Ultrasound assisted extraction of antioxidative phenolics from cashew (Anacardium occidentale L.) leaves.

Optimization of ultrasound-assisted extraction (UAE) of antioxidative phenolics from the leaves of cashew (Anacardium occidentale L.) was carried out by response surface methodology along with the central composite design. Two independent variables were considered: amplitude (30-77%) and time (7-31 min). The highest extraction yield was 23.61% when the optimal extraction condition (77% amplitude for 31 min) was implemented. The extract containing total phenolic content of 579.55 mg GAE/g dry extract possessed radical scavenging activities and reducing power. The experiment values were in line with the predicted counterparts. Extract contained gallic acid, isoquercetin, tannic acid, quercetin, catechin, apigenin, hydroquinin, eriodictyol, and rutin. The extract with increasing levels inhibited AAPH-induced DNA damage to a higher extent. Thus, UAE was demonstrated to potentially increase the extraction efficacy of phenolics from cashew leaves and the extract could be applied as a natural antioxidant.