Phenolics from Chrozophora oblongifolia Aerial Parts as Inhibitors of α-Glucosidases and Advanced Glycation End Products: In-Vitro Assessment, Molecular Docking and Dynamics Studies

α-Glucosidase, butyrylcholinesterase and acetylcholinesterase inhibitory activities of phenolic compounds from Carthamus tinctorius L. flowers: In silico and in vitro studies

Chemical investigation of Carthamus tinctorius L. flowers resulted in isolation of seven metabolites that were identified as; p-Hydroxybenzoic acid (1), trans hydroxy cinnamic acid (2), kaempferol-6-C-glucoside (3), astragalin (4), cartormin (5), kaempferol-3-O-rutinoside (6), and kaempferol-3-O-sophoroside (7). Virtual screening of the isolated compounds against human intestinal α-glucosidase, acetylcholinesterase, and butyrylcholinesterase was carried out. Additionally, the antioxidant activity of the bioactive compounds was assessed. Compounds 1 and 5 exhibited moderate binding affinities to acetylcholinesterase (binding energy -5.33 and -4.18 kcal/mol, respectively), compared to donepezil (-83.33kcal/mol). Compounds 1-7 demonstrated weak affinity to butyrylcholinesterase. Compounds 2 and 4 displayed moderate binding affinity to human intestinal α-glucosidase,compared to Acarbose (reference compound), meanwhile compound 2 exhibited lower affinity. Molecular dynamic studies revealed that compound 4 formed a stable complex with the binding site throughout a 100 ns simulation period. The in-vitro results were consistent with the virtual experimental results, as compounds 1 and 5 showed mild inhibitory effects on acetylcholinesterase (IC50s 150.6 and 168.7 µM, respectively). Compound 4 exhibited moderate α-glucosidase inhibition with an IC50 of 93.71 µM. The bioactive compounds also demonstrated notable antioxidant activity in ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)], ORAC (oxygen radical-absorbance capacity), and metal chelation assays, suggesting their potential in improving dementia in Alzheimer's disease (AD) and mitigating hyperglycemia.

Potential antioxidant, α-glucosidase, butyrylcholinesterase and acetylcholinesterase inhibitory activities of major constituents isolated from Alpinia officinarum hance rhizomes: computational studies and in vitro validation

Alpinia officinarum is a commonly used spice with proven folk uses in various traditional medicines. In the current study, six compounds were isolated from its rhizomes, compounds 1-3 were identified as diarylheptanoids, while 4-6 were identified as flavonoids and phenolic acids. The isolated compounds were subjected to virtual screening against α-glucosidase, butyrylcholinesterase (BChE), and acetylcholinesterase (AChE) enzymes to evaluate their potential antidiabetic and anti-Alzheimer's activities. Molecular docking and dynamics studies revealed that 3 exhibited a strong binding affinity to human a α- glucosidase crystal structure compared to acarbose. Furthermore, 2 and 5 demonstrated high potency against AChE. The virtual screening results were further supported by in vitro assays, which assessed the compounds' effects on α-glucosidase, cholinesterases, and their antioxidant activities. 5-Hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenylheptan-3-one (2) showed potent antioxidant effect in both ABTs and ORAC assays, while p-hydroxy cinnamic acid (6) was the most potent in the ORAC assay. In contrary, kaempferide (4) and galangin (5) showed the most potent effect in metal chelation assay. 5-Hydroxy-1,7-diphenylhepta-4,6-dien-3-one (3) and 6 revealed the most potent effect as α-glucosidase inhibitors where compound 3 showed more potent effect compared to acarbose. Galangin (5) revealed a higher selectivity to BChE, while 2 showed the most potent activity to (AChE).

Hydrocotyle umbellata L.; a natural source of bioactives to mitigate diabetes mellitus and its complications

Metabolomics study of Hydrocotyle umbellata L. revealed the richness of its aerial parts in phenolics primarily; quercetin and its glycoside derivatives, which are well-reported to exert antidiabetic activity owing to their powerful antioxidant capacity. Hence, the antioxidant and antidiabetic potentials of the quercetin standardized ethanolic extract of H. umbellata aerial parts were investigated. The antioxidant activity was examined by using in-vitro 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay, while the antidiabetic activity was examined by using in-vitro α-glucosidase inhibitory assay and further confirmed by in-vivo experiments using streptozotocin-induced diabetes in rat model. Interestingly, the standardized ethanolic extract showed significant in-vitro antioxidant activity, and effectively inhibited Saccharomyces cerevisiae α-glucosidase enzyme activity. Moreover, it significantly reduced fasting blood glucose, triglycerides, and cholesterol levels. Thus, H. umbellata is a potential natural candidate to attenuate diabetes mellitus and its altered lipid profile complications, which could be attributed to its quercetin and quercetin glycosides content.

