Radical scavenging and radiomodulatory effects of Psoralea corylifolia Linn. substantiated by in vitro assays and EPR spectroscopy

Abstract

The present study is the first report of the radiomodulatory effects of Psoralea corylifolia Linn. The extract (IBG-RA-26) prepared from P. corylifolia was chemically analysed by HPLC, LC-MS/MS and NMR. The total polyphenolic content of IBG-RA-26 was 0.287 mg/ml of quercetin equivalents. IBG-RA-26 exhibited a dose-dependent increase in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. It exhibited comparable (> 50%) site-specific and non-site-specific hydroxyl radical scavenging activity in higher concentration ranges (500 - 1000 μg/ml), while at lower concentrations (5 - 50 μg/ml) it exhibited significantly (p < 0.05) higher non-site-specific scavenging ability compared to site-specific activity. Nitric oxide scavenging activity of IBG-RA-26 (5 - 1000 μg/ml) increased in a concentrationdependent manner, while maximum superoxide ion scavenging ability (79%) was observed at 50 μg/ml. The electron donation potential of IBG-RA-26 was found to be higher than that of ascorbic acid at lower concentrations (up to 5 μg/ml). Analysis of the ability of IBGRA-26 to protect membranes against γ-radiation, utilizing an artificial membrane system (liposome), revealed a signifi cant (p < 0.05) decrease in the formation of malondialdehyde (MDA) as a function of the concentration of IBG-RA-26. Radiation-induced lysis of human erythrocytes was monitored and effi cacy of IBG-RA-26 was tested in the concentration range 25 - 1000 μg/ml, with significant protective efficacy observed in the range 25 - 50 μg/ml. IBG-RA-26 rendered significant (p < 0.05) protection against radiation (0.25 kGy)-induced DNA damage. EPR spectroscopy was used to investigate the DPPH radical scavenging capacity of IBG-RA-26. IBG-RA-26 exhibited a good DPPH radical scavenging capacity in a concentration-dependent manner. By direct EPR spectroscopy we have also demonstrated the possible formation of free radical species in a solution of IBG-RA-26. The wide spectrum of radioprotective and antioxidant properties exhibited by IBG-RA-26 indicate that P. corylifolia has potential as a radiomodulatory agent. © 2011 Verlag der Zeitschrift für Naturforschung.