• Applied Biological Chemistry
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• v.50 no.4
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• pp.334-343
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• 2007

The water extracts and 80% ethanol extracts from mulberry leaves of 108 kinds were tested their antimicrobial activities against Helicobacter pylori and antioxidant effects. The ABTS [2,2'-azino-bis(3-ethylbenzothiaznoline-6-sulfornic acid)] radical decolorization, electron donating ability (EDA), thiobarbituric acid reactive substance (TBARS) and antioxidant protection factor (PF) were determined for water extracts and 80% ethanol extracts from mulberry leaves. In the electron donating activity, the 13 kinds of water extracts showed high inhibition (>80%), whereas the 59 kinds of 80% ethanol extracts showed high inhibition. The inhibitory activities of water extracts from all kinds of mulberry leaves were higher than 90% in ABTS [2,2'-azinobis(3-ethylbenzothiaznoline-6-sulfornic acid)] radical decolorization. The thiobarbituric acid reactive substance (TBARS) and antioxidant protection factor (PF) of the 80% ethanol extracts were higher than that of water extracts. Antimicrobial activity against Helicobacter pylori showed high value in 80% ethanol extracts of 15 kinds mulberry leaves. The results implied that the mulberry leaves can be useful for natural antimicrobial medicine.

• Archives of Pharmacal Research
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• v.21 no.1
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• pp.6-11
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• 1998

The activities of two types of antiulcer agents against 9 strains of Helicobacter pylori (H. pylori) were determined by the agar dilution method. The antiulcer agents were YJA20379, a newly synthesized proton pump inhibitor developed by Yung-jin Pharmaceutical company, and omeprazole. Both compounds were found to have significant activities against this organism. The MIC values of YJA20379 and omeprazole were 11.7 and $31.25{\mu.g/ml}$ respectively. In addition, the inhibitory potency of both compounds was investigated on H. pylori urease which is believed to be an important colonization and virulence factor in the pathogenesis of gastritis and peptic ulcers. These compounds dose-dependently inhibited urease extracted with distilled water and their $IC_50$ values were $16.4{\times}10^{-5} M and 14.3{\times}10^{-5}M,$ respectively. In addition, a pH-dependent study to determine whether inhibitory potency would be activated by acid condition was performed. It was found that unlike omeprazole, YJA20379 was not affected by acid condition. To determine the inhibition pattern and optimal concentration of substrate, kinetics were evaluated at various pH levels (pH 5.0, 7.0, and 8.5). The data show that YJA20379 noncompetitively inhibited H. pylori urease and $K_M/K_i$values were 0.96 $mM/60{\mu}M (pH 5.0), 0.56 mM/141.5 {\mu}M (pH 7.0)$, and $1.94mM/34{\mu}M (pH 8.5)$, respectively. Based on data obtained, it is concluded that YJA20379 is a significant inhibitor of H. pylori growth and urease and therefore, taking these results into consideration, YJA20379 might be a beneficial therapy for gastritis and peptic ulcers induced by H. pylori.