Immobilization of porcine pancreatic lipase onto a metal-organic framework, PPL@MOF: A new platform for efficient ligand discovery from natural herbs

Carboxy-Functionalized Covalent Organic Framework as a Carrier for Lipase Immobilization and Its Application in Inhibitors Screening

Covalent organic frameworks (COFs) with large specific surface areas, high porosity, good stability, and designable structure are promising carriers for immobilized enzymes. It is important to explore lipase inhibitors from natural foods as lipase inhibitors are closely related to the treatment of obesity. In this work, a carboxyl functionalized covalent organic framework (TpBD-3COOH) was prepared by solvothermal method for covalent immobilization of porcine pancreatic lipase (PPL) and obtained the enzyme-decorated COF (PPL@COF). The immobilized lipase showed wider pH and temperature tolerance with the same optimal pH and temperature of 7.5 and 50 ℃ compared to free lipase. After 6 successive reuses, the PPL@COF maintained 53.0% of its original activity. Immobilized lipase also displayed enhanced storage stability (55.4% after 14 days at 4 ℃). When p-nitrophenyl acetate was applied as the substrate, the calculated Michaelis constant was 3.57 mM and the half maximal inhibitory concentration of orlistat was 3.20 μM. Finally, the PPL@COF was used for enzyme inhibitors screening from natural foods combined with UV spectrophotometry, and Hawthorn was screened for excellent lipase inhibitory activity.

A dual recognition-based strategy employing Ni-modified metal-organic framework for in situ screening of SIRT1 inhibitors from Chinese herbs

Sirtuin1 (SIRT1), an NAD+-dependent histone deacetylase, plays a crucial role in regulating molecular signaling pathways. Recently, inhibition of SIRT1 rather than its activation shows the therapeutic potential for central nervous system disorder, however, the discovered SIRT1 inhibitors remains limited. In this work, a dual recognition-based strategy was developed to screen SIRT1 inhibitors from natural resources in situ. This approach utilized a Ni-modified metal-organic framework (Ni@Tyr@UiO-66-NH2) along with cell lysate containing an engineered His-tagged SIRT1 protein, eliminating the need for purified proteins, pure compounds, and protein immobilization. The high-performance Ni@Tyr@UiO-66-NH2 was synthesized by modifying the surface of UiO-66-NH2 with Ni2+ ions to specifically capture His-tagged SIRT1 while persevering its enzyme activity. By employing dual recognition, in which Ni@Tyr@UiO-66-NH2 recognized SIRT1 and SIRT1 recognized its ligands, the process of identifying SIRT1 inhibitors from complex matrix was vastly streamlined. The developed method allowed the efficient discovery of 16 natural SIRT1 inhibitors from Chinese herbs. Among them, 6 compounds were fully characterized, and suffruticosol A was found to have an excellent IC50 value of 0.95 ± 0.12 μM. Overall, an innovative dual recognition-based strategy was proposed to efficiently identify SIRT1 inhibitors in this study, offering scientific clues for the development of drugs targeting CNS disorders.

Paper-based ligand fishing method for rapid screening and real-time capturing of α-glucosidase inhibitors from the Chinese herbs

Identifying medicinally relevant compounds from natural resources generally involves the tedious work of screening plants for the desired activity before capturing the bioactive molecules from them. In this work, we created a paper-based ligand fishing platform to vastly simplify the discovery process. This paper-based method exploits the enzymatic cascade reaction between α-glucosidase (GAA), glucose oxidase (GOx), and horseradish peroxidase (HRP), to simultaneously screen the plants and capture the GAA inhibitors from them. The designed test strip could capture ligands in tandem with screening the plants, and it features a very simply operation based on direct visual assessment. Multiple acylated flavonol glycosides from the leaves of Quercus variabilis Blume were newly found to possess GAA inhibitory activities, and they may be potential leads for new antidiabetic medications. Our study demonstrates the prospect of the newly discovered GAA ligands as potential bioactive ingredients as well as the utility of the paper-based ligand fishing method.

Review on sterilization techniques, and the application potential of phage lyase and lyase immobilization in fighting drug-resistant bacteria

Many human health problems and property losses caused by pathogenic contamination cannot be underestimated. Bactericidal techniques have been extensively studied to address this issue of public health and economy. Bacterial resistance develops as a result of the extensive use of single or multiple but persistent usage of sterilizing drugs, and the emergence of super-resistant bacteria brings new challenges. Therefore, it is crucial to control pathogen contamination by applying innovative and effective sterilization techniques. As organisms that exist in nature and can specifically kill bacteria, phages have become the focus as an alternative to antibacterial agents. Furthermore, phage-encoded lyases are proteins that play important roles in phage sterilization. The in vitro sterilization of phage lyase has been developed as a novel biosterilization technique to reduce bacterial resistance and is more environmentally friendly than conventional sterilization treatments. For the shortcomings of enzyme applications, this review discusses the enzyme immobilization methods and the application potential of immobilized lyases for sterilization. Although some techniques provide effective solutions, immobilized lyase sterilization technology has been proven to be a more effective innovation for efficient pathogen killing and reducing bacterial resistance. We hope that this review can provide new insights for the development of sterilization techniques.

Efficient screening of pancreatic lipase inhibitors from Rheum palmatum by affinity ultrafiltration-high-performance liquid chromatography combined with high-resolution inhibition profiling

INTRODUCTION

Pancreatic lipase is one of the most important key targets in the treatment of obesity. Inhibition of pancreatic lipase can effectively reduce lipid absorption and treat obesity and other related metabolic disorders.

OBJECTIVES

The goal of this study is the efficient screening of pancreatic lipase inhibitors in the root and rhizome of Rheum palmatum using affinity ultrafiltration-high-performance liquid chromatography (AUF-HPLC) combined with high-resolution inhibition profiling (HRIP).

