The compounds and biological activity of Thamnosma africana
The aerial parts and fruits of Thamnosma africana were investigated for chemical compounds present in them. The volatile oil of T. africana was prepared by hydrodistillation of leaves, flowers and stems, and characterized by GC-MS. The oil was tested for antimicrobial activity on cultures of E. coli, B. subtilis and S.aureus, and found to inhibit Bacillus subtilis and Staphylococcus aureus at 0.1% dilution. The oil was also active against Plasmodium falciparum in micromolar concentrations. Chromatographic separation of the ethyl acetate extract of the aerial parts yielded two isomers of methoxypsoralen (xanthotoxin and bergapten) and 6-(1c,2c-dihydroxy-3c-methyl-3c-butenyl)-7-methoxychromen-2-one (thamnosmonin). The epoxide of thamnosmonin, 6-(1c,2c-epoxy-3c-methylbut-3c-en-1c-yl)-7-methoxychromen-2-one (thamnosmin), and methyl p-isopentenyloxycinnamate were isolated from the hexane extract of the fruits, while another furanocoumarin, 4,9-dimethoxy-7H-furo[3,2-g]benzopyran-7-one (isopimpinellin) was isolated from a dichloromethane extract of the aerial parts.