Biochemical and tissue physiopathological evaluation of the preclinical efficacy of Solanum torvum Swartz leaves for treating oxidative impairment in rats administered a β-cell-toxicant (STZ)

Abstract

The current study evaluated the protective role of Solanum torvum Swartz against diabetes-induced oxidative stress and tissue impairment in streptozotocin (STZ)-intoxicated rats. Rats with STZ (40 mg/kg intraperitoneally (i.p.))-induced diabetes were divided into five groups (n = 5) and treated with (i) normal saline, (ii) 150 mg/kg body weight (BW) of the ethanol extract of S. torvum leaf (EESTL), (ii) 300 mg/kg BW EESTL, (iv) 100 mg/kg BW metformin, and (v) 50 m/kg BW metformin + 100 mg/kg BW EESTL orally for 21 days. Our results revealed that the EESTL displayed dose-dependent ferric-reducing antioxidant power (FRAP) activity, scavenged DPPH radicals (IC₅₀) = 13.52 ± 0.45 µg/mL), and inhibited lipid peroxidation in an in vitro models. In addition, the EESTL demonstrated dose-dependent inhibitory activity against α-amylase (IC₅₀ =138.46 ± 3.97 µg/mL) and promoted glucose uptake across plasma membranes of yeast cells in a manner comparable to that of metformin. Interestingly, the extract demonstrated in vivo blood glucose normalization effects with concomitant increased activities of antioxidant parameters (superoxide dismutase (SOD), catalase, and reduced glutathione (GSH)) while decreasing malondialdehyde (MDA) levels when compared to untreated rats. Similarly, serum biochemical alterations, and tissues (liver, kidney, and pancreases) histopathological aberrations in untreated rats with STZ-induced diabetes were attenuated by treatment with the EESTL. Biometabolite characterization of the extract identified gallic acid (45.81 ppm), catechin (1.18 ppm), p-coumaric acid (1.43e^-1 ppm), DL-proline 5-oxo-methyl ester (9.16 %, retention time (RT): 8.57 min), salicylic acid (3.26% and 7.61 min), and butylated hydroxytoluene (4.75%, RT: 10.18 min) as the major polyphenolic compounds in the plant extract. In conclusion, our study provides preclinical evidence of the antioxidant properties and oxidative stress-preventing role of S. torvum in STZ-dosed diabetic rats. Taken together, the EESTL represents a reserve of bioactive metabolites for managing diabetes and associated complications.

Keywords: Antioxidant; Diabetes mellitus; Organ histopathology; Oxidative stress; Solanum torvum Swartz.