Identification of isobenzofuranone derivatives as promising antidiabetic agents: Synthesis, in vitro and in vivo inhibition of α-glucosidase and α-amylase, computational docking analysis and molecular dynamics simulations

Synthesis, in vitro and in vivo evaluation, and computational modeling analysis of thioxothiazolidine derivatives as highly potent and selective α-amylase inhibitors

Diabetes mellitus is not only a critical health concern in this era but also a major cause of damage to other organs such as eyes, nerves, kidneys, hearts and liver. Inhibiting α-amylase enzyme is considered as one of the key strategies for controlling chronic hyperglycemia. Therefore, the current work focuses on design and discovery of a series of thioxothiazolidine derivatives (5a-u and 6a-g) as selective α-amylase inhibitors. The target compounds were synthesized using the Knoevenagel condensation approach and evaluated for their α-amylase and α-glucosidase inhibitory activities. The in vitro assay results demonstrated that the tested thioxothiazolidine derivatives possess significantly high potency than the standard drug acarbose against α-amylase but were inactive against α-glucosidase. Among them, compound 5r exhibited remarkable inhibitory potential depicting an IC50 value of 0.71 ± 0.01 μM, significantly outperforming acarbose against α-amylase. In vivo results further demonstrated that the treatment of diabetic rats with compound 5r led to a significant reduction in blood glucose level, indicating its effectiveness in managing hyperglycemia. Biochemical profiling of the treated rats revealed favorable outcomes, including improved urea, creatinine, ALT, AST, ALP, and HbA1C values. Furthermore, in vivo testing in diabetic rats also demonstrated that treatment with compound 5r caused significant histopathological improvements in the kidney, liver and pancreas compared to acarbose. The Lineweaver-Burk plot analysis indicated that compound 5r inhibits α-amylase through a mixed type of inhibition mechanism. Furthermore, molecular docking and dynamics simulations confirmed the in vitro findings while pharmacokinetic properties suggested compound 5r as a favorable drug candidate for the treatment of diabetic complications.

β-Cyclodextrin-functionalized nanocarriers for bromocriptine: development, evaluation and histopathological studies

Bromocriptine (BCM), a dopaminergic agonist used in Parkinson's disease treatment, has poor oral bioavailability due to extensive first-pass metabolism and limited gastrointestinal absorption. This study aimed to develop a β-cyclodextrin-functionalized bromocriptine nanoemulsion (oil-in-water) to enhance drug solubility, stability, and bioavailability while facilitating direct brain delivery via the intranasal route. The formulation was designed to overcome systemic metabolic barriers, improve drug permeation across the blood-brain barrier, and ensure sustained therapeutic effects with minimal systemic side effects. Nano-emulsions were prepared using high-shear homogenization. Characterization was performed using scanning electron microscopy (SEM) for morphological analysis. Globule size and zeta potential were measured using Malvern Zetasizer. Fourier Transform Infrared Spectroscopy (FTIR) was used for structural analysis, while X-ray diffraction (XRD) assessed crystallinity. Differential Scanning Calorimetry (DSC) was conducted for thermal analysis. Drug content and in-vitro drug release were evaluated using UV-visible spectroscopy. Stability studies were performed using centrifugation and freeze-thaw methods. Docking studies and Histopathological evaluation were also performed of the prepared formulations. Morphological studies revealed nano-sized globular particles with a mean diameter of 117.2 nm and a low polydispersity index (PDI 0.810), indicating uniformity. The nanoemulsion exhibited a zeta potential of -10.5 mV, ensuring colloidal stability. The encapsulation efficiency (EE%) of the optimized formulation (F4) was 95.36(% w/w,) with a drug load of approximately 9.5(% w/w). In-vitro drug release reached 85.65%, with permeation release of 78.44% and 70.13% ex-vivo. The formulation remained stable under freeze-thaw and centrifugation conditions. Cell toxicity assessments demonstrated excellent biocompatibility, with no significant cytotoxic effects observed in histopathological evaluations. This nanoemulsion presents a promising alternative to oral bromocriptine for Parkinson's treatment.

