Synthesis of indole analogs as potent β-glucuronidase inhibitors

An effort to find new α-amylase inhibitors as potent antidiabetics compounds based on indole-based-thiadiazole analogs

Inhibition of α-amylase enzyme is of key significance for the therapy of diabetes mellitus (DM). Numerous indole-based compounds have earlier been described for broad range of bioactivities. From our previous study, we knew that indole and thiadiazole are potent inhibitors of diabetics II. We design the hybrid molecules of them and synthesized 18 derivatives of indole-based-thiadiazole (1-18). All synthesized compounds were characterized using different spectroscopic methods and evaluated for their α-amylase inhibitory activities. All synthetic compounds, except 4, 13, 15 and 16, were found to be strongly active (IC₅₀ values in the range of 0.80 ± 0.05 - 9.30 ± 0.20 µM) than the standard drug, acarbose (IC₅₀ = 11.70 ± 0.10 µM). Nevertheless, compound 18 was found to be inactive. The modes of binding interactions of five most active compounds 2, 3, 5, 10 and 17 were also studies through molecular docking study. In brief, current study identifies a novel class of α-amylase inhibitors which can be further studied for the treatment of hyperglycemia and obesity.Communicated by Ramaswamy H. Sarma.

Therapeutic significance of β-glucuronidase activity and its inhibitors: A review

The emergence of disease and dearth of effective pharmacological agents on most therapeutic fronts, constitutes a major threat to global public health and man's existence. Consequently, this has created an exigency in the search for new drugs with improved clinical utility or means of potentiating available ones. To this end, accumulating empirical evidence supports molecular target therapy as a plausible egress and, β-glucuronidase (βGLU) - a lysosomal acid hydrolase responsible for the catalytic deconjugation of β-d-glucuronides has emerged as a viable molecular target for several therapeutic applications. The enzyme's activity level in body fluids is also deemed a potential biomarker for the diagnosis of some pathological conditions. Moreover, due to its role in colon carcinogenesis and certain drug-induced dose-limiting toxicities, the development of potent inhibitors of βGLU in human intestinal microbiota has aroused increased attention over the years. Nevertheless, although our literature survey revealed both natural products and synthetic scaffolds as potential inhibitors of the enzyme, only few of these have found clinical utility, albeit with moderate to poor pharmacokinetic profile. Hence, in this review we present a compendium of exploits in the present millennium directed towards the inhibition of βGLU. The aim is to proffer a platform on which new scaffolds can be modelled for improved βGLU inhibitory potency and the development of new therapeutic agents in consequential.

Action of Thioglycosides of 1,2,4-Triazoles and Imidazoles on the Oxidative Stress and Glycosidases in Mice with Molecular Docking

Background:

,2,3-Triazoles and imidazoles are important five-membered heterocyclic scaffolds due to their extensive biological activities. These products have been an area of growing interest to many researchers around the world because of their enormous pharmaceutical scope.

Methods:

The in vivo and in vitro enzyme inhibition of some thioglycosides encompassing 1,2,4- triazole N1, N2, and N3 and/or imidazole moieties N4, N5, and N6. The effect on the antioxidant enzymes (superoxide dismutase, glutathione S-transferase, glutathione peroxidase and catalase) was investigated as well as their effect on α-glucosidase and β-glucuronidase. Molecular docking studies were carried out to investigate the mode of the binding interaction of the compounds with α- glucosidase and β -glucuronidase. In addition, quantitative structure-activity relationship (QSAR) investigation was applied to find out the correlation between toxicity and physicochemical properties.

Results:

The decrease of the antioxidant status was revealed by the in vivo effect of the tested compounds. Furthermore, the in vivo and in vitro inhibitory effects of the tested compounds were clearly pronounced on α-glucosidase, but not β-glucuronidase. The IC50 and Ki values revealed that the thioglycoside - based 1,2,4-triazole N3 possesses a high inhibitory action. In addition, the in vitro studies demonstrated that the whole tested 1,2,4-triazole are potent inhibitors with a Ki magnitude of 10-6 and exhibited a competitive type inhibition. On the other hand, the thioglycosides - based imidazole ring showed an antioxidant activity and exerted a slight in vivo stimulation of α-glucosidase and β- glucuronidase. Molecular docking proved that the compounds exhibited binding affinity with the active sites of α -glucosidase and β-glucuronidase (docking score ranged from -2.320 to -4.370 kcal/mol). Furthermore, QSAR study revealed that the HBD and RB were found to have an overall significant correlation with the toxicity.

