Rambutan shell, a major agro-industrial by-product, is a promising source of bioactive polyphenols. This study aimed to optimize polyphenol extraction from the rambutan shell of Baoyan NO.7 (BY-7) using deep eutectic solvent (DES) and to purify the extract with AB-8 resin. The adsorption mechanism was elucidated, and the polyphenol profile was characterized via next-generation metabolomics (NGM). The optimized extract showed high total phenolic (178.89 mg GAE/g), flavonoid (152.93 mg RE/g), and proanthocyanidin (41.89 mg CE/g) contents, along with potent antioxidant (DPPH: 7061.49, FRAP: 6925.34 μmol TE/g) and anti-glycemic activities ( α -amylase IC 50 : 2.62 mg/mL; α -glucosidase IC 50 : 70.78 μg/mL). Adsorption followed Langmuir and pseudo-second-order kinetic models, indicating a spontaneous process. To the best of our knowledge, proanthocyanidin B1 was identified in the rambutan shell of BY-7 for the first time. Significant correlations were found between 11 polyphenols and the bioactivities. This work provides a theoretical foundation for valorizing rambutan shell resources. • The DES-bsed extraction process of RSP was optimized for the first time. • Proanthocyanidins B1, B2, and C1 were identified in RSP for the first time based on NGM. • The adsorption behavior of RSP on macroporous resin was comprehensively investigated for the first time. • Ultrasound and enzyme assistance offered negligible improvement in the DES-based extraction of RSP.
Bian et al. (Fri,) studied this question.