Growth inhibition of Escherichia coli, Staphylococcus aureus and Bacillus subtilis by wild grasses extracts [Japanese]

摘要

The methanol extracts from 27 species of wild grasses were assessed for their inhibitory effects on the growth of Escherichia coli IFO 3301, Staphylococcus aureus IFO 12732 and Bacillus subtilis IFO 13722 with the smear culture method on agar plate. About half of the extracts, including such edible plants as Reynoutmia japonica, Gnaphalium affine and so on, completely repressed the growth of one or more kind of the microbes at the concentration of 1% (w/v). The minimum inhibitory concentration values of those extracts were further determined with the twofold dilution methods. As a result, both extracts from fresh and dried sample of Euphorbia maculata, called 'Oonishikisou' in Japanese, had particularly high antibacterial activities against all test microbes. Furthermore, the acid and phenolic fractions prepared from the methanol extract of E. maculata were found to have higher antibacterial activities than the basic and neutral fractions. The inhibitory effects of those fractions on the growth of S. aureus in particular were 4 times as strong as that of the original methanol extract and comparable with gallic acid.