title: Oxidative stress-induced methemoglobinemia is the silent killer during snakebite: a novel and strategic neutralization by melatonin.
abstract: Oxidative stress-induced methemoglobinemia remained an untouched area in venom pharmacology till date. This study for the first time explored the potential of animal venoms to oxidize hemoglobin to methemoglobin. In in vitro whole-blood assay, methemoglobin forming ability of venoms varied as Naja naja > Ophiophagus hannah > Echis carinatus > Daboia russellii > Apis mellifera > Mesobuthus tamulus > Hippasa partita. Being highly potential, N. naja venom was further studied to observe methemoglobin formation in RBCs and in combinations with PMNs and PBMCs, where maximum effect was observed in RBCs + PMNs combination. Naja naja venom/externally added methemoglobin-induced methemoglobin formation was in parallel with ROS generation in whole blood/RBCs/RBCs + PMNs/RBCs + PBMCs. In in vivo studies, the lethal dose (1 mg/kg body weight, i.p.) of N. naja venom readily induced methemoglobin formation, ROS generation, expression of inflammatory markers, and hypoxia-inducible factor-3α. Although the mice administered with three effective doses of antivenom recorded zero mortality; the methemoglobin and ROS levels remained high. However, one effective dose of antivenom when administered along with melatonin (1:50; venom/melatonin, w/w), not only offered 100% survival of experimental mice, but also significantly reduced methemoglobin level, and oxidative stress markers including hypoxia-inducible factor-3α. This study provides strong drive that, complementing melatonin would not only reduce the antivenom load, but for sure greatly increase the success rate of antivenom therapy and drastically minimize the global incidence of snakebite deaths. However, further detailed investigations are needed before translating the combined therapy towards the bed side.
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.
authors.forename: Rachana D
authors.initials: RD
authors.lastname: Sharma
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.
authors.forename: Gajanan D
authors.initials: GD
authors.lastname: Katkar
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.
authors.forename: Mahalingam S
authors.initials: MS
authors.lastname: Sundaram
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.
authors.forename: Manoj
authors.initials: M
authors.lastname: Paul
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.
authors.forename: Somanathapura K
authors.initials: SK
authors.lastname: NaveenKumar
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.
authors.forename: Basavarajaiah
authors.initials: B
authors.lastname: Swethakumar
authors.affiliation: Department of Internal Medicine, Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Mahadevappa
authors.initials: M
authors.lastname: Hemshekhar
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.|Department of Studies and Research in Biochemistry, Tumkur University, Tumkur, India.
authors.forename: Kesturu S
authors.initials: KS
authors.lastname: Girish
authors.affiliation: Department of Studies in Biochemistry, University of Mysore, Mysuru, India.
authors.forename: Kempaiah
authors.initials: K
authors.lastname: Kemparaju
mesh_terms: D000818:Animals; D006801:Humans; D008550:Melatonin / Q000494:pharmacology*; D008708:Methemoglobinemia / Q000097:blood / Q000188:drug therapy* / Q000209:etiology; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012909:Snake Bites / Q000097:blood / Q000188:drug therapy*; D012910:Snake Venoms / Q000633:toxicity
chemical_list: D017382:Reactive Oxygen Species; D012910:Snake Venoms; D008550:Melatonin
keywords: antivenom; hypoxia; melatonin; methemoglobin; oxidative stress; red blood cells; venom