METHODS

Potential pancreatic lipase ligands and pancreatic lipase inhibitors in ethyl acetate fraction of R. palmatum were screened using AUF-HPLC and HRIP, respectively. All screened compounds were identified by HPLC- quadrupole time-of-flight (Q-TOF)/MS. Eight compounds were screened out by both AUF-HPLC and HRIP, and six compounds were screened out by either AUF-HPLC or HRIP alone. The pancreatic lipase inhibitory activities of all screened compounds were verified by enzyme inhibition assay and molecular docking.

RESULTS

Five new potent pancreatic lipase inhibitors were discovered, namely procyanidin B5 3,3'-di-O-gallate (IC50 = 0.06 ± 0.01 μM), 1,6-di-O-galloyl-2-O-cinnamoyl-β-D-glucoside (IC50 = 12.83 ± 0.67 μM), 1-O-(1,3,5-trihydroxy)phenyl-2-O-galloyl-6-O-cinnamoyl-β-D-glucoside (IC50 = 17.84 ± 1.33 μM), 1,2-di-O-galloyl-6-O-cinnamoyl-β-D-glucoside (IC50 = 18.39 ± 1.52 μM), and 4-(4'-hydroxyphenyl)-2-butanone-4'-O-β-D-(2"-O-galloyl-6"-O-cinnamoyl)-glucoside (IC50 = 2.91 ± 0.40 μM). It was found that procyanidin B5 3,3'-di-O-gallate showed higher pancreatic lipase inhibitory activity than the positive control orlistat (IC50 = 0.12 ± 0.02 μM).

CONCLUSION

The combination of affinity ultrafiltration-high-performance liquid chromatography (AUF-HPLC) and high-resolution inhibition profiling (HRIP) could reduce the risk of false-negative screening and missed screening and could achieve more efficient screening of bioactive compounds in complex natural products.

Mudanpioside C Discovered from Paeonia suffruticosa Andr. Acts as a Protein Disulfide Isomerase Inhibitor with Antithrombotic Activities

Paeonia suffruticosa Andr. is a well-known landscape plant worldwide and also holds significant importance in China due to its medicinal and dietary properties. Previous studies have found that Cortex Moutan (CM), the dried root bark of P. suffruticosa, showed antiplatelet and cardioprotective effects, although the underlying mechanism and active compounds remain to be revealed. In this study, protein disulfide isomerase (PDI) inhibitors in CM were identified using a ligand-fishing method combined with the UHPLC-Q-TOF-MS assay. Further, their binding sites and inhibitory activities toward PDI were validated. The antiplatelet aggregation and antithrombotic activity were investigated. The results showed that two structurally similar compounds in CM were identified as the inhibitor for PDI with IC50 at 3.22 μM and 16.73 μM; among them Mudanpioside C (MC) is the most effective PDI inhibitor. Molecular docking, site-directed mutagenesis, and MST assay unequivocally demonstrated the specific binding of MC to the b'-x domain of PDI (Kd = 3.9 μM), acting as a potent PDI inhibitor by interacting with key amino acids K263, D292, and N298 within the b'-x domain. Meanwhile, MC could dose-dependently suppress collagen-induced platelet aggregation and interfere with platelet activation, adhesion, and spreading. Administration of MC can significantly inhibit thrombosis formation without disturbing hemostasis in mice. These findings present a promising perspective on the antithrombotic properties of CM and highlight the potential application of MC as lead compounds for targeting PDI in thrombosis therapy.

Target Separation and Potential Anticancer Activity of Withanolide-Based Glucose Transporter Protein 1 Inhibitors from Physalis angulata var. villosa

The glucose transporter 1 (GLUT1) protein is involved in the basal-level absorption of glucose in tumor cells. Inhibiting GLUT1 decreases tumor cell proliferation and induces tumor cell damage. Natural GLUT1 inhibitors have been studied only to a small extent, and the structures of known natural GLUT1 inhibitors are limited to a few classes of natural products. Therefore, discovering and researching other natural GLUT1 inhibitors with novel scaffolds are essential. Physalis angulata L. var. villosa is a plant known as Mao-Ku-Zhi (MKZ). Withanolides are the main phytochemical components of MKZ. MKZ extracts and the components of MKZ exhibited antitumor activity in recent pharmacological studies. However, the antitumor-active components of MKZ and their molecular mechanisms remain unknown. A cell membrane-biomimetic nanoplatform (CM@Fe3O4/MIL-101) was used for target separation of potential GLUT1 inhibitors from MKZ. A new withanolide, physagulide Y (2), together with six known withanolides (1, 3-7), was identified as a potential GLUT1 inhibitor. Physagulide Y was the most potent GLUT1 inhibitor, and its antitumor activity and possible mechanism of action were explored in MCF-7 human cancer cells. These findings advance the development of technologies for the targeted separation of natural products and identify a new molecular framework for the investigation of natural GLUT1 inhibitors.

Infiltration of porcine pancreatic lipase into magnetic hierarchical mesoporous UiO-66-NH2 metal-organic frameworks for efficient detoxification of patulin from apple juice

Patulin (PAT) is a mycotoxin known to globally contaminate fruits. The economic losses and health hazards caused by PAT desires a safe and efficient strategy for detoxifying PAT. Here, a magnetic core-shell hierarchical mesoporous metal-organic framework (Fe3O4@HMUiO-66-NH2) was synthesized via a salt-assisted nanoemulsion guided assembly method. This mesoporous structure (centered at 4.25 nm) allowed porcine pancreatic lipase (PPL) to infiltrate into the MOF shell at an immobilized amount of 255 mg/g, providing protection for PPL and enabling rapid separation and recovery. Compared with free PPL, PPL/Fe3O4@HMUiO-66-NH2 at 70 °C possessed 4.7 folds improved thermal stability in terms of half-life. The detoxification rates of immobilized enzyme for PAT in neutral water, acidic water, and apple juice were 99.6%, 60.9%, and 52.6%, respectively. Moreover, the so designed PPL/Fe3O4@HMUiO-66-NH2 showed extraordinary storage stability, reusability, and biocompatibility. Crucially, the quality of apple juice did not change significantly after PPL/Fe3O4@HMUiO-66-NH2 treatment, which facilitated its application in apple juice. The magnetic core-shell mesoporous structure along with the revealed mechanism of immobilized enzyme detoxification of PAT provide tremendous opportunity for designing a safe and efficient PAT detoxification method.

