Synthesis, characterization, crystal structure of the coordination polymer Zn(II) with thiosemicarbazone of glyoxalic acid and their inhibitory properties against some metabolic enzymes

Synthesis and Characterization of Copper(II) and Nickel(II) Complexes with 3-(Morpholin-4-yl)propane-2,3-dione 4-Allylthiosemicarbazone Exploring the Antibacterial, Antifungal and Antiradical Properties

The eleven new copper(II) and nickel(II) coordination compounds [Cu(L)Br]2 (1), [Cu(L)Cl] (2), [Cu(L)NO3] (3), [Ni(L)Cl] (4), [Ni(HL)2](NO3)2 (5), and [Cu(A)(L)]NO3, where A is 1,10-phenanthroline (6), 2,2'-bipyridine (7), 3,4-dimethylpyridine (8), 3-methylpyridine (9), pyridine (10) and imidazole (11) were synthesized with 3-(morpholin-4-yl)propane-2,3-dione 4-allylthiosemicarbazone (HL). The new thiosemicarbazone was characterized by NMR and FTIR spectroscopy. All the coordination compounds were characterized by elemental analysis and FTIR spectroscopy. Also, the crystal structures of HL and complexes 1, 6, 7, and 11 were determined using single-crystal X-ray diffraction analysis. Complex 1 has a dimeric molecular structure with two bromide bridging ligands, while 6, 7, and 11 are ionic compounds and comprise monomeric complex cations. The studied complexes manifest antibacterial and antifungal activities and also have an antiradical activity that, in many cases, surpasses the activity of trolox, which is used as a standard antioxidant in medicine. Copper complexes 1-3 have very weak antiradical properties (IC50 > 100 µM), but nickel complexes 4-5 are strong antiradicals with IC50 values lower than that of trolox. The mixed ligand copper complexes with additional ligand of N-heteroaromatic base are superior to complexes without these additional ligands. They are 1.4-5 times more active than trolox.

Highly Selective Ratiometric Sensors for Pb2+ Based on Luminescent Zn(II)-Coordination Polymers with Thiophenedicarboxylate. Crystal Structures and Spectroscopic Studies

The development of luminescent coordination polymers for the selective sensing of Pb2+ in water constitutes an active area of research that impacts analytical, environmental, and inorganic chemistry. Herein, two novel water-stable 2D Zn-coordination polymers {[Zn2(H2O)2(tdc)2(bpy)]·(H2O)}n 1 and [Zn(tdc)(tmb)]n 2 (tdc = thiophenedicarboxylate; bpy = 4,4'-bipyridine and tmb = 4,4'-trimethylenebipyridine) were synthesized, structurally determined by single crystal X-ray diffraction, and studied in-depth as luminescent sensors for a series of cations (Ca2+, Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ Cd2+, Hg2+ and Pb2+) in 20% aqueous ethanol. These Zn-polymers possess photostability in 20% aqueous ethanol with a strong emission at 410 upon excitation at 330 nm and quantum yields of around Φ = 0.09. Under these conditions, Pb+2 can be efficiently sensed with polymer 2 through a fluorescent ratiometric response with selectivity over common interfering metal ions such as Cu2+, Cd2+ and Hg2+ in the micromolar concentration range (detection limit = 1.78 ± 10 μM). Such selectivity/affinity of Pb2+ over Hg2+ for luminescent chemosensors is still rare. On the basis of spectroscopic tools (1H NMR, far ATR-IR, PXRD), the X-ray crystal structure of 2, and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopic analysis, the ratiometric fluorescent response is proposed via an efficient metal-ion exchange driven through interactions between thiophenedicarboxylate rings and Pb2+ ions. The use of flexible luminescent Zn-coordination polymers as sensors for selective and direct detection of Pb2+ in aqueous media has been unexplored until now.

