Optimization of extraction condition of Gynura procumbens extract enriched with flavonoid and antioxidant compounds using Response Surface Methodology

Gynura procumbens is known as one of the herbal medicinal plants found in Indonesia and has been used from time to time. It is claimed to have various efficacy such as anti-hyperglycemic, anti-hypertension, anti-microbial, anti-cancer, and antioxidant. Other studies mention that G. procumbens possessed high antioxidant compounds and had been used as a natural-based medicinal supplement. However, further studies on optimizing the extraction process of Gynura procumbens in Indonesia have yet to be reported. Therefore, this study aimed to optimize the extraction condition of G. procumbens leaves by maceration with three variables: solvent concentration, extraction time, and the ratio of solid-liquid used. Each of those variables contained three different levels. Determination of total flavonoid and antioxidant activity was measured using aluminium chloride colourimetric assay and 2, 2-diphenyl-1-picryl-hydrazil (DPPH) assay, respectively. In the optimization process, Response Surface Methodology (RSM) was used to explore the main effects and interaction between parameters and their correlations with dependent variables. The results were analyzed using the Box-Behnken method using Minitab software 17. This study shows that the most significant effect of the variable for both flavonoid and antioxidant activity was solvent concentration, with a P<0.05. The results showed that the extraction process to obtain G. procumbens extract with optimal flavonoid content and antioxidant activity (IC50) was predicted at 70% solvent concentration, 1 h maceration time, and a solid-liquid ratio of 1:9.8 w/v, with results of 17.599 mg QE/g extract and 0.211 mg/mL, respectively. This study was expected to complement other studies and can be used as an additional reference for the development of the extraction process on a larger scale.