<p>High-Performance Thin-Layer Chromatography (HPTLC) Fingerprinting, Bioactive Composition, and Antioxidant Activity of <em>Citrus sinensis </em>Peel Extract</p>

Citrus sinensis (Malta) fruit peels, often regarded as waste, represent a cost-effective and eco-friendly source of bioactive compounds. The present investigation focused on phytochemical screening, High-Performance Thin-Layer Chromatography (HPTLC) fingerprinting, citric acid quantification, and antioxidant evaluation of C. sinensis peel extract. Preliminary phytochemical analysis confirmed the presence of alkaloids, flavonoids, phenols, saponins, and terpenoids in the 70% ethanolic peel extract. Quantitative estimation revealed 0.5% citric acid content in the peel. HPTLC fingerprinting was performed for absolute hexane, acetone, and 70% ethanolic extracts of C. sinensis peel. Among the tested extracts, the acetone extract showed the most promising results, exhibiting greater compound separation compared to the others. Furthermore, the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay demonstrated a concentration-dependent activity of the extract, ranging from 40.97% inhibition at 200 μg to a maximum of 87.38% at 1,000 μg, establishing it as a potent natural antioxidant. These findings highlight the potential of Malta peel as a sustainable source for incorporation into food, pharmaceutical, and cosmetic formulations, thereby improving product safety, shelf life, and consumer acceptability while reducing reliance on synthetic preservatives with possible toxic effects.