Ultrasound-Assisted Aqueous Extraction of Phenolic, Flavonoid Compounds and Antioxidant Activity of Mucuna Macrocarpa Beans: Response Surface Methodology Optimization

Objective: This investigation was undertaken to optimize the effective extraction of total phenolics content (TPC), total flavonoids content (TFC), and antioxidant activity from the Mucuna macrocarpa (MM) beans. An ultrasound-assisted extraction (UAE) technique with water as an effective solvent was proposed for the response surface methodology (RSM) optimization.

Methods: A three-level, two-factor central composite design (CCD) was employed to reveal the optimal points of variables. Different extraction times (5, 10, 15 minutes) and ultrasonic power levels (10, 20, 30 W) were used for the optimization. The experimental runs given by the RSM were evaluated for TPC, TFC, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (RSA), and N,N-dimethyl-p-phenylenediamine (DMPD) RSA and ferric reducing antioxidant power (FRAP).

Results: The predicted times for maximum extraction of TPC (186.61 mg GAE g), TFC (148.87 mg QUE g), and DPPH RSA (99.37%), and DMPD RSA (50.58%) and FRAP (2.38 O.D. at 593 nm) were 12.57, 12.84, 12.43, 12.97, and 13.24 min, and ultrasonic power levels were found to be 27.30, 26.76, 26.22, 27.03, and 27.84 W, respectively. Reverse-phase high-performance liquid chromatography (RP-HPLC) analysis of phenolics compounds from the RSM optimized sample showed tannic acid (48.09 ± 1.92 mg/g), gallic acid (1.17 ± 0.19 mg/g), p-coumaric acid (0.56 ± 0.03 mg/g), and p-hydroxybenzoic acid (0.049 ± 0.01 mg/g) content.

Conclusion: Water and ultrasonication were found to be an effective extraction solvent and technique. RSM was effectively employed to investigate the optimal process conditions for the maximum extraction of TPC, TFC, and antioxidant compounds from the MM beans. Further, MM beans can be explored as a prominent antioxidant source for the treatment of several disorders.