New palladium complexes with N-heterocyclic carbene and morpholine ligands: Synthesis, characterization, crystal structure, molecular docking, and biological activities

This work includes the synthesis of a new series of palladium-based complexes containing both morpholine and N-heterocyclic carbene (NHC) ligands. The new complexes were characterized using NMR (1 H and 13 C), FTIR spectroscopic, and elemental analysis techniques. The crystal structure of complex 1b was obtained by utilizing the single-crystal X-ray diffraction method. X-ray studies show that the coordination environment of palladium atom is completed by the carbene carbon atom of the NHC ligand, the nitrogen atom of the morpholine ring, and a pair of bromide ligand, resulting in the formation of slightly distorted square planar geometry. All complexes were determined for some metabolic enzyme activities. Results indicated that all the synthetic complexes exhibited powerful inhibitory actions against all aims as compared to the control molecules. Ki values of new morpholine-liganded complexes bearing 4-hydroxyphenylethyl group 1a-e for hCA I, hCA II, AChE, BChE, and α-glycosidase enzymes were obtained in the ranges 0.93-2.14, 1.01-2.03, 4.58-10.27, 7.02-13.75, and 73.86-102.65 µM, respectively. Designing of reported complexes is impacted by molecular docking study, and interaction with the current enzymes also proclaimed that compounds 1e (-12.25 kcal/mol for AChE and -11.63 kcal/mol for BChE), 1c (-10.77 kcal/mol and -9.26 kcal/mol for α-Gly and hCA II, respectively), and 1a (-8.31 kcal/mol for hCA I) are showing binding affinity and interaction from the synthesized five novel complexes.

Synthesis and Biological Activity of Some Bromophenols and Their Derivatives Including Natural Products

In addition to the first synthesis of the natural bromophenol butyl 2-(3,5-dibromo-4-hydroxyphenyl)acetate (1), indene derivatives 34 and 35 were synthesized from 3-phenylpropenal derivatives in BBr3 medium. Five known natural bromophenols and some derivatives were synthesized by known methods. Cholinesterase (ChEs) inhibitors reduce the breakdown of acetylcholine and are used in the treatment of Alzheimer's disease (AD) and dementia symptoms. The inhibition effects of all obtained compounds were examined towards acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glycosidase enzymes. All synthesized compounds demonstrated the strong inhibition effects against both cholinergic enzymes. For determination of Ki values of novel bromophenols Lineweaver-Burk graphs were obtained. Ki values were found in the ranging of 0.13-14.74 nM for AChE, 5.11-23.95 nM for BChE, and 63.96-206.78 nM for α-glycosidase, respectively. All bromophenols and their derivatives exhibit effective inhibition profile when compared to positive controls.

Novel tetrakis-phthalocyanines bearing pyrimidine derivative: crystal XRD analysis, enzyme inhibition, molecular docking, and anticancer effects

In this study, the novel 4-(4-Aminopyrimidin-2-ylthio) phthalonitrile (1) as starting material was synthesized and its 3D structure was verified by the single crystal X-ray diffraction experiment. Then, its peripherally tetra-substituted phthalocyanines (2,3) and the methylated derivatives (2a,3a) containing pyrimidine derivative were synthesized. All these newly synthesized compounds were characterized with various spectroscopic methods such as UV-Vis, FT-IR, ¹H-NMR, ¹³C-NMR and MALDI-TOF MS by obtaining satisfactory results. In addition, these novel phthalocyanines effectively inhibited acetylcholinesterase enzyme, with K_i values in the range of 10.43 ± 2.38 to 41.70 ± 9.32 µM. For the related enzyme, the IC₅₀ values were obtained in the range of 11.68 to 44.28 µM. For α-glycosidase enzyme the most effective K_i values of (3a) and (2) were with K_i values of 92.87 ± 10.70 and 95.18 ± 17.83 µM, respectively. Indeed, the most potent phthalocyanines against both enzymes were recorded for the purpose of investigating interaction modes of these complexes in the active site of the target enzyme. The cytotoxicity potential of these phthalocyanines against human breast, colon, and prostate cancers demonstrated that these compounds had normal cytotoxic effects.Communicated by Ramaswamy H. Sarma.

