsetse belt, and in relation to distribution of human settlements; and (ii) key land-use and socioeconomic factors in the human settlements, with reference to human-associated tsetse habitat degradation in the study sites. Trapping of the tsetse flies was done in defined sample points, identified with use of a Global Position System (GPS) unit, in the transect line, with use of the Black-screen fly round (BFR) and Epsilon traps. From the sampled flies, the following were recorded; species of fly, sex, body size, age and hunger stage (as indicators of levels of occurrence of stress), and screening for trypanosome infection using microscopy and the loop-mediated isothermal amplification (LAMP). A semi-structured questionnaire was administered in each of the settlements within our study location, and national land cover maps for the years 2000 and 2010, produced by the country’s Forest Department, were used to estimate vegetation cover change during the period 2000 to 2010 in each of the sites. Regression models were applied to determine and measure the level of association of the distance from the edge into the inner parts of the tsetse belt with; size, age and hunger stages of tsetse samples, and prevalence of trypanosome infection in the tsetse flies. In each settlement, data were collected on key land-use and socio-economic factors that may be linked to human-associated habitat degradation and changes in the vegetation cover during the period 2000 and 2010, was calculated in QGIS. The results showed that in the Mpika and Rufunsa sites, the number of Glossina morsitans morsitans tsetse flies caught increased along with the increase in distance from the edge into the inner parts of the tsetse belt. This was also associated with increase in the body size (p < 0.0001 in both sites), and reduction in the age (p < 0.001 in each site) and the hunger stages (p < 0.0001 in both sites), and reduction in the prevalence of trypanosome infection (p = 0.024 and p = 0.012 in the case of all sub-species of trypanosomes tested for in the Mpika and Rufunsa sites respectively; and p = 0.013 and p = 0.025 in the case of only nannomonas sub-species in the two sites, respectively). The level of vegetation cover change was insignificant in each of the sites, such that it was unlikely to have had any significant impact on the quality of the tsetse habitat in each of the sites. In the Mpika and Rufunsa sites, human activities associated with access to resources might have had significant effect on the distribution of wild mammals that served as tsetse hosts in the area, such that numbers (of wild mammals) were low in locations that were close to the settlements and high in locations that were furthest from the settlements – giving rise to a gradient of increasing levels of availability of tsetse hosts with increase in distance away from the human settlements. This same trend was observed with regard to the distribution of body size of the flies, age, hunger stages, and prevalence of nannomonas and trypanozoon trypanosome infection, in G. m. morsitans in the Mpika and Rufunsa sites. This was indication that (in the Mpika and Rufunsa sites) increase in the levels of availability of tsetse hosts was associated with increase in levels of tsetse wellbeing – in turn associated with increase in levels of tsetse habitat quality. With regard to the findings in the Lundazi site (where human settlement was evenly distributed in transect line), the absence of any such variation (in each of the respective attributes in G. m. morsitans) with distance from the edge of the belt, could be taken as supportive to the reason indicated above as the likely basis for the existence of a gradient of reducing levels of tsetse habitat degradation in the Mpika and Rufunsa sites. In the case of G. pallidipes, the results showed no variation in the respective features in the tsetse flies, with increase in distance from the edge of the tsetse belt, and factors such as the relatively fewer numbers of the species caught, and a large proportion of the transect length not having registered any catch of the species, in each site in the study, likely contributed to this outcome.
Investigating the role of small RNAS in transcriptome regulation of genetically diverse clinical strains of mycobacterium tuberculosis.
(2021) Govender, Divenita.; Mvubu, Nontobeko Eunice.
