Non-aqueous DPPH spectrophotometric assay for evaluating lipophilic compounds with tocopherol acetate calibration

Abstract

For assessing antioxidant activity of hydrophilic and lipophilic compounds, hydrophilic standards (Trolox, ascorbic acid, gallic acid, rutin, etc.) are most commonly used in spectrophotometric studies. However, for lipophilic substances, it is more appropriate to perform the analysis in non-aqueous conditions and compare their activity with a lipophilic standard. α‑Tocopherol serves as such a standard, demonstrating activity comparable to Trolox (1). Therefore, a DPPH-based method in a non-aqueous medium was developed using α‑tocopherol as a standard and applied to chamomile essential oil