Enzyme inhibition, molecular docking, and density functional theory studies of new thiosemicarbazones incorporating the 4-hydroxy-3,5-dimethoxy benzaldehyde motif

New Schiff base-bearing thiosemicarbazones (1-13) were obtained from 4-hydroxy-3,5-dimethoxy benzaldehyde and various isocyanates. The structures of the synthesized molecules were elucidated in detail. Density functional theory calculations were also performed to determine the spectroscopic properties of the compounds. Moreover, the enzyme inhibition activities of these compounds were investigated. They showed highly potent inhibition effects on acetylcholinesterase (AChE) and human carbonic anhydrases (hCAs) (K_I values are in the range of 51.11 ± 6.01 to 278.10 ± 40.55 nM, 60.32 ± 9.78 to 300.00 ± 77.41 nM, and 64.21 ± 9.99 to 307.70 ± 61.35 nM for AChE, hCA I, and hCA II, respectively). In addition, molecular docking studies were performed, confirmed by binding affinities studies of the most potent derivatives.

Zn(II) metal-organic architectures from ether-bridged tetracarboxylate linkers: assembly, structural variety and catalytic features

Semi-flexible aromatic polycarboxylic acids are gaining impetus in crystal engineering of functional coordination polymers (CPs). This work opens up the use of two ether-bridged tetracarboxylic acids, 3-(2,5-dicarboxyphenoxy)phthalic acid (H4dpa) and...

Probing the acetylcholinesterase inhibitory activity of a novel Ru(II) polypyridyl complex and the supramolecular interaction by (STD)-NMR

Currently, acetylcholinesterase (AChE) inhibitors are the only anti-Alzheimer drugs commercially available. Despite their wide use those drugs are all dose dependent and their effect last for no longer than two years, with several side effects. The search of novel acetylcholinesterase (AChE) inhibitors remains as the main scientific route. Here we describe the synthesis, characterization, biological activity and an NMR binding-target study of a novel cis-[Ru(Bpy)₂(EtPy)₂]²⁺, (RuEtPy), Bpy = 2,2'-bipyridine and EtPy = 4,2-Ethylamino-pyridine) as a potential AChE inhibitor. The classic Ellman's colorimetric assay suggests that the RuEtPy exhibits a high inhibitory activity, following a competitive mechanism, with a remarkable low inhibition constant (Ki ≈ 16.8 μM), together with a IC₅₀ = 39 μM. Hence, we have studied the spatial interactions for this novel candidate towards the human acetylcholinesterase (hAChE) using saturation transfer difference (STD)-NMR, in order to describe the mechanism of the interaction. NMR binding-target results shows that the 4,2-Ethylamino-Pyridine group is spatially closer to hAChE surface chemical arrangement than 2,2' bipyridine counterpart, exerting an efficient intermolecular interaction, with a low dissociation constant (K_D ≈ 55 μM), probing that 4,2-Ethylamino-pyridine motif plays a key role in the inhibitory action.

The Synthesis of a Bis(thiosemicarbazone) Macrocyclic Ligand and the Mn(II), Co(II), Zn(II) and 68Ga(III) Complexes

A 1,4,7,10-tetraazacyclododecane (cyclen) variant bearing two thiosemicarbazone pendant groups has been prepared. The ligand forms complexes with Mn2+, Co2+ and Zn2+. X-ray crystallography of the Mn2+, Co2+ and Zn2+ complexes showed that the ligand provides a six-coordinate environment for the metal ions. The Mn2+ and Zn2+ complexes exist in the solid state as racemic mixtures of the Δ(δ,δ,δ,δ)/Λ(λ,λ,λ,λ) and Δ(λ,λ,λ,λ)/Λ(δ,δ,δ,δ) diastereomers, and the Co2+ complex exists as the Δ(δ,δ,δ,δ)/Λ(λ,λ,λ,λ) and Δ(λ,λ,λ,δ)/Λ(δ,δ,δ,λ) diastereomers. Density functional theory calculations indicated that the relative energies of the diastereomers are within 10 kJ mol-1. Magnetic susceptibility of the complexes indicated that both the Mn2+ and Co2+ ions are high spin. The ligand was radiolabelled with gallium-68, in the interest of developing new positron emission tomography imaging agents, which produced a single species in high radiochemical purity (>95%) at 90 °C for 10 min.

