Definitive screening design and I-optimal design for optimization of ultrasound-assisted extraction of phenolic content and antioxidant capacity from Salviaofficinalis L. leaves

Abstract

A definitive screening design and an I-optimal design were carried out for the screening and optimization of ultrasound's extraction conditions of total phenolic compounds (TPC) and antioxidant capacities (TEAC and TAC) from S. officinalis L. leaves. The optimal conditions for maximum TPC, TEAC, and TAC were 52% ethanol-water, 60 °C temperature, 30 mL g−1 solvent to solid ratio, and 10 min of extraction time. The optimal extract showed higher TPC, TEAC, and TAC with 31.84 ± 0.248 mgGAE/gdw, 237.95 ± 0.771 μmolTE/gdw, and 38.928 ± 0.548 mgAAE/gdw respectively. Furthermore, the optimal extract obtained exhibited a higher scavenging activity against DPPH•, NO• free radicals, and β-carotene/linoleic acid bleaching activity with IC50 of 0.276 ± 0.001 mg/mL, and 0.069 ± 0.0005 mg/mL, and 0.159 ± 0.008 mg/mL respectively. The reducing power of the optimal extract at 0.3 mg/mL of lyophilized powder was approximately 2 mmol Fe+2 equivalent/g. Thus, S. officinalis L. leaves are expected to be an excellent source for pharmaceutical and cosmetic industries for developing potential drugs.