Antimicrobial Cotton Cloth Utilizing Chemicals of Plant Origin ―Antibacterial Action of the Cotton Cloth Fixed with Tannic Acid―

In our previous paper, aminoethylated cotton cloth fixed with tannic acid was reported to have a high antibacterial activity against E. coli W3110 and S. aureus IFO13276. ln this paper, the results of the experiments carried out to investigate the mechanisms of the antibacterial action of the tannic acid－modified cotton cloth are described. Antibacterial activities of model compounds having different numbers of phenolic hydroxyl group were evaluated against E. coli W3110 and S. aureus IFO13276. lt was found that the value of minimum inhibitory concentration （MIC） of the model compound decreased with an increase in the number of phenolic hydroxyl group in a molecule. lt was also found that the model compound having a calboxyl group had a greater MIC than the corresponding model compound having no calboxyl group did. Thus, the antibacterial activities of phenolic compounds were ascribed to their phenolic hydroxyl groups. Aminoethylated cotton cloths fixed with model compounds having,different numbers of phenolic hydroxyl group and a calboxyl group showed antibacterial activities. ln this case, too, the activity increased with an increase in the number of hydroxyl group in the model compound fixed. As no distinct halo was observed in the culture－tests of the both bacteria the phenolic compounds were considered to have antibacterial activities in the state of being fixed on the cotton cloth.E．coliおよびS．aureusに対するフェノール化合物のMICを測定した結果，フェノール化合物一分子あたりのフェノール性水酸基数が多いほど，抗菌活性が大きかった．また，フェノール化繊物分子中に力ルボキシル基が存在する場合，そのフェノール化合物の抗菌活性は，フェノール性水酸基のみの場合より低くかった．すなわち，タンニン酸などのフェノール化合物の抗菌活性は，フェノール性水酸基によって発現し，その数が多いほど抗菌活性は大きいと書える．フェノール化合物を綿布に固定した場合にも，フェノール化合物は抗菌活性を有し，MIC測定の場合に見られたフェノール性水産基数が多いほど抗菌活性が大きいという関係は，布に固定した場合にも保たれていた．これらのフェノール化合物の抗菌活性は，綿布に固定された状態で発現していると推測された．すなわち本研究において，抗菌剤としてフェノール化合物を固窪した抗菌性綿布は，従来の抗菌剤徐雛型の抗菌性繊維にない新しいタイプの抗菌性繊維と言え，中でもタンニン酸を固定した綿布は，優れた抗菌性繊維であると言える