Inhibitory effect of some methanol plant extracts on dihydrofolate reductase

Abstract

Cancer claims the lives of more than 6 million people each year globally. Current treatment approaches have yielded significant progress in the fight against cancer, but the incidence of certain types of cancer continues to rise. Dihydrofolate reductase (DHFR) is a key target for cancer chemotherapeutic agents. In this study, some plant extracts were evaluated for their inhibitory activity against DHFR. One hundred species of plants were collected or purchased from the medicinal herbal markets and identified botanically. Methanol extracts were prepared by maceration. DHFR activity was assayed spectrophotometrically by monitoring the decrease in absorbance at 340nm. Km and Vmax of the enzyme were determined using Lineweaver-Burk graphs. Among 100 extracts prepared, methanol extracts of Terminalia chebula and Quercus infectoria showed 100% inhibitory activity while another 11 extracts demonstrated more than 10% inhibitory effect on DHFR. Lineweaver-Burk plots revealed a non-competitive mode of inhibition for both active plants. Under standard condition, Km value for the enzyme was 1.2μmol and Vmax was 0.01 μmol min-1. Ki value for T. chebula was 1.5μmol and for Q. infectoria was 3.33 μmol. Data indicated that both T. chebula and Q. infectoria plants may be good candidates for therapeutic use. © 2011 Taylor & Francis.