Immunomodulating effects of Biophytum petersianum, a Malian medicinal plant

Biophytum petersianum is an herb with a wide distribution in tropical countries. Field studies carried out in Mali show extensive use against cerebral malaria in children. It is used against pain and as a wound healing agent, as well. The aim of this study was to investigate the immunomodulating effects of extracts and flavonoids isolated from B. petersianum.

Aerial parts of B. petersianum were extracted with dichloromethane followed by methanol. The methanol extract was further partitioned between ethyl acetate, butanol and water. The ethyl acetate extract was fractionated by flash chromatography and preparative HPLC, and chemical structures of isolated compounds were elucidated by NMR spectroscopy. The effect on NO secretion from macrophages and complement fixing activity were used to evaluate the immunomodulating activities.

Three flavonoids were isolated from the ethyl acetate extract; cassiaoccidentalin A, isoorientin and isovitexin. The crude methanolic extract was a good inhibitor of NO secretion and it showed strong effect in the complement fixation test. The immunomodulating effects were potentiated in the ethyl acetate extract, thus indicating that the bioactive compounds are medium lipophilic. However, the flavonoids isolated in this study were either inactive or they showed only moderate effects in the bioassays. It appears that so far unidentified bioactive substances are present in the ethyl acetate extract and that further research is needed to identify immunomodulators in B. petersianum.