|摘要: ||本研究利用十二種中藥以微波方法所得之萃取液來評估下列幾種抗氧化機制：(1)黑色素生合成的抗氧化作用，藉由抑制酪胺酸酶的活性使得酪胺酸無法氧化成黑色素；(2)一氧化氮的清除作用，藉由Griess reaction偵測Sodium nitroprusside(SNP)所生成的一氧化氮濃度降低；(3)自由基的清除能力，藉由1, 1-diphenyl-2-picryl hydrazyl (DPPH)自由基接受氫原子而產生吸光值下降；(4)抑制過氧亞硝酸(ONOOH)之生成，藉由超微弱化學冷光儀偵測SNP結合H2O2而使即時產生之自由基數目減少。首先，在經由不同萃取方法的評估後，顯示甘草利用微波萃取經過酪胺酸酶抑制作用與一氧化氮清除效果的分析，發現在720W、6分鐘的萃取條件下分別有90.73%及82.39%的最佳活性。在理想的萃取模式下，微波萃取桑枝、甘草、桑白皮不論在抑制酪胺酸酶(SC50分別為0.3, 0.9及3.11mg/ml)、一氧化氮生成之清除(SC50分別0.238,0.249及0.236mg/ml)都具有較高的作用活性﹔而在DPPH自由基清除與抑制過氧亞硝酸生成方面則以刺五加(SC50分別為0.755mg/ml,0.713mg/ml)與銀杏(SC50分別為0.583mg/ml,0.756mg/ml)較佳。在純化物方面，分為甘草酸衍生物、類黃酮、抗氧化劑、酪胺酸酶抑制劑等四類用來當成評估活性作用的參考指標。結果顯示，在100μM濃度下Kojic acid 抑制酪胺酸酶(63.14%)，Hydroquinone 清除一氧化氮(40.17%)，Catechin清除DPPH自由基(97.99%)以及Quercetin抑制過氧亞硝酸的生成作用(52.25%)呈現了顯著的活性功能。因此，本論文得到的結論是，中藥利用微波萃取具有不錯的抗氧化、抑制酪胺酸酶生物活性；至於相關機制仍有待進一步探討。|
Microwave aqueous extracts (MAE) from twelve Chinese herbs and fifteen commercial pure compounds were evaluated for their (1) melanin biosynthesis anti-oxidative activities by tyrosinase inhibition, (2) nitric oxide (NO) scavenging activities by SNP, (3) radical scavenging effects by the DPPH and (4) peroxynitrite scavenging activities by the SNP / H2O2 / luminal chemiluminescence’s methods. The results of our investigation show that glycyrrhizae radix for the preliminary assay optimal tyrosinase inhibition (90.73%) and NO scavenging effects (82.39%) of microwave Chinese herbs extracts can be concluded that the duration of microwave radiation is 6 min, the microwave energy is 720w. Our studies also show three Chinese herbs by MAE (Ramulus mori, Glycyrrhizae radix and Cortex mori) exhibited high anti-tyrosinase (SC50=0.3,0.9 and 3.11mg/ml, respectively) and NO scavenging effect (SC50=0.238, 0.249 and 0.236mg/ml, respectively). On the other hands, Acanthopanax senticosus (SC50=0.755, 0.713mg/ml, respectively) and Ginkgo biloba (SC50=0.583, 0.756mg/ml, respectively) scavenged DPPH free radical and peroxynitrite production, most effectively. Commercial pure compounds (such as licorice-derived, flavonoids, antioxidants and tyrosinase inhibitors compounds) were referenced index for their anti-tyrosinase, free radical scavenging and antioxidant properties. The results indicated that under 100μM concentration, Kojic acid against tyrosinase (63.14%), Hydroquinone scavenged NO (40.17%), Catechin scavenged DPPH free radical (97.99%), and Quercetin decreased peroxynitrite production (52.25%) present more effect for bioactivities. Collectively, these data suggest that Chinese herbs by MAE maybe extract some effect such as anti-oxidative and anti-tyrosinase. Consequently, some detail bioactive mechanisms and MAE in order to isolate and identify photochemical compounds, involved in some biological activities will be studied.