Magnetic metal-organic frameworks immobilized enzyme-based nano-biocatalytic systems for sustainable biotechnology

Nanobiocatalysts, in which enzyme molecules are integrated into/onto multifunctional materials, such as metal-organic frameworks (MOFs), have been fascinating and appeared as a new interface of nanobiocatalysis with multi-oriented applications. Among various nano-support matrices, functionalized MOFs with magnetic attributes have gained supreme interest as versatile nano-biocatalytic systems for organic bio-transformations. From the design (fabrication) to deployment (application), magnetic MOFs have manifested notable efficacy in manipulating the enzyme microenvironment for robust biocatalysis and thus assure requisite applications in several areas of enzyme engineering at large and nano-biocatalytic transformations, in particular. Magnetic MOFs-linked enzyme-based nano-biocatalytic systems offer chemo-regio- and stereo-selectivities, specificities, and resistivities under fine-tuned enzyme microenvironments. Considering the current sustainable bioprocesses demands and green chemistry needs, we reviewed synthesis chemistry and application prospects of magnetic MOFs-immobilized enzyme-based nano-biocatalytic systems for exploitability in different industrial and biotechnological sectors. More specifically, following a thorough introductory background, the first half of the review discusses various approaches to effectively developed magnetic MOFs. The second half mainly focuses on MOFs-assisted biocatalytic transformation applications, including biodegradation of phenolic compounds, removal of endocrine disrupting compounds, dye decolorization, green biosynthesis of sweeteners, biodiesel production, detection of herbicides and screening of ligands and inhibitors.

Immobilized enzyme for screening and identification of anti-diabetic components from natural products by ligand fishing

Diabetes is a chronic metabolic disease caused by insufficient insulin secretion and insulin resistance. Natural product is one of the most important resources for anti-diabetic drug. However, due to the extremely complex composition, this research is facing great challenges. After the advent of ligand fishing technology based on enzyme immobilization, the efficiency of screening anti-diabetic components has been greatly improved. In order to provide critical knowledge for future research in this field, the application progress of immobilized enzyme in screening anti-diabetic components from complex natural extracts in recent years was reviewed comprehensively, including novel preparation technologies and strategies of immobilized enzyme and its outstanding application prospect in many aspects. The basic principles and preparation steps of immobilized enzyme were briefly described, including entrapment, physical adsorption, covalent binding, affinity immobilization, multienzyme system and carrier-free immobilization. New formatted immobilized enzymes with different carriers, hollow fibers, magnetic materials, microreactors, metal organic frameworks, etc., were widely used to screen anti-diabetic compositions from various natural products, such as Ginkgo biloba, Morus alba, lotus leaves, Pueraria lobata, Prunella vulgaris, and Magnolia cortex. Furthermore, the challenges and future prospects in this field were put forward in this review.

Immobilization of Lipase in Cu-BTC MOF with Enhanced Catalytic Performance for Resolution of N-hydroxymethyl Vince Lactam

Metal-organic frameworks (MOFs) can be used as the immobilization carriers to protect the physicochemical properties of enzymes and improve their catalytic performance. Herein, we report an in situ co-precipitation method to immobilize lipase from Candida sp. 99-125 in Cu-BTC MOF (BTC = 1, 3, 5-benzene tricarboxylic acid, H₃BTC). Characterizations of the immobilized lipase (lipase@Cu-BTC) have confirmed the entrapment of lipase molecules in Cu-BTC MOF. The immobilized lipase has been successfully applied for resolving N-hydroxymethyl vince lactam (N-HMVL) and its catalytic activity is five times that of native enzyme. More importantly, we found that Cu-BTC MOF can afford powerful protection for enzyme in nearly dry organic solvent and endow the immobilized lipase with excellent reusability and storage stability. Our present study may widen the application of immobilized enzyme with MOF as the immobilized carrier.

Efficient discovery of potent α-glucosidase inhibitors from Paeoniae lactiflora using enzyme-MOF nanocomposites and competitive indicators

A great deal of attention has been paid to the seeds of Paeoniae lactiflora pall., an underutilized food resource, since its extract exhibits excellent α-glucosidase (GAA) inhibitory activity. In the present study, to gain further insight into this plant and find out potent GAA inhibitors, we established a novel ligand fishing strategy by introducing a competitive inhibitor as an indicator. After the successful establishment of this approach was verified by a series of methods, including kinetic assay, fluorescence determination, and HPLC, the newly developed ligand fishing method was applied to acquire potent GAA inhibitors from P. lactiflora seeds. Nine bioactive compounds were captured, and seven of them were identified as suffruticosol A, suffruticosol B, resveratrol, vitisin E, luteolin, trans-δ-viniferin, and ampelopsin E. The data of their GAA inhibitory activity demonstrated that these constituents were vigorously active against GAA with IC₅₀ values of 1.67-30.47 μM, while such value of 1-DNJ was 228.77 μM. Among them, vitisin E and ampelopsin E were reported to show such inhibitory activity for the first time. Collectively, our findings provide valuable clues for the further utilization of P. lactiflora seeds as a functional food, and offer a new avenue for acquiring potent inhibitors from natural resources.

Unraveling the mystery of efficacy in Chinese medicine formula: New approaches and technologies for research on pharmacodynamic substances

Traditional Chinese medicine (TCM) is the key to unlock treasures of Chinese civilization. TCM and its compound play a beneficial role in medical activities to cure diseases, especially in major public health events such as novel coronavirus epidemics across the globe. The chemical composition in Chinese medicine formula is complex and diverse, but their effective substances resemble "mystery boxes". Revealing their active ingredients and their mechanisms of action has become focal point and difficulty of research for herbalists. Although the existing research methods are numerous and constantly updated iteratively, there is remain a lack of prospective reviews. Hence, this paper provides a comprehensive account of existing new approaches and technologies based on previous studies with an in vitro to in vivo perspective. In addition, the bottlenecks of studies on Chinese medicine formula effective substances are also revealed. Especially, we look ahead to new perspectives, technologies and applications for its future development. This work reviews based on new perspectives to open horizons for the future research. Consequently, herbal compounding pharmaceutical substances study should carry on the essence of TCM while pursuing innovations in the field.