Tuberculosis (TB), caused by the human adapted members of the Mycobacterium tuberculosis complex (MTBC), is a threat to global health. Understanding the regulatory network of the MTBC members may reveal novel vaccine candidates and drug targets. The small RNAs (sRNAs) have only recently been investigated for their role in Mycobacterium tuberculosis (M. tb) transcriptome regulation with none being explored in clinical strains or within the MTBC lineages. The present study aimed to investigate the regulatory role of sRNAs on the M. tb transcriptome in a lineage-specific manner, with emphasis on the clinical strains most prevalent in South Africa. In silico whole genome sequence alignment of strains belonging to the eight MTBC lineages was performed to identify sRNAs containing lineage-specific mutations and their respective potential targets. To elucidate transcriptome regulation in clinical strains of M. tb belonging to the Beijing and F15/LAM4/KZN lineages, mRNA and sRNA sequencing were performed followed by Hisat-Ballgown Bioinformatics analysis to identify novel sRNAs and their respective targets. The sRNAs discovered from sRNA sequencing were confirmed through real time qPCR. The in silico data revealed several sRNAs that may play a role in transcriptome regulation at a lineage-specific level, such as those involved in macrophage entry, lipid biosynthesis pathway, adaptation mechanisms during antibiotic exposure, and environmental stress. They may also be able to disrupt genes that are detrimental and restore functions to those that are beneficial. The mutated and consensus sRNAs were identified to target the same function, but one pathway may be more efficient than the other. Novel sRNAs were discovered from sRNA sequencing of the Beijing and F15/LAM4/KZN clinical strains, with their predicted targets absent from the mRNA sequencing results, indicating these sRNAs may elicit an inhibitory function. Real time-PCR analysis revealed significant fold change differences between the clinical strains belonging to the Beijing, F15/LAM4/KZN, F11 and Unique families suggesting an underlying regulation of these transcripts at a family level. This data could explain the underlying phenotypic differences observed within the MTBC and understanding of the regulatory function of these sRNAs, may identify novel alternative strategies in the fight against M. tb.
Micromorphology and biological activities of leaves and stem bark of Diospyros villosa (L.) De Winter.
(2021) Adu, Oluwatosin Temilade.; Naidoo, Yougashree.; Lin, Johnson.
Review Article: The genus Diospyros consists of many species which are distributed throughout the world. There is no elaborate information about the holistic importance of the plants. This review aims to delve for more information about the usefulness of the plants for humans. A detailed study of the genus Diospyros with a targeted focus on Diospyros villosa (L.) De Winter plant was carried out information on the plants’ morphology was taken as observed during harvest. Other information with respect to geographical distribution, secretory structures, chemical composition, embedded bioactive constituents and the associated mechanism of action of the bioactive constituents were acquired. The genus Diospyros yields products of medicinal importance throughout the world. This study gives some detailed information about the genus Diospyros as well as the potential use of the species as functional medicinal plants with bioactive compounds. Manuscript 1: This study evaluated the phytochemical constituents, antioxidant and antimicrobial potentials of Diospyros villosa (L.) De Winter leaves and stem bark. The extracts were obtained using different media (methanol, chloroform and hexane). DPPH and FRAP methods were used to investigate the antioxidant potentials of the crude extracts. The antimicrobial potency of Diospyros villosa extracts against five pathogenic bacteria was determined using MIC, MBC and agar well diffusion methods. Flavonoids, alkaloids and phenols were identified in D. villosa extracts. The mean concentrations of methanol extracts Diospyros villosa leaves and stem against DPPH providing 50% inhibition were 9.53 ± 0.25 μg ml-1 and 9.52 ± 0.30 μg ml-1 respectively. The methanolic leaves extracts further showed promising antimicrobial activity against Klebsiella pneumonia, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and Staphylococcus aureus with inhibition zones which are almost as high as the control. The antimicrobial methods also demonstrated that the leaves and stem bark extracts had wide antimicrobial abilities. The results revealed that D. xxvii villosa leaves and stem bark contain reasonable amount of bioactive compounds. Hence, these compounds may serve as natural antioxidants and antibacterial agents for the treatment of bacterial infections and diseases. Manuscript 2: Nanoparticles are synthesized through wet chemical techniques. Meanwhile, the chemicals used often are toxic and flammable. While considering safe substances, Diospyros villosa leaves and stem bark are both observed to be suitable for the biosynthesis of silver nanoparticles. In this research study, we described a less expensive and environmental-friendly technique for the biosynthesis of silver nanoparticles from silver nitrate (AgNO3) solution and Diospyros villosa extracts. The obtained silver nanoparticles were characterized using the UV-vis absorption spectroscopy, FT-IR, EDX, SEM and TEM, DPPH scavenging ability, ferric reducing antioxidant potential, antimicrobial susceptibility and quorum sensing inhibition tests. The biosynthesized silver nanoparticles showed good antibacterial activity against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermis and Enterococcus faecalis. The D. villosa nanoparticles demonstrated potential antioxidant and quorum sensing inhibition and may thus represent a source of antioxidant as well as quorum sensing inhibition candidate for infection and disease control. Manuscript 3: The structural adaptation, histological compatibility and ecological functions of trichomes in Diospyros villosa, however remain largely unclear. This study aimed to interpret the structure and histochemical analysis of the leaves and stem bark of Diospyros villosa using light and electron microscopy and different histochemical tests as well as to elucidate the composition of the secretory products. Trichome density and length were also determined in three developmental stages of the leaves. The results of histochemical tests also revealed the presence of alkaloids and phenolic compounds which are medicinally important and used to treat multiple ailments. xxviii Manuscript 4: Diospyros villosa is traditionally used for processing anti-bacterial properties. Its cytotoxic effects have not been studied before. Therefore, this study aimed to examine the nutritional properties as well the cytotoxic effects of D. villosa. The leaves and stem barks were subjected to three different extraction methods (methanol, chloroform and hexane) and their nanoparticles were synthesized at two different temperatures (room temperature and at 80 ºC). Thereafter, extracts were assessed using the associated AOCC protocols, for their nutritional content (moisture, fibre, proteins, lipid, ash and hydrolysable carbohydrates). Diospyros villosa extracts and their corresponding nanoparticles were then incubated overnight with cancerous and noncancerous cell lines to evaluate their cytotoxic potential.
