LABEL-FREE BIO-AFFINITY MASS SPECTROMETRY FOR SCREENING AND LOCATING BIOACTIVE MOLECULES

Bio-affinity ultrafiltration combined with UPLC Q-Exactive Plus Orbitrap HRMS to screen potential COX-2 and 5-LOX inhibitors in mulberry (Morus alba L.) leaf

ETHNOPHARMACOLOGICAL RELEVANCE

Mulberry (Morus alba L.) leaf is a well-known herbal medicine in China for thousands of years. Mulberry leaf can regulate arachidonic acid (ARA) metabolism disorder in obesity and type 2 diabetes mellitus. However, the active ingredients involved in this process are still unclear.

AIM OF STUDY

To explore the potential active ingredients in mulberry leaf against ARA metabolism disorder.

MATERIALS AND METHODS

In this research, an efficient method combining affinity ultrafiltration, molecular docking, and network pharmacology was developed and applied to explore cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) inhibitors from mulberry leaf.

RESULTS

A total 17 potential inhibitors were screened by affinity ultrafiltration assay and identified by high resolution mass spectrometry. In addition, 8 bioactive ingredients were obtained after re-evaluated by molecular docking and network pharmacology, and their inhibitory activities on COX-2 and 5-LOX were confirmed by in vitro inhibitory assays. The results of cell experiments showed that the expressions of COX-2 and 5-LOX were significantly suppressed by neochlorogenic acid, rutin, isoquercetin, and (-)-syringaresinol-4-O-glucoside.

CONCLUSION

Neochlorogenic acid, rutin, isoquercetin, and (-)-syringaresinol-4-O-glucoside may be the potential material basis of mulberry leaf in the regulation of ARA metabolism of obesity and type 2 diabetes mellitus.

Conyza bonariensis (L.) Impact on Carbohydrate Metabolism and Oxidative Stress in a Type 2 Diabetic Rat Model

This study was conducted to assess the possible antidiabetic potential of Conyza bonariensis by employing in vitro as well as in vivo assessments. The dried plant material was extracted in methanol, ethanol, and water. The in vitro results showed that the ethanolic extract (EthCb) was found to have higher antioxidant and antidiabetic potential as compared with the aqueous (AqCb) and methanolic extracts (MthCb) so it was further evaluated in the in vivo trial using a diabetic rat model. Diabetes was induced in male Wistar rats by administering 5% sucrose in drinking water and a cafeteria diet for 8 weeks, followed by nicotinamide and streptozotocin administration. Subsequently, the diabetic rats were divided into 4 groups (n = 8 each): Positive control (no treatment), standard control (Metformin @ 10 mg/kg bw), treatment 1 (C. bonariensis ethanolic extract @ 200 mg/kg bw), and treatment 2 (C. bonariensis ethanolic extract @ 400 mg/kg bw). In addition, there was a negative control group of 8 rats without diabetes induction or treatment. After 21 days of treatment, blood samples were collected from all rats. The serum was evaluated through different means for glucose level, lipid profile, oxidative stress, carbohydrate metabolic enzymes and thyroid hormones. ANOVA was used to evaluate the data statistically. Total oxidant status (TOS) and the serum glucose levels of the streptozotocin-treated rats were reduced significantly (P ⩽ .05) in Conyza bonariensis treated group. Whereas total antioxidant capacity (TAC) along with enzymes like paraoxonase and arylesterase were increased in Conyza bonariensis treated group. The antihyperlipidemic activity was also observed in Conyza bonariensis treated group Interestingly the subnormal levels of T3 and T4 which were observed in the PC group were also normalized in both treatment groups. This study demonstrated the antidiabetic as well as antioxidant activity of different extracts of Conyza bonariensis.