Screening of potent α-glucosidase inhibitory and antioxidant polyphenols in Prunella vulgaris L. by bioreaction-HPLC-quadrupole-time-of-flight-MS/MS and in silico analysis

Prunella vulgaris L. is a well-known traditional Chinese medicine for blood glucose homeostasis and antioxidant potential. Ethyl acetate fraction of P. vulgaris L. demonstrated higher phenolic content (85.53 ± 6.74 mg gallic acid equivalents per gram dry weight), α-glucosidase inhibitory (IC₅₀ , 69.13 ± 2.86 μg/mL), and antioxidant (IC₅₀ , 8.68 ± 1.01 μg/mL) activities. However, the bioactive polyphenols responsible for the beneficial properties remain unclear. Here, bioreaction-HPLC-quadrupole-time-of-flight-MS/MS method was developed for rapid, accurate, and efficient screening and identification of polyphenols with α-glucosidase inhibitory and antioxidant activities from P. vulgaris L. Bioactive polyphenols can specifically bind with α-glucosidase or react with 1,1-diphenyl-2-picryl-hydrazyl radical, which was easily discriminated from nonactive compounds. Subsequently, twenty bioactive polyphenols (sixteen phenyl propionic acid derivatives and four flavonoids) were screened and identified. Furthermore, molecular docking analysis revealed that screened twenty polyphenols bind with the active sites of α-glucosidase through hydrogen bonding and π-π stacking. Density functional theory calculations demonstrated their electron transport ability and chemical reactivity. The in silico analysis confirmed the screened results. In summary, this study provided a valuable strategy for rapid discovering bioactive compounds from complex natural products, and offered scientific evidence for further development and application of P. vulgaris L. This article is protected by copyright. All rights reserved.

Ligand fishing based on tubular microchannel modified with monoamine oxidase B for screening of the enzyme's inhibitors from Crocus sativus and Edgeworthia gardneri

A novel strategy of performing ligand fishing with enzyme-modified open tubular microchannel was proposed for screening bioactive components present in medicinal plants. Monoamine oxidase B was immobilized onto the surface of the microchannel for the first time to specifically extract its ligands when the plant's extracts solution flows through the channel. The thermal and the storage stability of immobilized monoamine oxidase B were significantly enhanced after immobilization. Crocin I and Ⅱ were extracted from Crocus sativus, and tiliroside was extracted from Edgeworthia gardneri. All the three compounds were inhibitors of the enzyme with the half-maximal inhibitory concentration values of 26.70 ± 0.91, 19.88 ± 2.78, and 15.65 ± 0.85 μM, respectively. The enzyme inhibition kinetics and molecular docking were investigated. This is the first report on the inhibitory effects of tiliroside and crocin Ⅱ. The novel ligand fishing method proposed in this work possesses advantages of rapidness, high efficiency, and tiny sample consumption compared to routine ligand fishing, with promising potential for screening active natural products in complex mixtures.

Immobilization of Cytochrome C by Benzoic Acid (BA)-Functional UiO-66-NO2 and the Enzyme Activity Assay

Recently, metal-organic frameworks (MOFs) are considered to be the moderate hosts for the bio-enzymes owing to their unique 3D pores and controllable surface affinity to the target molecules. In this work, the benzoic acid (BA)-modulated UiO-66-NO₂ was introduced, and cytochrome c (Cyt C) was chosen as the target enzyme to evaluate the immobilization efficiency of the resulting UiO-66-NO₂-BA. The immobilization conditions including pH, adsorption time, and temperature and the initial concentrations of BA were optimized. The adsorption kinetics and thermodynamics were analyzed to further explore the enhanced adsorption mechanism. It is worth noted that all the UiO-66-NO₂-BA exhibited evidently enhanced adsorption capacities in comparison with the unmodified UiO-66-NO₂ due to the formation of the chemical bonds between the UiO-66-NO₂-BA and cytochrome C, indicating the positive roles of BA modification. Finally, the activities of the immobilized cytochrome C were assessed by using the catalytic oxidation of ABTS in the presence of H₂O₂, which reactions were also conducted over the free cytochrome C for comparison. The evidently improved stability under definite pH range, prolonged durability against the organic solvents, and the good reusability of the immobilized cytochrome C highlight the prospect applications of functional MOF immobilized enzymes in the practical catalytic reactions.

Rapid Screening of Lipase Inhibitors in Scutellaria baicalensis by Using Porcine Pancreatic Lipase Immobilized on Magnetic Core–Shell Metal–Organic Frameworks

As for ligand fishing, the current immobilization approaches have some potential drawbacks such as the small protein loading capacity and difficult recycle process. The core–shell metal–organic frameworks composite (Fe3O4-COOH@UiO-66-NH2), which exhibited both magnetic characteristics and large specific surface area, was herein fabricated and used as magnetic support for the covalent immobilization of porcine pancreatic lipase (PPL). The resultant composite Fe3O4-COOH@UiO-66-NH2@PPL manifested a high loading capacity (247.8 mg/g) and relative activity recovery (101.5%). In addition, PPL exhibited enhanced tolerance to temperature and pH after immobilization. Then, the composite Fe3O4-COOH@UiO-66-NH2@PPL was incubated with the extract of Scutellaria baicalensis to fish out the ligands. Eight lipase inhibitors were obtained and identified by UPLC-Q-TOF-MS/MS. The feasibility of the method was further confirmed through an in vitro inhibitory assay and molecular docking. The proposed ligand fishing technique based on Fe3O4-COOH@UiO-66-NH2@PPL provided a feasible, selective, and effective platform for discovering enzyme inhibitors from natural products.

