The polyphenolic composition and antioxidant activity of the aerial parts of 18 medicinal or food plants of the As- teraceae family were studied. Five main caffeoyl derivatives were determined individually by HPLC and...The polyphenolic composition and antioxidant activity of the aerial parts of 18 medicinal or food plants of the As- teraceae family were studied. Five main caffeoyl derivatives were determined individually by HPLC and compared with levels determined by colorimetry for total dihydroxycinnamic derivatives and total phenolics. The aim of this study was to assess the contribution of these constituents to the antioxidant activity of the herbs determined by DPPH radical scavenging tests. Significant correlations were found between total phenolic (R2 = 0.8904), total dihydroxycinnamic derivative (R2 = 0.8529) and total caffeoyl derivative (R2 = 0.7172) concentrations and the DPPH-scavenging ability of all herbs. The antioxidant activity of the main constituents, including chicoric acid (EC50 = 8.24 μmol/l) or 3,5- dicaffeoylquinic acid (EC50 = 7.62 μmol/l), was very high compared to vitamin C (EC50 = 15.66 μmol/l). Thus, for each species, antioxidant activity mainly involves the major caffeoyl derivatives. The contribution to antioxidant activity were assessed as 48.92% for 3,5-dicaffeoylquinic acid in Tanacetum parthenium (30.08 g/kg), and 68.96% for chicoric acid in Taraxacum officinale (34.08 g/kg). The main caffeoyl derivatives among polyphenols can be considered as the major antioxidant compounds of the studied Asteraceae herbs.展开更多
Two new triterpene esters, 2-O-caffeoylalphitolic acid (1) and methyl 2-O-caffeoyl- alphitolate (2), together with two known triterpenes were isolated from the shrub Daphniphyllum oldhami. The structures of new compou...Two new triterpene esters, 2-O-caffeoylalphitolic acid (1) and methyl 2-O-caffeoyl- alphitolate (2), together with two known triterpenes were isolated from the shrub Daphniphyllum oldhami. The structures of new compounds were elucidated on the basis of detailed spectroscopic analysis and compared with related compound.展开更多
Five caffeoyl conjugates were isolated from the ethyl acetate soluble fraction of Erigeron breviscapus (Van.) Hand_Mazz for the first time. Along with them, nine other chemical constituents were also identified. O...Five caffeoyl conjugates were isolated from the ethyl acetate soluble fraction of Erigeron breviscapus (Van.) Hand_Mazz for the first time. Along with them, nine other chemical constituents were also identified. One new caffeoyl conjugate, erigoster A (1) with a novel basic skeleton was mainly assigned by the using a combination of two_dimensional NMR techniques.展开更多
文摘The polyphenolic composition and antioxidant activity of the aerial parts of 18 medicinal or food plants of the As- teraceae family were studied. Five main caffeoyl derivatives were determined individually by HPLC and compared with levels determined by colorimetry for total dihydroxycinnamic derivatives and total phenolics. The aim of this study was to assess the contribution of these constituents to the antioxidant activity of the herbs determined by DPPH radical scavenging tests. Significant correlations were found between total phenolic (R2 = 0.8904), total dihydroxycinnamic derivative (R2 = 0.8529) and total caffeoyl derivative (R2 = 0.7172) concentrations and the DPPH-scavenging ability of all herbs. The antioxidant activity of the main constituents, including chicoric acid (EC50 = 8.24 μmol/l) or 3,5- dicaffeoylquinic acid (EC50 = 7.62 μmol/l), was very high compared to vitamin C (EC50 = 15.66 μmol/l). Thus, for each species, antioxidant activity mainly involves the major caffeoyl derivatives. The contribution to antioxidant activity were assessed as 48.92% for 3,5-dicaffeoylquinic acid in Tanacetum parthenium (30.08 g/kg), and 68.96% for chicoric acid in Taraxacum officinale (34.08 g/kg). The main caffeoyl derivatives among polyphenols can be considered as the major antioxidant compounds of the studied Asteraceae herbs.
基金supportd by the National Natural Science foundation for Outstanding Youth(30125044)partly funded by the"foundation for scholars come back from abroad"provided by Ministry of Education,Ministry of Personnel,and Chinese academy of Sciences.
文摘Two new triterpene esters, 2-O-caffeoylalphitolic acid (1) and methyl 2-O-caffeoyl- alphitolate (2), together with two known triterpenes were isolated from the shrub Daphniphyllum oldhami. The structures of new compounds were elucidated on the basis of detailed spectroscopic analysis and compared with related compound.
文摘Five caffeoyl conjugates were isolated from the ethyl acetate soluble fraction of Erigeron breviscapus (Van.) Hand_Mazz for the first time. Along with them, nine other chemical constituents were also identified. One new caffeoyl conjugate, erigoster A (1) with a novel basic skeleton was mainly assigned by the using a combination of two_dimensional NMR techniques.
