National Agronomy Institute (INAT), Avenue Charles Nicolle, Mahrajène, Tunisia.
Laboratory "Energy and Matter for Development of Nuclear Sciences" (LR16CNSTN02), National Center for Nuclear Sciences and Technology (CNSTN), Sidi Thabet Technopark, Sidi Thabet, Tunisia.
Int J Radiat Biol. 2019 Nov;95(11):1552-1563. doi: 10.1080/09553002.2019.1649501. Epub 2019 Aug 14.
To assess exopolysaccharides (EPS) of CV5, isolated from irradiated roots of , for their induction by ionizing radiation (IR) and their antioxidant and radioprotective power. Isolated bacteria from the roots of were screened for EPS production. The most EPS-producing bacterium was selected and the response surface methodology (RSM) was applied to elucidate the IR dose effects on EPS production. Gamma irradiation effects on the morphology and functional groups of EPS were studied using microscopy and Fourier transform infra-red (FT-IR). The radioprotective potential of EPS on the survival of CV5 following IR was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Free radicals scavenging potentialities (FRSP) of non-irradiated and irradiated EPS were evaluated through 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and ferric reducing ability of plasma (FRAP) assays. Twenty strains, isolated from irradiated roots of , were screened for their EPS production. IR-resistant CV5 was the most EPS-producing strain. Its purified EPS contained rhamnose, fructose, mannose and glucose. RSM indicated that EPS of CV5 (CV5-EPS) are radiation inducible. Micrographs of CV5-EPS suggested an increase in the total area and a decrease in the Feret's statistical diameter following exposure to IR. FT-IR spectra of these EPS revealed an increase of various functional groups. The MTT survival assay demonstrated a positive correlation between the added quantity of CV5-EPS and the viability of irradiated CV5 ( < .01). DPPH, ABTS and FRAP assays indicated that the antioxidant activities of CV5-EPS increased significantly with the irradiation dose ( < .01). CV5-EPS were demonstrated as radiation-inducible and radioprotective biomolecules. This radioprotective potential of CV5-EPS could be associated with their antioxidant activities. In the future, irradiated EPS could be tested as a gel in cancer radiotherapy for minimizing the damage caused by rays to surrounding healthy tissues.
为了评估从 辐照根部分离的 CV5 的胞外多糖 (EPS) 是否能被电离辐射 (IR) 诱导，并具有抗氧化和辐射防护能力。从 的根部分离出细菌，筛选出 EPS 产量最高的细菌。选择最具 EPS 产生能力的细菌，并应用响应面法 (RSM) 来阐明 IR 剂量对 EPS 产生的影响。使用显微镜和傅里叶变换红外 (FT-IR) 研究了伽马辐照对 EPS 形态和官能团的影响。通过 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐 (MTT) 测定法评估 EPS 对 CV5 在 IR 后存活的辐射防护潜力。通过 2,2-二苯基-1-苦基肼 (DPPH)、2,2'-联氮-双 (3-乙基苯并噻唑啉-6-磺酸 (ABTS) 和血浆铁还原能力 (FRAP) 测定法评估了非辐照和辐照 EPS 的自由基清除能力 (FRSP)。从 的辐照根部分离出 20 株菌，筛选其 EPS 产量。IR 抗性 CV5 是 EPS 产量最高的菌株。其纯化的 EPS 含有鼠李糖、果糖、甘露糖和葡萄糖。RSM 表明，CV5 的 EPS (CV5-EPS) 是辐射诱导的。CV5-EPS 的显微照片表明，暴露于 IR 后，总面积增加，Feret 统计直径减小。这些 EPS 的 FT-IR 光谱显示，各种官能团的数量增加。MTT 存活测定表明，添加的 CV5-EPS 数量与辐照 CV5 的存活率呈正相关（<0.01）。DPPH、ABTS 和 FRAP 测定表明，CV5-EPS 的抗氧化活性随辐照剂量显著增加（<0.01）。CV5-EPS 被证明是辐射诱导和辐射防护的生物分子。CV5-EPS 的这种辐射防护潜力可能与其抗氧化活性有关。在未来，辐照 EPS 可以作为癌症放疗中的凝胶进行测试，以最大程度地减少射线对周围健康组织造成的损伤。
