BACKGROUND: Cancer is one of the major health problems worldwide and medicinal plants constitute a common alternative for cancer treatment having no or fewer side effects. This study aimed to assess total phenolic (TPC) and flavonoid (TFC) contents, antioxidant, biological activities (especially antibacterial, antifungal, and anticancer), and chemical composition of methanol extract of M. napaulensis DC. bark (MNBM). This is the first study evaluating its anticancer activity and chemical composition by LC-MS/MS analysis. METHODS: TPC, TFC, antioxidant, antimicrobial, and anticancer activities were determined by Folin-Ciocalteu, AlCl RESULTS: The preliminary phytochemical screening revealed the presence of various phytochemicals viz. alkaloids, steroids, glycosides, polyphenols, tannins, flavonoids, coumarins, terpenoids, and quinone. MNBM showed 38.00 ± 1.50 mg GAE g