Tannic acid-modified ZIF-67 immobilized CRL for screening CRL inhibitors from traditional Chinese medicines

With the increasing demand for lipase inhibitors and novel anti-obesity therapies, it is of paramount importance to screen Candida rugosa lipase (CRL) inhibitors from traditional Chinese medicines (TCMs) as anti-obesity drugs. Immobilized enzyme screening technology combined with capillary electrophoresis has become a powerful tool for the exploration of CRL inhibitors due to its easy separation characteristics and high separation efficiency. In this work, tannic acid (TA)-modified ZIF-67 was adopted as a readily available carrier for CRL immobilization. ZIF-67 was fabricated by mixing Co(NO 3 ) 2 ·6 H 2 O with 2-methylimidazole under ambient conditions. TA was subsequently introduced to chelate the surface metal ions of ZIF-67, yielding a ZIF-67/TA hybrid carrier. CRL was then immobilized onto the ZIF-67/TA via physical adsorption. The immobilization of CRL on TA-modified ZIF-67 minimally alters its conformation, enabling 98.7 % recovery of enzymatic activity. Additionally, it exhibits a high CRL loading capacity of 36.5 mg·g⁻¹ determined by the Bradford protein assay. The ZIF˗67/TA/CRL demonstrated notable improvements in thermal resistance, operational durability, recyclability, and storage performance. Its calculated Michaelis constant ( K m ) was determined to be 1.41 mM, while the half-maximal inhibitory concentration (IC 50 ) of orlistat against the system was measured to be 19.74 µM. Finally, capillary electrophoresis was employed to evaluate CRL inhibitions across 18 TCMs, identifying Schisandrae Chinensis Fructus as the most potent CRL inhibitor. This investigation not only presents an innovative strategy for discovering lipase inhibitors and prospective anti-obesity agents, but also underscores the therapeutic potential of TCMs in metabolic disorder intervention.