Morphological and molecular characterization of Fasciola hepatica and Fasciola gigantica phenotypes from Mpumalanga and KwaZulu-Natal provinces of South Africa.
(2020) Haridwal, Sayurika.; Mukaratirwa, Samson.
Fascioliasis is a food- and waterborne disease. It is one of the most common helminthic infections in domesticated ruminants. The disease is caused by liver flukes, Fasciola hepatica and Fasciola gigantica. Increased attention has been geared toward studying these flukes due to their ever-expanding geographical distribution, enormous economic impact, increased human infections, increased resistance to treatment and the existence of hybrid forms. Both these species are co-endemic in the Mpumalanga and KwaZulu-Natal provinces of South Africa and even though, hybrids have been reported in other areas where both species exist it has not been attempted in South Africa. Therefore, this study was conducted to determine the existence of Fasciola hybrids in South Africa using morphological and molecular characterization. A total of 71 flukes were collected from naturally infected cattle slaughtered at abattoirs located in Enhlazeni and Nelspruit in Mpumalanga province and Pietermaritzburg in KwaZulu-Natal province of South Africa as well as control samples from Zimbabwe (Bulawayo abattoir) where only F. gigantica exist. The samples were categorized morphologically as either F.hepatica, F.gigantica, or Fasciola sp. The morphometrics (body length, body width, and length/width) were analyzed through a PCA and produced three distinct groups. A one-way ANOVA indicated that the length and length/width could be used to differentiate the species (P < 0.05) and the width was not useful in differentiating the species (P > 0.05). Molecular analysis based on ITS-1/5.8S/ITS2 marker showed that specimens morphologically identified as Fasciola sp were F.gigantica, with one sample morphologically identified as F.gigantica was molecularly identified as Fasciola sp. Similar results were observed with the CO1 marker, however, one sample came up as unknown, this sample however, formed a well-supported sister clade to F. gigantica. . It was also observed that aspermatic specimens are not only limited to hybrids, as some individuals that were molecularly identified as F. hepatica lacked sperm in their seminal vesicles. This study confirms species identification of F. hepatica and F.gigantica cannot be solely based on morphological characters where both these species are co-endemic. This was also the first study to report the existence of hybrid Fasciola spp. in South Africa.
The morphological characterization, chemical composition and biological activity of barleria albostellata (Acanthaceae).
(2021) Gangaram, Serisha.; Naidoo, Yashini.; Dewir, Yaser Hassan.
