Radioprotective and Free Radicals Scavenging Activity of Phyllanthin: Isolated from Phyllanthus Niruri

Background: The present study aimed at evaluation of in vitro antioxidant and radioprotective potential of lignan phyllanthin isolated from Phyllanthus niruri. Materials and Methods: Four preparative TLC isolates of P. niruri whole plant methanolic extract were assessed for hydroxyl radical scavenging ability. The hydroxyl radical scavenging potentials of S1 and S4 were found to be comparable [i.e. 33.4% (S1) and 26.5% (S4)], S1 exhibited significant (p<0.05) antioxidant activity at 250 μg/ml concentration. Compound S1 was identified as phyllanthin by TLC and HPLC analysis. Further authentication and characterized of phyllanthin was done by mp, UV spectrometry, elemental, IR, NMR and Mass analysis. Radioprotective effect of phyllanthin (S1) was studied against 4 Gy radiation induced chromosome damage in mouse bone marrow at a dose rate of 20, 40, 60 and 80 mg/kg, i.p. Bone marrow was scored for aberration in metaphase chromosomes after cytogenetic damage in the bone marrow cells was studied by chromosomal aberration analysis. Results: S1 fraction significantly reduced all types of aberrations at 40, 60 and 80 mg/kg dose. Phyllanthin significantly (p<0.001) decreased percentage of severely damaged cell to only 0.91% at 80 mg/kg dose. Conclusion: Free radical scavenging appears to be the likely mechanism of radiation protection by the phyllanthin isolated from the P. niruri. Together these findings clearly prove that lignin phyllanthin content influences the radiation protective potential of P. niruri to a great extent.