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Evidence-Based Complementary and Alternative Medicine
Volume 2016 (2016), Article ID 7869710, 6 pages
Research Article

Traditional Preparations and Methanol Extracts of Medicinal Plants from Papua New Guinea Exhibit Similar Cytochrome P450 Inhibition

1Department of Pharmacology and Toxicology, University of Utah, 30 S. 2000 E., Salt Lake City, UT 84112, USA
2School of Medicine and Health Sciences, University of Papua New Guinea, P.O. Box 5623, Boroko, NCD, Papua New Guinea
3School of Natural and Physical Sciences, University of Papua New Guinea, P.O. Box 5623, Boroko, NCD, Papua New Guinea

Received 25 April 2016; Accepted 21 July 2016

Academic Editor: Dolores García Giménez

Copyright © 2016 Erica C. Larson et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The hypothesis underlying this current work is that fresh juice expressed from Papua New Guinea (PNG) medicinal plants (succus) will inhibit human Cytochrome P450s (CYPs). The CYP inhibitory activity identified in fresh material was compared with inhibition in methanol extracts of dried material. Succus is the most common method of traditional medicine (TM) preparation for consumption in PNG. There is increasing concern that TMs might antagonize or complicate drug therapy. We have previously shown that methanol extracts of commonly consumed PNG medicinal plants are able to induce and/or inhibit human CYPs in vitro. In this current work plant succus was prepared from fresh plant leaves. Inhibition of three major CYPs was determined using human liver microsomes and enzyme-selective model substrates. Of 15 species tested, succus from 6/15 was found to inhibit CYP1A2, 7/15 inhibited CYP3A4, and 4/15 inhibited CYP2D6. Chi-squared tests determined differences in inhibitory activity between succus and methanol preparations. Over 80% agreement was found. Thus, fresh juice from PNG medicinal plants does exhibit the potential to complicate drug therapy in at risk populations. Further, the general reproducibility of these findings suggests that methanol extraction of dried material is a reasonable surrogate preparation method for fresh plant samples.