Identification of bioactive natural products using yeast：Application to monoacylglycerol lipase inhibitor extraction from Corydalis Rhizoma

Identification of bioactive principles from natural products is considered a challenging task in drug discovery. Recently, ligand fishing has been growing in interest as a sustainable strategy. In this study, a yeast-based drug discovery strategy was investigated to screen and fish active ingredients from natural products. Human monoacylglycerol lipase (MAGL) was first displayed on the cell wall of Pichia pastoris. The expression of MAGL on the cell surface was confirmed by immunofluorescence analysis. The activity toward 7-HCA which was consistent with free enzymes in solution. Recombinant yeast strains were used to screen the potential inhibitors from traditional Chinese medicines. Preliminary screening showed that the extracts of 12 herbs showed inhibition on MAGL activity, among which Corydalis Rhizoma had the highest inhibition rate of 60.66 ± 2.44%. Recombinant yeast fishing combined with HPLC-Q-TOF-MS/MS analysis was further used to identify the potential MAGL inhibitors. Finally, dehydrocorydaline (DHC) in Corydalis Rhizoma was determined as a ligand to MAGL with the IC₅₀ value at 154.7 μΜ. Corydalis Rhizoma has been used as a pain reliever in TCM. Intraperitoneal injection of 7 mg kg^- 1 DHC in chronic constriction injury model rats significantly attenuated the mechanical allodynia and thermal hyperalgesia. Meanwhile, 2-arachidonoylglycerol, the major MAGL substrate in the brain, was significantly increased both in the hippocampus and striatum. In conclusion, yeast-based ligand fishing combined with HPLC-Q-TOF-MS/MS is a powerful strategy for drug discovery in complex mixtures and DHC from Corydalis Rhizoma was confirmed with high inhibitory activity to MAGL either in vitro or in vivo .

Construction of a Microfluidic Platform With Core-Shell CdSSe@ZnS Quantum Dot-Encoded Superparamagnetic Iron Oxide Microspheres for Screening and Locating Matrix Metalloproteinase-2 Inhibitors From Fruits of Rosa roxburghii

The microfluidic platform is a versatile tool for screening and locating bioactive molecules from functional foods. Here, a layer-by-layer assembly approach was used to fabricate core-shell CdSSe@ZnS quantum dot encoded superparamagnetic iron oxide microspheres, which served as a carrier for matrix metalloproteinase-2. The matrix metalloproteinase-2 camouflaged magnetic microspheres was further incorporated into a homemade microfluidic platform and incubated with extracts of fruits of Rosa roxburghii. The flow rate of the microfluidic platform was tuned. The major influencing parameters on ligand binding, such as dissociate solvents, incubation pH, ion strength, temperature, and incubation time were also optimized by using ellagic acid as a model compound. The specific binding ligands were sent for structure elucidation by mass spectrometry. The absolute recovery of ellagic acid ranged from 101.14 to 102.40% in the extract of R. roxburghii under the optimal extraction conditions. The linearity was pretty well in the range of 0.009–1.00 mg·ml⁻¹ (R² = 0.9995). The limit of detection was 0.003 mg·ml⁻¹. The relative SDs of within-day and between-day precision were <1.91%. A total of thirteen ligands were screened out from fruits of R. roxburghii, which were validated for their inhibitory effect by enzyme assay. Of note, eleven new matrix metalloproteinase-2 inhibitors were identified, which may account for the antitumor effect of fruits of R. roxburghii.

Discovery and Characterization of the Naturally Occurring Inhibitors Against Human Pancreatic Lipase in Ampelopsis grossedentata

Pancreatic lipase (PL) inhibitor therapy has been validated as an efficacious way for preventing and treating obesity and overweight. In the past few decades, porcine PL (pPL) is widely used as the enzyme source for screening the PL inhibitors, which generates a wide range of pPL inhibitors. By contrast, the efficacious inhibitors against human PL (hPL) are rarely reported. This study aims to discover the naturally occurring hPL inhibitors from edible herbal medicines (HMs) and to characterize the inhibitory mechanisms of the newly identified hPL inhibitors. Following the screening of the inhibition potentials of more than 100 HMs against hPL, Ampelopsis grossedentata extract (AGE) displayed the most potent hPL inhibition activity. After that, the major constituents in AGE were identified and purified, while their anti-hPL effects were assayed in vitro. The results clearly showed that two abundant constituents in AGE (dihydromyricetin and iso-dihydromyricetin) were moderate hPL inhibitors, while myricetin and quercetin were strong hPL inhibitors [half-maximal inhibitory concentration (IC50) values were around 1.5 μM]. Inhibition kinetic analyses demonstrated that myricetin and quercetin potently inhibited hPL-catalyzed near-infrared fluorogenic substrate of human pancreatic lipase (DDAO-ol) hydrolysis in a non-competitive inhibition manner, with Ki values of 2.04 and 2.33 μM, respectively. Molecular dynamics simulations indicated that myricetin and quercetin could stably bind on an allosteric site of hPL. Collectively, this study reveals the key anti-obesity constituents in AGE and elucidates their inhibitory mechanisms against hPL, which offers convincing evidence to support the anti-obesity and lipid-lowering effects of this edible herb.

