Abstract

• The heartwood of Mansonia gagei. locally known as Kala-met, was studied for its antioxidant, antimicrobial, and cytotoxic properties, which are used in treating heart disease and diabetes. The DPPH free radical scavenging assay revealed that the ethanol extract (IC50 63.88 ?g/mL) exhibited higher antioxidant potency than the watery extract (IC50 157.75 ?g/mL). However, they were found to have weaker antioxidant potency than standard ascorbic acid (IC50 3.33 ?g/mL). The antimicrobial activity of the four crude extracts, such as watery, ethanol, ethyl acetate, and pet-ether extracts, was screened by the Agar well diffusion method using eight pathogenic strains: Agrobacterium tumefaciens, Bacillus pumilus, Bacillus subtilis, Candida albicans, Escherichia coli, Micrococcus luteus, Pseudomonas fluorescens, and Staphylococcus aureus. All tested crude extracts exhibited medium to high antimicrobial activity, with inhibition zone diameters ranging between 14 and 26 mm on all strains. In addition, the cytotoxicity of ethanol and watery extracts was conducted using a brine shrimp lethality bioassay, indicating that both watery and ethanol extracts showed cytotoxic activity on brine shrimp with LC50 values < 1000 µg/mL, a medium toxic effect.