Key molecular scaffolds in the development of clinically viable α-amylase inhibitors

The escalating cases of type II diabetes combined with adverse side effects of current antidiabetic drugs spurred the advancement of innovative approaches for the management of postprandial glucose levels. α-Amylase is an endoamylase responsible for the breakdown of internal α-1,4-glycosidic linkages in dietary starch, producing oligosaccharides. Subsequently, α-glucosidase degraded these oligosaccharides to monosaccharides, which are absorbed into the bloodstream and become available to the body. The inhibitors of α-amylase reduced the digestibility of carbohydrates accompanied by delayed glucose absorption, leading to decreased blood glucose levels after meals and thus, inhibition of the enzyme seems to be a crucial strategy for diabetes management and improving overall glycemic control in diabetic patients. The present review article emphasizes the therapeutic promise of recently discovered potential α-amylase inhibitors, highlighting their in vitro, in silico and in vivo profiles. Ultimately, we addressed the contemporary challenges and potential routes ahead in the search for safe and reliable α-amylase inhibitors for clinical use, summarizing the most recent research in the field.

Novel carbazole-oxadiazole derivatives as anti-α-glucosidase and anti-α-amylase agents: Design, synthesis, molecular docking, and biological evaluation

To find novel inhibitors of α-glucosidase and α-amylase, a series of new carbazole-oxadiazole derivatives (6a-6n) were prepared, and screened for their anti-α-glucosidase and anti-α-amylase effects. Most of the tested derivatives showed different degrees of α-glucosidase and α-amylase inhibitory activity (IC50: 21.39 ± 0.69-92.05 ± 1.54 μM, 45.53 ± 1.50-126.14 ± 6.33 μM, respectively) compared to the standard acarbose (IC50: 427.00 ± 9.56 μM, 24.68 ± 1.10 μM, respectively). Thereinto, 6c (IC50 = 21.39 ± 0.69 μM) displayed the most effective anti-α-glucosidase activity and 6e presented the best anti-α-amylase activity with an IC50 value of 45.53 ± 1.50 μM. Lineweaver-Burk plot analysis suggested that 6c and 6e behaved as mixed α-glucosidase inhibitor and mixed α-amylase inhibitor, respectively. The results of circular dichroism, atomic force microscope, and molecular docking simulation exposed interaction mechanisms between two preferred compounds (6c and 6e) and their corresponding enzymes. Combined with the possible properties of reducing the elevation in postprandial blood glucose, oral activity, positive bioavailability, and low cytotoxicity of 6c and 6e, it could be concluded that the target derivatives may be able to act as lead molecules for the development of new hypoglycemic agents.

Inhibition mechanism of different structural polyphenols against α-amylase studied by solid-state NMR and molecular docking

Polyphenol has the considerable effects for inhibition of digestive enzymes, however, inhibition mechanism of molecular size-dependent polyphenols on enzyme activity is still lacking. Herein, inhibition effect and binding interactions of three different structural polyphenols (catechol, quercetin and hesperidin) on α-amylase were studied. Inhibition assays proved that polyphenols significantly inhibited α-amylase and their effects were increased with their molecular sizes. Hesperidin showed the highest inhibition ability of α-amylase, which was determined as IC50 = 0.43 mg/mL. Fluorescence and FT-IR spectroscopy proved that inter-molecular interactions between polyphenols and α-amylase occurred through non-covalent bonds. Besides, the secondary structure of α-amylase was obviously changed after binding with polyphenols. Inter-molecular interactions were investigated using solid-state NMR and molecular docking. Findings proved that hydrogen bonds and π-π stacking interactions were the mainly inter-molecular interactions. We hope this contribution could provide a theoretical basis for developing some digestive enzyme inhibitors from natural polyphenols.

Effective α-glycosidase inhibitors based on polyphenolic benzothiazole heterocycles

α-Glycosidase inhibition is one of the main approaches to treat Diabetes mellitus. Polyphenolic moieties are known to be responsible for yielding exhibit potent α-glycosidase inhibitory effects. In addition, compounds containing benzothiazole and Schiff base functionalities were previously reported to show α-glycosidase inhibition. In this paper, the synthesis of seven new phloroglucinol-containing benzothiazole Schiff base derivatives through the reaction of 6-substituted-2-aminobenzothiazole compounds with 2,4,6-trihydroxybenzaldehyde using acetic acid as a catalyst was reported. The synthesized compounds were characterized using spectroscopic methods such as FT-IR, 1H NMR, 13C NMR, and elemental analysis. The synthesized compounds were evaluated for their inhibitory effects on α-glycosidase, compounds 3f and 3g were found to show significant inhibitory properties when compared to the positive control. The IC50 values of 3f and 3g were calculated as 24.05 ± 2.28 and 18.51 ± 1.19 µM, respectively. Kinetic studies revealed that compounds 3f and 3g exhibited uncompetitive mode of inhibition against α-glycosidase. Molecular modeling predicted druglikeness for the title compounds and underpinned the importance of phloroglucinol hydroxyls for interacting with the key residues of α-glycosidase.