In Vitro And In Vivo Radioprotective Activities Of Polyalthia Longifolia Against Lethal Irradiation
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Date
2015-07
Authors
Subramanion, Jo Thy Lachumy
Journal Title
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Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Medicinal plants rich with various phytochemicals with antioxidant properties could serve as an alternative radioprotective agent. The current study was designed to evaluate the P. longifolia leaf extract as a potential radioprotector. Rutin quantification was performed for standardization and was found to be 8.96 μg (0.896%) in 1000 μg of P. longifolia leaf extract. Light microscopy of a transverse section of the leaf of P. longifolia revealed the presence of various plant cells. Phytochemical screening results of the extract revealed the presence of alkaloids, triterpenoids, tannins, saponin, anthraquinones, and glycosides. The concentrations of heavy metals determined in the extract were well below the permissible limit. The HPTLC analysis of the methanolic extract of P. longifolia leaf showed ten specific peaks. Twelve major peaks in the range of 4,000 to 500 cm-1 were observed in the FTIR spectra, which represented various specific functional groups. The in vitro antioxidant assays showed considerable in vitro antioxidant activities in a dose-dependent manner when compared to the standard antioxidant Phenolic and flavonoid content of these extracts is significantly correlated with antioxidant capacity. Therapy of P. longifolia showed the liver protective effect on biochemical and histopathological alterations. Moreover, histological studies also supported the biochemical finding, that is, the maximum improvement in the histoarchitecture of the liver. In the comet assay, the treatment of 23.88 μg/mL of P. longifolia extract for 24 h on Vero cells caused decrease in DNA damage by approximately 50.94% compared to the unchallenged control. In the plasmid relation and comet assay, the P. longifolia leaf extract exhibited strong inhibitory effects against H2O2-mediated DNA damage. A dose-dependent increase of chromosome aberrations was also observed in the Allium cepa assay. The abnormalities scored were stickiness, c-mitosis, bridges, and vagrant chromosomes. Micronucleated cells were also observed at the interphase. This experiment is the first report for the protective effect of P. longifolia on DNA damage-induced by hydroxyl radicals. Additionally in an acute oral toxicity study, female rats were treated at 5000 mg/kg body weight of P. longifolia leaf extract and observed for signs of toxicity for 14 days. P. longifolia leaf extract did not produce any signs of toxicity which indicates that the P. longifolia was not toxic. Subsequently, the radioprotective effect of P. longifolia was studied in mice. P. longifolia treatment rendered remarkable improvement in mice survival (27 days), compared to 100% mortality in irradiated groups mice within 14 days. Significant increases in hemoglobin concentration, red blood cell, white blood cells and platelets counts were observed in the animals pretreated with P. longifolia leaf extract in comparison to the irradiation-alone group. Pre-irradiation administration of P. longifolia leaf extract also increased the CFU counts of spleen colony and increased spleen relative size. A dose-dependent decrease in lipid peroxidation levels was observed in animals pretreated with P. longifolia. However, the animals pretreated with P. longifolia exhibited a significant increase in superoxide dismutase and catalase activity, but the values remained below normal both in liver and intestine. Pre-irradiation administration of P. longifolia also resulted in regeneration of mucosal crypts and villi of intestine. Moreover, pretreatment of P. longifolia leaf extract also shows protective effects on X-ray irradiation-induced liver damage in mice by restoration of normal liver cell structure
and significant reduction in the elevated levels of ALT, AST and bilirubin level compared with the X-ray irradiated mice. These results suggest that the radioprotective ability of P. longifolia leaf extract which was manifested in several systems in experimental animal. To identify the antioxidant compound, P. longifolia leaf extract was subjected to bioassay-guided fractionation. P. longifolia ethyl acetate fraction, namely EtOAc_F007 demonstrated highest antioxidant activity among all the fractions tested. Further LC-MS analysis of EtOAc_F007 led to identification of rutin as the antioxidant agent in P. longifolia extract. In conclusion, the results from this study strongly imply the potential use of P. longifolia leaf extracts from natural product in future application for the development of natural products based radioprotection agents.
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Keywords
Radioprotective