Nephroprotective effect of Physalis peruviana L. calyx extract and its butanolic fraction against cadmium chloride toxicity in rats and molecular docking of isolated compounds

Abstract

Background: Cadmium is an environmentally toxic metal that has deleterious effects on both animals and humans due to its accumulation in different body tissues. Physalis peruviana L. fruit and calyx contain many active constituents which are used traditionally for their different biological activities. Based on the traditional uses of P. peruviana L. calyx, we aimed to evaluate the nephroprotective effect of their 80% aqueous methanol extract (AME) and n-butanol fraction (Bu.F.) against cadmium chloride-induced nephrotoxicity in rats and to correlate this activity with phytoconstituents isolated using molecular docking studies.

Methods: The n-butanol fraction of P. peruviana L. calyx was fractionated using various chromatographic techniques and the isolated compounds were identified based on their chemical and spectroscopic data. The nephroprotective activity was assessed using cadmium chloride-induced nephrotoxicity in the rat model, by measuring some important parameters such as body weight, kidney weight, serum urea, and creatinine levels, oxidative stress markers, inflammatory markers, and histopathological examinations of kidney tissue. Molecular docking studies of the isolated compounds were performed.

Results: Three withanolides named 4 β-hydroxywithanolide E (1), Physalin B (2) and 3α, 14β-dihydroxywithaphysalin N (3) were isolated and identified from the n-butanol fraction of P. peruviana L calyx extract. The extract and its butanol fraction significantly improved the serum kidney function markers and tissue oxidative status including malondialdehyde (MDA), reduced glutathione (GSH) and catalase (CAT). Additionally, the extracts significantly decreased the levels of tumor necrosis factor-alpha (TNF-α) and nuclear factor kappaB (NF-κβ). Moreover, the histological changes were ameliorated by the extracts. The molecular docking study showed that the isolated compounds displayed a remarkable inhibitory activity against IκB kinase.

Conclusion: The AME and its butanol fraction of P. peruviana L calyx showed potential nephroprotective activity against cadmium chloride-induced nephrotoxicity which is correlated at least in part to its considerable withanolides content.

Keywords: Anti-inflammatory; Antioxidant; Nephrotoxicity; Physalis peruviana L calyx; Withanolides.

Fig. 1

Schematic diagram for the experimental design. CdCl₂: Cadmium chloride, AME: Aqueous methanolic extract, Bu.F: Butanol Fraction

Fig. 2

Withanolides isolated from P. peruviana L. calyx Bu. F

Fig. 3

Effect of AME and Bu.F. of P. peruviana L. calyx on oxidative stress markers in Cd-induced nephrotoxicity in rats. Data presented as Mean ± SE (n = 6); a: significant from the control group at P < 0.05; b: significant from the CdCl₂ group at P < 0.05; CdCl₂: c: significant from the standard group at P < 0.05; Cadmium chloride, AME: Aqueous Methanolic Extract, Bu.F: Butanol Fraction

Fig. 4

Effect of AME and Bu.F. of P. peruviana L. calyx on inflammatory markers in Cd-induced nephrotoxicity in rats. Data presented as Mean ± SE (n = 6); a: significant from the control group at P < 0.05; b: significant from the CdCl₂ group at P < 0.05; CdCl₂: c: significant from the standard group at P < 0.05; Cadmium chloride, AME: Aqueous Methanolic Extract, Bu.F: Butanol Fraction

Fig. 5

Effect of AME and Bu.F. of P. peruviana L. calyx on histopathological examinations with hematoxylin and eosin (H&E) in CdCl₂-induced nephrotoxicity in rats: Control: Normal distal convoluted tubules (arrow), proximal convoluted tubules (red arrow), glomeruli (asterisk), and urinary spaces (short arrow); CdCl₂-I: Inflammatory infiltration (arrow), glomerular hypercellularity (asterisk) with narrow urinary spaces (arrowhead); CdCl₂-II: Interstitial hemorrhage (arrows), and desquamation of tubular epithelial cells (arrowhead); AME 500–1: Renal structure appeared nearly to normal form; AME 500-II: Inflammatory infiltration (arrow), glomerular hypercellularity (asterisk), with narrow urinary spaces (arrow head), and tubular interstitial hemorrhage (arrowheads); AME 1000-I: Renal structure appeared nearly to normal form; AME 1000-II: Glomerular hypercellularity (asterisk) with narrow urinary spaces (arrow head), and interstitial Hemorrhage (arrows); Bu.F. 500-I: More or less normal renal corpuscles (arrow head), and renal tubular degenerative changes (arrow); Bu.F. 500-II: Normal renal corpuscles and tubules; Bu.F. 1000: Renal corpuscles and the renal tubules appeared nearly too normal form; Silymarin-I: Renal structure appeared nearly to normal form; Silymarin-II: Glomerular congestion and hypercellularity and narrow urinary space (arrow head), and tubular degenerative changes with pyknotic nuclei (arrow) (Scale Bar 100 µm). CdCl₂: Cadmium chloride, AME: Aqueous Methanolic Extract, Bu.F: Butanol Fraction

Fig. 6

2D view of Co-crystallized Ligand with the key amino acid of 4KiK protein

Fig. 7

Selected key 2D docking views of Compounds 1–3