Optimization of microwave-assisted extraction of total flavonoid content from red betel leaf (Piper crocatum Ruiz and Pav) and its correlation with antioxidant and antibacterial activities using response surface methodology

Abstract

The optimization of microwave-assisted extraction (MAE) was conducted using response surface methods to improve the extraction of flavonoids from Piper crocatum Ruiz and Pav leaf. The optimization process included a Box–Behnken experimental design (BBD), which involved three variables at three levels. The present study aimed to evaluate the impact of varying ethanol concentrations (50%, 75%, and 100%), microwave power levels (180, 300, and 450 W), and extraction durations (3, 8.5, and 14 minutes) on the respective responses. The experimental data was subjected to fitting using a second-order polynomial model. Subsequently, an analysis of variance (ANOVA) and multiple regression analysis were employed to assess the adequacy of the model and determine the ideal settings. Taking into account the highest concentration of extracted total flavonoids, as well as the antioxidant and antibacterial properties. The experimental results indicate that the optimum conditions for all the reactions under investigation were an ethanol concentration of 78.48%, a microwave power of 327.96 W, and an extraction duration of 8.60 minutes. Under the ideal conditions, the anticipated outcomes of the sample indicate a total flavonoid content (TFC) of 229.647 mg QE/g dry weight (DW), a 1,1-diphenyl-2-picryhydrazyl (DPPH) scavenging activity of 73.915%, and an inhibition zone measuring 18.621 mm. The implementation of a concurrent MAE methodology for the isolation of total flavonoids, as well as the evaluation of antioxidant and antibacterial properties from P. crocatum, signifies the recognition of the extract as a significant reservoir of bioactive substances.