Metabolite Profiling and Nephroprotective Potential of the Zea mays L. Silk Extract against Diclofenac-Induced Nephrotoxicity in Wistar Rats

The lack of sufficient scientific evidence prompted the analytical investigation of nephroprotective potential of the silk extract of Zea mays L., which is traditionally and ethnomedicinally used for various disorders including kidney dysfunction. The present study was conducted to investigate the phytochemical analysis and demonstrate the nephroprotective potential of the methanolic silk extract of Z. mays L. using a rodent model. High-performance thin-layer chromatography (HPTLC) analysis was carried out to standardize the methanolic silk extract of Z. mays (ZME) using naringenin as a marker. The metabolite profiling of the ZME was carried out using ultrahigh-performance liquid chromatography mass spectrometry (UPLC-MS) on a monolithic capillary silica-based C18 column to identify bioactive compounds and for confirmation of the identified markers. Furthermore, for acute toxicity study, a single dose (2000 mg/kg bw) of the ZME was administered orally to Wistar rats. Also, nephrotoxicity was induced in Wistar rats by injecting diclofenac (DC) (50 mg/kg, bw, i.p.) at a single dose. The efficacy of the ZME as a nephroprotective agent was then evaluated at doses of 100, 200, and 400 mg/kg/day, bw, p.o. Furthermore, the kidney, liver, antioxidant, inflammatory, and apoptotic biochemical markers and histopathological and immunohistochemical alterations (caspase-3 and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-4 (NOX-4)) were evaluated. Phytochemical analysis by HPTLC and UPLC-MS revealed the presence of naringenin, vanillic acid, ferulic acid, gallic acid (GA), ellagic acid, quercetin, and morin, along with other bioactive constituents exhibiting multiple pharmacological properties. The acute toxicity study of the ZME showed no mortality or any clinical signs of toxicity through all the 14 days of the toxicity study at a dose of 2000 mg/kg. Also, administration of DC caused a significant elevation (P < 0.001) in kidney biochemical parameters and also caused oxidative, inflammatory, and apoptotic stress. Furthermore, DC also caused histopathological and immunohistochemical changes. Pretreatment with the ZME attenuated the elevated biochemical markers significantly at medium and high doses along with improvement in histopathological and immunohistochemical damages and showing comparable results to those of α-ketoanalogue. The present study verifies the traditional claims of Z. mays silk alleviating various kidney and related disorders by