槐花フラボノイドの相互作用によるPropionibacteriumに対する抗菌活性

抄録

Since proliferation of Propionibacterium is thought to play a significant role in inflammation of acne vulgaris, the antibacterial activities of several crude drugs to this bacteria were examined by agar diffusion method using paper disc, and it was found that the ethanol extract of flower buds of Sophora japonica L. shows a remarkable antibacterial activity against Propionibacterium acnes, P. avidum, Staphylococcus aureus under weak acidic conditions. After purification of active component (s) of the extract, the activity was found to be attributed to the result of the interaction caused by such three components as quercetin (I), rutin (II) and isorhamnetin-3-rutinoside (III). When I, II and III were applied singly, only I shows very weak activity, but others do not show at all. By mixing I and II, or I and III, 50% or 70% activity of the ethanol extract appeared, respectively. Moreover, after mixing the three flavonoids, the full activity of the extract was recovered. A small amount of kaempferol-3-rutinoside was also obtained from this extract. This compound was found to have a similar effect to that III has, though weaker than the latter. The examination of this interaction by use of liquid culture system, showed that the antibacterial activity of the system increased with an increase in the solubility of I caused by II. That is to say, the true principle of the activity is I, and by the addition of II to it, the solubility of I increased to increase apparent activity. A similar increase in activity by the addition of III is thought to be based on the same mechanism as II.