Isolation and Structural Characterization of Bioactive Compounds from Vitis vinifera L. Peel

Background: Vitis vinifera L. (Vitaceae) is an important medicinal and nutritional plant rich in polyphenolic compounds, particularly trans-resveratrol, a naturally occurring stilbene with well-documented antioxidant and antiinflammatory properties. Grape peel, an abundant agro-industrial by-product, represents a sustainable and economical source of this valuable phytoconstituent. Objective: The present study aimed to extract, isolate, purify, and characterize trans-resveratrol from Vitis vinifera peel and evaluate its in vitro antioxidant, anti-inflammatory, and cytotoxic activities. Materials and Methods: Dried grape peel powder was extracted using 70% ethanol by Soxhlet extraction, followed by ethyl acetate partitioning and silica gel column chromatography for isolation of resveratrol. The purified compound was characterized using thin-layer chromatography (TLC), UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, high-performance liquid chromatography (HPLC), and liquid chromatography–tandem mass spectrometry (LC–MS/MS). Antioxidant activity was evaluated by DPPH, ABTS, and ferric reducing antioxidant power (FRAP) assays. Anti-inflammatory activity was assessed using albumin denaturation, proteinase inhibition, and human red blood cell membrane stabilization assays. Cytotoxicity was determined by the MTT assay using RAW 264.7 macrophage cells. Results: Hydroalcoholic extraction followed by chromatographic purification successfully yielded trans-resveratrol with chromatographic and spectroscopic characteristics comparable to the authentic standard. The isolated compound exhibited concentration-dependent antioxidant activity in DPPH, ABTS, and FRAP assays and demonstrated significant inhibition of protein denaturation, proteinase activity, and erythrocyte membrane lysis. MTT analysis indicated low cytotoxicity toward RAW 264.7 cells within the tested concentration range. Conclusion: The findings suggest that Vitis vinifera peel is a promising and sustainable source of naturally occurring trans-resveratrol. The isolated compound exhibited favorable antioxidant, anti-inflammatory, and cellular safety profiles, supporting its potential application in pharmaceutical, nutraceutical, and functional food formulations. Further in vivo studies and formulation development are warranted.