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Although the crystals of coordination polymer {[CuCl(μ-O,O’-L-Br₂Tyr)]}n (1) (L-Br₂Tyr = 3,5-dibromo-L-tyrosine) were formed under basic conditions, crystallographic studies revealed that the OH group of the ligand remained protonated. Two adjacent [CuCl(L-Br₂Tyr)] monomers, bridged by the carboxylate group of the ligand in the syn-anti bidentate bridging mode, are differently oriented to form a polymeric chain; this specific bridging was detected also by FT-IR and EPR spectroscopy. Each Cu(II) ion in polymeric compound 1 is coordinated in the xy plane by the amino nitrogen and carboxyl oxygen of the parent ligand and the oxygen of the carboxyl group from the symmetry related ligand of the adjacent [Cu(L-Br₂Tyr)Cl] monomer, as well as an independent chlorine ion. In addition, the Cu(II) ion in the polymer chain participates in long-distance intermolecular contacts with the oxygen and bromine atoms of the ligands located in the adjacent chains; these intramolecular contacts were also supported by NCI and NBO quantum chemical calculations and Hirshfeld surface analysis. The resulting elongated octahedral geometry based on the [CuCl(L-Br₂Tyr)] monomer has a lower than axial symmetry, which is also reflected in the symmetry of the calculated molecular EPR g tensor. Consequently, the components of the d-d band obtained by analysis of the NIR-VIS-UV spectrum were assigned to the corresponding electronic transitions. Full article

(1) Background: Almost 500 million people worldwide are suffering from diabetes. Since ancient times, humans have used medicinal plants for the treatment of diabetes. Medicinal plants continue to serve as natural sources for the discovery of antidiabetic compounds. Prangos pabularia Lindl. is a widely distributed herb with large reserves in Tajikistan. Its roots and fruits have been used in Tajik traditional medicine. To our best knowledge, there are no previously published reports concerning the antidiabetic activity and the chemical composition of the essential oil obtained from roots of P. pabularia. (2) Methods: The volatile secondary metabolites were obtained by hydrodistillation from the underground parts of P. pabularia growing wild in Tajikistan and were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Protein tyrosine phosphatase 1B (PTP-1B) inhibition assay and molecular docking analysis were carried out to evaluate the potential antidiabetic activity of the P. pabularia essential oil. (3) Results: The main constituents of the volatile oil of P. pabularia were 5-pentylcyclohexa-1,3-diene (44.6%), menthone (12.6%), 1-tridecyne (10.9%), and osthole (6.0%). PTP-1B inhibition assay of the essential oil and osthole resulted in significant inhibitory activity with an IC₅₀ value of 0.06 ± 0.01 and 0.93 ± 0.1 μg/mL. Molecular docking analysis suggests volatile compounds such as osthole inhibit PTP-1B, and the results are also in agreement with experimental investigations. (4) Conclusions: Volatile secondary metabolites and the pure isolated compound (osthole) from the roots of P. pabularia exhibited potent antidiabetic activity, twenty-five and nearly two times more than the positive control (3-(3,5-dibromo-4-hydroxybenzoyl)-2-ethylbenzofuran-6-sulfonic acid-(4-(thiazol-2-ylsulfamyl)-phenyl)-amide)) with an IC₅₀ value of 1.46 ± 0.4 μg/mL, respectively. Full article

3,4-Dibromo-5-(2-bromo-3,4-dihydroxy-6-(isopropoxymethyl)benzyl)benzene-1,2-diol (HPN) is a synthetic analogue of 3,4-dibromo-5-(2-bromo-3,4-dihydroxy-6-(ethoxymethyl)benzyl)benzene-1,2-diol (BPN), which is isolated from marine red alga Rhodomela confervoides with potent protein tyrosine phosphatase 1B (PTP1B) inhibition (IC₅₀ = 0.84 μmol/L). The in vitro assay showed that HPN exhibited enhanced inhibitory activity against PTP1B with IC₅₀ 0.63 μmol/L and high selectivity against other PTPs (T cell protein tyrosine phosphatase (TCPTP), leucocyte antigen-related tyrosine phosphatase (LAR), Src homology 2-containing protein tyrosine phosphatase-1 (SHP-1) and SHP-2). The results of antihyperglycemic activity using db/db mouse model demonstrated that HPN significantly decreased plasma glucose (P < 0.01) after eight weeks treatment period. HPN lowered serum triglycerides and total cholesterol concentration in a dose-dependent manner. Besides, both of the high and medium dose groups of HPN remarkably decreased HbA1c levels (P < 0.05). HPN in the high dose group markedly lowered the insulin level compared to the model group (P < 0.05), whereas the effects were less potent than the positive drug rosiglitazone. Western blotting results showed that HPN decreased PTP1B levels in pancreatic tissue. Last but not least, the results of an intraperitoneal glucose tolerance test in Sprague–Dawley rats indicate that HPN have a similar antihyperglycemic activity as rosiglitazone. HPN therefore have potential for development as treatments for Type 2 diabetes. Full article