皮屑芽孢菌(Pityrosporum ovale, P. ovale)主要存在於人體皮脂腺，當皮脂分泌過度旺盛時，皮屑芽孢菌會迅速增加，造成角質細胞增生或不斷剝落。而形成頭皮屑目前的治療，可以用抗生素來抑制皮屑芽孢菌生長，但其容易導致細菌抗藥性與發炎等相關問題。
本實驗的目的就在於評估12種精油應用於抗頭皮屑相關產品之可行性，第一部分為抑制皮屑芽孢菌測試，以培養液稀釋法(Broth dilution method)測試其最小抑制濃度(MIC)，最佳抑制效果為茴香菖蒲(Acorus macrospadiceus) (0.0550 %)、次之檸檬香茅(Cymbopogon citrates) (0.0850 %)，其餘MIC顯示皆在0.1~0.2 %之間。
第二部份為植物精油抗發炎測試，以酵素免疫連結吸附法(Enzyme Linked Immunosorbent Assay, ELISA)評估THP-1分泌細胞激素IL-8的量，其實驗結果顯示義大利馬郁蘭 (Origanum x majoricum)、甜羅勒(Ocimum basilicum)、甜萬壽菊(Tagetes lucida)和茴藿香(Agastache foeniculum)可抑制由LPS (Lipoplysaccharide)誘導產生IL-8的分泌量。培養3天或5天的皮屑芽孢菌菌液，誘導產生IL-8的分泌量，可得知茴藿香無論是發炎前期或後期，都有抑制效果。
第三部份為成品抑制皮屑芽孢菌試驗，12種精油中有10種精油樣品在72小時的時候抑制率達95.0% 以上，其中以檸檬香茅洗髮精或頭皮水，能夠100.0 %抑制皮屑芽孢菌生長。綜合以上幾點述論，精油是值得我們發展，創造新的抑制皮屑芽孢菌之洗髮精，同時也賦予精油新生命。 Dandruff is mainly due to speedy skin turnover which results in epidermal cells hyper proliferation and flaking off. When excessively sebum secrets, the number of Pityrosporum ovale, P. ovale, which resides in sebaceous glands, increases a lot. Dandruff can be controlled by antibiotics at present, but it may easily result in antibiotic drug resistance and skin inflammation.
The objective of this study is to investigate the feasibility of essential oils added in anti-dandruff products. In the first part of this study, the antimicrobial activity of P. ovale was determined by broth dilution method in terms of MIC (minimum inhibitory concentration). Acorus macrospadiceus demonstrated the best antimicrobial activity in the concentration of 0.055%, then was Cymbopogon citrates in 0.085%, and the remainders were between 0.1% and 0.2%.
The second part of this study was to verify the anti-inflammation ability of essential oils. Protein concentration of IL-8 in the supernatant of THP-1 cells was detected by ELISA. After LPS stimulating, Origanum x majoricum, Ocimum basilicum, Tagetes lucida and Agastache foeniculum had the ability to inhibit IL-8 secretion. Besides, after stimulated by 3 and 5 days’ P. ovale cultured supernatants, Agastache foeniculum also inhibited IL-8 secretion. This result demonstrated that Agastache foeniculum can inhibit inflammation in not only early but also late inflammatory stages.
Finally, the anti-P. ovale activity of products using essential oils were evaluated. Ten out of 12 essential oils showed inhibition ability higher than 95% after 72 hours inhibition period. The shampoo and scalp tonic containing Cymbopogon citrates had the inhibition ability of 100%.
In conclusion, essential oils had large potentials to be anti-dandruff shampoo additives.