Herbal preparations of plants continue to present mankind with novel remedies as many of these plants contain important secondary metabolites. Medicines manufactured by pharmaceutical companies are largely synthetic. The fear for ineffectiveness, adverse side-effects and toxicity, has brought about further scientific investigations on the potential usage of medicinal plants. Plants of the family Acanthaceae are rich in bioactive phytochemicals. Several plant species are being utilized for their ethnomedicinal properties based on their phytocompounds they acquire, with Barleria (Acanthaceae) being one of such genera. Barleria albostellata C.B. Clarke (Acanthaceae) is a shrub indigenous to South Africa. Herbal use of this plant has not been fully documented, however, several species of Barleria are used in traditional medicine. Little or no investigations have been undertaken to evaluate the micromorphology secretory mechanisms, through which such phytochemicals are synthesized and secreted; floral biology; phytochemical profile; antibacterial and antioxidant activity, cytotoxicity and synthesis of nanoparticles using the leaf and stem extracts of B. albostellata. Therefore, this study aimed at bridging these gaps by first characterizing the morphology, chemical composition and biological activity of leaves and stems of B. albostellata, using various microscopy techniques and biological assays. Floral biology of the plant was conducted using stereo- and scanning electron microscopic (SEM) techniques. ImageJ was used to measure the length and diameter of the different trichome types and pollen structures. Histo-phytochemical, thin-layer chromatography (TLC), fluorescence microscopy and gas-chromatography mass spectrometry (GC-MS) analysis were performed on crude extracts (hexane, chloroform and methanol) to determine the composition of the compounds that may be of medicinal importance. Biological (antibacterial and antioxidant) analyses were also conducted on the crude extracts. Cytotoxicity of the crude extracts were evaluated established using 3-[(4,5- dimethylthiazol- 2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay in the human embryonic kidney (HEK293), cervical cancer (HeLa), and breast adenocarcinoma (MCF-7) cell lines. Silver nanoparticles (AgNPs) were synthesized using methanolic, aqueous- powdered and -fresh leaf and stem extracts. These AgNPs were characterized using UV–visible spectroscopy, high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectral analysis and nanoparticle tracking analysis (NTA). Antibacterial analysis of the synthesized AgNPs was assessed using the disk diffusion method. Cytotoxicity of the synthesized nanoparticles were investigated using the MTT assay on the three cell lines. Histochemically stained sections, stereo, SEM and TEM micrographs revealed a dense indumentum with the presence of five morphologically distinct glandular capitate trichome types, multangulate-dendritic branched (MDB) non-glandular trichomes and a glandular head attached to a branched non-glandular trichome. Both glandular and non-glandular trichomes in the leaves and stems of B. albostellata are important diagnostic features of this species. The secretory head of glandular typed trichomes varied from 20.72 ± 1.36 µm to 54.23 ± 2.08 µm. Additionally, the length of these stalks varied from 15.11 ± 3.89 µm to 101.92 ± 1.78 µm, and the width ii from 11.62 ± 1.03 µm to 35.32 ± 3.87 µm. Multangulate-dendritic branched trichomes had a stalk length of 554.10 ± 92.27 µm and width of 28.55 ± 2.48 µm. Stained sections and crude extracts indicated the presence of important medicinal compounds such as alkaloids and phenolics. The histochemical tests indicated the presence of various phytocompounds that have medicinal importance and aid in defense against pathogens and herbivores. Pollen grains of B. albostellata are complex, intricate and display reticulate sculpturing, with a diameter of 77.53 ± 5.63 μm and aperture of 14.31 ± 0.59 µm. This will contribute significantly to our growing understanding on the floral and pollen biology of this species. Qualitative phytochemical screening, GC-MS and florescence microscopy of the leaf and stem extracts revealed various biologically active compounds and the presence of different colours in the leaf and stem powder. Different colour intensities obtained from TLC suggested concentrations of the separated compounds were varied. Additionally, the phyto-constituents found in the leaf and stem crude extracts of could inhibit the growth of various pathogenic strains. Results from this study revealed the medicinal potential of B. albostellata in the treatment of various bacterial diseases Ultraviolet spectra, NTA and EDX, revealed varying absorption peaks, size distribution, and elemental Ag in all extracts. Crude extracts and synthesized AgNPs displayed varying degrees of antioxidant, antibacterial and cytotoxic activities. Significance was established at P 63 µg/mL and >9 µg/mL, respectively) may be due to the presence of flavonoids, phenols, and antioxidant activity in the different parts of this species. Synthesized AgNPs showed possible bacteriostatic effects against Gram-positive and -negative human pathogenic bacteria. Their broad spectrum of bioactivity suggested that they may be as promising agents in fighting infections. This study ultimately proved that leaf and stem extracts of B. albostellata contained numerous biologically active compounds such as alkaloids and phenolics. These results are suggestive that the leaves and stems of B. albostellata are rich in bioactive compounds which, could be a possible source of antibacterial agents in treating several diseases .There is a great potential for B. albostellata as this plant displays valuable biological activities. Future studies on this plant are recommended, as this could advance the use of indigenous herbal medicine or product novel drug leads.
Morphology, phytochemistry, and medicinal properties of South African Mangifera indica L. leaves for summer and winter seasons.
(2021) Maharaj, Arvish.; Naidoo, Yougasphree.; Dewir, Yaser Hassan.