Fast anisotropic growth of the biomineralized zinc phosphate nanocrystals for a facile and instant construction of laccase@Zn3(PO4)2 hybrid nanoflowers

Organic-inorganic hybrid nanoflowers (HNFs) of laccase@Zn₃(PO₄)₂ were fabricated through a facile, simple, and rapid one-step strategy. In this process, laccase was involved in nucleation and fast anisotropic growth reactions with Zn (II) and phosphate ions. The average pore size of the prepared HNFs was 54.5 nm, and its BET-specific surface area was 59.5 m² g^-1. In comparison with the free laccase, the entrapped enzyme activity in the constructed HNFs was 86.4%. In addition, the hybrid biocatalyst displayed a maximum rate of reaction (V_max) of 1640.2 ± 3.6 μmol min^-1 with respect to the native enzyme. The constructed HNFs maintained 45.1% and 60% of the original laccase activity after 12 successive reusability cycles and 30 days of storage at 4 °C, respectively. The as-obtained HNFs demonstrated a high bioremoval percentage of Direct blue-71 (94.1%) within a 10-h-treatment at 40 °C and 15 mg l^-1 of the dye concentration. The pseudo-first order and second order were the best-fitted kinetic models for the dye removal using Zn₃(PO₄)₂ nanoflakes and the fabricated HNFs, respectively. Besides, liquid chromatography-mass spectrometry (LC-MS) revealed biotransformation of the dye into less toxic metabolites as verified by testing on some bacterial strains.

Hydroxyapatite/Glycyrrhizin/Lithium-Based Metal-Organic Framework (HA/GL/Li-MOF) Nanocomposite as Support for Immobilization of Thermomyces lanuginosus Lipase

The hydroxyapatite/glycyrrhizin/lithium-based metal-organic framework (HA/GL/Li-MOF) nanocomposites were synthesized via the hydrothermal method in the presence of lecithin and glycyrrhizin. Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) were applied for characterization of the fabricated nanocomposites. The HA/GL/Li-MOF and Li-MOF nanocomposites were employed as support for immobilization of Thermomyces lanuginosus lipase (TLL). The Plackett-Burman and Box-Behnken designs were used for screening and optimizing of variables affecting the immobilization conditions, respectively. The optimum specific activity of immobilized TLL on HA/GL/Li-MOF and Li-MOF nanocomposites (41.8 ± 1.2 U/mg and 39.4 ± 3.1 U/mg, respectively) was predictably determined at support concentration of 0.5 mg/mL, glutaraldehyde concentration of 5 mM, and enzyme activity of 20 U/mg, while the specific activities of TLL@ HA/GL/Li-MOF and TLL@Li-MOF were experimentally found to be 39.5 ± 3.7 U/mg and 38.5 ± 2.3 U/mg, respectively. The stability results showed that the TLL@ HA/GL/Li-MOF has suitable stability against pH and thermal denaturation. However, the immobilized TLL on Li-MOF represented lower stability compared with that of the HA/GL/Li-MOF. The immobilized TLL on HA/GL/Li-MOF maintained near 70% of its original activity after 15 days' storage and during 5 runs of application. In addition, TLL@HA/GL/Li-MOF exhibited higher enzyme-substrate affinity (K_m, 10.1 mM) compared to that of TLL@Li-MOF (K_m, 23.4 mM). Therefore, these findings demonstrated the potential use of HA/GL/Li-MOF nanocomposites for enzyme immobilization.

Recent Advances in Emerging Metal- and Covalent-Organic Frameworks for Enzyme Encapsulation

Enzyme catalysis enables complex biotransformation to be imitated. This biomimetic approach allows for the application of enzymes in a variety of catalytic processes. Nevertheless, enzymes need to be shielded by a support material under challenging catalytic conditions due to their intricate and delicate structures. Specifically, metal-organic frameworks and covalent-organic frameworks (MOFs and COFs) are increasingly popular for use as enzyme-carrier platforms because of their excellent tunability in structural design as well as remarkable surface modification. These porous organic framework capsules that host enzymes not only protect the enzymes against harsh catalytic conditions but also facilitate the selective diffusion of guest molecules through the carrier. This review summarizes recent progress in MOF-enzyme and COF-enzyme composites and highlights the pore structures tuned for enzyme encapsulation. Furthermore, the critical issues associated with interactions between enzymes and pore apertures on MOF- and COF-enzyme composites are emphasized, and perspectives regarding the development of high-quality MOF and COF capsules are presented.

Capillary electrophoresis for enzyme-based studies: Applications to lipases and kinases

Capillary electrophoresis (CE) is a powerful technique continuously expanding into new application fields. One of these applications involves the study of enzymes, their catalytic activities and the alteration of this activity by specific ligands. In this review, two model enzymes, lipases and kinases, will be used since they differ substantially in their modes of action, reaction requirements and applications making them perfect subjects to demonstrate the advantages and limitations of CE-based enzymatic assays. Indeed, the ability to run CE in various operation modes and hyphenation to different detectors is essential for lipase-based studies. Additionally, the low sample consumption provided by CE promotes it as a promising technique to assay human and viral nucleoside kinases. Undeniably, these are rarely commercially available enzymes and must be frequently produced in the laboratory, a process which requires special sets of skills. CE-based lipase and kinase reactions can be performed outside the capillary (pre-capillary) where the reactants are mixed in a vial prior to their separation or, inside the capillary (in-capillary) where the reactants are mixed before the electrophoretic analysis. These enzyme-based applications of CE will be compared to those of liquid chromatography-based applications in terms of advantages and limitations. Binding assays based on affinity CE and the compelling microscale thermophoresis (MST) will be briefly presented as they allow a broad understanding of the molecular mechanism behind ligand binding and of the resulting modulation in activity.

Magnetic particles for enzyme immobilization: A versatile support for ligand screening

Enzyme inhibitors represent a substantial fraction of all small molecules currently in clinical use. Therefore, the early stage of drug-discovery process and development efforts are focused on the identification of new enzyme inhibitors through screening assays. The use of immobilized enzymes on solid supports to probe ligand-enzyme interactions have been employed with success not only to identify and characterize but also to isolate new ligands from complex mixtures. Between the available solid supports, magnetic particles have emerged as a promising support for enzyme immobilization due to the high superficial area, easy separation from the reaction medium and versatility. Particularly, the ligand fishing assay has been employed as a very useful tool to rapidly isolate bioactive compounds from complex mixtures, and hence the use of magnetic particles for enzyme immobilization has been widespread. Thus, this review provides a critical overview of the screening assays using immobilized enzymes on magnetic particles between 2006 and 2021.

