title: Antioxidant activity of fractionated extracts of rhizomes of high-altitude Podophyllum hexandrum: role in radiation protection.
abstract: Whole extract of rhizomes of Podophyllum hexandrum has been reported earlier by our group to render whole-body radioprotection. High-altitude P. hexandrum (HAPH) was therefore fractionated using solvents of varying polarity (non-polar to polar) and the different fractions were designated as, n-hexane (HE), chloroform (CE), alcohol (AE), hydro-alcohol (HA) and water (WE). The total polyphenolic content (mg% of quercetin) was determined spectrophotometrically, while. The major constituents present in each fraction were identified and characterized using LC-APCI/MS/MS. In vitro screening of the individual fractions, rich in polyphenols and lignans, revealed several bioactivities of direct relevance to radioprotection e.g. metal-chelation activity, antioxidant activity, DNA protection, inhibition of radiation (250 Gy) and iron/ascorbate-induced lipid peroxidation (LPO). CE exhibited maximum protection to plasmid (pBR322) DNA in the plasmid relaxation assay (68.09% of SC form retention). It also showed maximal metal chelation activity (41.59%), evaluated using 2,2'-bipyridyl assay, followed by AE (31.25%), which exhibited maximum antioxidant potential (lowest absorption unit value: 0.0389 +/- 0.00717) in the reducing power assay. AE also maximally inhibited iron/ascorbate-induced and radiation-induced LPO (99.76 and 92.249%, respectively, at 2000 microg/ml) in mouse liver homogenate. Under conditions of combined stress (radiation (250 Gy) + iron/ascorbate), at a concentration of 2000 microg/ml, HA exhibited higher percentage of inhibition (93.05%) of LPO activity. HA was found to be effective in significantly (p < 0.05) lowering LPO activity over a wide range of concentrations as compared to AE. The present comparative study indicated that alcoholic (AE) and hydro-alcoholic (HA) fractions are the most promising fractions, which can effectively tackle radiation-induced oxidative stress.
authors: Division of Radiopharmaceuticals and Radiation Biology, Institute of Nuclear Medicine and Allied Sciences, New Delhi, India.
authors: Raman
authors: R
authors: Chawla
authors: Rajesh
authors: R
authors: Arora
authors: Raj
authors: R
authors: Kumar
authors: Ashok
authors: A
authors: Sharma
authors: Jagdish
authors: J
authors: Prasad
authors: Surendar
authors: S
authors: Singh
authors: Ravinder
authors: R
authors: Sagar
authors: Pankaj
authors: P
authors: Chaudhary
authors: Sandeep
authors: S
authors: Shukla
authors: Gurpreet
authors: G
authors: Kaur
authors: Rakesh Kumar
authors: RK
authors: Sharma
authors: Satish Chander
authors: SC
authors: Puri
authors: Kanaya Lal
authors: KL
authors: Dhar
authors: Geeta
authors: G
authors: Handa
authors: Vinay Kumar
authors: VK
authors: Gupta
authors: Ghulam Nabi
authors: GN
authors: Qazi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D005720:Gamma Rays; D007502:Iron Chelating Agents / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects / Q000528:radiation effects; D008099:Liver / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D018384:Oxidative Stress; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal; D011035:Podophyllum / Q000737:chemistry*; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D027343:Rhizome / Q000737:chemistry
chemical_list: D000975:Antioxidants; D007502:Iron Chelating Agents; D010936:Plant Extracts; D011837:Radiation-Protective Agents