Supaluk PrachayasittikulPatumporn ManamManeekarn ChinworrungseeChartchalerm Isarankura-Na-AyudhyaSomsak RuchirawatVirapong Prachayasittikul2012-07-242017-06-202012-07-242017-06-202009Molecules. Vol.14, No.11 (2009), 4414-44241420-3049https://repository.li.mahidol.ac.th/handle/20.500.14594/2108This study investigated bioactive extracts of Polyalthia debilis (Annonaceae) with antimicrobial, antimalarial and cytotoxic activities. Extensive chromatographic isolations provided azafluorenone alkaloids; onychine (1) and 7-methoxyonychine (2) together with a mixture of β–sitosterol and stigmasterol. The two alkaloids were isolated from the P. debilis for the first time. Isolated fractions containing a mixture of triterpenoids (C7, C8 and C9) exhibited the most potent antimicrobial activity against many bacterial strains with minimum inhibitory concentration of 64 μg/mL. Fractions with antimalarial and cytotoxic activities were also observed. The findings suggest the potential use of P. debilis in medicinal applications.engMahidol UniversityPolyalthia debilisazafluorenoneonychineantimicrobialantimalarial and cytotoxic activitiesOpen Access articleArticle