Process Optimization and in vitro Hypoglycemic Effect of Polyphenols Extracted from Jaboticaba Leaves

  Objective  To optimize the polyphenol extraction from leaves of jaboticaba and determine the α-glucosidase inhibition by the extract.

  Method  The ethanol extraction with ultrasound application was optimized by an orthogonal experiment. Effects of the power and time of ultrasonic application as well as the ethanol volume fraction, material-solvent ratio, and processing temperature on the total polyphenols extracted from the leaves were analyzed. The inhibition on α-glucosidase activity by the extract was determined in vitro by an enzyme kinetic study and uv-vis absorption spectrometry.

  Result  The optimal extraction conditions included the use of 120 W ultrasonic wave for 10 min, 40% ethanol volume fraction, 1:160(g:mL) material-solvent ratio, and 40℃ processing temperature to achieve a polyphenol extraction rate of 33.84%. The α-glucosidase activity was significantly inhibited by the extract with a low IC₅₀ of 0.0031 mg·mL^-1, as compared to IC₅₀ of 8.110 8 mg·mL^-1 on acarbose. The kinetic study by the Lineweaver-Burk plot showed that the polyphenol extract was an anti-competitive inhibitor of α-glucosidase.

  Conclusion  The polyphenol extract from jaboticaba leaves significantly inhibited α-glucosidase and could be explored for use as a hypoglycemic agent.