"Determination of Sterol Content in Some Vegetable Oils and Study of their Biological Activity as Antioxidants"

Abstract

     Plant-derived phytosterols, as naturally occurring constituents in plants, have attracted increasing attention due to the association between their consumption and a reduced risk of cardiovascular diseases and cancer. Extraction procedures and separation methods for sterol compounds were applied to eleven vegetable oil samples obtained from the local market. Brassicasterol, Campesterol, Stigmasterol, and                  β-Sitosterol were quantitatively determined using HPLC-DAD. The mobile phase consisted of a mixture of (Acetonitrile : 0.1% Formic acid in Water) in a ratio of (80:20)% v/v. β-Sitosterol was found to be the predominant sterol in all analyzed oils. Among the tested samples, evening primrose oil exhibited the highest total sterol content, indicating its potential nutritional and therapeutic value due to its sterol-rich composition. Furthermore, the antioxidant activity of the investigated phytosterols was evaluated using a rapid spectrophotometric method based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. Notably, the coconut oil extract exhibited a significantly higher IC₅₀ value          (2643.40 µg.mL^-1) compared with the evening primrose oil extract (134.95 µg.mL^-1), indicating a stronger antioxidant activity for evening primrose oil under the applied experimental conditions.