Conclusion:

These data suggest that the inhibition of α-glucosidase is accompanied by an oxidative stress action.

Synthesis, Molecular Docking and β-Glucuronidase Inhibitory Potential of Indole Base Oxadiazole Derivatives

β-glucuronidase is a lysosomal glycosidase enzyme which catalyzes the extracellular matrix of cancer and normal cells and the glycosaminoglycans of the cell membrane, which is important for cancer cell proliferation, invasion, and metastasis. Liver cancer, colon carcinoma, and neoplasm bladder are triggered by the increase of the level of β-glucuronidase activity. The most valuable structures are indole and oxadiazole which has gain immense attention because of its pharmacological behavior and display many biological properties. Twenty-two (1⁻22) analogs of indole based oxadiazole were synthesized and screened for their inhibitory potential against β-glucuronidase. Majority of the compounds showed potent inhibitory potential with IC₅₀ values ranging between 0.9 ± 0.01 to 46.4 ± 0.9 µM, under positive control of standard drug d-saccharic acid 1,4 lactone (IC₅₀ = 48.1 ± 1.2 µM). Structural activity relationship (SAR) has been established for all synthesized compounds. To shed light on molecular interactions between the synthesized compounds and β-glucuronidase, 1, 4, and 6 compounds were docked into the active binding site of β-glucuronidase. The obtained results showed that this binding is thermodynamically favorable and β-glucuronidase inhibition of the selected compounds increases with the number of hydrogen bonding established in selected compound-β-glucuronidase complexes.

Simultaneous determination of intestinal permeability and potential drug interactions of complex mixtures using Caco-2 cells and high-resolution mass spectrometry: Studies with Rauwolfia serpentina extract

Caco-2 cells are a commonly used model for estimating the intestinal bioavailability of single chemical entity pharmaceuticals. Caco-2 cells, when induced with calcitriol, also express other biological functions such as phase I (CYP) and phase II (glucuronosyltransferases) drug metabolizing enzymes which are relevant to drug-supplement interactions. Intestinal bioavailability is an important factor in the overall safety assessment of products consumed orally. Foods, including herbal dietary supplements, are complex substances with multiple chemical components. Because of potential interactions between components of complex mixtures, more reliable safety assessments can be obtained by studying the commercial products "as consumed" rather than by testing individual chemical components one at a time. The present study evaluated the apparent intestinal permeability (P_app) of a model herbal extract, Rauwolfia serpentina, using both whole plant extracts and the individual purified Rauwolfia alkaloids. All test compounds, endpoint substrates, and their metabolites were quantified using liquid chromatography and high-resolution mass spectrometry. The P_app values for individual Rauwolfia alkaloids were comparable whether measured individually or as components of the complete extract. Both Rauwolfia extract and all individual Rauwolfia alkaloids except yohimbine inhibited CYP3A4 activity (midazolam 1'-hydroxylation). Both Rauwolfia extract and all individual Rauwolfia alkaloids except corynanthine and reserpic acid significantly increased glucuronosyltransferase activity (glucuronidation of 4-methylumbelliferone). The positive control, ketoconazole, significantly inhibited both CYP3A4 and glucuronosyltransferase activities. These findings suggest that the Caco-2 assay is capable of simultaneously identifying both bioavailability and potentially hazardous intestinal drug-supplement interactions in complex mixtures.

Synthesis: Small library of hybrid scaffolds of benzothiazole having hydrazone and evaluation of their β-glucuronidase activity

Due to the great biological importance of β-glucuronidase inhibitors, here in this study, we have synthesized a library of novel benzothiazole derivatives (1-30), characterized by different spectroscopic methods and evaluated for β-glucuronidase inhibitory potential. Among the series sixteen compounds i.e.1-6, 8, 9, 11, 14, 15, 20-23 and 26 showed outstanding inhibitory potential with IC₅₀ value ranging in between 16.50 ± 0.26 and 59.45 ± 1.12 when compared with standard d-Saccharic acid 1,4-lactone (48.4 ± 1.25 µM). Except compound 8 and 23 all active analogs showed better potential than the standard. Structure activity relationship has been established.