Flavonoid and triterpenes from the leaves of Senecio gossypinus Baker from Madagascar

Senecio gossypinus Bakeris an endemic species encountered in the northern, southern, western and central parts of Madagascar. Phytochemical screening of the EtOH extract from the leaves revealed the presence of flavonoids, sterols and polysaccharides. Fractionation of the hexane and EtOAc extracts led to the isolation of the mixture of a-amyrin (1) and b-amyrin (2), and kaempferol-3-O-α-L-arabinopyranoside (3), respectively. Compound 3 exhibited potent antimicrobial activity in vitro against Pseudomonas aeruginosa, Proteus mirabilis, Streptococcus agalactiea, Staphylococcus aureus, Candida albicans with inhibition zones of 13mm, 19mm, 15mm, 12mm and 9mm, respectively, at a test dose of 10 µg/disk using the disk diffusion method. Moreover, compound 3 showed moderate antioxidant activity against the free radical DDPH with an IC50 value of 1.90mg/mL. These results gave support to the traditional uses of the studied plant for the treatment of colic, bronchitis and wounds.