The human population can get exposed to various hazardous environmental agents, knowingly or unknowingly, by way of lifestyle, habit, pollution, or even treatment for a disease. The ionising radiation is used for treating cancer; however, this is not without severe side effects on the normal tissues which hamper optimal dose delivery to cancer tissues. The protection of noncancerous tissues is necessary to minimise radiation-associated toxicities. Radioprotectors are a class of drugs which selectively protects the normal cells during radiotherapy in cancer patients. However, the clinical use of radioprotectors is limited due to the toxicities that compromise a cancer patient’s quality of life. To overcome this problem, radioprotectors from natural sources can be considered safer alternatives to synthetic ones. Various plants are used in Chinese and Ayurveda medicines like nutmeg, vanilla, turmeric, ginger, apricot, snap weed, and peppermint, due to their antioxidant properties. Some medicinal plants show activity against oxidative stress due to the presence of certain polyphenols that combat the free radicals generated by ionising radiation and thus protect the genetic material or DNA from radiation-induced damage. It is also comparatively easy and cost-effective to prepare plant extract for medicinal use rather than chemical syntheses of drugs. It is extremely important to develop an effective radioprotector from plant sources.
The Bamboo plant is widely used against oxidative stress; however, its effectiveness as a radioprotector has not been reported. This project aimed to measure the extent of radioprotection in terms of reduction in DNA damage induced by gamma radiation. The plants were selected from the National Mission on Bamboo Application (NMBA) listed Indian Bamboo species which are also part of several Ayurvedic formulations. These species include Bambusa arundinacea, Bambusa vulgaris, Dendrocalamus strictus and Phyllostachys parvifolia. Peripheral blood lymphocytes were grown in the laboratory by short-term culture method after treatment with methanolic extracts of four species each after exposing cells to gamma radiation. The lymphocytes were studied at the chromosome level following procedures based on the type of assay performed. The cytogenetic biomarkers were evaluated using four different assays; Cytokinesis Blocked Micronucleus (CBMN) assay, Chromosomal aberration assay (CA), Dicentric assay, and Single Cell Gel Electrophoresis (COMET) assay. This study shows that Bamboo Leaf Extract from the four Indian species provided considerable protection against genetic damage by gamma radiation. The protective effect was found to improve with an increase in dose. The radioprotective property of the extract can be attributed to the polyphenolic content. Out of four different bamboo species used the Bambusa arundinacea contained the highest number of polyphenols and showed the maximum effect in terms of all the laboratory measurement techniques. The study demonstrated that the radioprotective activity of the bamboo species depends on the number and type of polyphenols present. The radioprotective efficacy of the four bamboo species in our studies can be summarised as; highest for Bambusa arundinacea, followed by Dendrocalamus Strictus, P parvifolia, and B vulgaris. The radioprotective effects of the bamboo plant extract were similar for CBMN, Chromosomal aberration, Dicentric analysis and COMET assay. Thus, Bamboo leaf extracts can reduce genetic damage at cellular, chromosomal and DNA level in laboratory analysis. It remains to study in detail if bamboo extracts also provide protection from radiation-induced genetic damage in animal models followed by humans. The mechanistic study of radioprotective activity by evaluating alteration in gene expression in related cell signalling and DNA repair pathways is indicated.
Dr Shikha Tewari, an external PhD scholar of Dr Sonal Bakshi, Assistant Professor, Institute of Science, is a biotechnology professional with research experience focused on screening, analyses, and testing (safety and efficacy) of potential natural radioprotectors.