Synthesis and biological activities of natural homoisoflavanones.
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Date
2011
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Abstract
Plants have formed the foundation of traditional medicine systems throughout the world for
thousands of years and continue to provide mankind with new remedies for various ailments.
A large portion of the black South African population still depends on medicinal plants as
primary health care due to its affordability, accessibility and cultural importance. These
medicinal plants need to be investigated since new lead compounds are often found in nature.
Homoisoflavanones isolated from South African and Indian plants were found to exhibit anti inflammatory activities although the mechanism of action has not yet been determined. A
few reports on the anti fungal activities of these compounds were also found.
Four new and three known homoisoflavanones of the 3-benzylidene-4-chromanone type were
synthesized and tested for anti-inflammatory and antifungal activities. Two novel
intermediates were also synthesised. Enantiomers of a homoisoflavanone of the 3-benzyl-4-
chromanone types were also synthesized from the corresponding 3,5-dimethoxy phenol via 4-
chromanone in six steps. This is the first report of the synthesis of an enantiomerically pure
homoisoflavanone compound together with its opposite isomer. The enantiomers and
racemate were tested for anti-inflammatory activity. All the synthesized homoisoflavanones
were screened for cytotoxicity. The structures of these homoisoflavanones were elucidated
by NMR spectroscopy along with HRMS data. The crystal structure of a homoisoflavanone
with anti-inflammatory and antifungal activity is reported.
The anti-inflammatory activity of the homoisoflavanones was determined in an acute croton
oil-induced auricular dermatitis mouse model. The antifungal activity was performed in vitro
against a Candida albicans strain. Compounds were tested for cytotoxicity against a Chinese
Hamster Ovarian (CHO) cell line using the 3-(4,5-dimethylthiazol-2-yl)-3,5-
diphenyltetrazoliumbromide (MTT) assay.
In conclusion, the synthetic homoisoflavanones showed anti-inflammatory as well as
antifungal activity. Some of the compounds showed anti-inflammatory activity comparable
to that of the commercially available diclofenac.
Description
Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.
Keywords
Hyacinthaceae., Medicinal plants--Analysis., Pharmaceutical chemistry., Theses--Pharmacy and pharmacology.