| Summary: | 碩士 === 中國文化大學 === 化學系應用化學碩士班 === 101 === 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.
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