清熱型中草藥萃取液之抗氧化、抗發炎、美白與紫外線防護效能分析

Abstract

在過去的文獻中指出，紫外線輻射會誘導活性氧物質（Reactive oxygen species，ROS）的生成。當ROS在皮膚中大量累積時，會穿透皮膚組織中角質形成細胞的細胞膜，與去氧核醣核酸（Deoxyribonucleic acid，DNA）相關的過渡金屬反應，進一步地造成DNA損傷，因此，對於人體肌膚會造成相當大的傷害。此外，皮膚發炎反應和色素沉澱也與細胞氧化壓力過高有關，因此對於具有美白及防曬需求的情況下，經常使用抗氧化劑作為ROS的清除劑。作為清熱藥之中草藥—蒲公英、金銀花、連翹與臺灣佛甲草以其卓越的抗氧化能力聞名，因此在本研究中，我們推測清熱型中草藥萃取物具有抗發炎、美白與抵禦紫外線輻射的能力。首先，利用不同溫度和百分比的水與乙醇對四種清熱型中草藥進行萃取，並以ABTS·+和DPPH·自由基清除能力試驗鑑定了清熱型中草藥萃取物的抗氧化能力。結果顯示，50%乙醇萃取物的抗氧化效果明顯較其他萃取方式優異。在J774A.1小鼠單核巨噬細胞中，蒲公英和連翹之50%乙醇萃取液能夠清除由脂多醣（Lipopolysaccharide，LPS）所誘導的一氧化氮生成量，進而減緩發炎反應。而乙醇萃取物更是在中波紫外線（Ultraviolet radiation B，UVB）波段中展現了良好的紫外線阻絕能力。此外，我們也發現了蒲公英之乙醇萃取物在B16F10小鼠黑色素瘤細胞中具有抑制黑色素含量與酪胺酸酶（Tyrosinase，TYR）活性的能力，有效地減少了黑色素生成量。綜合上述結果，清熱型中草藥之萃取物具有作為天然且有效之美白、舒緩肌膚與防曬試劑的潛力，期望於未來被開發為藥妝產品。

Ultraviolet (UV) radiation induces the production of reactive oxygen species (ROS), which are harmful to human skin. ROS excessively accumulated in the skin was found to penetrate the cell membrane of keratinocytes, react with DNA-related transition metals, and cause DNA damage. Moreover, ROS also increases the level of cellular oxidative stress, leading to skin inflammation and hyperpigmentation, hence the antioxidants can be used to scavenge ROS to lessen inflammation and reduce melanin content. In traditional Chinese medicine, heat-clearing Chinese herbal products are well-known for their superior antioxidant activities. It is thus reasonable to infer that extracts of heat-clearing Chinese herbal products may have the ability to resist UV radiation. We herein extracted four types of heat-clearing Chinese herbs - dandelion, Japanese honeysuckle, weeping Forsythia and alfred stonecrop using water and ethanol at different temperatures and percentages. The 50% ethanolic extracts of Chinese herbs showed higher antioxidant activities as determined by the ABTS·+ and DPPH· assays than other extracts. In murine macrophages J774A.1, 50% ethanolic extracts of dandelion and weeping Forsythia effectively cleared the nitric oxide content induced by lipopolysaccharide (LPS) to reach the anti-inflammatory ability. The ethanolic extracts of heat-clearing Chinese herbs also exhibited significant UV-blocking ability in the UVB region. Furthermore, we observed that the ethanolic extracts of heat-clearing Chinese herbs reduced tyrosinase activity to block the synthetic pathway of melanin. In summary, extracts of heat-clearing Chinese herbs investigated in the current study may hold promise to be used as effective natural cosmetic ingredients with skin-soothing, skin-whitening and sun-protective functions.