Response of antioxidants to semisynthetic bacteriostatic antibiotic (erythromycin) concentrations: A study on freshwater fish Sivashankar Renuka a , Sathisaran Umamaheswari a , Chellappan Shobana a , Mathan Ramesh a , ⁎, Rama Krishnan Poopal b , ⁎ a Unit of Toxicology, Department of Zoology, School of Life Sciences, Bharathiar University, Coimbatore 641046 , Tamil Nadu, India b Environmental Toxicology and Toxicogenomics Laboratory, Department of Environmental Biotechnology, School of Environmental Sciences, Bharathidasan University, Tiruchirappalli 620024 , Tamil Nadu, India abstract article info Article history: Received 26 April 2018 Received in revised form 17 August 2018 Accepted 20 August 2018 Available online xxxx The present study was envisioned to assess the short (96 h) and long-term (35 days) antioxidant responses of Labeo rohita exposed to different concentrations (10, 50, and 100 μg/L) of commonly used antibiotic, erythromy- cin. When compared to the control groups, superoxide dismutase (SOD) activity in the gills of the erythromycin treated fingerlings was significantly (P b .05) decreased during short-term, and the activity was increased (except 7 th day in 10, and 50 μg/L) during long-term study period. Whereas in the liver, SOD activity of the eryth- romycin treated fingerlings was significantly (P b .05) elevated throughout the exposure period. In both the study period, catalase (CAT) activity in the gills, and liver of the erythromycin treated fingerlings were signifi- cantly (P b .05) decreased, when compared to the control groups. Glutathione peroxidase GPx, and lipid peroxi- dation (LPO) activities in the gills, and liver of the erythromycin treated fingerlings were found higher than the control groups in the both (short, and long-term) study period. In conclusion, erythromycin induce oxidative stress in aquatic organism (L. rohita), and this data could be an effective baseline for molecular toxicology to mon- itor the impact of antibiotics on non-target organisms. © 2018 Ecological Society of China. Published by Elsevier B.V. All rights reserved. Keywords: Eco-toxicology Antibiotic Indian major carp Antioxidant Emerging contaminant 1. Introduction Rapid development in medical field contributes new pharmaceuti- cals to the humankind. It has dual role that is beneficial as medication and tough as aquatic contaminant. Pollution from medical stuffs, espe- cially medications are a serious aquatic problem throughout the world [1,2]. Direct discharge of the medical wastes, domestic wastes, and dis- posal of unused and expired drugs were the major sources of pharma- ceuticals in the aquatic environment [3]. As a result, the pharmaceuticals have been detected up to mg levels in various environ- mental matrices such as, streams, rivers, ground water, drinking water, and creates many problems including water borne diseases [4–6]. Among the medications, antibiotics were predominant/common in treating animals, and humans against pathogens, as well as growth reg- ulators in livestock [7]. The overuse/production of the antibiotics could lead serious environmental and health issues [8]. Several studies have been reported on the presence of the antibiotics in the surface water [8,9], ground water [10,11], municipal wastewater [12,13], soil [14] and even in the drinking water [15]. Rico et al. [16] mentioned the oc- currence of antibiotics in the aquatic environment relatively low ranges (0.001 μg/L-10 μg/L). The antibiotics are considered as “pseudo-persis- tent” contaminants, it is due to their continuous entry and presence in the aquatic environment [17]. Antibiotics are classified broadly as β-Lactams, macrolides, fluroquinolones, tetracycline, and aminoglycoside. Among them, macrolides are used against gram positive bacteria. The available types of macrolides are erythromycin, azithromycin, telithromycin, clarithromycin, and fidaxomicin. Erythromycin is a semisynthetic bacte- riostatic antibiotic formed by the gram-positive bacterium Saccharopolyspora erythraea and used prevalent antibiotic since the 1950s [18]. Erythromycin has low log Kow = 3.06 thus more water sol- uble, it is optimal at pH 7–8 and the degradation is based on the pH, the photodegradable period under natural light is 45 days, and the rate is 36.7% [19]. Erythromycin A is the major component, which at slightly higher and high pH medium it converts to erythromycin A enol ester, and pseudo erythromycin A enol ester, respectively. Erythromycin have been used as single or combined forms, for instance, the antibiotic activity found to be higher in combination of erythromycin and zinc ac- etate [20]. The methods adopted in sewage treatment plants were not much efficient to remove organic contaminants, as result removal effi- ciency for erythromycin is b50% and thus it is ubiquitous in the environ- ment [13]. Erythromycin acts on the prevention of protein synthesis by irre- versibly binding to the subunit 50S of the bacterial ribosome [21], thus Acta Ecologica Sinica xxx (2018) xxx–xxx ⁎ Corresponding authors. E-mail addresses: mathanramesh@yahoo.com (M. Ramesh), poopalramakrishanan@ymail.com (R.K. Poopal). CHNAES-00592; No of Pages 7 https://doi.org/10.1016/j.chnaes.2018.08.002 1872-2032/© 2018 Ecological Society of China. Published by Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Acta Ecologica Sinica journal homepage: www.elsevier.com/locate/chnaes Please cite this article as: S. Renuka, et al., Response of antioxidants to semisynthetic bacteriostatic antibiotic (erythromycin) concentrations: A study on freshwater fish, Acta Ecologica Sinica (2018), https://doi.org/10.1016/j.chnaes.2018.08.002