RESUMO
To study the chemical constituents from the stems of Picrasma quassioides. The constituents were isolated and purified by silica gel, Sephadex LH-20, ODS column chromatographies, and preparative HPLC. Their structures were determined on the basis of their physicochemical properties and spectral data. The cytotoxic and antibacterial activities were assessed by MTT and MIC, respectively. Three β-carboline alkaloids were obtained from the 95% ethanol extract of the stems of P. quassioides and identified as picrasidine F (1), picrasidine G (2), and picrasidine S (3). Compound 1 showed selective cytotoxicity to HeLa cell, while compounds 2 and 3 showed the potent cytotoxicity against human HeLa cervical, gastric MKN-28, and mouse melanoma B-16 cancer cells. Compounds 1-3 showed the potent antibacterial activity against two strains of pathogenic bacteria methicillin-resistant Staphylococcus aureus (MRSA) and two strains of pathogenic bacteria methicillin-sensitive Staphylococcus aureus (MSSA). The assignments of NMR data of compound 1 are reported in this paper for the first time. Compounds 1-3 show the potent cytotoxic and antibacterial activities.