Institute of Nuclear Medicine and Allied Sciences, Brig S.K. Mazumdar Road, Delhi-110 054, INDIA.
Abstract Radiation mediated free radical flux interferes with oxidation/reduction-based physiological mechanisms. These free radicals react with a number of biomolecules including Deoxyribonucleic acid (DNA), lipids and proteins. The rate and selectivity of these free radical mediated reactions depend upon the concentration, half-life and state of delocalization of electrons in the free radicals and the free radicals’ oxidizing ability.
Podophyllum hexandrum Royle (Himalayan Mayapple) was known as Aindri (“a divine drug”) in ancient times. It has been reported to be used through the ages and in modern times as a cure for allergic and inflammatory conditions of the skin; biliary fever; burning sensation; cold; constipation; cancer of the brain, bladder and lung; erysipelas; Hodgkin’s disease; insect bites; mental disorders; monocytoid leukemia; non-Hodgkin’s lymphoma; rheumatism; septic wounds; plague; and venereal warts. It has served as a commercial source of podophyllotoxin and related aryltetralin lignans and several other bioactive constituents. Podophyllotoxin finds use as a precursor for the semi-synthetic topisomerase inhibitors in the treatment of leukemias, lung and testicular cancers, dermatological disorders like warts, rheumatoid arthritis, psoriasis and malaria. It also has numerous applications in modern medicine by virtue of its free radical scavenging capacity. An extract of P. hexandrum has been shown to provide approximately 80% whole-body radioprotection in mice.
The present review highlights the state of knowledge about the radioprotective mechanism of P. hexandrum at different levels of organization in living organisms. Further, an insight into its mode of action at the molecular level, including the studies of the expression patterns of various proteins associated with inhibition of apoptosis in the spleen of male Swiss albino strain ‘A’ mice by immunoblotting, has been presented. In conclusion, the studies clearly demonstrated that P. hexandrum extract provides protection from gamma-radiation by the modulation of expression of proteins associated with cell death attributed to its ability to modulate free radical flux.