| 摘要: | Ugonin T (1a)是由錫蘭七指蕨分離出來的天然物，錫蘭七指蕨為傳統中藥作為消炎解熱劑，ugonin T結構為flavone，並帶有一個furan環取代，具有很強的抗發炎活性，由於天然物分離的量很少，且這個天然物到目前為止並未有合成之報導，為了進一步探討其結構與活性間之關係，在本論文中，建立了一個有效的合成方法來合成ugonin T 及類似物，並探討這些化合物的抗氧化活性。
從apigenin為起始物開始經5個合成步驟，成功的合成了類似物7-(3,4-dihydroxyphenyl)-4-hydroxy-2,3,3-trimethyl-2H-furo[3,2-g]chromen-5(3H)-one及6-(1,1-Dimethylallyl)-4’,5,7-trihydroxyflavone，從luteolin為起始物開始依照相同的合成策略，ugonin T將會合成出來；另外，類似物2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-
dihydro-4H-furo[2,3-h]chromen-4-one、2-(4-hydroxyphenyl)-5-meth-
oxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one、2-(3,4-di-
hydroxyphenyl)-5-hydroxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one及5-hydroxy-2-(4-hydroxyphenyl)-8,9,9-trimethyl-8,9-
dihydro-4H-furo[2,3-h]chromen-4-one，也分別經由數個合成步驟順利的合成出來。
這些合成的化合物使用DPPH方法檢測其抗氧化活性，結果顯示2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one與2-(3,4-dihydroxyphenyl)-5-hydroxy-8,9,9-
trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one具有很好的清除自由基的活性，活性程度與luteolin及-tocopherol相當，2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one、2-(3,4-dihydroxyphenyl)-5-hydroxy-8,9,9-
trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one、luteolin 的活性又分別大於2-(4-hydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-dihydro
-4H-furo[2,3-h]chromen-4-one、5-hydroxy-2-(4-hydroxyphenyl)-8,9,9
-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one、 apigenin，此結果顯示苯環上dihydroxyl group對抗氧化活性是重要的因素，2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one及2-(3,4-dihydroxyphenyl)-5-hydroxy-8,9,9-
trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one的EC50 值分別為21.8及16.8 g/mL。
Ugonin T (1a) was isolated and characterized as a new flavonoid from the rhizomes of Helminthostachys zeylanic. The rhizomes of H. zeylanica is a Chinese herbal medicine used as an antipyretic and antiphlogistic agent. Ugonin T possesses a flavone skeleton in which a furan ring is connected to phenolic moiety. Ugonin T was found to show strong anti-inflammatory activity. Until now, the total synthesis of ugonin T has not been reported yet. In order to obtain more quantity of material for further study of the biological activities, the synthesis of ugonin T and analogues were investigated.
In this thesis, an efficient method to synthesize ugonin T and analogues was described. Analogues 7-(3,4-dihydroxyphenyl)-4-hydroxy-
2,3,3-trimethyl-2H-furo[3,2-g]chromen-5(3H)-one and 6-(1,1-Dimethyl-
allyl)-4’,5,7-trihydroxyflavone were successfully synthesized from apigenin in five steps. Ugonin T will be prepared from luteolin. In addition, analogues (2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-
8,9-dihydro-4H-furo[2,3-h]chromen-4-one, 2-(4-hydroxyphenyl)-5-meth-
oxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one, 2-(3,4-
dihydroxyphenyl)-5-hydroxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one, and 5-hydroxy-2-(4-hydroxyphenyl)-8,9,9-trimethyl-8,9-
dihydro-4H-furo[2,3-h]chromen-4-one) were also prepared.
The antioxidative activity of synthesized compounds using DPPH method was evaluated. 2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trime-
thyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one and 2-(3,4-dihydroxy-
phenyl)-5-hydroxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one showed similar DPPH radical scavenging activity as those of luteolin and -tocopherol (a positive control). The activities of 2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one, 2-(3,4-dihydroxyphenyl)-5-hydroxy-8,9,9-trimet-
hyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one, and luteolin were greater than those of 2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-di-
hydro-4H-furo[2,3-h]chromen-4-one, 2-(3,4-dihydroxyphenyl)-5-hydroxy
-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one, and apigenin, respectively. These indicated that the dihydroxyl group of B ring in 2-(3,4-dihydroxyphenyl)-5-methoxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one, 2-(3,4-dihydroxyphenyl)-5-hydroxy-8,9,9-trimeth-
yl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one, and luteolin is important for the antioxidative activity. The EC50 values of 2-(3,4-dihydroxyphenyl
)-5-methoxy-8,9,9-trimethyl-8,9-dihydro-4H-furo[2,3-h]chromen-4-one and 2-(3,4-dihydroxyphenyl)-5-hydroxy-8,9,9-trimethyl-8,9-dihydro-4H-
furo[2,3-h]chromen-4-one were 21.8and 16.8g/mL, respectively. |