Coupling of surface plasmon resonance and mass spectrometry for molecular interaction studies in drug discovery

Various analytical technologies have been developed for the study of target-ligand interactions. The combination of these technologies gives pivotal information on the binding mechanism, kinetics, affinity, residence time, and changes in molecular structures. Mass spectrometry (MS) offers structural information, enabling the identification and quantification of target-ligand interactions. Surface plasmon resonance (SPR) provides kinetic information on target-ligand interaction in real time. The coupling of MS and SPR complements each other in the studies of target-ligand interactions. Over the last two decades, the capabilities and added values of SPR-MS have been reported. This review summarizes and highlights the benefits, applications, and potential for further research of the SPR-MS approach.

A comprehensive review on the biomedical frontiers of nanowire applications

This comprehensive review examines the immense capacity of nanowires, nanostructures characterized by unbounded dimensions, to profoundly transform the field of biomedicine. Nanowires, which are created by combining several materials using techniques such as electrospinning and vapor deposition, possess distinct mechanical, optical, and electrical properties. As a result, they are well-suited for use in nanoscale electronic devices, drug delivery systems, chemical sensors, and other applications. The utilization of techniques such as the vapor-liquid-solid (VLS) approach and template-assisted approaches enables the achievement of precision in synthesis. This precision allows for the customization of characteristics, which in turn enables the capability of intracellular sensing and accurate drug administration. Nanowires exhibit potential in biomedical imaging, neural interfacing, and tissue engineering, despite obstacles related to biocompatibility and scalable manufacturing. They possess multifunctional capabilities that have the potential to greatly influence the intersection of nanotechnology and healthcare. Surmounting present obstacles has the potential to unleash the complete capabilities of nanowires, leading to significant improvements in diagnostics, biosensing, regenerative medicine, and next-generation point-of-care medicines.

Native mass spectrometry for the investigation of protein structural (dis)order

A central challenge in structural biology is represented by dynamic and heterogeneous systems, as typically represented by proteins in solution, with the extreme case of intrinsically disordered proteins (IDPs) [1-3]. These proteins lack a specific three-dimensional structure and have poorly organized secondary structure. For these reasons, they escape structural characterization by conventional biophysical methods. The investigation of these systems requires description of conformational ensembles, rather than of unique, defined structures or bundles of largely superimposable structures. Mass spectrometry (MS) has become a central tool in this field, offering a variety of complementary approaches to generate structural information on either folded or disordered proteins [4-6]. Two main categories of methods can be recognized. On one side, conformation-dependent reactions (such as cross-linking, covalent labeling, H/D exchange) are exploited to label molecules in solution, followed by the characterization of the labeling products by denaturing MS [7-11]. On the other side, non-denaturing ("native") MS can be used to directly explore the different conformational components in terms of geometry and structural compactness [12-16]. All these approaches have in common the capability to conjugate protein structure investigation with the peculiar analytical power of MS measurements, offering the possibility of assessing species distributions for folding and binding equilibria and the combination of both. These methods can be combined with characterization of noncovalent complexes [17, 18] and post-translational modifications [19-23]. This review focuses on the application of native MS to protein structure and dynamics investigation, with a general methodological section, followed by examples on specific proteins from our laboratory.

Screening and identification of natural α-glucosidase and α-amylase inhibitors from partridge tea (Mallotus furetianus Muell-Arg) and in silico analysis

Partridge leaves (Mallotus furetianus Muell-Arg.) have long been consumed as popular folk substitute tea for treating hyperglycemia in China. In this study, the inhibiting effects of partridge tea extracts on α-glucosidase and α-amylase were investigated, and then effect of partridge tea aqueous extracts (PTAEs) on glucose consumption capacity of 3 T3-L1 preadipocytes cells was determined. Results verified that PTAEs showed excellent anti-α-glucosidase and anti-α-amylase effects. In addition, the PTAEs evidently promoted glucose consumption capacity of 3T3L1 preadipocytes cells. To this end, a combined method of affinity ultrafiltration and HPLC-ESI-qTOF-MS/MS was used for rapidly screening and identifying the potential inhibitors in the PTAEs. Catechin, epicatechin, rutin, ferulic acid, and kaempferitrin with high affinity capacity indicated strong inhibiting effect on α-glucosidase and α-amylase. Docking studies revealed the potential interactive mechanisms between these major inhibitors and two digestive enzymes. This research shows that partridge tea is effective in preventing and treating post hyperglycemia.

