title: N-acetyl tryptophan glucopyranoside (NATG) provides radioprotection to murine macrophage J774A.1 cells.
abstract: Ionizing radiation induced perturbations in cellular redox homeostasis are manifested as cell cycle arrest, inflammatory response, and apoptosis. Present study was focused on determination of radioprotective efficacy of a secondary metabolite N-acetyl-l-tryptophan glucoside (NATG) isolated from radioresistant bacterium Bacillus sp. INM-1. Macrophage J774A.1 cells were treated with NATG (0.025-200 μg/ml) before γ-irradiation (10-50 Gy) and radioprotective efficacy in terms of cellular metabolic activity was assessed using MTT assay. Radiation-induced intracellular ROS generation and its inhibition by NATG (0.25 μg/ml) pretreatment was evaluated using 2',7'-dichlorodihydrofluorescein diacetate (H(2)DCFDA) probe. Effects of NATG pretreatment with or without γ-irradiation (20 Gy) on cell cycle perturbations and apoptosis regulation was evaluated using flowcytometry. Results of the study displayed 0.25 and 50 μg/ml as effective dose (ED) and lethal dose (LD(50)) dose of NATG. A significant (p < 0.05) decrease in DCFDA fluorescence corresponding to decreased ROS levels was observed in NATG pretreated irradiated cells as compared to irradiated alone cells. Cell cycle progression analysis demonstrated decrease (∼10%) in G(1), G(2), and S phase cells at 24 h post-treatment time interval in NATG pretreated cells as compared to control group. However, radiation-induced or NATG-induced treatment did not cause any alterations in G(2)/M arrest. APO-BrDU analysis demonstrated significant (p < 0.05) reduction in apoptosis level at 24 h time interval in NATG pretreated irradiated cells as compared to alone irradiated cells. Conclusively, present study suggests that NATG offers radioprotection by apoptosis inhibition mechanism without altering cell-cycle progression in J774A.1 cells. Further studies to evaluate detailed molecular mechanisms of radioprotection offered by NATG are ongoing.
authors.affiliation: a Radiation Biotechnology Group, Division of Radiation Biosciences , Institute of Nuclear Medicine and Allied Sciences , Delhi , India.
authors.forename: Poonam
authors.initials: P
authors.lastname: Malhotra
authors.affiliation: a Radiation Biotechnology Group, Division of Radiation Biosciences , Institute of Nuclear Medicine and Allied Sciences , Delhi , India.
authors.forename: Manish
authors.initials: M
authors.lastname: Adhikari
authors.affiliation: a Radiation Biotechnology Group, Division of Radiation Biosciences , Institute of Nuclear Medicine and Allied Sciences , Delhi , India.
authors.forename: Shravan K
authors.initials: SK
authors.lastname: Singh
authors.affiliation: a Radiation Biotechnology Group, Division of Radiation Biosciences , Institute of Nuclear Medicine and Allied Sciences , Delhi , India.
authors.forename: Raj
authors.initials: R
authors.lastname: Kumar
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D005720:Gamma Rays / Q000009:adverse effects*; D005960:Glucosides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D005960:Glucosides; D011837:Radiation-Protective Agents; C416666:tryptophan N-glucoside; D014364:Tryptophan
keywords: APO-BrDU analysis; bacterial secondary metabolite; cell-cycle progression; gamma radiation; intracellular ROS