Bioactive dicaffeoylquinic acid derivatives from the root extract of Calea urticifolia

ABSTRACT

ABSTRACT Calea urticifolia (Mill.) DC., Asteraceae, is a native plant of the Yucatan Peninsula used in traditional medicine to treat inflammation and pain. The bioassay-guided purification of the ethanol root extract allowed the isolation of the main bioactive metabolites, which were identified as an inseparable mixture of thymol (1) and 3-methyl-4-isopropylphenol (2), together with 3,4-O-dicaffeoylquinic acid methyl ester (3), 3,4-O-dicaffeoyl-epi-quinic acid methyl ester (4), 3,5-O-dicaffeoyl-epi-quinic acid methyl ester (5) and 3,5-O-dicaffeoylquinic acid (6). The results showed that the analgesic activity detected in the root extract of C. urticifolia could be attributed mainly to the mixture of 1 and 2 and to the novel 3,4-O-dicaffeoyl-epi-quinic acid methyl ester (4). Alternatively, the similarity on the antiinflammatory and antioxidant activities of the dicaffeoylquinic acid derivatives 3-5 suggests that the former might be related to their ability as radical scavengers.