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.

Bio-affinity ultra-filtration combined with HPLC-ESI-qTOF-MS/MS for screening potential α-glucosidase inhibitors from Cerasus humilis (Bge.) Sok. leaf-tea and in silico analysis

Cerasus humilis(Bge.) Sok. leaf-tea (CLT) has a potential anti-α-glucosidase effect. However, its anti-α-glucosidase functional compositions remain unclear. Results showed that 70% methanol extract of CLT (IC₅₀ = 36.57 μg/mL) with the highest total phenolic/flavonoid contents exhibited significantly higher α-glucosidase inhibitory activity (α-GIA) than acarbose (IC₅₀ = 189.57 μg/mL). Additionally, phenolic constituents of the CLT extract were analyzed for the first time in this work. Ten major potential α-glucosidase inhibitors (α-GIs) with high bio-affinity degree in the CLT extract were recognized using a bio-affinity ultra-filtration and HPLC-ESI-qTOF-MS/MS method. In vitro α-GIA assay confirmed that myricetin (IC₅₀ = 36.17 μg/mL), avicularin (IC₅₀ = 69.84 μg/mL), quercitrin, isoquercitrin, prunin and guajavarin were responsible for the α-GIA of the CLT extract. More importantly, the interaction mechanism between α-GIs and α-glucosidase was investigated via in silico analysis. This study provides a high-throughput screening platform for identification of the potential α-GIs from natural products.

Efficient discovery of potential inhibitors for SARS-CoV-2 3C-like protease from herbal extracts using a native MS-based affinity-selection method

The 3C-like protease (3CLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential to the virus life cycle and is supposed to be a potential target for the treatment of coronaviral infection. Traditional Chinese medicines (TCMs) have played an impressive role in the treatment of COVID-19 in China. The effectiveness of TCM formulations prompts scientists to take continuous effort on searching for bioactive small molecules from the ancient resources. Herein, we developed a native mass spectrometry-based affinity-selection method for rapid screening of active small molecules from crude herbal extracts applied for COVID-19 therapy. Six common herbs named Lonicera japonica, Scutellaria baicalensis, Forsythia suspensa, Glycyrrhiza uralensis, Cirsium japonicum, and Andrographis paniculata were investigated. After preliminary separation of the crude extracts, the fractions were incubated with 3CLpro. A native MS-based affinity screening assay was then conducted to search for the protein-ligand complexes. A UHPLC-Q/TOF-MS with UNIFI data acquisition and data processing software was applied to identify the hit compounds. Standard compounds were used to verify the outcomes. Among the 16 hits, three flavonoids, baicalein, scutellarein and ganhuangenin, were identified as potential noncovalent inhibitors against 3CLpro with IC₅₀ values of 0.94, 3.02, and 0.84 μM, respectively. Their binding affinities were further characterized by native MS, with K_d values being 1.43, 3.85, and 1.09 μM, respectively. Overall, we established an efficient native MS-based strategy for discovering 3CLpro ligands from crude mixtures, which supplies a potential strategy of small molecule lead discovery from TCMs.

Exploring new targets and chemical space with affinity selection-mass spectrometry

Affinity selection-mass spectrometry (AS-MS) is a high-throughput screening (HTS) technique for drug discovery that enables rapid screening of large collections of compounds to identify ligands for a specific biomolecular target. AS-MS is a binding assay that is insensitive to the functional effects a ligand might have, which is important because it lets us identify novel ligands irrespective of their binding site. This approach is gaining popularity, notably due to its role in the emergence of useful agents for targeted protein degradation. This Perspective highlights the use of AS-MS techniques to explore broad chemical space and identify small-molecule ligands for biological targets that have proven challenging to address with other screening paradigms. We present chemical structures of reported AS-MS hits to illustrate the potential of this screening approach to deliver high-quality hits for further optimization. AS-MS has, thus, evolved from being an infrequent alternative to traditional HTS or DNA-encoded library strategies to now firmly establishing itself as a HTS approach for drug discovery.