Synthesis, biological activity and docking calculations of bis-naphthoquinone derivatives from Lawsone

Some metabolic enzyme inhibitors can be used as Multi-target-Directed-Ligands (MTDL) in Medicinal chemistry therefore, synthesis and determination of alternative inhibitors are essential. In this study, novel bis-napthoquinone derivatives (5a-o) were synthesized through a multi-component cascade reaction of two molecules of 2-hydroxy-1,4-naphthoquinone with an aromatic aldehyde in basic media using triethylamine as a catalyst. This novel heterocyclic derivatives (5a-o) are applied to inhibit the carbonic anhydrase (hCA I and hCA II) isoform in low levels of nano molecules with Ki values exist between 4.62 ± 1.01 to 70.45 ± 9.03 nM for hCA I and for hCA II which is physiologically dominant K_is values are in the range of 5.61 ± 1.04 to 73.26 ± 10.25 nM. Further these novel derivatives (5a-o) efficiently inhibit AChE with Ki values in the range of 0.13 ± 0.02 to 3.16 ± 0.56 nM. The compounds are also applied for BChE with Ki values varying between 0.50 ± 0.10 to 9.23 ± 1.15 nM. For α-glycosidase, the most efficient Ki values of 5e and 5f are 76.14 ± 9.60 and 95.27 ± 12.55 nM respectively. Finally, molecular docking calculations against enzymes (acetylcholinesterase, butyrylcholinesterase, and the human carbonic anhydrase I and II) are compared using biological activities of heterocyclic derivatives. After these calculations, an ADME/T analysis is performed to study the future medicinal use of heterocyclic derivatives from lawsone.

Fatty acid composition, enzyme inhibitory effect, antioxidant and anticancer activity of extract from Saponaria prostrata WILLD. subsp. anatolica HEDGE

This study attempts to evaluate the antioxidant, enzyme inhibitory, and anticancer properties as well as fatty acid compositions of endemic Saponaria prostrata WILLD. subsp. anatolica HEDGE. The gas chromatography-mass spectrometry (GC-MS) was used to determine the fatty acid content of methanol: dichloromethane extract from S. prostrata subsp. anatolica (SPA). Enzymatic activity was measured against acetylcholinesterase, butyrylcholinesterase and α-glucosidase. DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity and Ferric reducing antioxidant power assay (FRAP) were conducted to antioxidant properties. The anticancer effect of SPA on human MCF-7 breast cancer and human HCT116 colorectal cancer cell line was evaluated by WST-1 cell viability assay, colony formation assay and wound healing assay. In addition, human VEGF Elisa method was used to determine the anti-angiogenic effect, and the quantitative real-time PCR (qRT-PCR) method on p53, Bax and Bcl-2 mRNA levels were used to evaluate apoptosis. While high amounts of palmitic acid (40.8%), linoleic acid (17.75%) and α-linolenic acid (16.84%) were detected in the SPA, the total amount of unsaturated fatty acid (51.34%) was higher than the total amount of saturated fatty acid (48.66%). SPA displayed the most promising acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and α-glycosidase (AG) inhibitory activities (AChE: IC₅₀: 18.03 µg/mL, BuChE: IC₅₀: 44.24 µg/mL and AG: IC₅₀: 210.85 µg/mL). The half maximum inhibitory concentration (IC₅₀) of SPA in MCF-7 and HCT116 cells was determined as 259.79 µg/mL and 97.24 µg/mL, respectively. In addition, it was determined that SPA suppresses colony formation and wound closure, and suppresses angiogenesis as well as triggering apoptosis at a significant level. It is true that endemic S. prostrata subsp. anatolica is a potential source of functional food ingredients, but more analytical and in vivo experiments are needed to explore further secondary metabolite diversity and pharmacological properties.

