Extração verde de compostos bioativos da folha da gravioleira: aplicação de solventes eutéticos profundos

Abstract

The leaves of the Annona muricata Lin. plant, popularly known as soursop, are rich in bioactive compounds such as polyphenols and other antioxidants, with potential applications in the pharmaceutical and food industries. These compounds can be efficiently extracted using designer solvents known as Deep Eutectic Solvents (DES), an innovative and sustainable class of solvents with diverse applications, including the extraction of compounds from various biomass sources. In this study, different DES formulations based on choline chloride and menthol were used as hydrogen bond acceptors (HBA), combined with lactic acid, oxalic acid, and 1,2-propanediol as hydrogen bond donors (HBD). Extractions were carried out using two different systems: heated stirring and ultrasonic bath, with variations in time and temperature. The samples were analyzed using spectrophotometric methods to determine the total extractive content, total phenolic content, and antioxidant activity (ABTS, DPPH, and FRAP assays). The performance of the DES was further evaluated through physicochemical and thermal characterizations, including density, viscosity, pH, and thermogravimetric analysis. DES containing oxalic acid and lactic acid showed the best extraction performances, with optimal conditions observed at 50 °C for 120 minutes under agitation and 30 °C for 30 minutes in the ultrasonic bath. Extracts obtained using the oxalic acid- based DES (CCAO) exhibited the highest antioxidant activity (ABTS = 244 µmol trolox·g⁻¹; TPC = 130 mg GAE·g⁻¹), outperforming aqueous and ethanolic extracts under the same conditions. After recovery with dichloromethane (DCM) and hexane (HEX), promising bioactivity was observed. The CCAO-DCM fraction showed cytotoxic activity against breast cancer (MDA-MB-231, IC₅₀ = 227 µg·mL⁻¹), prostate cancer (PC-3, IC₅₀ = 265.1 µg·mL⁻¹), and colon cancer cells (RKO, IC₅₀ = 259.6 µg·mL⁻¹), while maintaining selectivity toward healthy fibroblasts (BJ-5TA, IC₅₀ = 604.6 µg·mL⁻¹). The CCAO-HEX fraction was not cytotoxic but exhibited antimicrobial activity against S. aureus and P. aeruginosa (MIC = 6.25

mg·mL⁻¹) and E. coli (MIC = 12.5 mg·mL⁻¹). These results demonstrate that DES-based extraction is an effective and sustainable strategy for obtaining compounds with antioxidant, anticancer, and antimicrobial properties, with potential applications in bioactive formulations.