Studies on the antibacterial chemical constituents of Senecio cannabifolius Less。(I)

Objective To study the antibacterial constituents of Senecio cannabifolius Less.Methods All the extractants were tested with Staphylococcus aureus,Bacillus subtilis (gram-positive bacilli) and Escherichia coli (gram-negative bacillus),which guided directively the isolation of the antibacterial constituents in vitro.Chemical constituents were isolated by chromatography.Physico-chemical characters and spectroscopic analyses were employed for the structural identification.Results The ethyl acetate fraction partitioned with water from the water extract and the ethanol precipitate of S.cannabifolius Less.showed the significant bacteriostatic activity.Nine compounds were isolated,and the structures were elucidated by chemical and spectroscopic methods as follows:p-hydroxy benzeneacetic acid (E-1),1,4-benzenediol (E-2),methyl p-hydroxy benzeneacetate (E-3),3,4-dihydroxy benzoic acid (E-4),2,5-dihydroxy benzeneacetic acid (E-5),2,5-dihydroxy benzeneacetic acid methyl ester (E-6),3-hydroxy-4-methoxy benzoic acid (E-7),p-hydroxy benzoic acid (E-8),and o-hydroxy benzoic acid (E-9).The extract of S.cannabifolius Less.exhibited potent antibacterial activity against S.aureus and B.subtilis.Among these compounds,E-3～E-9 were isolated from S.cannabifolius Less.for the first time.