Optimization of ultrasound-assisted extraction of antioxidant compounds from Mucuna pruriens pods using response surface methodology: a waste-to-value approach

Abstract

Mucuna pruriens, a leguminous plant known for the rich bioactive content of its seeds, also exhibits significant antioxidant potential in its pods, an underutilized agricultural by-product. This study aimed to optimize ultrasound-assisted extraction (UAE) conditions to maximize the recovery of phenolic compounds with antioxidant capacity (AOC) from M. pruriens pods. Optimization was conducted using response surface methodology (RSM), evaluating the effects of extraction time (10–20 min), ethanol concentration (0–100%), and ultrasound amplitude (0–80%). Ethanol concentration was identified as the most influential variable affecting both total phenolic content (TPC) and AOC. Optimal UAE conditions (10 min, 30% ethanol, 80% amplitude) yielded significantly higher TPC (274.21 ± 1.43 mg GAE per g) and AOC (DPPH: 2.41 ± 0.11, ABTS: 1.87 ± 0.09 and FRAP: 3.67 ± 0.08 mmol TEAC per g) compared to the traditional decoction method. HPLC-MS-based metabolite profiling tentatively identified 22 bioactive compounds in the pod and seed extracts. Furthermore, a notable L-Dopa content (5.8%) was quantified in the optimized pod extract, highlighting its potential as a valuable bioresource. These findings demonstrate the efficiency and sustainability of UAE in valorizing M. pruriens pods and support their potential application in food, nutraceutical, and pharmaceutical formulations.