山苦瓜萃取物抑制黑色素生成及抗光老化效應的評估
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2011
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黑色素可保護皮膚免於紫外線傷害，但是過多的黑色素生成會造成黑色素沉澱形成色素斑塊。黑色素生合成主要受到酪胺酸酶(tyrosinase)調控。荷爾蒙、壓力和紫外線照射...等因素會促進黑色素生成。光老化(photoaging)為長期暴露在紫外線下造成皮膚提早老化的現象。紫外線誘導reactive oxygen species (ROS)的產生會提高皮膚中的氧化壓力、增加matrix metalloproteinases (MMP-1, collagenases)表現而降低皮膚中type I procollagen含量，亦促進cyclooxygenase (COX), PGE2和 nitric oxide (NO)等生成誘導發炎反應，導致皮膚乾燥形成皺紋。
苦瓜(bitter melon)或山苦瓜(wild bitter melon)的果實不僅當成蔬菜食用，也被認為具有抗菌、抗病毒、抗腫瘤、抗胃潰瘍、抗瘧、抗發炎及抗氧化等活性。在東南亞，苦瓜的葉子被用來煮汁治療皮膚病。
本研究以in vitro細胞模式評估台灣山苦瓜萃取物對於黑色素生成以及光老化的影響，再以in vivo人體試驗評估山苦瓜萃取物是否具有皮膚保健功效。
研究結果顯示，山苦瓜葉子甲醇萃取物具有良好清除自由基(DPPH, NO, superoxide, and hydroxyl radical)的能力。於in vitro細胞實驗模式中，山苦瓜葉子甲醇萃取物與果實乙酸乙酯萃取物可顯著抑制α-MSH刺激之B16-F10 melanoma細胞的黑色素生成與tyrosinase活性。另觀察UVB誘導人類角質細胞株(HaCaT)的ROS, MMP-1, and COX-2表現，山苦瓜果實萃取物(乙酸乙酯、乙醇、正己烷萃取物)、葉子(甲醇萃取物)或藤(甲醇萃取物)皆可以抑制UVB誘導HaCaT細胞的MMP-1與COX-2 mRNA表現。花蓮1號山苦瓜葉子甲醇萃取物與果實乙酸乙酯萃取物可以抑制UVB誘導HaCaT cells產生的ROS生成和MMP-1與COX-2 之mRNA與蛋白質表現。進一步探討其抑制作用機轉，發現UVB會顯著促進HaCaT cells ERK與JNK的磷酸化，而花蓮1號山苦瓜葉子甲醇萃取物與果實乙酸乙酯萃取物則能抑制此ERK磷酸化情形，故推測山苦瓜萃物經由抑制ROS生成、ERK的磷酸化而降低MMP-1表現。綜合細胞實驗結果，推測山苦瓜萃物應具有抑制黑色素生成與預防光老化的潛力。
另外招募29名受試者進行人體試驗，結果發現山苦瓜萃取物不會產生皮膚過敏或不適等症狀，具良好的外用安全性。而且塗抹含山苦瓜萃物乳霜於第8週、第12週均顯著改善斑點與細紋，與細胞實驗結果相符，故本研究已初步證實山苦瓜萃取物的皮膚保健功效。
Tyrosinase is a key enzyme in melanogenesis. Melanin is essential for protecting human skin against radiation, but the accumulation of abnormal melanin induces pigmentation disorders. UV radiation is responsible as a causative factor for various skin lesions including photoaging and photocarcinogenesis. Photoaging is characterized by severe wrinkling and pigmentary changes. In addition, UV induced MMP-1and then caused collagen breakdown and induced inflammatory responses. Bitter melon (Momordica charantia) extracts exerted hypoglycemic, anti-diabetic, antiviral, antitumor, antiulcer, anti-leukemic, antibacterial, anti-mutagenic, anti-inflammatory, and antioxidant properties. In Asia, the infusion of stems and leaves of bitter melon has been proposed as an agent for skin care. In this study, we investigated the anti-melanogenic and anti-photoaging properties of wild bitter melons (WBM; Momordica charantia Linn. var. abbreviata Ser.). Results showed that methanolic (MeOH) extracts of WBM leaves showed significant DPPH free radical, superoxide, nitric oxide and hydroxyl radical scavenging activity. Ethyl acetate (EA) and ethanolic (EtOH) extracts of fruits, MeOH extracts of leaves and viny juice of WBM significantly inhibited mushroom tyrosinase activity. EA fruit extracts and MeOH leaf extracts of WBM significantly suppressed tyrosinase activity and decreased melanin levels in α-MSH-stimulated B16-F10 melanocytes. EA fruit extract and MeOH leaf extract of WBM, Hualien-1 (HL-1), significantly reduced UVB-induced intracellular ROS production and inhibited mRNA and protein levels of COX-2 and MMP-1. Besides, both extract significantly inhibited UVB-enhanced phosphorylation of ERK and JNK. Our findings suggested that both HL-1 extracts