An efficient method based on an inhibitor-enzyme complex to screen an active compound against lipase from Toona sinensis

Artificial antibody-antigen-directed immobilization of α-amylase to hydrolyze starch for cascade reduction of 2-nitro-4-methylphenol to 2-amino-4-methylphenol

Nitrophenol is a hazardous substance that poses a threat to the environment and human health, and its treatment has attracted widespread attention. The purpose of this study is to establish an environmentally friendly α-amylase system for the hydrolysis of starch to reduce nitrophenol to aminophenol through cascade reactions. The α-amylase system was obtained through artificial antibody-antigen-directed immobilization, including the synthesis of artificial antibodies, synthesis of artificial antigens, and affinity assembly. In this process, catechol and protocatechuic aldehyde were used to prepare artificial antibodies and artificial antigens respectively through polymerization and Schiff base reactions. Then, artificial antibodies captured the catechol in the artificial antigen structure to form immobilized α-amylases. Compared with free α-amylase, the immobilized α-amylase showed a good reusability and excellent regenerative ability. Subsequently, the immobilized α-amylase were used in the reaction of catalyzing starch hydrolysis to synthesize 2-amino-4-methylphenol, and the yield of 2-amino-4-methylphenol was 58.88 ± 0.19 %. After 5 consecutive catalytic reactions, a yield of 47.61 ± 1.27 % can still be achieved.

Artificial antibody-antigen-directed immobilization of lipase for consecutive catalytic synthesis of ester: Benzyl acetate case study

A strategy based on artificial antibody-antigen recognition was proposed for the specific directed immobilization of lipase. The artificial antibody was synthesized using catechol as a template, α-methacrylic acid as a functional monomer, and Fe3O4 as the matrix material. Lipase was modified with 3,4-dihydroxybenzaldehyde as an artificial antigen. The artificial antibody can specifically recognize catechol fragment in the enzyme structure to achieve the immobilization of lipase. The immobilization amount, yield, specific activity, and immobilized enzyme activity were 13.2 ± 0.2 mg/g, 78.9 ± 0.4 %, 7.9 ± 0.2 U/mgprotein, and 104.6 ± 1.7 U/gcarrier, respectively. Moreover, the immobilized lipase exhibited strong reusability and regeneration ability. Additionally, the immobilized lipase successfully catalyzed the synthesis of benzyl acetate and demonstrated robust continuous catalytic activity. These results fully demonstrate the feasibility of the proposed artificial antibody-antigen-directed immobilization of lipase.

Biomimetic immobilization of α-glucosidase inspired by antibody-antigen specific recognition for catalytic preparation of 4-methylumbelliferone

Immobilization technology plays an important role in enhancing enzyme stability and environmental adaptability. Despite its rapid development, this technology still encounters many challenges such as enzyme leakage, difficulties in large-scale implementation, and limited reusability. Drawing inspiration from natural paired molecules, this study aimed to establish a method for immobilized α-glucosidase using artificial antibody-antigen interaction. The proposed method consists of three main parts: synthesis of artificial antibodies, synthesis of artificial antigens, and assembly of the artificial antibody-antigen complex. The critical step in this method involves selecting a pair of structurally similar compounds: catechol as a template for preparing artificial antibodies and protocatechualdehyde for modifying the enzyme to create the artificial antigens. By utilizing the same functional groups in these compounds, specific recognition of the antigen by the artificial antibody can be achieved, thereby immobilizing the enzymes. The results demonstrated that the immobilization amount, specific activity, and enzyme activity of the immobilized α-glucosidase were 25.09 ± 0.10 mg/g, 5.71 ± 0.17 U/mgprotein and 143.25 ± 1.71 U/gcarrier, respectively. The immobilized α-glucosidase not only exhibited excellent reusability but also demonstrated remarkable performance in catalyzing the hydrolysis of 4-methylumbelliferyl-α-D-glucopyranoside.

Dual-target affinity analysis and separation of α-amylase and α-glucosidase inhibitors from Morus alba leaves using a magnetic bifunctional immobilized enzyme system

Morus alba leaves are a natural product with great antidiabetic potential. However, the therapeutic efficacy of natural products is usually achieved through the interaction of active compounds with specific targets. Among them, active compounds with multi-target therapeutic functions are more effective than single-target enzymes. In this study, a bienzyme system was constructed by co-immobilizing α-amylase and α-glucosidase onto Fe₃ O₄ for affinity screening of dual-target active components in the complex extract from M. alba leaves. As a result, a potential active compound was selectively screened by ligand fishing, separated by high-speed countercurrent chromatography using a solvent system of ethyl acetate-n-butanol-water (3:2:5, v/v), and identified as rutin. In addition, the result of molecular docking showed that rutin could interact with the active center of α-amylase and α-glucosidase through multiple hydrogen bonds, van der Waals forces, etc. to play an inhibitory role. These results demonstrate the effectiveness of the polydopamine magnetically immobilized bienzyme system for dual-target affinity screening of active substances. This study not only reveals the chemical basis of the antidiabetic activity of M. alba leaves from a dual-target perspective, but also promotes the progress of multitarget affinity screening.

