Optimization of UAE of phenolic and antioxidant compounds from Ephedra foeminea by RSM

Abstract

Ephedra foeminea Forssk, a widely distributed shrub in the East Mediterranean, possesses numerous traditional medicinal applications and is an abundant source of bioactive phytochemical metabolites. In this study, ultrasonic-assisted extraction (UAE) was utilized to optimize the extraction yield (Y%), total phenolic content (TPC), and radical scavenging activity (RSA%) of E. foeminea's aerial parts using response surface methodology (RSM). A central composite design (CCCD) was implemented to investigate the effects of four independent variables, namely the extraction volume (V ranging from 20-40 mL/g of dry powder), Ethanol percentage in the extraction solvent (E ranging from 50-70%), sonication time (S ranging from 10-20 min), and temperature (T ranging from 35-45°C). The optimal conditions for Y%, TPC, and RSA% were predicted by enhanced models generated by RSM analysis. The quadratic and enhanced models effectively fitted the observed results, as demonstrated by lack-of-fit tests (p > 0.05) and high R2, R2adj, and R2pred values. These models were also able to produce a Y% of 11.93 ± 0.09%, with parameters V = 28.2 mL/g, E = 69.1%, S = 19.3 min, and T = 39.1°C. Additionally, the models produced a TPC of 3.06 ± 0.06 mg GAE/g, with parameters V = 32.2 mL/g, E = 65.5%, S = 17.1 min, and T = 40.7°C, as well as a radical scavenging activity RSA% of 90.63 ± 1.08%, with parameters V = 31.0 mL/g, E = 67.1%, S = 19.5 min, and T = 40.9°C. Validation by HPLC analysis revealed an optimization of extraction of phenolic compounds such as gallic acid, luteolin, and apigenin. Principal component analysis (PCA) indicated that PC1 and PC2 accounted for 98.0% of the variables, illustrating a strong correlation between TPC and antioxidant activity. Overall, this study demonstrated the effectiveness of using RSM-optimized conditions for UAE extraction of phytochemicals from E. foeminea and substantiating further research on the phenolic content of the plant.