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標題: Contents of coumarins in methanol and water extracts of Angelica dahurica and the effects on tyrosinase activity
作者: 陳兆祥
Hsiang, Chen Chao
關鍵字: Angelica dahurica;白芷;tyrosinase;coumarin;酪胺酸酶;香豆精
出版社: 食品科學系
繖形科植物白芷(Angelica dahurica),是一種普遍使用之中藥材,具祛風解表之功用,應用於鼻塞、頭痛等症;在近代藥學研究上,白芷亦具有抗發炎、促進血管擴張或收縮、間接影響脂肪代謝、促進皮膚黑色素增加與表皮增厚、抑制酪胺酸酶(美白)與抑制微生物生長等作用,其藥理活性成分,可能為白芷中所富含之香豆精類化合物。
自白芷之甲醇萃取物再以水煎煮所得到的抽取物中,分離得到四種香豆精化合物,分別為xanthotoxol(1)、oxypeucedanin hydrate(2)、byak-angelicin(3)及5-methoxy-8-hydroxypsoralen(4)。
當白芷以甲醇及水分別煎煮萃取時,可以得到An-M及An-H兩種萃取物。An-M中化合物1~4之含量分別為0.06、0.39、0.14及0.01mg/g,而An-H中則為0.37、0.34、0.11及0.14 mg/g。然而將An-M再以水煎煮後得到An-M-H,則發現化合物1~4的含量均提高,分別達1.00、0.56、0.21及0.38mg/g,尤以1及4的增加最為明顯,含量較An-M提高了16.7及38.0倍之多,顯示甲醇煎劑中之化合物組成,在高溫水煎煮下,確實發生了變化。
探討煎煮溫度對白芷香豆精含量的影響,結果顯示在50 ~ 90℃之間,化合物2及3之含量並無太大變化,而化合物1及4的含量則會隨著溫度的升高而漸次提升。在100℃的水煎液中,四種香豆精的含量較其他組別有明顯的提高。
探討加熱時間對白芷香豆精成分之影響,顯示在80℃定溫煎煮下,0.5 ~ 4.0小時之間,化合物2及3之含量並無太大變化,而化合物1及4的含量則會隨著加熱時間的延長而漸次提升。

Studies of herbal extracts have identified many chemical constituents that have important pharmaceutical uses. Angelica dahurica (Umbelliferae) is a commonly used Chinese medicine, which contains many coumarin compounds that are said to possess pharmaceutical activities such as prevention and even cure of common colds and headaches. Recent studies have also suggest that the coumarins of Angelica dahurica can improve vessel contraction, affect lipid metabolism, increase skin health, and enhance skin whitening by inhibiting tyrosinase activity. Because the form of crude herbal medicine that people use is mostly hot-water extracts, it is conceivable that many components of the plant extract may change during hot water extraction.
Angelica dahurica was extracted using methanol (An-M), water (An-H), or methanol first and then water (An-M-H). Four furanocoumarins were isolated from the these extracts. They were identified as xanthotoxol (1), oxypeucedanin hydrate (2), byak-angelicin (3) and 5-methoxy-8-hydroxy psoralen (4), respectively. Different contents of the four furanocoumarins 1~4 were found in these extracts. Compounds 1~4 were 0.06, 0.39, 0.14 and 0.01mg/g in An-M, respectively, and were 0.37, 0.34, 0.11 and 0.14mg/g in An-H, respectively. In An-M-H, the contents of compounds 1~4 were increased to 1.00, 0.56, 0.21 and 0.38mg/g, respectively. The contents of compounds 1 and 4 in An-M-H were 16.7 and 38.0-fold of those in An-M.
When An-H was extracted with ethyl acetate, n-butanol or chloroform, the contents of compounds 1~4 were the same. The contents of compounds 2 and 3 in the water extract of A. dahurica did not change with extraction temperature from 50 to 90℃, but the contents of compounds 1 and 4 were gradually increased with increasing temperature. In the boiling water extract of A. dahurica, the contents of compounds 1 to 4 were higher than those obtained at lower temperatures.
During the constant extraction at 80℃ for 0.5 to 4.0 hours, compounds 2 and 3 in water extract also did not change while compounds 1 and 4 were gradually increased with longer extraction time.
The result of tyrosinase assay showed that compounds 2 and 3 did not affect tyrosinase activity, while compounds 1 and 4 slightly increased the enzyme activity.
Overall, this study demonstrates the chemical changes in the methanol extract of A. dahurica during the hot water extraction process following methanol extraction.
Keyword:Angelica dahurica (Umbelliferae)、tyrosinase、coumarin
Appears in Collections:食品暨應用生物科技學系

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