薄荷精油之成分分析及其抑制皮膚發炎之功效

Abstract

薄荷屬植物(Mentha sp.)為唇形科之芳香植物，被認為具有抗病毒、抗菌、緩解水腫、止痛及抗氧化之功能。此研究的目的，主要為分析十種薄荷精油之化學組成份及探討其抗發炎之能力。十種薄荷精油之化學組成份是以二維氣相層析飛行式質譜儀(2D GCGCTOF MS, two-dimensional gas chromatography coupled with time-of-flight mass spectrometry)進行偵測。薄荷精油之體外抗發炎效果是以脂多糖(LPS, lipopolysaccharide) 誘導小鼠巨噬細胞產生過量一氧化氮之發炎反應模式進行測試。而體內活性則利用巴豆油(TPA, 12-O-tetradecanoylphorbol- 13-acetate)誘導ICR小鼠皮膚產生發炎反應以及1-氟-2,4-二硝基苯(DNFB, 1-fluoro-2,4-dinitrobenzene)之動物模型進行。利用統計學方法principle component analysis (PCA)分析不同薄荷品種之化學組成分，發現依精油成分之分佈與含量差異性，可將十種薄荷品種主要區分為三大組。第一組含豐富之carvone和limonene骨架化合物，分別為奧地利薄荷、中國薄荷、綠薄荷、萊姆薄荷及墾丁薄荷。第二組含menthofuran骨架化合物和menthyl acetate主成分，為瑞士薄荷、金沙薄荷及甜薄荷。第三組主要含有linalyl acetate 與 linalool，為柳橙薄荷及葡萄柚薄荷。比較十種薄荷中，奧地利薄荷及中國薄荷具明顯的抑制脂多糖誘導巨噬細胞產生一氧化氮(IC50為50.17 g/mL及55.20 g/mL)，且不具細胞毒性。在利用巴豆油，TPA誘導ICR小鼠產生發炎實驗中發現，中國薄荷及甜薄荷精油以及其分別之主要成分carvone和isomenthol之預處理的小鼠皮膚上給予處理，具有與同劑量之celecoxib (1 mg/site) 相似之抑制皮膚發炎的效果，其中包括抑制TPA引起皮膚之COX-2及iNOS過度表達。利用1-氟-2,4-二硝基苯誘導接觸性皮膚炎動物模式發現中國薄荷、甜薄荷、及其主要成份carvone和isomenthol可以有效地減少小鼠耳朵之腫脹程度。此外，1-氟-2,4-二硝基苯誘導COX-2 及iNOS之過度表現也可經由中國薄荷、甜薄荷、carvone和isomenthol的處理而降低。進一步利用比較性氧化脂質代謝物 (comparative oxylipin metabolites) 分析小鼠皮膚之氧化脂質代謝物，發現被TPA顯著誘導表現之促發炎oxylipin分子，包括9-HODE, 9-oxo-ODE和9(10)-EpOME等可有效被中國薄荷精油及其主要成分carvone抑制。總而言之，此研究證明中國薄荷，甜薄荷，carvone和isomenthol可經由抑制參與或促進發炎反應之因子達到顯著預防皮膚發炎之效果。

Mentha sp. (Mints) plants from family Lamiaceae has been reported for antiviral, antibacterial, anti-edema, antioxidant activities, etc. The objective of this study was to analyse the chemical compositions and to investigate the anti-inflammation activities of the essential oils extracted from ten Mentha sp. plant species. The chemical profiles of the essential oils were analyzed using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (2D GCGCTOF MS) system. The activities of the ten mint-derived essential oils against inflammation induced by lipopolysaccharide (LPS) in RAW 264.7 cells, 12--tetradecanoylphorbol-13-acetate (TPA)-induced cutaneous inflammation and, 1-fluoro-2,4-dinitrobenzene (DNFB)-induced allergic contract dermatitis in ICR mice were studied. Principal component analysis (PCA) was used to analyze chemical components from ten Mentha sp. essential oils, with the ten Mentha sp. clustering into three distinct groups. Group 1 plants include Mentha × gracilis ‘Austria’, M. arvensis, M. spicata, M. aquatica ‘Lime Mint’ and M. aquatica which are abundant in carvone and limonene analogues. Group 2 plants include Mentha × piperita ‘Variegated Mint’, Mentha × piperita 'swiss’ and M. spicata ‘Julia’s Sweet Citrus’, mainly containing menthofuran analogues and menthyl acetate. Group 3 plants include M. piperita and M. aquatica var. citrata, mainly containing linalyl acetate and linalool. Two among the ten tested mint essential oils from Mentha × gracilis ‘Austria’ and M. arvensis exhibited the most significant activity in inhibiting nitric oxide production in LPS stimulated macrophages without showing cell toxicity with IC50 values 50.17 g/mL and 55.20 g/mL. TPA-induced skin inflammation in mice was also significantly attenuated by topical pre-administration of M. arvensis, M. spicata ‘Julia’s Sweet Citrus’ essential oils and major component carvone and isomenthol with comparable effect to that of celecoxib at 1 mg/site. TPA-induced COX-2 and iNOS accumulation in mouse skin were significantly suppressed by M. arvensis, M. spicata ‘Julia’s Sweet Citrus’, carvone and isomenthol. In DNFB-induced allergic contact dermatitis model, M. arvensis, M. spicata ‘Julia’s Sweet Citrus’, carvone and isomenthol can significantly reduce ears swelling cause by DNFB. Furthermore, DNFB-induced COX-2 and iNOS overexpression were suppressed by post-treatment of M. arvensis, M. spicata ‘Julia’s Sweet Citrus’, carvone and isomenthol. Comparative oxylipin metabolite analysis showed that TPA-irritated skins were observed with the increase of varied proinflammatory oxylipin metabolites, including 9-HODE, 9-oxo-ODE and 9(10)-EpOME which could be inhibited by M. arvensis, M. spicata ‘Julia’s Sweet Citrus’ essential oil and their major component carvone and isomenthol treatment. This study suggests that M. arvensis, M. spicata ‘Julia’s Sweet Citrus’, carvone and isomenthol protect skin inflammation through de-regulating the expression of iNOS, COX-2, and the levels of inflammatory mediators and selected oxylipins.