Abstract
To explore the metabolism of 1,5-dicaffeoylquinic acid (1,5-DCQA) in rats, liquid chromatography-mass spectrometry in parallel to diode-array detection was used for the rapid detection/characterization of the metabolites formed in bile, urine, and plasma of rats following oral administration of 1,5-DCQA (160 mg/kg). The methylation and glucuronidation of 1,5-DCQA occurring in vitro using rat liver and small intestinal microsomes and cytosols were studied in comparison with those occurring in vivo, and the enzymes involved were also determined. In addition, the anti-HIV (human immunodeficiency virus) activity of three important metabolites was preliminarily evaluated in MT-4 cells infected with HIV-1. A total of 22 metabolites in vivo and in vitro were identified, including four isomeric O-mono-methylated metabolites (M8–M11), nine isomeric O-di-methylated metabolites (M3, M6, M22, and M12–M17), four isomeric O-mono-methyl-glucuronidated metabolites (M2 and M19–M21), four isomeric O-di-methyl-glucuronidated metabolites (M1, M4, M5, and M7), and one glucuronidated metabolite (M18). The O-methylation positions of three important metabolites (M8, M9, and M12) were determined (3″-, 3′-, and 3′,3″-) by comparing with synthesized standards. The efficacy experiments showed that M8, M9, and M12 could inhibit HIV replication with IC50 values of about 25, 25, and 46 μM, respectively. These results suggest that O-methylation and glucuronidation are two important metabolic pathways of 1,5-DCQA, that both rat liver and small intestine can catalyze such reactions by catechol-O-methyltransferase and UDP-glucuronosyltransferases, and that the HIV-1 inhibitory activity of M8, M9, and M12 is comparable to or slightly weaker than that of 1,5-DCQA.
Footnotes
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This work was supported by Grant 30371669 from the National Natural Sciences Foundation of China and by Grant 2003AA2Z347B from the National High Technology Research and Development Program of China (863 Program).
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.104.002154.
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ABBREVIATIONS: DCQA, dicaffeoylquinic acid; HPLC, high-performance liquid chromatography; LC-MS, liquid chromatography-mass spectrometry; DAD, diode-array detection; MS/MS, tandem mass spectrometry; COMT, catechol-O-methyltransferase; UDPGA, uridine 5′-diphosphoglucuronic acid; UGT, UDP-glucuronosyltransferase.
- Received August 31, 2004.
- Accepted March 29, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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