An on-line detection system for screening small molecule inhibitors of α-Amylase and α-Glucosidase in Prunus mume

UHPLC-PDA-Q-TOF-MS-α-amylase-FLD activity detection system and molecular docking

INTRODUCTION

Traditional and some scientific literature document the antidiabetic effects of the Ziziphi Spinosae Semen (ZSS). However, the bioactive compounds of ZSS responsible for the antidiabetic effects are not well known.

OBJECTIVES

This study aimed to investigate the material basis of the antidiabetic effects of ZSS by inhibiting α-amylase.

METHODOLOGY

An online analysis platform was established and optimized using an ultra-performance liquid chromatography-photo-diode array-quadrupole-time-of-flight-mass spectrometry-α-amylase-fluorescence detector (UHPLC-PDA-Q-TOF-MS-α-amylase-FLD) system to screen α-amylase inhibitors in ZSS rapidly. The inhibitory effect of these compounds was confirmed by molecular docking screening. and the molecular interactions between α-amylase and active compounds were evaluated, which strongly supported the experimental results.

RESULTS

Seventy-eight compounds were identified in the ZSS extract, eleven of which were screened to have significant α-amylase binding activity.

CONCLUSION

This study demonstrated the feasibility of using an established platform to screen for effective components in ZSS, providing a practical method for the rapid screening of potential antidiabetic active ingredients in traditional Chinese medicine.

Fluorometric and colorimetric dual-mode sensing of α-glucosidase based on aggregation-induced emission enhancement of AuNCs

Herein, a fluorometric and colorimetric dual-mode assay platform used for α-glucosidase (α-Glu) activity sensing based on aggregation-induced emission enhancement (AIEE) of AuNCs was developed for the first time. The quantum yield (QY) and fluorescence lifetime of AuNCs were successfully ameliorated by Ce3+-triggered AIEE (Ce@AuNCs). Subsequently, on the basis of the inner filter effect (IFE) and dynamic quenching effect (DQE) between 2,6-dichlorophenolindophenol (DCIP) and Ce@AuNCs as well as the reduction of DCIP by ascorbic acid (AA) generated from α-Glu-catalyzed hydrolysis of L-ascorbic acid-2-O-α-D-glucopyranosyl (AA2G), the marriage of fluorometric and colorimetric modes applied for α-Glu activity monitoring was achieved. Besides, the feasibility of this dual-mode sensing system was confirmed by the assays versus potential interfering substances and in real samples. In particular, this system was further applied to evaluate natural α-Glu inhibitors (AGIs) including luteolin, apigenin, and hesperidin. Overall, the multi-mode optical sensor newly designed here has the potential for the accurate discovery of natural anti-diabetes drugs and the therapy of diabetes.

Synthesis, biological evaluation and action mechanism of 7H-[1,2,4] triazolo [3,4-b] [1,3,4] thiadiazine-phenylhydrazone derivatives as α-glucosidase inhibitors

In our work, several 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-phenylhydrazone derivatives as α-glucosidase inhibitors (α-GIs) were synthesized and characterized by 1H NMR, 13C NMR, and HRMS spectrum. Then, their bio-activity against the α-glucosidase (α-Glu) was further evaluated. Among them, almost all compounds displayed better bio-activity with IC50 from 31.23 ± 0.89 to 213.50 ± 4.19 μM than acarbose (IC50 = 700.20 ± 10.55 μM). In particular, compound 5o showed the best potency to inhibit α-Glu in a mixed manner. Moreover, the action mechanisms of 5o were further clarified including fluorescence quenching, circular dichroism spectra, three-dimensional fluorescence spectra, molecular docking, etc. All mechanism studies revealed that 5o could arouse the changed secondary structure of α-Glu to hinder enzyme catalytic activity. It was observed from an in vivo study that 5o of 20 mg/kg could significantly decrease by 24.45 % postprandial blood glucose in mice vs. the control. Meanwhile, 5o had low drug-drug interaction potential and was likely to be an orally active compound. Moreover, 5o was observed to be no obvious cytotoxicity to HEK-293 cells. In summary, compound 5o exhibited one potential to be further applied as an antidiabetic drug.

