Anti-bacterial and anti-oxidant activity of Hypoxis hemerocallidea (Hypoxidaceae): Can leaves be substituted for corms as a conservation strategy?

Hypoxis hemerocallidea Fisch. & C.A. Mey (Hypoxidaceae) is an important plant species in traditional medicine in southern Africa. The use of the corms of hypoxis, commonly known as "African potato" is so popular that the species is threatened by over-harvesting. This study was aimed at comparing the chemical composition and biological (anti-bacterial and anti-oxidant) activities of fresh and dried aerial, and dried underground parts of hypoxis with the view of promoting the use of the former, as a conservation strategy. Leaves (fresh and dried) and dried corms were milled and extracted with acetone and then ethanol and analysed by TLC with two different solvent systems. The extracts were also then tested against four species of nosocomial bacteria in a micro-dilution assay and also for DPPH anti-oxidant activity. There were clear differences in the chemistry and biological activity of leaves versus corms of hypoxis. Ethanol extracts of fresh leaves showed overall best activity in the anti-bacterial assay with MIC<0.63 mg/ml. Components in the acetone extracts of both leaves and corms showed good anti-oxidant activity. Substituting leaves for corms in the medicinal use of hypoxis is not recommended because of the lack of phytochemical and bioactive similarities. (C) 2008 SAAB. Published by Elsevier B.V. All rights reserved.