Antioxidant and radioprotective effect of the active fraction of Pilea microphylla (L.) ethanolic extract

The ethanolic extract of Pilea microphylla (L.) was defatted, successively fractionated with acetone and the residue so obtained was found to be most potent when subjected to detailed free radical scavenging and in vivo radioprotection studies. The most active fraction reacts with free radicals, such as DPPH (50 μM), ABTS{radical dot}- (100 μM) and {radical dot}OH (generated by Fenton reaction) with IC50 value of 23.15 μg/ml, 3.0 μg/ml and 310 μg/ml, respectively. The most active fraction inhibited iron-induced lipid peroxidation in phosphatidyl choline liposomes with an IC50 of 13.74 μg/ml. The kinetics of scavenging of DPPH and ABTS{radical dot}- radicals were followed at different concentrations of the fraction by employing stopped-flow studies. The observed first order decay rate constants at 200 μg/ml and 50 μg/ml of fraction with DPPH (50 μM) and ABTS{radical dot}- (50 μM) were found to be 0.4 s-1 and 2.1 s-1, respectively. The fraction when screened for in vivo radioprotection in Swiss albino mice showed 80% protection at a dose of 900 mg/kg and with a DRF of about 1.12. The fraction was also found to protect livers of irradiated mice from depletion of endogenous antioxidant enzymes like glutathione, GST, SOD, catalase and thiols. The fraction also protected the villi height, increased the number of crypt cells while offering general protection to the intestine from acute radiation effects. The fraction also protected the hematopoietic system as assessed by endogenous spleen colony assay, contributing to the overall radioprotective ability. © 2006 Elsevier Ireland Ltd. All rights reserved.