Utilizing bio-affinity ultrafiltration combined with UHPLC Q-Exactive Plus Orbitrap HRMS to detect potential α-glucosidase inhibitors in Oxalis corniculate L

Oxalis corniculate L. (O. corniculate) was used to treat diabetes in Chinese folk as a popular tea drink. In this work, 31 compounds from O. corniculate were screened and identified as potential α-Glucosidase inhibitors (α-GIs). Among them, 6 compounds displayed stronger inhibitory activity than acarbose (IC50 = 212.9 ± 5.98 μg/mL). Especially, the most effective compounds quercetin (Qu, IC50 = 4.70 ± 0.40 μg/mL) and luteolin (Lu, IC50 = 15.72 ± 0.75 μg/mL) inhibited α-Glu in competitive and mixed manners, respectively. Moreover, fluorescence quenching, circular dichroism (CD), and molecular docking study revealed that they can arouse the changes in the secondary structure and hydrophobic micro-environment of the enzyme mainly through a hydrophobic binding. Furthermore, it was observed that oral administration of Qu (20 mg/kg) can significantly reduce postprandial blood glucose (PBG) levels in mice vs. the control group. To sum up, the above research confirmed that O. corniculate could prevent and treat postprandial hyperglycemia as a good tea drink, and the plant was an excellent source to obtain natural α-GIs.

Interaction of narcissoside with α-amylase from Bacillus subtilis and Porcine pancreatic by multi-spectral analysis and molecular dynamics simulation

In this work, interaction mechanism of narcissoside with two α-amylase from Bacillus subtilis (BSA) and Porcine pancreatic (PPA) are comparatively studied by multi-spectral analysis, molecular docking and molecular dynamics simulation. The results prove that narcissoside can statically quench fluorescence of BSA/PPA. Two complexes are mainly formed by hydrogen bond and van der Waals force. With the increase of temperature, the two complexes formed by narcissoside and two enzymes become unstable. At the same experimental temperature, the binding force of narcissoside to PPA is higher than that of BSA. The binding of narcissoside to PPA/BSA increases the hydrophobicity of microenvironment. Moreover, the secondary structure of PPA/BSA is mainly changed by decreasing the α-helix. The optimal binding modes of narcissoside with BSA/PPA are predicted by molecular docking, and the stability of the two complexes is evaluated by molecular dynamics simulations.

Lonicera caerulea L. polyphenols improve short-chain fatty acid levels by reshaping the microbial structure of fermented feces in vitro

Increasing evidence suggests that the pathogenesis of type 2 diabetes mellitus (T2DM) is closely related to the gut microbiota. Polyphenols have been shown to alleviate T2DM, but the effects of L. caerulea L. polyphenols (LPs) on the gut microbiota and metabolites remain elusive. In this study, the inhibitory effects of fermented L. caerulea L. polyphenols (FLPs) and unfermented L. caerulea L. polyphenols (ULPs) on α-amylase and α-glucosidase and the impact of LP on the gut microbiota and metabolites were investigated. Furthermore, the relationship between the two was revealed through correlation analysis. The results showed that ULP and FLP had the highest inhibitory rates against α-amylase and α-glucosidase at 4 mg ml-1, indicating a strong inhibitory ability. In addition, LP plays a regulatory role in the concentration of short-chain fatty acids (SCFAs) and tends to restore them to their normal levels. LP reversed the dysbiosis of the gut microbiota caused by T2DM, as evidenced by an increase in the abundance of bacterial genera such as Lactobacillus, Blautia, and Bacteroides and a decrease in the abundance of bacterial genera such as Escherichia-Shigella and Streptococcus. Similarly, after LP intervention, the relationships among microbial species became more complex and interconnected. In addition, the correlation between the gut microbiota and metabolites was established through correlation analysis. These further findings clarify the mechanism of action of LP against T2DM and provide a new target for T2DM interventions.

