In vitro evaluation of antioxidant and radioprotective properties of a novel extremophile from mud volcano: implications for management of radiation emergencies Atlar Singh Dhaker • Rohit Marwah • Rakesh Damodar • Damodar Gupta • Hemant Kumar Gautam • Sarwat Sultana • Rajesh Arora Received: 13 December 2010 / Accepted: 17 March 2011 / Published online: 3 April 2011 Ó Springer Science+Business Media, LLC. 2011 Abstract A thermophilic bacterium, designated as RH 127, was isolated from mud volcano (Baratang Islands) of Andaman region, India (12°07 0 N 92°47 0 E/12.117°N 92.783°E) for the first time. Biochemical tests and 16S rRNA gene sequencing indicate that it belongs to the genus Geo- bacillus. The strain showed 98% confirmed 16S rRNA gene sequence homology with Geobacillus toebii. The bacteria was extracted in various solvent systems and three different fractions prepared. In the present study, antioxidant and radioprotective activity of extracts (INM-7860, INM-7861, and INM-7862) of bacterium G. toebii (strain RH 127) were evaluated. The fractions were evaluated for their introspec- tive comparison of the relative antioxidant efficiency. The antioxidative activities, DPPH radical scavenging effects, hydroxyl radical scavenging effects, membrane protection, antihemolytic activity, and linoleic acid degradation effica- cies were assayed. INM-7861 and INM-7862 activated NF-jB expression, as evidenced by reporter assay studies, and thereby contributed to overall radioprotective effect. INM-7862 exhibited best results. This study explicitly shows that the extracts of G. toebii have immense potential as a radiation countermeasure agent. Keywords Antioxidant Á Geobacillus toebii (strain RH 127) Á Linoleic acid Á Liposome Á Radioprotective Á NF-jB Introduction Extremophiles are organisms that thrive in physically or geochemically extreme environments that are otherwise detrimental to the majority of life on earth. Extremophiles are classified, according to the conditions in which they exist, as thermophiles, hyperthermophiles, psychrophiles, halophiles, acidophiles, alkaliphiles, barophiles, and endo- liths [1]. Due to their ability to endure and survive in extreme environments, these organisms have developed mechanisms for producing high capacity biologically active compounds (BAC) and have been the focus of attention for discovery of novel drugs. Some of the extremozymes, derived from such microbes, have been studied in detail indicating that they produce a variety of antibacterial, antifungal, antilarval, antiprotozoan, antialgal, anti- helminthic, and generally cytotoxic secondary metabolites [2], besides they can be genetically modified to produce entirely new, clinically relevant compounds [3]. Their ability to act as an anticancer agent is equally promising [4]. Thermophiles are the group of extremophiles that can sur- vive in high temperature conditions. Rather they thrive at rel- atively high temperatures, i.e. between 45°C and 80°C (113°F and 176°F) [5]. They have been reported to be extremely useful for humans with diverse industrial as well as clinical applica- tions. They have been exploited to date in many fields like bioremediation, bioleaching, and biomining [6]. The thermophiles have received a lot of attention in the recent years. Thermophilic bacteria such as Geobacillus ste- arothermophilus, Geobacillus thermocatenulatus, Geobacil- lus thermoleovorans, Geobacillus kaustophilus, Geobacillus A. S. Dhaker Á R. Marwah Á D. Gupta Á R. Arora (&) Radiation Biotechnology Group, Institute of Nuclear Medicine and Allied Sciences (Defence Research and Development Organization; DRDO), Brig S. K. Mazumdar Marg, Delhi 110054, India e-mail: rajesharoradr@rediffmail.com R. Damodar Á H. K. Gautam Institute of Genomics and Integrative Biology, Mall Road, Delhi 110054, India S. Sultana Department of Toxicology and Medical Elementology, Jamia Hamdard, Hamdard Nagar, Delhi, 110062, India 123 Mol Cell Biochem (2011) 353:243–250 DOI 10.1007/s11010-011-0792-7