抗菌加工繊維製品中のヒノキチオールの分析法と光分解による抗菌効果の増強

抄録

Since an antimicrobial ingradient of hiba oil (Japanese cypress oil), hinokitiol, has a wide antimicrobial spectrum, it has long been added to toothpaste and hair cosmetics. Hinokitiolis approved as a food additive for preservation. Currently, hinokitiol is chemically synthesized. Recently, addition of hinokitiol and hinoki oil, as a safe natural antimicrobial agent, to antimicrobial-processed textiles has rapidly increased. However, patients with allergic disorders caused by hinokitiol and its teratogenicity have been reported, indicating that the safety of hinokitiol has not been sufficiently established. First, we developed an analytical method for measuring the concentration of hinokitiol used in commercially available antimicrobial products. There had been no reproducible methods. for analysis of hinokitiol due to its characteristics, such as photodegradability, sublimation ability, and high metal complex formation ability. We established a method for the detection of hinokitiol at a level of μg/ml by HPLC using a photodiode array detector. We also established a method for the extraction of hinokitiol with methanol from fabric samples prepared by treating with hiba oil, and a purification method using sodium dihydrogen phosphate buffer/cyclohexane partition and a C₁₈ cartridge column. We examined commercially available textiles with which processing with hiba oil or hinokitiol was indicated by the analytic method, but did not detect hinokitiol in any sample.

To clarify the causes, we produced standard fabric samples by fixing microcapsules filled with synthesized hinokitiol, hinoki oil, or hinoki leaf oil, performed the JIS light fastness test of the fabric samples, and examined the amount of residual hinokitiol at intervals by HPLC. As a result, the major cause of the disappearance of hinokitiol was photolysis. We also examined the antimicrobial activity of hinokitiol by the new agar plate method using gram-positive bacteria Staphylococcus aureus and gram-negative bacteria Klebsiella pneumoniae, and found that the hinokitiol treated fabric samples after photoirradiation showed higher antimicrobial activity, suggesting that degradation products of hinokitiol by photoirradiation had higher antimicrobial activity. It will be necessary to evaluate the safety of degradation products of hinokitiol by photoirradiation.