Biologically active phthalocyanine metal complexes: Preparation, evaluation of α-glycosidase and anticholinesterase enzyme inhibition activities, and molecular docking studies

In this study, preparation, as well as investigation of α-glycosidase and cholinesterase (ChE) enzyme inhibition activities of furan-2-ylmethoxy-substituted compounds 1-7, are reported. Peripherally, tetra-substituted copper and manganese phthalocyanines (5 and 6) were synthesized for the first time. The substitution of furan-2-ylmethoxy groups provides remarkable solubility to the complex and redshift of the phthalocyanines Q-band. Besides, the inhibitory effects of these compounds on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glycosidase (α-Gly) enzymes have been investigated. The AChE was inhibited by these compounds (1-7) in low micromolar levels, and K _i values were recorded between 11.17 ± 1.03 and 83.28 ± 11.08 µM. Against the BChE, the compounds demonstrated K _i values from 7.55 ± 0.98 to 81.35 ± 12.80 µM. Also, these compounds (1-7) effectively inhibited α-glycosidase, with K _i values in the range of 744.87 ± 67.33 to 1094.38 ± 88.91 µM. For α-glycosidase, the most effective K _i values of phthalocyanines 3 and 6 were with K _i values of 744.87 ± 67.33 and 880.36 ± 56.77 µM, respectively. Moreover, the studied metal complexes were docked with target proteins PDB ID: 4PQE, 1P0I, and 3WY1. Pharmacokinetic parameters and secondary chemical interactions that play an active role in interaction were predicted with docking simulation results. Overall, furan-2-ylmethoxy-substituted phthalocyanines can be considered as potential agents for the treatment of Alzheimer's diseases and diabetes mellitus.

Design, synthesis, characterization, enzymatic inhibition evaluations, and docking study of novel quinazolinone derivatives

In this study, novel quinazolinone derivatives 7a-n were synthesized and evaluated against metabolic enzymes including α-glycosidase, acetylcholinesterase, butyrylcholinesterase, human carbonic anhydrase I, and II. These compounds exhibited high inhibitory activities in comparison to used standard inhibitors with K_i values in the range of 19.28-135.88 nM for α-glycosidase (K_i value for standard inhibitor = 187.71 nM), 0.68-23.01 nM for acetylcholinesterase (K_i value for standard inhibitor = 53.31 nM), 1.01-29.56 nM for butyrylcholinesterase (K_i value for standard inhibitor = 58.16 nM), 10.25-126.05 nM for human carbonic anhydrase I (K_i value for standard inhibitor = 248.18 nM), and 13.46-178.35 nM for human carbonic anhydrase II (K_i value for standard inhibitor = 323.72). Furthermore, the most potent compounds against each enzyme were selected in order to evaluate interaction modes of these compounds in the active site of the target enzyme. Cytotoxicity assay of the title compounds 7a-n against cancer cell lines MCF-7 and LNCaP demonstrated that these compounds do not show significant cytotoxic effects.

