In Vitro Antioxidant Activities and In Vivo Modulation of Testicular Oxidative Stress Markers by Verminoside and Specioside Isolated from Spathodea campanulata

Abstract

Background: Lead exposure remains a major public health concern, with oxidative stress being a principal mechanism underlying its reproductive toxicity. Due to adverse effects associated with conventional chelation therapy, plant-derived antioxidants are increasingly explored as safer alternatives. Verminoside and specioside, iridoid glycosides isolated from Spathodea campanulata, possess antioxidant properties that may protect against lead-induced oxidative damage. Methods: The in vitro antioxidant activities of verminoside and specioside were evaluated using DPPH radical scavenging and ferric reducing antioxidant power (FRAP) assays. Oxidative stress markers including malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), nitric oxide (NO), and total antioxidant capacity (TAC) were assessed in testicular tissue homogenates following lead exposure. Results: Verminoside and specioside demonstrated significant concentration-dependent antioxidant activity in DPPH and FRAP assays. The FRAP EC50 values were 39.36±4.09 µg/ml, 48.50±8.98 µg/ml and 34.05±4.94 µg/ml for specioside, verminoside and ascorbic acid respectively, while the DPPH IC50 values were 59.67±0.58 µg/ml, 61.50±0.50 µg/ml and 50.00±0.00 µg/ml for specioside, verminoside and ascorbic acid respectively. Both compounds significantly (p< 0.05) reduced lipid peroxidation and nitrosative stress, while significantly (p< 0.05) restoring antioxidant enzyme activities and non-enzymatic antioxidant levels in testicular tissues. Conclusion: Verminoside and specioside exhibit strongin vitro antioxidant activity and demonstrate protective effects against lead-induced oxidative stress in vivo.