inhibited UVB-induced MMP-1 expression, which may be through reduced ROS production and ERK phosphorylation. Twenty-nine subjects were enrolled in a randomized, double-blind, placebo-controlled, split-face comparative study. HL-1 extracts was found to be topical safe and well tolerated. A gradual and time-related improvement in pigmentary abnormality and wrinkle was shown under the treatment with HL-1 extracts. HL-1 extracts significantly reduced spot and wrinkle after 8-wk and 12-wk treatment. Our study herein demonstrated the skin care potential of wild bitter melon.
Tyrosinase is a key enzyme in melanogenesis. Melanin is essential for protecting human skin against radiation, but the accumulation of abnormal melanin induces pigmentation disorders. UV radiation is responsible as a causative factor for various skin lesions including photoaging and photocarcinogenesis. Photoaging is characterized by severe wrinkling and pigmentary changes. In addition, UV induced MMP-1and then caused collagen breakdown and induced inflammatory responses. Bitter melon (Momordica charantia) extracts exerted hypoglycemic, anti-diabetic, antiviral, antitumor, antiulcer, anti-leukemic, antibacterial, anti-mutagenic, anti-inflammatory, and antioxidant properties. In Asia, the infusion of stems and leaves of bitter melon has been proposed as an agent for skin care. In this study, we investigated the anti-melanogenic and anti-photoaging properties of wild bitter melons (WBM; Momordica charantia Linn. var. abbreviata Ser.). Results showed that methanolic (MeOH) extracts of WBM leaves showed significant DPPH free radical, superoxide, nitric oxide and hydroxyl radical scavenging activity. Ethyl acetate (EA) and ethanolic (EtOH) extracts of fruits, MeOH extracts of leaves and viny juice of WBM significantly inhibited mushroom tyrosinase activity. EA fruit extracts and MeOH leaf extracts of WBM significantly suppressed tyrosinase activity and decreased melanin levels in α-MSH-stimulated B16-F10 melanocytes. EA fruit extract and MeOH leaf extract of WBM, Hualien-1 (HL-1), significantly reduced UVB-induced intracellular ROS production and inhibited mRNA and protein levels of COX-2 and MMP-1. Besides, both extract significantly inhibited UVB-enhanced phosphorylation of ERK and JNK. Our findings suggested that both HL-1 extracts inhibited UVB-induced MMP-1 expression, which may be through reduced ROS production and ERK phosphorylation. Twenty-nine subjects were enrolled in a randomized, double-blind, placebo-controlled, split-face comparative study. HL-1 extracts was found to be topical safe and well tolerated. A gradual and time-related improvement in pigmentary abnormality and wrinkle was shown under the treatment with HL-1 extracts. HL-1 extracts significantly reduced spot and wrinkle after 8-wk and 12-wk treatment. Our study herein demonstrated the skin care potential of wild bitter melon.
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Keywords
山苦瓜, 紫外線, MMP-1, 黑色素生成, wild bitter melon, UV irradiation, MMP expression, melanogensis