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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2011-5-2
pubmed:abstractText
Phyllanthus amarus has long been used as a herbal medicine in several countries. Phytochemicals in herbal medicine may interact with cytochromes P450 (CYP) and thus raise the potential of herb-drug interactions; therefore, the inhibitory effects of P. amarus and its major phytochemicals phyllanthin and hypophyllanthin on CYP isoforms were determined using human liver microsomes and selective substrates. Both ethanolic and aqueous extracts of P. amarus inhibited CYP1A2, CYP2D6, CYP2E1 and CYP3A4 in a dose-dependent manner. Compared to known CYP3A inhibitors, the IC(50) values of the ethanolic and aqueous extracts on testosterone 6?-hydroxylation were higher than that of ketoconazole but were lower than those of erythromycin and clarithromycin. Both extracts were weak inhibitors of CYP1A2, CYP2D6 and CYP2E1. In addition, phyllanthin and hypophyllanthin were potent mechanism-based inhibitors of CYP3A4 with K(I) values of 1.75 ± 1.20 µM and 2.24 ± 1.84 µM and k(inact) values of 0.18 ± 0.05 min(-1) and 0.15 ± 0.06 min(-1), respectively. The k(inact)/K(I) ratios of these lignans were higher than those reported for some therapeutic drugs that act as mechanism-based inhibitors of CYP3A4. These results suggest that co-administration of P. amarus with drugs that are metabolized by CYP3A4 may potentially result in herb-drug interactions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1880-0920
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
26
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
154-61
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Inhibitory effects of Phyllanthus amarus and its major lignans on human microsomal cytochrome P450 activities: evidence for CYP3A4 mechanism-based inhibition.
pubmed:affiliation
Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Thailand.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't