Herbal preparations of plants continue to present mankind with novel remedies as many of these plants contain important secondary metabolites. Plant species of the family Anacardiaceae are rich in bioactive phytochemicals. Mangifera indica (Anacardiaceae) is an introduced and naturalised species to South Africa. Herbal use of this plant has not been fully documented; however, it is used in traditional medicine. This study aimed at characterizing the morphology, phytochemistry, and biological activity of Mangifera indica leaves harvested in winter and summer. The foliar biology of the plant was conducted by various microscopy techniques such as stereo- and Scanning electron microscopy. The length and diameter of the different trichome types were measured using ImageJ. The non-glandular trichome lengths range between 70 - 200 μm. The peltate gland trichomes consist of 2 rows of 8 oblong cells each with a size ranging from 32- 48 μm. Morphological observations using stereo- and SEM revealed the presence of non-glandular trichomes with cuticular warts and glandular peltate trichomes on the leaves of Mangifera indica. Transmission electron micrographs showed the presence of numerous mitochondria, starch grains, plastoglobuli, and plastids. The results for summer and winter leaves resembled somewhat similar-to-identical morphological characteristics on all fronts. For the phytochemical and biological assays, this study aimed to investigate some of the phytochemical and biological properties using different solvents (hexane, chloroform, and methanol) for extraction of the leaves of Mangifera indica for the summer and winter seasons. Preliminary phytochemical screening for the hexane, chloroform and methanolic extracts was done using a reflux extraction apparatus to uncover the presence of different metabolites and the anti-oxidant screening was done by the radical scavenging activity, which was established using the 2,2-diphenyl-1-picrylhydrazyl assay. Potent radical scavenging activity was exhibited for both summer and winter seasons with hexane and methanolic extracts for summer (IC50 of 19.53 μg/mL and 12.71 μg/mL respectively) and winter (22.32 μg/mL and 14.35 μg/mL respectively) in comparison to the control ascorbic acid which produced an IC50 of 3.20 μg/mL. The summer extracts had better radical scavenging IC50 capacity than winter extracts. The antibacterial activity of the methanolic leaf extracts for summer and winter of Mangifera indica were evaluated against the bacterial species: Gram-negative Escherichia coli (ATCC 25922) and Gram-positive: Staphylococcus aureus (ATCC ATCC 43300). For S. aureus (ATTC 43300), the summer crude extract displayed lower antibacterial activity than the control streptomycin, the summer extracts had a zone of inhibition of 14.17 mm while streptomycin had a 16.67 mm zone of inhibition. winter extracts had a zone of inhibition of 12 mm while streptomycin had a 13.67 mm zone of inhibition. For E. coli (ATCC 25922), the summer crude extract displayed higher antibacterial activity than the control gentamycin; the summer extract had a zone of inhibition of 18.05 mm while gentamycin had a 17.5 mm zone of inhibition. The winter extracts had a zone of inhibition of 8.5 mm. while gentamycin had a 14.5 mm zone of inhibition. Between seasons, summer had better antibacterial activity compared to winter for both Gram-positive and Gram-negative bacteria. Phytochemical screening showed the presence of phenols, flavonoids, tannins, and terpenoids, alkaloids, phytosterols, saponins, steroids, and carbohydrates. Potent radical scavenging activity was exhibited for the hexane and methanolic extracts for summer and winter, indicating that Mangifera indica is a potential source of medicinally important compounds. Antibacterial screening showed positive results with antibacterial properties for both summer and winter samples revealing its valuable biological activities. Summer overall performed better than the winter season. Future studies on this plant species are recommended to advance the use of indigenous herbal medicine or produce novel drug leads. To our knowledge, this study represents the first recent investigation in South Africa describing key foliar micromorphological features, phytochemicals, and biological activities of Mangifera indica L.
Recombinant expression and enzymatic characterisation of Trypanosoma vivax cathepsin L-like protease (TviCATL) for single chain variable fragment antibody production.
(2022) Ramjeawon, Bhavana Roshenlal.; Coetzer, Theresa Helen Taillefer.