[Determination of three diphenyl ether herbicides in rice by magnetic solid phase extraction using Fe3O4@MOF-808 coupled with high performance liquid chromatography]

利用溶剂热法构筑了Fe₃O₄@MOF-808吸附剂,将其用于大米中除草醚(NIT)、乙氧氟草醚(OXY)和甲羧除草醚(BIF)3种二苯醚类除草剂的富集,结合高效液相色谱法,建立了大米中该类除草剂的分析方法。研究通过傅里叶变换红外光谱、X射线衍射仪、扫描电子显微镜以及振动样品磁强计对构筑的磁性吸附剂的结构、表面形貌及磁强度进行表征。表征结果显示,球形的Fe₃O₄纳米颗粒与八面体形貌的MOF-808成功复合,Fe₃O₄@MOF-808饱和磁化强度可达40.35 emu/g,可以满足磁性固相萃取的需求;对吸附剂用于大米中3种二苯醚类除草剂富集的磁性固相萃取条件(吸附剂用量、吸附时间、洗脱溶剂种类以及洗脱体积)进行了优化。优化结果显示,25 mg吸附剂在6 min内即可达到对目标物的完全吸附,洗脱溶剂采用0.5 mL×2的甲醇。在最优的磁性固相萃取条件下,结合高效液相色谱-紫外检测法,建立了大米中3种二苯醚类除草剂的分析方法。方法在2~300 μg/L范围内线性关系良好(r > 0.998), NIT、OXY、BIF的检出限和定量限依次为0.6、0.6、0.4 μg/kg和2.0、2.0、1.5 μg/kg,在5、10和20 μg/kg 3个加标水平下的回收率为87.3%~96.7%,相对标准偏差不超过10.8%,且富集因子在25~29之间。将所建方法用于大米中NIT、OXY、BIF的分析,各样品均未检出这3种二苯醚类除草剂。该方法具有操作简单、快速、准确的特点,适用于大米样品中除草剂的残留分析。

Screening for pancreatic lipase natural modulators by capillary electrophoresis hyphenated to spectrophotometric and conductometric dual detection

The search for novel pancreatic lipase (PL) inhibitors has gained increasing attention in recent years. For the first time, a dual detection capillary electrophoresis (CE)-based homogeneous lipase assay was developed employing both the offline and online reaction modes. The hydrolysis of 4-nitrophenyl butyrate (4-NPB) catalyzed by PL into 4-nitrophenol and butyrate was monitored by spectrophotometric and conductimetric detection, respectively. The assays presented several advantages such as economy in consumption (few tens of nanoliters for online assays to few tens of microliters for offline assays), no modification of lipase, rapidity (<10 min) and versatility. Tris/MOPS (10 mM, pH 6.6) was used as the background electrolyte and the incubation buffer for enzymatic reactions. We confirmed that in the conditions of the study (small substrate 4-NPB, 37 °C, pH 6.6), the PL was active even in the absence of dipalmitoylphosphatidylcholine (DPPC) vesicles, generally used to mimic the lipid-water interface. This was confirmed by the maximum velocity (Vmax) and the Michaelis-Menten constant (Km) values that were the same order of magnitude in the absence and presence of DPPC. The developed method was used to screen crude aqueous plant extracts and purified compounds. We were able to identify the promising PL inhibition of hawthorn leaf herbal infusions at 1 mg mL-1 (37%) and PL activation by fresh and dry hawthorn flowers (∼24%). Additionally, two triterpenoids purified from extracts of oakwood were identified for the first time as potent PL inhibitors demonstrating 51 and 58% inhibition at 1 mg mL-1, respectively.

Rapid screening of lipase inhibitors in licorice extract by using porcine pancreatic lipase immobilized on Fe3O4 magnetic nanoparticles

Chalcones, a class of natural lipase inhibitors, have received substantial attention from researchers in recent years. Although many kinds of chalcones are typically distributed in G. inflata, there is little literature about the anti-lipase activity of G. inflata extracts (GIEs). In the present study, a ligand fishing strategy for fast screening of lipase inhibitors from GIEs was thus proposed. Porcine pancreatic lipase (PPL) was firstly immobilized on carboxyl modified Fe3O4 magnetic nanoparticles (MNPs) to obtain PPL functionalized MNPs (PPL@MNPs), and then the PPL@MNPs were incubated with a bioactive fraction to fish out the ligands. Eight ligands were obtained and identified as one flavone together with seven chalcones. Licochalcone A, licochalcone D and licochalcone E inhibited pancreatic lipase (PL) with IC50 of 4.9, 3.2 and 5.8 μM, respectively. Meanwhile, investigation of the structure-activity relationship also revealed that isopentenyl and hydroxyl substituents at ring A were essential for the noncovalent inhibitory potency of the chalcones.

Armoring bio-catalysis via structural and functional coordination between nanostructured materials and lipases for tailored applications

Nanostructured materials represent an interesting and novel class of support matrices for the immobilization of different enzymes. Owing to the high surface area, robust mechanical stability, outstanding optical, thermal, and electrical properties, nanomaterials have been rightly perceived as desired immobilization matrices for lipases immobilization with a wide array of biotechnological applications such as dairy, food technology, fine chemical, pharmaceutical, detergent, and oleochemical industries. Lipases immobilized on nanomaterials have demonstrated superior attributes than free counterparts, such as aggrandized pH and thermal stability, robustness, long-term stability, and the possibility of reuse and recycling in several times. Here we review current and state-of-the-art literature on the use of nanomaterials as novel platforms for the immobilization of lipase enzymes. The physicochemical properties and exploitation of a large number of new nanostructured materials such as carbon nanotubes, nano-silica, graphene/graphene oxide, metal nanoparticles, magnetic nanostructures, metal-organic frameworks, and hybrid nanoflowers as a host matrix to constitute robust lipases-based nanobiocatalytic systems are discussed. Conclusive remarks, trends, and future recommendations for nanomaterial immobilized enzymes are also given.