Probing 4-(diethylamino)-salicylaldehyde-based thiosemicarbazones as multi-target directed ligands against cholinesterases, carbonic anhydrases and α-glycosidase enzymes

With the fading of 'one drug-one target' approach, Multi-Target-Directed Ligands (MTDL) has become a central idea in modern Medicinal Chemistry. The present study aimed to design, develop and characterize a novel series of 4-(Diethylamino)-salicylaldehyde based thiosemicarbazones (3a-p) and evaluates their biological activity against cholinesterase, carbonic anhydrases and α-glycosidase enzymes. The hCA I isoform was inhibited by these novel 4-(diethylamino)-salicylaldehyde-based thiosemicarbazones (3a-p) in low nanomolar levels, the Ki of which differed between 407.73 ± 43.71 and 1104.11 ± 80.66 nM. Against the physiologically dominant isoform hCA II, the novel compounds demonstrated K_is varying from 323.04 ± 56.88 to 991.62 ± 77.26 nM. Also, these novel 4-(diethylamino)-salicylaldehyde based thiosemicarbazones (3a-p) effectively inhibited AChE, with Ki values in the range of 121.74 ± 23.52 to 548.63 ± 73.74 nM. For BChE, Ki values were obtained with in the range of 132.85 ± 12.53 to 618.53 ± 74.23 nM. For α-glycosidase, the most effective Ki values of 3b, 3k, and 3g were with Ki values of 77.85 ± 10.64, 96.15 ± 9.64, and 124.95 ± 11.44 nM, respectively. We have identified inhibition mechanism of 3b, 3g, 3k, and 3n on α-glycosidase AChE, hCA I, hCA II, and BChE enzyme activities. Hydrazine-1-carbothioamide and hydroxybenzylidene moieties of compounds play an important role in the inhibition of AChE, hCA I, and hCA II enzymes. Hydroxybenzylidene moieties are critical for inhibition of both BChE and α-glycosidase enzymes. The findings of in vitro and in silico evaluations indicate 4-(diethylamino)-salicylaldehyde-based thiosemicarbazone scaffold to be a promising hit for drug development for multifactorial diseases like Alzheimer's disease.

Novel quinazolin-sulfonamid derivatives: synthesis, characterization, biological evaluation, and molecular docking studies

In the design of novel drugs, the formation of hybrid molecules via the combination of several pharmacophores can give rise to compounds with interesting biochemical profiles. A series of novel quinazolin-sulfonamid derivatives (9a-m) were synthesized, characterized and evaluated for their in vitro antidiabetic, anticholinergics, and antiepileptic activity. These synthesized novel quinazolin-sulfonamid derivatives (9a-m) were found to be effective inhibitor molecules for the α-glycosidase, human carbonic anhydrase I and II (hCA I and hCA II), butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) enzyme, with Ki values in the range of 100.62 ± 13.68-327.94 ± 58.21 nM for α-glycosidase, 1.03 ± 0.11-14.87 ± 2.63 nM for hCA I, 1.83 ± 0.24-15.86 ± 2.57 nM for hCA II, 30.12 ± 3.81-102.16 ± 13.87 nM for BChE, and 26.16 ± 3.63-88.52 ± 20.11 nM for AChE, respectively. In the last step, molecular docking calculations were made to compare biological activities of molecules against enzymes which are achethylcholinesterase, butyrylcholinesterase and α-glycosidase.Communicated by Ramaswamy H. Sarma.

Synthesis, spectroscopic properties, crystal structures, DFT studies, and the antibacterial and enzyme inhibitory properties of a complex of Co(II) 3,5-difluorobenzoate with 3-pyridinol

A new complex, [Co(DFB)2(3-Pyr)2(H2O)2] (where DFB = 3,5-difluorobenzoate, 3-Pyr = 3-pyridinol), is synthesized and characterized using different techniques (elemental analysis, Fourier transform infrared spectroscopy, and single-crystal X-ray diffraction). Looking at the crystal structure of the complexes, the cobalt atom is coordinated by two nitrogen atoms from two 3-Pyr ligands, two carboxylate oxygen atoms from two DFB anions, and two oxygen atoms from two water molecules. The complex has distorted octahedral geometry around the cobalt atom center complex and crystallizes in the P21/n space group (monoclinic system). Geometry optimization, frequency analysis, and energy quantum chemical calculations on the complex are performed by Density Functional Theory [B3LYP/6-31G (d,p) basis set] to predict the molecular properties. The novel complex is tested against the metabolic isoenzymes human carbonic anhydrases I and II. The novel complex shows Ki values of 317.26 ± 23.25 µM against hCA I and 255.41 ± 48.05 µM against hCA II; the IC50 values for these isoenzymes are 274.37 and 204.33 µM.