Humans and animals in sub-Saharan Africa are at risk of African trypanosomiasis (AT), caused by tsetse fly-transmitted protozoan blood parasites of the Trypanosoma genus. Animal African trypanosomiasis (AAT), or nagana, is caused by T. brucei, T. congolense and T. vivax and negatively impacts livestock farming and consequently the economy of the continent. Since AAT occurs in rural areas, affordable rapid diagnostic tests (RDTs) and drugs are required. Diagnostic tests focus on antibody detection; however, antigen detection is more favorable since anti-trypanosome antibodies persist in blood for years following recovery. Due to the parasite’s defense by antigenic variation, development of a vaccine is unlikely. Molecules that are essential for parasite survival, such as peptidases, are currently being targeted for diagnosis and chemotherapy. A cathepsin-L-like cysteine protease from T. vivax, TviCATL, is released by dying parasites in the host bloodstream and was shown to be a diagnostic target for detecting host antibodies. To achieve diagnosis of current infections, detection of TviCATL is being explored. The overall aim of this study was to enzymatically characterise TviCATL; and to study the interaction of antibodies against the TviCATL antigen which could be used as a chemotherapeutic drug for the diagnosis of T. vivax infections. The protease, TviCATL, was recombinantly expressed in E. coli using the pET-28a expression vector and purified using a nickel chelate affinity column. The resulting 47 kDa protein was identified using western blot and was shown to hydrolyse H-D-Ala-Leu-Lys-AMC and was inhibited by bestatin and E-64 and had optimal activity between pH 6.5 and 7.5. The crossreactivity between TviCATL and antibodies produced against other Trypanosoma spp cysteine proteases was evaluated in western blots, and results confirmed cross-reactivity. In addition, chicken anti-TviCATL antibodies were able to detect TviCATL in TviCATL-spiked bovine serum. The production of antibodies using the Nkuku® phage library was employed as an alternative to the animal-based antibody production and single-chain variable fragment (scFvs) antibodies were selected by panning against the TviCATL antigen. After four rounds of panning, TviCATL-scFvs binders were enriched and four clones gave the highest signal when evaluated using a monospecific ELISA. Due to the low values obtained, optimisation of panning is necessary for improved results. Optimisation of recombinant expression and purification of the identified scFvs for use in a sandwich ELISA were explored to this end. This study showed that TviCATL is a promising chemotherapeutic and diagnostic target for African animal trypanosomiasis.
Status of research on two parasitic zoonoses (Toxoplasmosis and toxocariasis) in Sub-Saharan Africa and their prevalence in selected rural communities of Kwazulu-Natal Province of South Africa using free-range chickens as a case study.
(2022) Omonijo, Adejumoke Oluwatosin.; Mukaratirwa, Samson.
Free-range chickens are among the popular livestock that are owned by most households in rural communities. They constitute a major source of food security, financial income, and are used in socio-cultural practices. However, due to their habit of scavenging for food they are exposed to parasitic agents thereby making them host for several disease pathogens such as Toxoplasma gondii and Toxocara spp. Toxoplasma gondii and Toxocara spp are the etiological agents of human toxoplasmosis and human toxocariasis respectively. Humans become directly infected via accidental ingestion of sporulated oocysts of T. gondii from felids and tachizoites/bradyzoites of T. gondii from raw/undercooked meat or embryonated eggs with second stage larva of Toxocara spp via contact with contaminated faeces of definitive hosts (dogs and cats), or indirectly via ingestion of contaminated water or consumption of raw or undercooked chickens. Following infection, the parasites migrate through the human body causing varying degree of diseases known as toxoplasmosis and toxocariosis respectively. Consumption of poultry meat viscera is an increasing dietary habit common in different communities worldwide and depending on socio-cultural preferences it can either be eaten raw, undercooked, or well cooked. However, the habit of eating raw/under cooked meat or viscera poses the risk of transmitting T. gondii and Toxocara spp from animals to humans. Limited information exist on the epidemiology of T. gondii and Toxocara spp in sub-Saharan Africa and let alone the role of free-range chickens in the transmission of these zoonotic parasites, hence, this study was designed to: ➢ review the status of research on these two parasitic zoonoses in sub-Saharan Africa. ➢ determine prevalence of the parasites in free-range chickens from selected rural communities in KwaZulu-Natal province through molecular approach. determine the level of awareness of the zoonotic transmission of these parasites when the viscera or meat of Free-range chicken are consumed raw or undercooked. A sytematic review and meta-analysis was conducted following the Preferred Reporting items for systematic Reviews and Meta-Analysis (PRISMA) guidelines on the epidemiology of T. gondii in animals and humans in southern Africa and epidemiology of Toxocara spp in canine, feline, and humans in sub-Saharan Africa respectively. The reviews showed that there is paucity of information on T. gondii and Toxocara spp in food animals including free-range chickens. Furthermore, to determine the prevalence of T. gondii and Toxocara spp in free-range chickens, free-range chickens were randomly purchased from selected rural communities namely, Gingindlovu (GI), Ozwathini (O), uMzinto (MZ), and Shonwgweni (SH) in KwaZulu-Natal (KZN). The chickens were euthanized according to ethical guidelines. The brain tissue of each chicken was divided into two equal