Bioassay-guided isolation and structure elucidation of some metabolites from Pipturus arborescens

Chloroform (93PA1C) and ethyl acetate (93PA1E) were obtained from the graded extraction of the crude ethanolic extract of P. arborescens (93PA1). Exhaustive cold percolation of the second batch of P. arborescens sample afforded a second ethanolic extract (RPA). The three extracts showed low to moderate cytotoxic activity in Brine Shrimp Assay (BSA). Both the chloroform and the ethanolic extracts were active against B. subtilis and S. aureus. The ethyl acetate extract was active against B. subtilis only.Separation of the crude ethanol extract by gravity column chromatography afforded five (5) pure fractions out of eleven (11). These fractions showed activity against E. coli, S. aureus, B. subtilis, K. pneumoniae, A. niger and C. albicans.Fractionation of the chloroform crude extract (93PA1C) gave pure isolates: RPACCEt1A, RPACCEt4B, RPACCEt2. Most fractions of the chloroform extract and the ethanolic extract showed weak to moderate toxicity in the brine shrimp bioassay. Recrystallization of some active fractions of crude ethanolic extract gave pure isolates: RPA11D, RPA11MP, RPA11MS, RPA10M2 and RPA10MS. Rechromatography of fraction 93PA1E6 obtained from the crude EtOAc extract (93PA1E) afforded a pure isolate (93PA1E6/6). The pure isolate 93PA1E6/6 was found active against B. subtilis (ZI=8.0 mm). A structure for isolate 93PA1E6/6 is proposed from the analysis of its nmr, IR, MS and UV data. No compound with this structure has been reported