In vitro and in vivo Antioxidant and Toxicological Evaluation of Syzygium guineense (Wild.) DC. var. guineense under Salmonella Typhimurium-Induced Oxidative Stress

Abstract

Aims: To identify Syzygium guineense as a potential plant derived source of novel effective antioxidant therapeutics against typhoid. Study Design: Cytotoxicity (MTT) and in vitro antioxidant assays were performed on ethanolic leaf (SGLE) and stem bark (SGBE) extracts. Acute toxicity and oxidative stress modulation were evaluated in Salmonella Typhimurium infected Wistar rats and treated with SGLE within 14 days. Place and Duration of Study: Laboratory of Phyto-biochemistry and Medicinal Plant Studies and the Department of Animal Biology and Physiology, University of Yaoundé I, Cameroon (June-November 2024). Methodology: Crude ethanolic extracts (98%) of SGLE and SGBE were prepared. Cytotoxicity was assessed using RAW and Vero cell lines. In vitro antioxidant activity was evaluated via DPPH, ABTS, and FRAP assays. Wistar albino rats were used for evaluation of acute toxicity, oxidative stress parameters were evaluated using the liver, kidneys and intestine of rats. The parameters included reduced glutathione (GSH), hydrogen peroxide (H2O2) and Nitric oxide (NO), catalase (CAT), Superoxide dismutase (SOD) and Malondialdehyde activity (MDA) assays. Results: In vitro antioxidant activities of SGLE extract were; 15.35±1.774, 14.70±1.137 and 27.29±1.011 µg/mL for ABTS, DPPH and FRAP respectively. SGLE was non-cytotoxic (CC50>500 µg/mL). Acute toxicity studies suggested LD50>5000 mg/kg. Organs’ homogenates revealed a decrease in GSH, SOD (P <0.001) and CAT (P <0.001 in kidneys and intestines and P <0.01 for liver). Also, there was increased nitrite (P >0.05 for liver and kidneys, and P=0.001 for intestines and MDA (P <0.001) in Salmonella-infected and non-treated groups compared to the normal control group. Extract administration of 150 mg/kg, 300 mg/kg, and 600 mg/kg produced a highly significant improvement in oxidative stress markers (P< 0.001), restoring altered parameters toward normal levels. Conclusion: The in vitro cytotoxicity and antioxidant activities along in vivo acute oral toxicity and antioxidant activities observed shows that Syzygium guineense could be a potential candidate against typhoid.