halves. One half was examined for the presence of parasites while the remaining half was preserved in 70% alcohol for molecular analysis. To detect the presence of T. gondii, the preserved brain tissues were subjected to molecular analysis based on analysis of DNA sequences of the nuclear ribosomal internal transcribed spacer (ITS-1 and ITS-2) region using TOX4 and TOX5 primers. To detect the presence of Toxocara spp, various parts of chickens such as brain, heart, liver, spleen, kidney, duodenum, pectoral, thigh, and breast were digested using the acid/pepsin; 1:1 method and the larvae were recovered with 20-μm sieve. Three (3) larvae were recovered from the right pectoral from a chicken collected in GI; two (2) from the lungs of a chicken from MZ; three (3) each in the liver and left thigh of two separate chickens from SH. The recovered larvae were subjected to molecular analysis using Nem_18S primers. Toxoplasma gondii was not detected in the tissue samples which were subjected to molecular analysis, however, Toxocara canis was identified in Gingindlovu (n=1), uMzinto (n=1), and Shongweni (n=2). The identified T. canis showed 100% homology with Genbank isolates from China, the United Kingdom, and the United State of America. The occurrence of T. canis in free-range chickens from KZN province reveals the possibility of human toxocariasis transmission in the province. Moreover, we conducted a questionnaire survey to determine the knowledge and practices relating to consumption of free-range chicken viscera in selected rural communities of KwaZulu-Natal with respect to zoonotic transmission of T. gondii and Toxocara spp. There was low level of awareness of risk of zoonotic transmission of the parasites via ingestion of raw/undercooked free-range chicken meat/viscera and the majority of respondents consumed free-range chicken viscera. They preferred the viscera well cooked which reduces the risk of transmission of the the two parasites. The study contributes new knowledge on the prevalence of zoonotic parasites in free-range chickens as well as the level of knowledge and awareness on zoonosis transmission via consumption raw/undercooked free-range chicken viscera or meat.
The role of MMP-14 and MMP-2 in mediating myoblast fusion.
(2016) Nkosi, Mthokozisi Siphesihle.; Niesler, Carola Ulrike.
Satellite cells are muscle precursor cells that have the ability to self-renew, proliferate and differentiate into myoblasts that eventually elongate and fuse to form myotubes which are vital for regeneration and repair of muscle. Satellite cells reside in a niche, between the sarcolemma of the muscle fiber and the basal lamina, which consists of mostly collagen IV, proteoglycans and laminin. Matrigel is a gelatinous protein mixture that consists primarily of collagen IV and laminin and therefore resembles the basal lamina. Matrix Metalloproteinases (MMPs) are zinc endopeptidases, proteolytic peptidases which break peptide bonds within their substrates. MMP-14 (membrane bound) also known as membrane-type 1 matrix metalloproteinase (MT1-MMP) is one of the major matrix metalloproteinases (MMPs) involved in muscle repair and regeneration, together with MMP-2 (secreted). MMP-2 is a secreted gelatinase A, which is activated by MMP-14. MMP-2 is also known to be activated by nitric oxide (NO), therefore allowing active MMP-2 to release growth factors such as Hepatocyte Growth Factor (HGF) from the extracellular matrix (ECM). There are two forms of MMP-2, intracellular MMP-2 and extracellular (secreted) MMP-2. Secreted MMP-2 contains a peptide signal that helps direct it outside the cell, while intracellular MMP-2 lacks this feature and is therefore retained within the cell. Intracellular MMP-2 activity is known to be a major cause of muscular atrophy. Secreted MMP-2 is known to degrade ECM components, facilitating satellite cell mobility and release of growth factors such as HGF, aiding in muscle regeneration. MMP-2 can cleave collagen IV due to the presence of a fibronectin-like domain within its catalytic domain; this is not the case with MMP-14. MMP-14 and MMP-2 together degrade collagens, fibronectin, laminin-2/4 and other adhesion molecules. This clears the path for the myoblast to align and fuse to form myotubes which then finally align to form mature muscle fibers. The levels of MMP-14 and MMP-2 must be regulated; low levels can cause muscular dystrophy. The current study analysed expression levels, activity and role of MMP-14 and MMP-2 in C2C12 myoblast differentiation. C2C12 myoblasts first proliferated (Day 0), then aligned and elongated (Days 1-2) and then finally fused into myotubes (Days 3-5) during differentiation. MMP-14 and MMP-2 protein levels were high during the elongation period and also during fusion of C2C12 myoblasts. MMP-14 was localised at the focal adhesions, where actin filaments terminate during myoblast proliferation and fusion. ii Inhibition of MMPs using BB94 (10 µM) was observed to significantly reduce C2C12 myoblasts fusion. Secreted MMP-2 seems to play a vital role in the C2C12 differentiation, as activity was seen during myogenesis; when neutralised with an antibody, an 18% decrease in fusion was observed. Matrigel promoted an increase of MMP-2 expression within the cell during fusion (day 5 of differentiation), while no intracellular MMP-2 protein was observed at day 2 of differentiation. Levels of secreted MMP-2 increased significantly from day 2 to day 5 of differentiation; however, the presence of Matrigel significantly reduced levels of secreted MMP-2 detected in conditioned media at day 5 compared to uncoated conditions. The decrease is, in part, due to the fact that MMP-2 was found to bind to Matrigel. In conclusion, MMP-14 and MMP-2 play an important role in C2C12 myoblast elongation and fusion. This study provides further insight into the role of MMPs in myogenesis and lays the foundation for future work.