Molecular Characterization of Prunus lusitanica L. Fruit Extracts and Their Health-Promoting Potential in Inflammation, Diabetes, and Neurodegenerative Diseases

Prunus lusitanica L. is a shrub belonging to the genus Prunus L. (Rosaceae family) that produces small fruits with none known application. Thus, the aim of this study was to determine the phenolic profile and some health-promoting activities of hydroethanolic (HE) extracts obtained from P. lusitanica fruits, harvested from three different locations. Qualitative and quantitative analysis of extracts was performed using HPLC/DAD-ESI-MS and antioxidant activity was assessed by in vitro methods. Antiproliferative/cytotoxic activity was determined on Caco-2, HepG2, and RAW 264.7 cells, anti-inflammatory activity was assessed using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, and the antidiabetic, antiaging, and neurobiological action of extracts was determined in vitro by assessing their inhibitory effect against the activity of α-amylase, α-glucosidase, elastase, tyrosinase, and acetylcholinesterase (AChE). Results showed that P. lusitanica fruit HE extracts from the three different locations showed identical phytochemical profile and bioactivities, although small differences were observed regarding the quantities of some compounds. Extracts of P. lusitanica fruits contain high levels in total phenolic compounds, namely, hydroxycinnamic acids, as well as flavan-3-ols and anthocyanins, primarily cyanidin-3-(6-trans-p-coumaroyl)glucoside. P. lusitanica fruit extracts have a low cytotoxic/antiproliferative effect, with the lowest IC₅₀ value obtained in HepG2 cells (352.6 ± 10.0 μg/mL, at 48 h exposure), but high anti-inflammatory activity (50-60% NO release inhibition, at 100 μg/mL extract) and neuroprotective potential (35-39% AChE inhibition, at 1 mg/mL), and moderate antiaging (9-15% tyrosinase inhibition, at 1 mg/mL) and antidiabetic (9-15% α-glucosidase inhibition, at 1 mg/mL) effects. The bioactive molecules present in the fruits of P. lusitanica deserve to be further explored for the development of new drugs of interest to the pharmaceutical and cosmetic industry.

Structures, Sources, Identification/Quantification Methods, Health Benefits, Bioaccessibility, and Products of Isorhamnetin Glycosides as Phytonutrients

In recent years, people have tended to consume phytonutrients and nutrients in their daily diets. Isorhamnetin glycosides (IGs) are an essential class of flavonoids derived from dietary and medicinal plants such as Opuntia ficus-indica, Hippophae rhamnoides, and Ginkgo biloba. This review summarizes the structures, sources, quantitative and qualitative analysis technologies, health benefits, bioaccessibility, and marketed products of IGs. Routine and innovative assay methods, such as IR, TLC, NMR, UV, MS, HPLC, UPLC, and HSCCC, have been widely used for the characterization and quantification of IGs. All of the therapeutic effects of IGs discovered to date are collected and discussed in this study, with an emphasis on the relevant mechanisms of their health-promoting effects. IGs exhibit diverse biological activities against cancer, diabetes, hepatic diseases, obesity, and thrombosis. They exert therapeutic effects through multiple networks of underlying molecular signaling pathways. Owing to these benefits, IGs could be utilized to make foods and functional foods. IGs exhibit higher bioaccessibility and plasma concentrations and longer average residence time in blood than aglycones. Overall, IGs as phytonutrients are very promising and have excellent application potential.

Hesperetin-Cu(II) complex as potential α-amylase and α-glucosidase inhibitor: Inhibition mechanism and molecular docking

