Antibacterial and antioxidant activity of naphthofuranquinones from the twigs of tropical mangrove .

Mangrove plants are endowed with various biologically active compounds which have potent antibacterial and antioxidant properties. In present study, a bioactivity-guided fractionation for antibacterial and antioxidant active metabolites from the twigs of collected from Kuala Selangor Nature Park, Selangor, Malaysia gave 13 major fractions. The antibacterial activity of fractions using well-diffusion showed strong selectivity on the Gram-positive bacteria (, and ) with minimum inhibition concentration (MIC) values of 0.156-5.00 mg/mL. However, no antibacterial activities were observed on the Gram-negative bacteria (, and ). The active antibacterial fractions were further isolated using several chromatographic techniques to give two naphthofuranquinones, namely, avicenol C () and stenocarpoquinone B (). Meanwhile, the antioxidant activity of fractions were evaluated using DPPH radical scavenging assay exhibited low antioxidant activities. Molecular structure of the naphthofuranquinones was elucidated using 1 D and 2 D NMR spectroscopy.