Phytochemical analysis and antioxidant activity of wild and ex situ cultivated Harpagophytum procumbens 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 iridiods harpagosides comparable with those found in the wild plants. The total phenolic contents in wild plants were comparable to the ex situ cultivated plants. The free radical scavenging activities also correlated well with the total phenolic contents of both wild and ex situ cultivated plants. 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.

Keywords: Harpagophytum procumbens; Phenolic compounds; free radical scavenging activity; wild shoots and tubers; ex situ cultivation