Antioxidant activity of fractionated extracts of rhizomes of high-altitude Podophyllum hexandrum: role in radiation protection.
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.
Chawla
Raman
R
Division of Radiopharmaceuticals and Radiation Biology, Institute of Nuclear Medicine and Allied Sciences, New Delhi, India.
Arora
Rajesh
R
Kumar
Raj
R
Sharma
Ashok
A
Prasad
Jagdish
J
Singh
Surendar
S
Sagar
Ravinder
R
Chaudhary
Pankaj
P
Shukla
Sandeep
S
Kaur
Gurpreet
G
Sharma
Rakesh Kumar
RK
Puri
Satish Chander
SC
Dhar
Kanaya Lal
KL
Handa
Geeta
G
Gupta
Vinay Kumar
VK
Qazi
Ghulam Nabi
GN
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
D000975:Antioxidants; D007502:Iron Chelating Agents; D010936:Plant Extracts; D011837:Radiation-Protective Agents