Antioxidant activity of fractionated extracts of rhizomes of high-altitude Podophyllum hexandrum: role in radiation protection

• Published in: Molecular and cellular biochemistry Vol. 273; no. 1-2; pp. 193 - 208
• Main Authors: Chawla, Raman, Arora, Rajesh, Kumar, Raj, Sharma, Ashok, Prasad, Jagdish, Singh, Surendar, Sagar, Ravinder, Chaudhary, Pankaj, Shukla, Sandeep, Kaur, Gurpreet, Sharma, Rakesh Kumar, Puri, Satish Chander, Dhar, Kanaya Lal, Handa, Geeta, Gupta, Vinay Kumar, Qazi, Ghulam Nabi
• Format: Journal Article
• Language: English
• Published: Netherlands Springer Nature B.V 01.05.2005
• Subjects: Altitude; Animals; Antioxidants; Antioxidants - pharmacology; Aquatic plants; Chelation; Chloroform; Comparative studies; Deoxyribonucleic acid; DNA; DNA Damage - drug effects; DNA Damage - radiation effects; Gamma Rays; Iron; Iron Chelating Agents - pharmacology; Lipid Peroxidation - drug effects; Lipid Peroxidation - radiation effects; Liver - drug effects; Liver - radiation effects; Male; Mice; Mice, Inbred A; Oxidative Stress; Peroxidation; Plant Extracts - pharmacology; Plants, Medicinal; Podophyllum - chemistry; Podophyllum hexandrum; Radiation protection; Radiation-Protective Agents - pharmacology; Rhizome - chemistry
• ISSN: 0300-8177; 1573-4919
• DOI: 10.1007/s11010-005-0821-5

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.