Honey as a Solvent for the Green Extraction, Analysis, and Bioconversion of Daidzin from Pueraria candollei var. mirifica Root

Objectives: This study aims to apply honey (H‑NADES) and a sugar‑based NADES (S‑NADES) for the extraction, analysis, and bioconversion of daidzin from Pueraria candollei var. mirifica (PM) root. Materials and Methods: Various concentrations of H‑NADES and S‑NADES (water:sucrose:glucose: fructose, 18:3:18:22 by weight) were used as solvents for extraction. Indirect competitive enzyme‑linked immunosorbent assay (icELISA) was developed and validated for monitoring the extraction efficacy. The catalytic reactivity against daidzin of β‑glucosidase purified from honey was investigated. Results: Using NADESs as solvents, icELISA was suitable for the reliable determination of daidzin with high sensitivity (1.95–125 ng/mL), specificity (% cross‑reactivity ≤ 2.60), and accuracy (98.3‑106% daidzin recovery). Daidzin at a concentration of 75.8 ± 3.67 µg/mL was extracted using 50% (v/v) S‑NADES, which was the most effective for the extraction compared to H‑NADES, water and ethanol. In addition, daidzin was converted to daidzein by honey β‑glucosidase. Conclusion: Both S‑NADES and H‑NADES were useful for the extraction, analysis, and bioconversion of daidzin, and β‑glucosidase from honey might enhance the oestrogenic activity and bioavailability of PM phytochemicals.