Purification of verbascoside from plant extracts using column and countercurrent chromatography
Verbascoside, a phenylethanoid glycoside, displays diverse biological activities. The antifungal activities of polar extracts of Lippia species against Penicillium digitatum, a common pathogen of citrus, was attributed to the presence of verbascoside1. Partial purification of such plant extracts to increase the verbascoside content could provide natural mycobiocides for postharvest control of pathogens on fruit. Verbascoside was extracted from dried Lippia wilmsii H.Pearson plant material using aqueous methanol. The extracts were purified using silica gel column chromatography and the verbascoside concentrations were compared to that obtained by countercurrent chromatography (CCC). The crude extract contained 4.8g/L verbascoside, corresponding to 12.5% of the extract. After column chromatography, the verbascoside content of the purified extract was substantially increased, but was lower than that obtained by CCC (40.8%). High performance liquid chromatography was used for the analyses of the target compound.
The widespread invader weed Lantana camara L., was investigated as an alternative source of the compound. Five specimens of L. camara from 13 populations in South Africa were analysed by HPLC. Both intra- and interpopulation variability was observed in the verbascoside content. Combinations of flowers and leaves from L. camara could serve as a good source of verbascoside. Several stability tests were conducted to evaluate the stability of the compound under different conditions. The shelf life stability study proved that the compound is stable in a dry form when stored in the dark, but decomposes rapidly when exposed to light. Verbascoside also proved to be reasonably stable under steam distillation conditions
References: 1 Shikanga et al. (2009) Fruits 64:3–12.