Inhibition of α-amylase and α-glucosidase activity is an effective way for controlling postprandial blood glucose-related diabetes. The study found that hesperetin-Cu(II) complex (Hsp-Cu(II)) exhibited a stronger inhibitory ability on α-amylase and α-glucosidase compared to hesperetin (Hsp), with smaller IC₅₀ values of Hsp-Cu(II) (60.3 ± 0.9 µM for α-amylase; 1.25 ± 0.03 µM for α-glucosidase) than Hsp (115.6 ± 1.1 µM for α-amylase; 55.2 ± 0.1 µM for α-glucosidase). Interestingly, Hsp-Cu(II) and acarbose exerted a synergistic effect on inhibition of α-glucosidase. The binding affinities of Hsp-Cu(II) to α-amylase and α-glucosidase were strong with the Ka values (binding constant) in the magnitude order of 10⁵, which was 9 times larger than Hsp. After interacting, Hsp-Cu(II) reduced α-helix contents of α-amylase and α-glucosidase, resulting in a looser conformation of these two enzymes. Molecular simulations manifested that Hsp-Cu(II) bound to the active center of enzymes driven by hydrogen bonds and interacted with the key catalytic amino acids (α-amylase: Gln63, Asp300 and His305; α-glucosidase: Tyr158, Asp215, Glu277 and Glu411), altering the conformation of enzymes, blocking the entrance of substrates, ultimately reducing the activities of α-glucosidase and α-amylase. This study has demonstrated that Hsp-Cu(II) may be a promising candidate of functional nutritional additive and medicine for the prevention of diabetes.

A Review of Magnetic Nanoparticle-Based Surface-Enhanced Raman Scattering Substrates for Bioanalysis: Morphology, Function and Detection Application

Surface-enhanced Raman scattering (SERS) is a kind of popular non-destructive and water-free interference analytical technology with fast response, excellent sensitivity and specificity to trace biotargets in biological samples. Recently, many researches have focused on the preparation of various magnetic nanoparticle-based SERS substrates for developing efficient bioanalytical methods, which greatly improved the selectivity and accuracy of the proposed SERS bioassays. There has been a rapid increase in the number of reports about magnetic SERS substrates in the past decade, and the number of related papers and citations have exceeded 500 and 2000, respectively. Moreover, most of the papers published since 2009 have been dedicated to analytical applications. In the paper, the recent advances in magnetic nanoparticle-based SERS substrates for bioanalysis were reviewed in detail based on their various morphologies, such as magnetic core-shell nanoparticles, magnetic core-satellite nanoparticles and non-spherical magnetic nanoparticles and their different functions, such as separation and enrichment, recognition and SERS tags. Moreover, the typical application progress on magnetic nanoparticle-based SERS substrates for bioanalysis of amino acids and protein, DNA and RNA sequences, cancer cells and related tumor biomarkers, etc., was summarized and introduced. Finally, the future trends and prospective for SERS bioanalysis by magnetic nanoparticle-based substrates were proposed based on the systematical study of typical and latest references. It is expected that this review would provide useful information and clues for the researchers with interest in SERS bioanalysis.

Prunus lusitanica L. Fruits as a Novel Source of Bioactive Compounds with Antioxidant Potential: Exploring the Unknown

Prunus lusitanica L., also known as Portuguese laurel or locally known as ‘azereiro’, is a rare species with ornamental and ecological value. Only two studies regarding the bioactivity and chemical composition of its leaves were reported to date. Thus, the present study aims to qualitatively and quantitatively evaluate the phenolic profile, through HPLC-PAD-ESI-MS/MS (high-performance liquid chromatography–photodiode array detection–electrospray ionization tandem mass spectrometry), as well as the radical scavenging capacity, through ABTS (2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1 picrylhydrazyl), and the reducing power (FRAP, ferric reducing antioxidant power) assays, of P. lusitanica fruits during a 4-year study. In total, 28 compounds were identified and quantified in the fruits, including 21 hydroxycinnamic acids (60.3%); 2 flavan-3-ols (27.9%), 2 anthocyanins (10.5%), 2 flavonols (1.0%), and 1 secoiridoid (0.3%). High antioxidant capacity was observed, with ABTS values ranging from 7.88 to 10.69 mmol TE (Trolox equivalents)/100 g fw (fresh weight), DPPH values from 5.18 to 8.17 mmol TE/100 g fw, and FRAP values from 8.76 to 11.76 mmol TE/100 g fw. According to these results, it can be concluded that these are rich sources of phenolic compounds with very promising antioxidant capacity and, therefore, with potential applications in the food and/or phytopharmaceutical sectors.