OPTIMIZED HEAT-ASSISTED EXTRACTION OF BIOACTIVE PHENOLICS FROM ANDROGRAPHIS PANICULATA: A RESPONSE SURFACE MODELLING AND HPLC PROFILING STUDY

Abstract

This study investigated the heat-assisted extraction (HAE) of phenolic compounds from Andrographis paniculata leaves and optimized the process using D-optimal response surface methodology (RSM). The effects of extraction temperature (30–50 °C), solid-to-liquid ratio (1:20–1:60 g/mL), and extraction time (45–180 min) on total phenolic content (TPC), extraction yield (EY), and antioxidant activity (AA) were systematically evaluated. The developed quadratic models showed strong predictive accuracy with high coefficients of determination (R² > 0.97) and non-significant lack-of-fit (p > 0.05). Among the parameters investigated, the solid-to-liquid ratio exhibited the most significant influence on all responses, followed by extraction time and temperature. Multi-response numerical optimization predicted optimal conditions at 44.87 °C, 45 min, and 1:60 g/mL, yielding 125.33 mg GAE/g dw TPC, 25.88 % EY, and 41.83 µM AAE/g dw AA. Experimental validation confirmed the model’s reliability with relative standard deviations below 10%. HPLC analysis of the optimized extract identified key phenolic constituents, including botulinic, gallic, chlorogenic, caffeic, ellagic, and ferulic acids, along with rutin, catechin, and epicatechin, confirming a rich phenolic composition. The findings establish HAE as a robust and efficient green extraction technique for recovering bioactive phenolics from A. paniculata, providing a scientific foundation for its application in functional food and pharmaceutical product development.