Screening for the P-glycoprotein inhibitory pump activity of plant extracts that are used in Tanzanian traditional medicine

Abstract

An in vitro screening experiment of 45 methanolic plant extracts was carried out to investigate the inhibition of P-glycoprotein (P-gp) in MCF-7R cells. The investigation was carried out using standard functional assay with rhodamine 6G as the fluorescent probe and reserpine, a known inhibitor of P-glycoprotein pump, was used as a reference drug. The results revealed that out of the 45 plant extracts tested, 3 extracts i.e. Bauhinia thoningii, Clerodendrum myricoides and Rhus natalensis exhibited pronounced activity at the concentration of 100 µg/ml. In comparison to the negative control, B. thoningii, C. myricoides and R. natalensis extracts inhibited the pump by a factor of about 2.5, 4 and 4.3, respectively. The remaining 42 extracts did not show any activity. The reference drug reserpine (20 μM) inhibited the pump by a factor of about 11. These preliminary results indicate that the inhibition of P-gp in MCF-7R cells is through a concerted action of compounds present in the extracts and that if isolated might be effective P-gp pump inhibitors in the treatment of cancer.

Keywords: plant extract, P-glycoprotein inhibition; rhodamine 6G; MCF-7R cells

East and Central African Journal of Pharmaceutical Sciences Vol. 7 2004: 16-22