Optimization of extraction parameters of PTP1β (protein tyrosine phosphatase 1β), inhibitory polyphenols, and anthocyanins from Zea mays L. using response surface methodology (RSM)

Background: Protein tyrosine phosphatase expressed in insulin-sensitive tissues (such as liver, muscle, and adipose tissue) has a key role in the regulation of insulin signaling and pathway activation, making protein tyrosine phosphatase a promising target for the treatment of type 2 diabetes mellitus and obesity and response surface methodology (RSM) is an effective statistical technique for optimizing complex processes using a multi-variant approach. Methods: In this study, Zea mays L. (Purple corn kernel, PCK) and its constituents were investigated for protein tyrosine phosphatase 1 beta (PTP1 beta) inhibitory activity including enzyme kinetic study and to improve total yields of anthocyanins and polyphenols, four extraction parameters, including temperature, time, solid-liquid ratio, and solvent volume, were optimized by RSM. Results: Isolation of seven polyphenols and five anthocyanins was achieved by PTP1 beta assay. Among them, cyanidin-3-(6 '' malonylglucoside) and 3'-methoxyhirsutrin showed the highest PTP1 beta inhibition with IC50 values of 54.06 and 64.04 mu M, respectively and 4.52 mg gallic acid equivalent/g (GAE/g) of total polyphenol content (TPC) and 43.02 mg cyanidin-3-glucoside equivalent/100 g (C3GE/100g) of total anthocyanin content (TAC) were extracted at 40 degrees C for 8 h with a 33 % solid-liquid ratio and a 1: 15 solvent volume. Yields were similar to predictions of 4.58 mg GAE/g of TPC and 42.28 mg C3GE/100 g of TAC. Conclusion: These results indicated that PCK and 3'-methoxyhirsutrin and cyanidin-3-(6 '' malonylglucoside) might be active natural compounds and could be apply by optimizing of extraction process using response surface methodology.