The secretory scales and medicinal properties of combretum erythrophyllum.
(2021) Bantho, Sahejna.; Naidoo, Yougasphree.; Yaser, Hassan Dewir.; Singh, Moganavelli.
Medicinal plants are known to contain phytometabolites that could effectively improve an individual’s state of health. Species of Combretum are highly valued in Africa due to the plethora of their traditional medicinal uses. Combretum erythrophyllum. Burch. Sond., commonly known as the river bushwillow, is known to contain medicinally important phytometabolites. Traditionally, the foliage is used to treat venereal diseases and abdominal pain, whilst the bark is used to alleviate sores, infertility, and labour pains. Although C. erythrophyllum has numerous traditional medicinal uses, there is limited scientific knowledge on the micromorphological structures and the associated exudate. Thus, this study aimed to characterize the micromorphological features of leaf and stembark secretory apparatus of C. erythrophyllum, using light and electron microscopy. Furthermore, a histo-phytochemical analysis was conducted to determine the presence and localization of phytometabolites within the trichomes and exudate. The antioxidant, antibacterial, apoptotic and cytotoxic potential of the leaf and stembark extracts were also evaluated. The micromorphological analysis identified the presence of peltate scales and non- glandular trichomes across surfaces. Peltate scales were comprised of a sunken basal cell, bicellular stalk, and a multicellular head. Head cell count appeared to increase upon leaf maturation. The granulocrine pathway was identified as a possible mode of secretion for C. erythrophyllum due to the extensive presence of vesicles, vacuoles, and electron dense material within the peltate scales. Preliminary histo-phytochemical analyses revealed the presence of carbohydrates, sterols, lipids, phenolic compounds, total proteins, alkaloids, and essential oils. Thin-layer chromatography allowed for the visualization of 36 compound classes while gas chromatography-mass spectrometry showed 266 compounds present. Fourier-transform infrared spectroscopy analysis confirmed the presence of phenols, alkenes, amines, alcohols, and esters among many. The antioxidant ability of the generated extracts were evaluated using the 2,2- diphenyl-1-picryl-hydrazyl-hydrate antioxidant assay and Ferric Reducing Antioxidant Power assay. A positive correlation between % inhibition and extract concentrations, was noted in both. In both instances, the methanol stembark extracts performed the best, (Leaf- 5,2866 and Stembark- 4,2866 µg/mL). Furthermore, the results obtained from the total flavonoid assay correlated with the trend observed through the total phenolic assay, whereby methanolic extracts yielded most promising results. Additionally, this study aimed to generate silver nanoparticles using crude extracts. A novel protocol for the synthesis of silver nanoparticles (AgNPs) using the leaf and stembark extracts of C. erythrophyllum was established. The generated AgNPs were characterized and evaluated for its potential antibacterial activity. Methanolic extracts inhibited the growth of Pseudomonas aeruginosa, Bacillus subtilis, Methicillin Resistant Staphylococcus aureus, and Staphylococcus aureus. Lastly, the generated crude extracts displayed promising results when evaluated for their cytotoxic and apoptotic abilities however upon nano- vii encapsulation the cytotoxic and apoptotic capabilities increased significantly. In correlation with the above, the AgNPs appeared to intensify the overall inhibition activity. Based on the findings of the study, Combretum erythrophyllum has a reservoir of unexplored allopathic potential which could revolutionize the medicinal world.

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