Pharmacognostic, physicochemical, phytochemical, and preliminary phytoconstituent analysis of Allium cepa (Onion) bulbs

Allium cepa (onion) is a widely cultivated medicinal and dietary plant traditionally valued for its therapeutic properties, including antioxidant, anti-inflammatory, and antimicrobial activities. Despite its extensive use, systematic pharmacognostic and phytochemical standardization is essential to ensure its medicinal quality, safety, and efficacy. The present study was undertaken to conduct comprehensive pharmacognostic, physicochemical, and phytochemical evaluations, as well as preliminary quantitative analysis of phenolic and flavonoid contents in Allium cepa. The plant material was subjected to macroscopic, microscopic, and powder microscopy evaluations. Physicochemical parameters such as ash values, extractive values, foreign matter, moisture content, and swelling index were determined. Ethanolic and aqueous extracts were prepared for preliminary phytochemical screening. Total phenolic and flavonoid contents were quantified using Folin-Ciocalteu and aluminium chloride colorimetric methods, respectively. TLC profiling was also performed to assess phytochemical diversity. The physicochemical parameters complied with standard limits, with a total ash value of 5.80% and moisture content of 7.10%. Ethanolic extract exhibited higher yields (18.40%) and richer phytochemical profiles than aqueous extract. Total phenolic content was 65.20 mg GAE/g extract in ethanol, while flavonoid content was 48.35 mg QE/g extract, both superior to aqueous extracts. TLC analysis revealed more distinct phytoconstituent spots in ethanolic extracts, confirming higher chemical diversity. The study successfully established diagnostic, physicochemical, and phytochemical parameters for Allium cepa, confirming its medicinal authenticity and supporting its traditional therapeutic uses. The findings provide baseline data for future formulation and pharmacological investigations.