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In vitro evaluation of the effect of selected herbal extracts on drug transport across porcine jejunal tissue
P-glycoprotein (P-gp) is a membrane-bound transporter protein, which causes multidrug-resistance in tumour cells . It is also localized in the apical membrane of normal intestinal epithelial cells  where it actively pumps substrates from within the cell back into the intestinal lumen with a consequent reduction in their bioavailability . Many drugs, herbs and food substances may inhibit or induce P-gp, which may consequently influence the absorption of co-administered drugs . The aim of this study was to investigate the effect of selected herbal extracts on the bidirectional transport of cimetidine, a P-gp substrate, across porcine jejunal tissue segments. The herbs were selected on the basis of having medicinal properties, being commonly used daily as flavourants in food as well as being easily accessible. The water extracts of selected herbs (garlic, cranberry, buchu and rosemary) were used to determine their effects on the transport of cimetidine across porcine jejunal segments in both the apical-basolateral and basolateral-apical directions. Cimetidine alone and verapamil were included as negative and positive control groups, respectively. The apparent permeability coefficient (Papp) and flux (J) values  were calculated for cimetidine. Vaccinium macrocarpon (cranberry), Allium sativum (garlic) and Agathosma betulina (buchu) extracts inhibited P-gp efflux of cimetidine and thereby enhanced cimetidine transport in the apical-basolateral direction, while Rosmarinus officinalis (rosemary) induced P-gp efflux and thereby enhanced cimetidine transport in the basolateral-apical direction. The results clearly indicate that the four selected herbal extracts contain phytoconstituents that modulate P-gp mediated drug efflux.
References: 1. Sun et al. (2004). Med. Sci. Monitor, 10:RA5 -RA14.
2. Doppenschmitt et al. (1999). J. Pharm. Sci. 88:1067–1072.
3. Koren et al. (1998). Vet. Human Toxicol. 40:45–46.
4. Laitinen et al. (2004). Pharm. Res. 21:1904–1916.
5. Hansen et al. (2009). Phytother. Res. 23:86–91.