Optimization of ultrasound-assisted extraction by response surface methodology, antioxidant capacity, and tyrosinase inhibitory activity of anthocyanins from red rice bran.

Yujie Wang,Ruoyu Zhang,Yanghua Sun,Longlong Shi,Lei Zhao,Peng Xue,Xiushi Yang

doi:10.1002/fsn3.1371

Abstract

The anthocyanins contents from red rice bran were characterized by HPLC/MS. Response surface methodology was used to optimize the ultrasound‐assisted extraction of red rice bran anthocyanin. The antioxidant activities were evaluated in terms of IC50. The tyrosinase inhibitory activities of the anthocyanin samples from red rice bran and the standard substances were determined by a spectrophotometric method. According to mass spectrometry information, the main component of anthocyanins is paeoniflorin (m/z = 480). The optimized anthocyanin level was 5.80 mg/g under the following conditions: solid–liquid ratio of 1:17.46; ethanol concentration of 78.37%; ultrasonication time of 55.23 min; and pH of 2.31. The IC50 value of the DPPH radical scavenging and the superoxide anion scavenging activities of the sample were 53.51 and 2,375 μg/ml; those of the standard were 14.60 and 64.74 μg/ml; and those of vitamin C were 24.45 and 136.25 μg/ml, respectively. The IC50 values of the tyrosinase inhibition activities of the sample and Vc were 4.26 and 2.18 μg/ml, respectively. There is a significant difference (p < .05) between the activities of the three, which may be caused by the purity of the extract. Red rice bran anthocyanins have valuable research and development prospects as skin whiteners and healthcare products.

Highlights

As chemical methods have developed over the past century, various artificial pigments have been manufactured and applied to the food industry and cosmetics
This study provides the basis for the future application of red rice bran anthocyanins in the medical, cosmetic, and health industries, where they can be used to make healthy foods and natural pigments
Response surface methodology was used to evaluate the effect of temperature, time, and solid–liquid ratio on the extraction of compounds from red rice bran

Summary

| INTRODUCTION

As chemical methods have developed over the past century, various artificial pigments have been manufactured and applied to the food industry and cosmetics. The anthocyanins extracted from red rice bran are desirable for making cosmetics because of their antioxidant activity and ability to inhibit tyrosinase activity. They can be used in the food industry as a natural pigment additive. The total anthocyanin content was expressed as mg of paeoniflorin equivalent to g of freeze-dried powder as in the following equation: Y= n×c×V 1000 × m where Y is the total anthocyanin content, n is the dilution factor, c is the anthocyanin concentration of the extract calculated by the regression This experiment was performed according to Zhang's method (Zhang & Yang, 2005) with minor changes. The O2− clearance rate was calculated by the following formula: 2.7 | Determination of tyrosinase inhibitory activity

| RESULT AND DISCUSSION

Findings

| CONCLUSION