Development and extraction optimization of baicalein and pinostrobin from Scutellaria violacea through response surface methodology

Objective: To develop a process that involves optimization of the amount of baicalein and pinostrobin from the hydro‑methanolic extract of the leaves of Scutellaria violacea by response surface methodology (RSM). Materials and Methods: The combinatorial influence of various extraction parameters on the extraction yield was investigated by adopting Box–Behnken experimental design. Preliminary experiments carried out based on the traditional one variable at a time optimization revealed four such operational parameters to play a crucial role by influencing the yield. These four process parameters at three levels were considered to obtain the Box–Behnken experimental design. Results: RSM based model fitted to the resulting experimental data suggested that 52.3% methanol/water, 12.46:1 solvent‑solid ratio, 285 rpm agitation and 6.07 h of extraction time are the optimal conditions which yielded a maximized amount of baicalein and pinostrobin of 2.9 and 4.05 mg/g DM. Analysis of variance revealed a high correlation coefficient (R2 = 0.999 for baicalein and 0.994 for pinostrobin), signifying a good fit between the regression model (second order) and the experimental observations. Conclusion: The present study signifies that both the metabolites have been extracted from S. violacea for the first time. Further, this study developed an optimized extraction procedure to obtain maximum yield of the metabolites, which is unique and better than conventional extraction methodology. The operational parameters under optimized conditions accounts for the lowest cost in extraction process thus, providing an efficient, rapid and cost‑effective method for isolation and scale up of these commercially vital flavonoids.