Introducing reticular chemistry into agrochemistry

For survival and quality of life, human society has sought more productive, precise, and sustainable agriculture. Agrochemistry, which solves farming issues in a chemical manner, is the core engine that drives the evolution of modern agriculture. To date, agrochemistry has utilized chemical technologies in the form of pesticides, fertilizers, veterinary drugs and various functional materials to meet fundamental demands from human society, while increasing the socio-ecological consequences due to inefficient use. Thus, more useful, precise, and designable scaffolding materials are required to support sustainable agrochemistry. Reticular chemistry, which weaves molecular units into frameworks, has been applied in many fields based on two cutting-edge porous framework materials, namely metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs). With flexibility in composition, structure, and pore chemistry, MOFs and COFs have shown increasing functionalities associated with agrochemistry in the last decade, potentially introducing reticular chemistry as a highly accessible chemical toolbox into agrochemical technologies. In this critical review, we will demonstrate how reticular chemistry shapes the future of agrochemistry in the fields of farm sensing, agro-ecological preservation and reutilization, agrochemical formulations, smart indoor farming, agrobiotechnology, and beyond.

Lipase@zeolitic imidazolate framework ZIF-90: A highly stable and recyclable biocatalyst for the synthesis of fruity banana flavour

A zeolitic imidazolate framework (ZIF-90) has been synthesized through solvothermal method. The structure was characterized by means of FT-IR spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS). The synthesized ZIF-90 was applied as a support for immobilization of porcine pancreatic lipase (PPL). The immobilized enzyme (PPL@ZIF-90) exhibited immobilization yield and efficiency of 66 ± 1.8% and 89 ± 1.4%, respectively. The pH and thermal stability of PPL was improved after immobilization and the initial activity was retained at about 57% after 20 days of storage at 4 °C for PPL@ZIF-90. Moreover, about 57% of the original activity was remained following 10 cycles of application. In Michaelis-Menten kinetic studies, K_m value for PPL@ZIF-90 was lower, while, the V_max was higher than free PPL. Moreover, optimized conditions to produce fruity banana flavour upon esterification of butyric acid were investigated. The optimum esterification yield was 73.79 ± 1.31% in the presence of 245 mg PPL@ZIF-90, alcohol/acid ratio of 2.78 and 39 h reaction time. PPL@ZIF-90 showed 39% relative esterification yield after six cycles of reuse. The results suggested that PPL@ZIF-90 can be used as a potential effective biocatalyst for synthesis of isoamyl butyrate.

Immobilization of cell membrane onto a glucose-Zn-based porous coordination polymer and its application to rapid screening of potentially active compounds from Vaccinium corymbosum L. leaves

A novel glucose-Zn-based porous coordination polymer (PCP) was selected as a carrier of cell membranes (CMs) to fabricate CM-coated PCP (CMPCP) for rapid screening of potentially active compounds from natural products. The cell disruption and the amount of maximum CMs adsorbed on PCP were optimized according to the amount of immobilized protein. This new kind of matrix exhibited good reproducibility and stability, and was applied for fishing potentially active compounds from the extracts of Vaccinium corymbosum L. leaves (VCL). Using LC-MS/MS, chlorogenic acid and quercetin were identified as the potentially active compounds through comparison of normal and non-alcoholic fatty liver disease (NAFLD)-modeled CMPCP. Our results suggested that the proposed approach based on CMPCP was environmentally friendly, cost-effective, and convenient in terms of green porous material, stable protein loading capacity, and accessible operation process. The developed method could provide a promising platform for efficient drug discovery from natural product resources.Graphical abstract.

Construction of Fe3O4@α-glucosidase magnetic nanoparticles for ligand fishing of α-glucosidase inhibitors from a natural tonic Epimedii Folium

Inhibition of α-glucosidase activity is an effective way for treatment of type 2 diabetes mellitus. Epimedii Folium is an important source of α-glucosidase inhibitors (AGIs), however bioactive compounds and pharmacological mechanisms remained unclear. In this study, a novel strategy was established, which harnessed α-glucosidase functionalized magnetic beads to fish out potential AGIs, followed by UPLC-MS/MS analysis for their identification. Furthermore, molecular docking was employed to predict binding patterns between the AGIs and the enzyme, and IC₅₀ values was estimated as well. After response surface methodology optimization, the highest activity of Fe₃O₄@α-glucosidase has been achieved when 1.17 mg/mL of α-glucosidase was immobilized in phosphate buffer (pH 6.81) for 4.22 h. Moreover, eight flavonoids were fished out from the extract of Epimedii Folium, and then identified to be epimedin A, epimedin B, epimedin C, icariin, sagittatoside A, sagittatoside B, 2"-O-rhamnosyl icariside II and baohuoside I. All of them were further confirmed to be AGIs through in vitro inhibitory assay and molecular docking. Among those, baohuoside I and sagittatoside B possessed stronger inhibitory activity than acarbose. The approach has a significant prospect in conveniently screening bioactive compounds that target various receptors, which provided an efficient platform for new drug development from natural products.

Recent Advances in Affinity MOF-Based Sorbents with Sample Preparation Purposes

This review summarizes the recent advances concerning metal-organic frameworks (MOFs) modified with several biomolecules (e.g., amino acids, nucleobases, proteins, antibodies, aptamers, etc.) as ligands to prepare affinity-based sorbents for application in the sample preparation field. The preparation and incorporation strategies of these MOF-based affinity materials were described. Additionally, the different types of ligands that can be employed for the synthesis of these biocomposites and their application as sorbents for the selective extraction of molecules and clean-up of complex real samples is reported. The most important features of the developed biocomposites will be discussed throughout the text in different sections, and several examples will be also commented on in detail.

Lipase immobilization on UiO-66/poly(vinylidene fluoride) hybrid membranes and active catalysis in the vegetable oil hydrolysis

This is the first report in which UiO-66/PVDF hybrid membranes with high immobilization efficiency for lipase were constructed.