Phytochemical and antioxidant analysis of wild and ex situ cultivated shoots and tubers of Harpagophytum procumbens (Burch)DC ex. Meisn from Botswana

Comparative phytochemical analysis [TLC method] and antioxidant activity of wild and ex situ cultivated shoots and tubers of Harpagophytum procumbens were done. Total phenolic content [Folin-Ciocalteu method] and free radical scavenging activity [1,1-diphenyl-2-picryl-hydrazyl assay] of both chloroform and methanol extracts were determined. Analysis of ex situ cultivated plant material showed presence of phytochemicals comparable with those found in the wild plants. The total phenolic contents (mg GAE/L) of methanolic tuber extracts from wild plants (3366±22.68) were comparable to the methanolic tuber extracts (3297.00±54.56) from ex situ cultivated plants. The total phenolic contents of methanolic leaf extracts from wild (2562±158.77) plants were also not significantly different from the ex situ (2686.00±10.49) cultivated H. procumbens. Similar trends were observed in the chloroform extracts of both wild and ex situ cultivated H. procumbens. The free radical scavenging activities also correlated well with the total phenolic contents of both wild and ex situ cultivated plants. At all tested concentrations, the methanolic extracts of both wild and ex situ cultivated plants were ≥80%. The scavenging potencies of chloroform extracts were consistently lower than the methanol extracts in both ex situ cultivated plants and wild species. The consistency in presence of phenolic compounds in these plant materials is of interest from both the pharmacological and conservation point of view given the role played by these compounds in oxidative stress. These results indicate that ex situ cultivation can be both a conservation strategy and can provide an alternative and sustainable source of therapeutically active compounds.