Phytochemical and elemental analysis of nettles found in KwaZulu-Natal, South Africa.

Abstract

There is a rich diversity of indigenous edible plants in South Africa. Rural communities have for years, been collecting indigenous edible medicinal plants for food and for their medicinal properties. However, a combination of a shortage of food and lack of diversity in the diet has resulted in many South Africans suffering from malnutrition. Malnutrition, food insecurity and nutrient deficiencies which help propogate non-communicable diseases are amongst the top concerns in South Africa. Knowledge on the elemental composition, nutritional and medicinal value of medicinal plants would allow for safe consumption of these plants and improve overall health. The aim of this study was to investigate the secondary metabolites in the Laportea and Obetia nettles found in KwaZulu-Natal (South Africa) and to conduct an elemental investigation into the nutritional composition of these nettles to determine their suitability for consumption and their contribution to recommended dietary allowances. The study showed that cooked and raw leaves of nettles (L. peduncularis, L. alatipes, and O. tenax) were rich sources of macronutrients and essential elements which are comparable to common vegetables. The nettles, L. alatipes and O.tenax, have higher macronutrient content than elemental content relative to the nettles, L.peduncularis and U. dioica, after cooking. Soil quality indicators (geo-accumulation indices and enrichment factors) showed moderate to no contamination of nettle growth soils around KwaZulu-Natal. Statistical analysis showed the association of these metals in the different sites. Phytochemical analysis of the nettles showed that the nettles were rich in β-carotene and sterols owing to their use as natural anti-diabetic agents. This study provides information on the nutritional value of nettles and shows that they can serve as an affordable alternative to commercially available herbs and it also lends scientific credence to the ethno-medicinal use of nettles.