ABSTRACT
Licochalcone A (LCA) is a major bioactive compound in Licorice, a widely used herbal medicine. In this study, the inhibitory effects of LCA against human UDP-glucuronosyltransferases (UGTs) and LCA associated herb-drug interactions were systematically investigated. Our results demonstrated that LCA displayed broad-spectrum inhibition against human UGTs. LCA exhibited strong inhibitory effects against UGT1A1, 1A3, 1A4, 1A6, 1A7, 1A9, and 2B7 (both IC50 and Ki values lower than 5 µM), while showing moderate inhibitory effects against UGT1A8, 1A10, 2B4, 2B15, and 2B17. The inhibitory effects of LCA against two major UGTs, including UGT1A1 and 1A9, were further investigated in human liver microsomes (HLMs), where the potential risks of LCA via inhibition of UGT1A1 and 1A9 were predicted by combining the in vitro inhibitory data and physiological data. The results from this study also showed that several LCA-containing products were able to increase the area under the curve (AUC) of the substrates that were predominantly metabolized by UGT1A1 or 1A9. These findings together demonstrate that LCA has a potent and broad-spectrum inhibitory effect against most human UGTs and thus suggest that much caution should be exercised when high-dose LCA is co-administered with UGT substrates.
Subject(s)
Chalcones/pharmacology , Glucuronosyltransferase/antagonists & inhibitors , Chalcones/chemistry , Gene Expression Regulation, Enzymologic/drug effects , Glucuronosyltransferase/metabolism , Humans , KineticsABSTRACT
Plant derived compounds, as potentially safe and effective skin lightening agents (SLAs), have attracted great attention from many researchers. Curcumin is a plant-derived polyphenol, which has been reported to suppress melanogenesis in B16 melanoma cells. However, little is known about whether curcumin affects melanogenesis in cultured human melanocytes. In addition, the molecular mechanism for the antimelanogenic effects of curcumin remains largely unknown. The present study assessed the effects of curcumin on melanin synthesis, cellular tyrosinase activity, the expression of melanogenesis-related proteins (microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein 1 and 2 (TRP-1, TRP-2)), and activation of melanogenesis-regulating signals including phosphatidylinositol 3-kinase (PI3K)/Akt/ glycogen synthase kinase 3 (GSK 3ß), extracellular signal-regulated kinase (ERK) and p38 MAPK in human melanocytes. The results showed that the melanin content and tyrosinase activity, as well as the expression of melanogenesis-related proteins in human melanocytes, were significantly inhibited by curcumin in a dose dependent manner. In addition, PI3K/Akt/ GSK 3ß, ERK and p38 MAPK were activated by curcumin, while inhibitors of these signals attenuated the inhibitory effects of curcumin on melanogenesis. These results suggest that curcumin inhibits melanogenesis in human melanocytes through activation of Akt/GSK 3ß, ERK or p38 MAPK signaling pathways.
Subject(s)
Curcumin/pharmacology , Melanins/metabolism , Melanocytes/drug effects , Monophenol Monooxygenase/metabolism , Cells, Cultured , Extracellular Signal-Regulated MAP Kinases/metabolism , Glycogen Synthase Kinase 3/metabolism , Glycogen Synthase Kinase 3 beta , Humans , Intramolecular Oxidoreductases/metabolism , Membrane Glycoproteins/metabolism , Microphthalmia-Associated Transcription Factor/metabolism , Oxidoreductases/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction/drug effects , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
Liquiritigenin (7,4'-dihydroxyflavone), the primary active component of a traditional Chinese medicine Glycyrrhizae radix, has a wide range of pharmacological activities. Six oxidative metabolites of liquiritigenin (7,3',4'-trihydroxyflavone, a hydroxyl quinine metabolite, two A-ring dihydroxymetabolites, 7,4'-dihydroxyflavone, and 7-hydroxychromone) have been detected in rat liver microsomes (RLMs), and one CYP3A4-catalyzed metabolite (7,4'-dihydroxyflavone) has been identified in human liver microsomes (HLMs) recently. In this study, a novel mono-hydroxylated metabolite was detected in reaction catalyzed by HLMs, and was identified as 4',5,7-trihydroxyflavanone by comparing the tandem mass spectra and the chromatographic retention time with that of the standard compound. Significant difference in CL(int) (9-fold) was found between these two oxidative pathways of liquiritigenin, and C5-hydroxylation pathway was identified as the major oxidative metabolism of liquiritigenin. The study with chemical selective inhibitor, cDNA-expressed human CYPs, correlation assay, and kinetic study demonstrated that CYP1A2 was the specific isozyme responsible for the C5-hydroxylation metabolism of liquiritigenin in HLMs.
Subject(s)
Biocatalysis , Carbon/metabolism , Cytochrome P-450 CYP1A2/metabolism , Flavanones/metabolism , Adult , Animals , Biocatalysis/drug effects , Chromatography, Liquid , Cytochrome P-450 CYP1A2 Inhibitors , Enzyme Inhibitors/pharmacology , Flavanones/chemistry , Humans , Hydroxylation/drug effects , Kinetics , Male , Mass Spectrometry , Microsomes, Liver/metabolism , Middle Aged , Rats , Recombinant Proteins/metabolismABSTRACT
The traditional Chinese medicine formula Fuling Decoction (FD) has been clinically used for eczema treatment, but the unclear chemical distribution and the lack of quality control have strongly restricted its application. In this study, an analytical method incorporating ultra-fast liquid chromatography (UFLC) with MS and UV detection was developed for rapid profiling of the chemical constitutes from FD. Fourteen constitutes were identified by UFLC-ESI-MS, while four major components including genipingentiobioside, geniposide, paeoniflorin and liquiritin were quantified simultaneously by UFLC-DAD. The UFLC-based method was fully validated and can be applied to screening and determination of principal components in commercially FD prescriptions.