Evaluation of Radioprotective Potential of Selected Indian Bamboo Leaves

Abstract

Radioprotector is the prime antidote to radiation injury. The burning urge for an ideal radioprotector led us to explore natural resources. Medicinal plants, enriched with phytochemicals having antioxidant properties can serve as a radioprotector. Bamboo species is known for its antioxidant, anti-inflammatory, anti-cancer, anti-diabetic, cardioprotective, neuroprotective, hepatoprotective and immunomodulatory activities and enriched polyphenolic phytoconstituents spectrum. Thus it was selected for the present study. The study aims to evaluate the protective effect of bamboo leaf extract against gamma radiation. Four bamboo species Bambusa arundinacea (B.A), Bambusa vulgaris (B.V), Phyllostachys parvifolia (P.P), and Dendrocalamus strictus (D.S) are selected for the study. The polyphenol rich leaf extract was prepared using 30% ethanol and standardized using eight polyphenols (chlorogenic acid, orientin, isoorientin, vitexin, isovitexin, ferulic acid, luteolin, and apigenin) as biomarkers. The standardized extract was subjected to in vitro and in vivo screening of radioprotection. Quantification of these selected polyphenols using RP-HPLC revealed that all the selected polyphenol were in the highest amount in B.A leaf extract. The order for the prevalence of the biomarkers in the selected species is as follow B.A>D.S>P.P>B.V. The free radical scavenging assays indicated the antioxidant potential of extract when compared to ascorbic acid. In vitro protective role of leaf extract was studied using cytokinesis blocked micronuclei assay (CBMN) in human peripheral blood lymphocytes (HPBLs). CBMN results indicate that the treatment of HPBLs with varying concentration of extract before exposure to different dose of gamma radiation (4Gy & 6Gy) resulted in significant (p< 0.0001) decline of radiation induced micronuclei. It showed dose dependent and concentration driven activity with maximum protection ~ 70% at 9 μg/ml concentration. In vivo protective effect was studied using whole body gamma irradiated mice model. Drug dose response and radiation dose response studies revealed that extract treated whole body irradiated mice showed 50%, 83.3% and 100% survival for 400, 600, and 800 mg/kg with 1.05, 0.43 and 0 clinical scores, respectively when compared to irradiated mice having no survival with 6.03 clinical score. The extract showed a dose reduction factor (DRF) value 3 at a concentration of 800 mg/kg, which indicates signification radioprotection. Histopathology studies also revealed a protective effect of the extract by organ protection. To conclude, we found that bamboo leaf extract can reduce the radiation induced cytogenetic damage. B.A leaf extract increased the survival ratio, showed organ protection and reduced the radiation induced sickness and mortality indicating its potential to be a radioprotector.