Effect of Phenolics from Aeonium arboreum on Alpha Glucosidase, Pancreatic Lipase, and Oxidative Stress; a Bio-Guided Approach

Metabolic syndrome (MetS) is a global issue affecting over a billion people, raising the risk of diabetes, cardiovascular disorders, and other ailments. It is often characterized by hypertension, dyslipidemia and/or obesity, and hyperglycemia. Chemical investigation of Aeonium arboreum (L.) Webb & Berthel led to the isolation of six compounds, viz. β-sitosterol, β-sitosterol glucoside, myricetin galactoside, quercetin rhamnoside, kaempferol rhamnoside, and myricetin glucoside. Interestingly, A. arboreum's dichloromethane (DCM), 100 and 50% MeOH Diaion fractions and the isolated compound (quercetin-3-rhamnoside) revealed potent α-glucosidase inhibitory activity, especially 50% Diaion fraction. In addition, they also showed very potent antioxidant potential, especially the polar fractions, using DPPH, ABTS, FRAP, ORAC, and metal chelation assays. Notably, the 50% Diaion fraction had the highest antioxidant potential using DPPH and ORAC assays, while the 100% Diaion fraction and quercetin-3-rhamnoside showed the highest activity using ABTS, FRAP, and metal chelation assays. Also, quercetin-3-rhamnoside showed a good docking score of -5.82 kcal/mol in comparison to acarbose. In addition, molecular dynamic stimulation studies illustrated high stability of compound binding to pocket of protein. Such potent activities present A. arboreum as a complementary safe approach for the management of diabetes mellitus as well as MetS.

Deciphering Molecular Aspects of Potential α-Glucosidase Inhibitors within Aspergillus terreus: A Computational Odyssey of Molecular Docking-Coupled Dynamics Simulations and Pharmacokinetic Profiling

Hyperglycemia, as a hallmark of the metabolic malady diabetes mellitus, has been an overwhelming healthcare burden owing to its high rates of comorbidity and mortality, as well as prospective complications affecting different body organs. Available therapeutic agents, with α-glucosidase inhibitors as one of their cornerstone arsenal, control stages of broad glycemia while showing definitive characteristics related to their low clinical efficiency and off-target complications. This has propelled the academia and industrial section into discovering novel and safer candidates. Herein, we provided a thorough computational exploration of identifying candidates from the marine-derived Aspergillus terreus isolates. Combined structural- and ligand-based approaches using a chemical library of 275 metabolites were adopted for pinpointing promising α-glucosidase inhibitors, as well as providing guiding insights for further lead optimization and development. Structure-based virtual screening through escalating precision molecular docking protocol at the α-glucosidase canonical pocket identified 11 promising top-docked hits, with several being superior to the market drug reference, acarbose. Comprehensive ligand-based investigations of these hits' pharmacokinetics ADME profiles, physiochemical characterizations, and obedience to the gold standard Lipinski's rule of five, as well as toxicity and mutagenicity profiling, proceeded. Under explicit conditions, a molecular dynamics simulation identified the top-stable metabolites: butyrolactone VI (SK-44), aspulvinone E (SK-55), butyrolactone I 4''''-sulfate (SK-72), and terrelumamide B (SK-173). They depicted the highest free binding energies and steadiest thermodynamic behavior. Moreover, great structural insights have been revealed, including the advent of an aromatic scaffold-based interaction for ligand-target complex stability. The significance of introducing balanced hydrophobic/polar moieties, like triazole and other bioisosteres of carboxylic acid, has been highlighted across docking, ADME/Tox profiling, and molecular dynamics studies for maximizing binding interactions while assuring safety and optimal pharmacokinetics for targeting the intestinal-localized α-glucosidase enzyme. Overall, this study provided valuable starting points for developing new α-glucosidase inhibitors based on nature-derived unique scaffolds, as well as guidance for prospective lead optimization and development within future pre-clinical and clinical investigations.

Advanced Glycation End-Products and Diabetic Neuropathy of the Retina

Diabetic retinopathy is a tissue-specific neurovascular impairment of the retina in patients with both type 1 and type 2 diabetes. Several pathological factors are involved in the progressive impairment of the interdependence between cells that consist of the neurovascular units (NVUs). The advanced glycation end-products (AGEs) are one of the major pathological factors that cause the impairments of neurovascular coupling in diabetic retinopathy. Although the exact mechanisms for the toxicities of the AGEs in diabetic retinopathy have not been definitively determined, the AGE-receptor of the AGE (RAGE) axis, production of reactive oxygen species, inflammatory reactions, and the activation of the cell death pathways are associated with the impairment of the NVUs in diabetic retinopathy. More specifically, neuronal cell death is an irreversible change that is directly associated with vision reduction in diabetic patients. Thus, neuroprotective therapies must be established for diabetic retinopathy. The AGEs are one of the therapeutic targets to examine to ameliorate the pathological changes in the NVUs in diabetic retinopathy. This review focuses on the basic and pathological findings of AGE-induced neurovascular abnormalities and the potential therapeutic approaches, including the use of anti-glycated drugs to protect the AGE-induced impairments of the NVUs in diabetic retinopathy.