Novel 2-aminopyridine liganded Pd(II) N-heterocyclic carbene complexes: Synthesis, characterization, crystal structure and bioactivity properties

In this work, the synthesis, crystal structure, characterization, and enzyme inhibition effects of the novel a series of 2-aminopyridine liganded Pd(II) N-heterocyclic carbene (NHC) complexes were examined. These complexes of the Pd-based were synthesized from PEPPSI complexes and 2-aminopyridine. The novel complexes were characterized by using ¹³C NMR, ¹H NMR, elemental analysis, and FTIR spectroscopy techniques. Also, crystal structures of the two compounds were recorded by using single-crystal X-ray diffraction assay. Also, these complexes were tested toward some metabolic enzymes like α-glycosidase, aldose reductase, butyrylcholinesterase, acetylcholinesterase enzymes, and carbonic anhydrase I, and II isoforms. The novel 2-aminopyridine liganded (NHC)PdI₂(2-aminopyridine) complexes (1a-i) showed Ki values of in range of 5.78 ± 0.33-22.51 ± 8.59 nM against hCA I, 13.77 ± 2.21-30.81 ± 4.87 nM against hCA II, 0.44 ± 0.08-1.87 ± 0.11 nM against AChE and 3.25 ± 0.34-12.89 ± 4.77 nM against BChE. Additionally, we studied the inhibition effect of these derivatives on aldose reductase and α-glycosidase enzymes. For these compounds, compound 1d showed maximum inhibition effect against AR with a Ki value of 360.37 ± 55.82 nM. Finally, all compounds were tested for the inhibition of α-glycosidase enzyme, which recorded efficient inhibition profiles with Ki values in the range of 4.44 ± 0.65-12.67 ± 2.50 nM against α-glycosidase.

Synthesis, crystal structure and biological properties of Cd and Zn coordination polymers based on a flexible tripodal ligand

Two new coordination polymers, namely poly[[hexathiocyanatotetrakis{μ3-2,4,6-trimethyl-1,3,5-tris[(triazol-1-yl)methyl]benzene}tricadmium(II)] 3.5-hydrate], {[Cd3(SCN)6(C18H21N9)4]·3.5H2O} n (1), and poly[[hexathiocyanatotetrakis{μ3-2,4,6-trimethyl-1,3,5-tris[(triazol-1-yl)methyl]benzene}trizinc(II)] 3.5-hydrate], {[Zn3(SCN)6(C18H21N9)4]·3.5H2O} n (2), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction analysis. From the X-ray analysis, it is noteworthy that polymers 1 and 2 are isostructural, with their three-dimensional structures composed of three kinds of four-connection metal ions and two kinds of three-connection 2,4,6-trimethyl-1,3,5-tris[(triazol-1-yl)methyl]benzene (TTTMB) ligand nodes. Each metal ion is six-coordinated in a slightly distorted octahedral geometry. The antioxidant activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) and the antidiabetic activity against α-amylase of the synthesized compounds were evaluated in vitro. The results of the DPPH free-radical scavenging assay showed that polymers 1 and 2 exhibited strong antioxidant effects, with IC50 values of 3.81 and 2.56 mg ml−1, respectively. The IC50 value in the antidiabetic studies of polymer 1 was 3.94 mg ml−1, while polymer 2 exhibited no antidiabetic activity. Polymers 1 and 2 revealed different inhibitory activities on DPPH and α-amylase, which indicated that the metal ions play important roles in the biological activity of coordination polymers. In addition, the solid-state photoluminescence properties and thermal stability of 1 and 2 have been investigated.