Unlocking the Phenolic Potential of Libidibia coriaria Pods: Comparative Evaluation of Ultrasound-, Microwave-, and Hybrid-Assisted Extraction

Libidibia coriaria (Cascalote), an underutilized leguminous species native to the tropical Americas, is a promising source of bioactive phenolic compounds with pharmaceutical and nutraceutical potential. This study compared microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and their hybrid combination (UMAE) for the recovery of hydrolyzable and condensed phenolics from cascalote pods and evaluated the antioxidant capacity of the resulting extracts. UMAE achieved the highest total phenolic content (223.49 mg GAE/g dry matter), while antioxidant capacity varied by assay: MAE showed the highest DPPH radical scavenging activity and FRAP reducing power, whereas UAE exhibited the highest ABTS radical-scavenging activity. Nevertheless, UMAE showed the lowest IC50 values for DPPH and ABTS (228.91 and 155.65 mg/L, respectively), indicating greater concentration-dependent radical-scavenging efficiency. Qualitative HPLC–MS tentatively identified gallotannins, ellagitannins, and hydroxybenzoic acid derivatives. UAE yielded the broadest phenolic profile, whereas MAE and UMAE shared several major tannin-related compounds. FTIR analysis supported the presence of characteristic functional groups associated with gallotannins and ellagitannins. Overall, under the evaluated conditions, UMAE was the most effective extraction method for improving phenolic recovery. These findings highlight the potential of this hybrid extraction approach for the valorization of L. coriaria pods as a source of high-value bioactive phenolic compounds.