Iron chelation and related properties of Podophyllum hexandrum, a possible role in radioprotection.

Aqueous extract of Podophyllum species has been reported to render significant protection against radiation induced mortality, cytogenetic damage and cell death. In view of this, present study was undertaken to investigate its antioxidant properties. Chelation, oxidation and reduction of Fe2+ and Fe3+ were measured using chelating agents 2-2' bipiridyl and potassium thiocyanate respectively. Podophyllum extract, in a dose dependent manner, chelated Fe2+ more efficiently than Fe3+ and also modulated Fe2+/Fe3+ ratio. Homogenate of mouse liver was used to measure TBARS for estimating lipid peroxidation. Podophyllum extract also inhibited lipid peroxidation in a dose dependent manner and maximum inhibition (92%) was achieved at 1000 micrograms/ml concentration. These results demonstrates that Podophyllum exhibits antioxidant properties as seen through chelation and modulation of redox state of iron ions and these may primarily contribute towards its radioprotective manifestation.

Antitumour and radioprotective action of Podophyllum hexandrum.

A significant antitumour effect of P. hexandrum, a herb thriving at Himalayas (2500-4000 m), was observed in strain 'A' mice carrying solid tumours developed by transplanting Ehrlich ascites tumour (EAT). Subtoxic well tolerated sequential doses of aqueous extract of P. hexandrum (a daily dose of 34.5 mg/kg b.w. for 15 days) enhanced tumour doubling time (TDT) from 1.94 +/- 0.26 days to 19.1 +/- 2.5 days. However, no synergism was revealed between radiation and P. hexandrum, though both independently manifested antitumour effects. In normal mice, pre-irradiation administration of extract of P. hexandrum protected mice in a dose dependent manner (optimal dose being 34.5 mg/kg body.wt. rendering 72% survival for 30 days) against whole body lethal irradiation of 10 Gy. Radioprotective properties of P. hexandrum were found to be comparable to synthetic radioprotectors like diltiazem etc.