Non-classical digestive lipase BmTGL selected by gene amplification reduces the effects of mulberry inhibitor during silkworm domestication

Efficient utilization of dietary lipids is crucial for Bombyx mori, also known as domesticated silkworms. However, the effects of domestication on the genes encoding lipases remain unknown. In this study, we investigated the expression difference of one triacylglycerol lipase (BmTGL) between B.mori and wild (ancestor) silkworm strains (Bombyx mandarina). An immunofluorescence localization analysis showed that BmTGL was present in all parts of the gut and was released into the intestinal lumen. BmTGL expression was significantly enhanced in different domesticated silkworm strains compared to that in the B. mandarina strains. The BmTGL copy numbers in the genomes of the domesticated silkworm strains were 2-to-3 folds that of the B. mandarina strains and accounted for the enhanced expression of BmTGL in the domesticated silkworm strains. The Ser144Asn substitution in the Ser-Asp-His catalytic triads of BmTGL resulted in relatively lower lipase activity and reduced sensitivity to the lipase inhibitor morachalcone A. Moreover, BmTGL overexpression significantly increased the weights of the B. mori silkworms compared to those of the non-transgenic controls. Thus, the selection of BmTGL by gene amplification may be a trade-off between maintaining high enzymatic activity and reducing the effects of mulberry inhibitors during silkworm domestication.

Identification of yeast α-glucosidase inhibitors from Pueraria lobata by ligand fishing based on magnetic mesoporous silicon combined with knock-out/knock-in technology

In this study, a ligand fishing technique based on magnetic mesoporous silicon was established and used to screen α-glucosidase inhibitors from Pueraria lobata. To clarify quantity-activity relationships in a holistic view, the knock-out/knock-in technology was used to analyse the interactions of several active constituents in P. lobata. Magnetic mesoporous silicon with a large specific surface area and better biocompatibility was synthesised. Subsequently, α-glucosidase was immobilised on -NH₂-modified magnetic mesoporous silicon, and the compounds in the crude extract of P. lobata were screened across enzyme binding. The structures of the ligands were elucidated using UPLC-Q-TOF-MS/MS, and their activities were verified by knock-out/knock-in experiments and molecular docking. Daidzein and puerarin showed α-glucosidase inhibitory activities with an IC₅₀ of 0.088 ± 0.003 mg mL^-1 and 0.414 ± 0.005 mg mL^-1, respectively. Among them, puerarin, which accounted for more than 40% of the total content, showed synergistic effects with other components and was the main contributor to the α-glucosidase inhibitory activity of P. lobata.

Leaves of Cedrela sinensis Attenuate Chronic Unpredictable Mild Stress-Induced Depression-like Behavior via Regulation of Hormonal and Inflammatory Imbalance

This study aimed to evaluate the protective effects of ethyl acetate fraction from Cedrela sinensis (EFCS) against chronic unpredictable mild stress (CUMS)-induced behavioral dysfunction and stress response in C57BL/6 mice. The physiological compounds of EFCS were identified as rutin, isoquercitrin, ethyl gallate, quercitrin, kaempferol-3-O-rhamnoside, and ethyl digallate, using UPLC-Q-TOF/MS^E. To evaluate the neuroprotective effect of EFCS, H₂O₂^- and corticosterone-induced neuronal cell viability was conducted in human neuroblastoma MC-IXC cells. It was found that EFCS alleviated depression-like behavior by conducting the sucrose preference test (SPT), forced swimming test (FST), open field test (OFT), and tail suspension test (TST). EFCS inhibited mitochondrial dysfunction related to neuronal energy metabolism by regulating reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), and ATP contents in brain tissue. In addition, the administration of EFCS regulated the stress hormones in serum. EFCS regulated stress-related indicators such as CRF, ACTH, CYP11B1, and BDNF. Moreover, EFCS downregulated the inflammatory responses and apoptosis proteins such as caspase-1, TNF-α, IL-1β, p-JNK, BAX, and p-tau in brain tissues. These results suggest that EFCS might be a potential natural plant material that alleviates CUMS-induced behavior disorder by regulating inflammation in brain tissue against CUMS-induced depression.

A simple and effective method based on enzyme-ligand complex for affinity analysis of lipase inhibitor from Schisandra chinensis (Turcz.) Baill

Schisandra chinensis (Turcz.) Baill has various biological activities including anti-obesity. Rapid analysis and screening of active compounds from natural extracts is one of the challenges faced by natural drug research. In order to analyze and screen lipase inhibitor from Schisandra chinensis extract, a method inspired by the specific binding of enzyme to ligand was developed and established. Through optimization of incubation conditions, such as time, temperature, and pH, the potential active compound was locked by comparing the change of the chemical components of the S. chinensis extract before and after incubation with lipase. Subsequently, the target compound was isolated by high-speed counter-current chromatography and was identified as 5-hydroxymethyl-2-furaldehyde. Moreover, in vitro activity determination confirmed that 5-hydroxymethyl-2-furaldehyde with an IC₅₀ value of 284.78 ± 16.45 μg/mL interacted with the lipase through non-competitive inhibition. Furthermore, molecular docking further revealed that 5-hydroxymethyl-2-furaldehyde can be embedded into the active pocket of lipase via multiple hydrogen bonds and other interactions. This study not only screened a potential lipase inhibitor from S. chinensis through the newly developed method, but also can be used as a typical reference for the discovery of active components from functional foods and natural products.