A novel prenylfuroquinoline alkaloid capensenin (1), an alkaloid confusameline (2), two furanocoumarins psolaren (3) and bergapten (4), were isolated from hexane and dichloromethane crude extracts of stem bark, leaves and fruit pericarp of Calodendrum capense. Limonin (5) was also isolated from the stem bark, while limonin diosphenol (6) was isolated from the seeds. Capensenin (1) showed weak antimicrobial activity against Bacillus subtilis, while the leaves, stem bark and fruit pericarp crude extracts exhibited activity against Staphylococcus aureus, B. subtilis and P. citrinum. Hexane pericarp extract showed slight cytotoxicity to Vero cell E199 in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The structures of the compounds were elucidated by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and infra-red spectroscopy.
Keywords: Capensenin, 4-hydroxyfuroquinoline, furanocoumarin, Calodendrum capense, alkaloid, Rutaceae.