Impact of thermal processing and solvent extraction on antioxidants in Orobanche coerulescens

Orobanche coerulescens traditionally used in herbal medicine and as a nutraceutical, contains important antioxidant compounds. However, the antioxidant profile of O. coerulescens and the process conditions that maximize its antioxidant potential have never been systematically evaluated. This study provides the comprehensive assessment of how thermal processing combined with a range of organic solvent concentrations influences the antioxidant contents and activities of O. coerulescens. Initial screening showed that samples dried at 80 °C and extracted with 95% methanol exhibited the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability and reducing power, as well as elevated total flavonoid (TF) and total phenol (TP) contents, compared with samples dried at 40 °C and 60 °C. This identified 80 °C as the optimal drying temperature for enhancing antioxidant properties. Further comparisons of extraction methods revealed that combining 80 °C drying with 40% methanol or ethanol significantly increased DPPH scavenging, while 60% methanol or ethanol under the same drying temperature enhanced reducing power relative to other solvent concentrations and aqueous water-bath treatments. These findings indicate that optimized thermal and solvent conditions improve the antioxidant profile of O. coerulescens for its potential as a valuable natural antioxidant source. Future work should investigate the protective, inhibitory, and functional effects of these optimized extracts in animal models to verify their in vivo bioactivities.