The growth‐inhibitory activity of Galla Rhois‐derived materials towards 17 intestinal bacteria was evaluated using an impregnated paper disc method. The biologically active components of Galla Rhois were characterized as the tannins methyl gallate (MG) and gallic acid (GA) by spectral analysis. The growth responses varied with bacterial strain tested. In the test using 10 mg disc−1, MG and GA produced a clear inhibitory effect on harmful bacteria such as Clostridium perfringens, Cl. paraputrificum, Eubacterium limosum, Bacteroides fragilis, Staphylococcus aureus and Escherichia coli. Methyl gallate showed no growth‐inhibitory activity towards Bifidobacterium adolescentis or B. longum whereas the growth of B. bifidum, B. breve, B. infantis, B. animalis, B. thermophilum, Lactobacillus acidophilus, Lact. plantarum and Streptococcus faecalis was slightly affected. However, GA did not adversely affect the growth of the bifidobacteria and lactobacilli. At 5 mg disc−1, MG significantly inhibited the growth of Cl. perfringens and Cl. paraputrificum but did not affect the growth of the bifidobacteria and lactobacilli. At 1 mg disc−1, MG greatly inhibited the growth of Cl. perfringens alone. These results may be an indication of at least one of the pharmacological actions of Galla Rhois.
Growth responses of a variety of human intestinal bacteria to methanol extracts of green tea (Thea sinensrs L.) were investigated in vitro. Thc extracts moderately enhanced growth of some bifidobacteria strains in tests on carbon sourcecontaining media but not carbon source-free media, suggesting that bifidus factor(s) might be involved. It did not stimulate growth of clostridia, bacteroides, eubacteria or Escherichia coli. However, the extract was found to be selectively inhibitory against the growth of some clostridia including C. dificile, C. paraputrificum and C. perfringens; this effect was not observed with bifidobacteria. eubacteria or E. coli.
Highly resistant strains of the brown planthopper were obtained after 30 generations of laboratory selection by carbofuran or fenobucarb. Topical LD 50 for fenobucarb increased 93-101-times and topical LD 50 for carbofuran increased 51-68-times on selection by either carbofuran or fenobucarb, while the LD 50 for diazinon increased only 6-7-times by the same selections. Sensitivity of AChE to carbofuran or fenobucarb was reduced remarkably in vitro in the resistant strains while sensitivity to diazoxon changed only slightly. Insensitive AChE was considered to be the major resistance mechanism of the carbamate-resistant strains of the brown planthopper.
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