Molecular mechanism of antidiabetic zinc–allixin complexes: regulations of glucose utilization and lipid metabolism

Effect of Zinc Supplementation on Lipid Profile and Body Composition in Patients with Type 2 Diabetes Mellitus: A GRADE-Assessed Systematic Review and Dose-Response Meta-analysis

The aim of this systematic review and meta-analysis of randomized controlled trials (RCTs) is to investigate the overall effects of zinc supplementation on lipid profile and body composition such as body weight (BW), body mass index (BMI), triglycerides (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) in patients with type 2 diabetes mellitus (T2DM). Scopus, Web of Science, PubMed, and Embase databases were searched from inception through October, 2023. The I2 and Cochran's Q tests were used to assess heterogeneity between studies. Nineteen RCTs (n = 1357 participants) were included in the meta-analysis. Zinc supplementation significantly reduced TG (WMD = - 17.41 mg/dL; 95% CI: - 22.60, - 12.22; P < 0.001), TC (WMD: - 19.60 mg/dL; 95% CI: - 28.46, - 10.73, P < 0.001), LDL-C (WMD = - 8.80 mg/dL; 95% CI: - 14.80, - 2.81; P = 0.004), and BMI (WMD = - 0.53 kg/m2; 95% CI: - 1.05, - 0.01; P = 0.046) but not BW (WMD: - 0.51 kg, 95 % CI: - 1.99, 0.97, P = 0.498). Moreover, zinc supplementation increased HDL-C (WMD = 4.82 mg/dL; 95% CI: 0.88, 8.76; P = 0.016) in patients with T2DM. Our results propose that zinc supplementation may be an effective strategy for improving lipid profile and body composition in patients with T2DM.

Structural investigations and antibacterial, antifungal and anticancer studies on zinc salicylaldimine complexes

Aim: Zinc salicylaldimines may act as multidrug agents.Results: Three zinc salicylaldimines C1-C3 and respective ligands HL1-HL3 were examined for antimicrobial/anticancer drug action and C3 was structurally analyzed (tetrahedral, triclinic). Against two fungi, C1 inhibited Candida albicans with 12 mm (21 mm for amphotericin B). Among four bacteria, two ligands inhibited Staphylococcus aureus and Escherichia coli (9-10 mm), but the complexes inhibited all bacteria with 10-14 mm (21-26 mm for ampicillin). The half-maximal inhibitory concentrations for the ligands, complexes and doxorubicin were 195.5-310.7, 22.18-70.05 and 9.66 μM against cancerous MCF-7 cells and 186.4-199.9, 14.95-18.87 and 36.42 μM against normal BHK cells.Conclusion: The complexation produced pronounced enhancement in the ligand antimicrobial/anticancer activities, despite these activities are moderate comparing with standards.

Genetic deletion of zinc transporter ZnT3 induces progressive cognitive deficits in mice by impairing dendritic spine plasticity and glucose metabolism

Zinc transporter 3 (ZnT3) is abundantly expressed in the brain, residing in synaptic vesicles, where it plays important roles in controlling the luminal zinc levels. In this study, we found that ZnT3 knockout in mice decreased zinc levels in the hippocampus and cortex, and was associated with progressive cognitive impairments, assessed at 2, 6, and 9-month of age. The results of Golgi-Cox staining demonstrated that ZnT3 deficiency was associated with an increase in dendritic complexity and a decrease in the density of mature dendritic spines, indicating potential synaptic plasticity deficit. Since ZnT3 deficiency was previously linked to glucose metabolism abnormalities, we tested the expression levels of genes related to insulin signaling pathway in the hippocampus and cortex. We found that the Expression of glucose transporters, GLUT3, GLUT4, and the insulin receptor in the whole tissue and synaptosome fraction of the hippocampus of the ZnT3 knockout mice were significantly reduced, as compared to wild-type controls. Expression of AKT (A serine/threonine protein kinase) and insulin-induced AKT phosphorylation was also reduced in the hippocampus of ZnT3 knockout mice. We hypothesize that the ZnT3 deficiency and reduced brain zinc levels may cause cognitive impairment by negatively affecting glycose metabolism via decreased expression of key components of insulin signaling, as well as via changes in synaptic plasticity. These finding may provide new therapeutic target for treatments of neurodegenerative disorders.

Modeling Zinc Complexes Using Neural Networks

Understanding the energetic landscapes of large molecules is necessary for the study of chemical and biological systems. Recently, deep learning has greatly accelerated the development of models based on quantum chemistry, making it possible to build potential energy surfaces and explore chemical space. However, most of this work has focused on organic molecules due to the simplicity of their electronic structures as well as the availability of data sets. In this work, we build a deep learning architecture to model the energetics of zinc organometallic complexes. To achieve this, we have compiled a configurationally and conformationally diverse data set of zinc complexes using metadynamics to overcome the limitations of traditional sampling methods. In terms of the neural network potentials, our results indicate that for zinc complexes, partial charges play an important role in modeling the long-range interactions with a neural network. Our developed model outperforms semiempirical methods in predicting the relative energy of zinc conformers, yielding a mean absolute error (MAE) of 1.32 kcal/mol with reference to the double-hybrid PWPB95 method.

Synthesis of novel zinc porphyrins with bioisosteric replacement of Sorafenib: Efficient theranostic agents for anti-cancer application

Novel zinc porphyrins (trans-A2B2 and A3B type) are reported containing pharmacophoric groups derived from Sorafenib at the meso-positions. The pharmacophoric and bioisosteric modification of Sorafenib was done with 2-methyl-4-nitro-N-phenylaniline. The in-vitro photo-cytotoxicity studies of zinc porphyrins on HeLa cells revealed excellent PDT based autophagy inhibition of cancer cells, with IC50 values between 6.2 to 15.4 μM. The trans-A2B2 type zinc porphyrin with two bioisosteric groups gave better cytotoxicity than A3B type. Molecular docking studies revealed excellent binding with mTOR protein kinase of the designed porphyrins. The confocal studies indicated significant ER localization of trans-A2B2 type zinc porphyrin in HeLa cells along with ROS generation. trans-A2B2 type zinc porphyrin induced ER stress in cancer cells, thereby causing elevation of Ca+2 ions in cytoplasm, which led to cancer cell death via autophagy pathway. The studies suggested that trans-A2B2 and A3B type zinc porphyrins can be developed as theranostic agents for anti-cancer applications.

The Effect of Zinc Supplementation on Lipid Profiles in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Dose-Response Meta-Analysis of Randomized Clinical Trials

Research on the effects of zinc supplementation on lipid profiles in people with type 2 diabetes mellitus (T2DM) has been inconsistent. This systematic review and meta-analysis was performed to summarize the current data on the effects of zinc supplementation on lipid profiles in patients with T2DM. Three online databases including PubMed, Scopus, and Web of Science were searched to find relevant studies published until September 2022. The exposure was zinc supplementation, and the outcomes were low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), and total cholesterol (TC). Fourteen randomized clinical trials consisting of 1067 patients were included in the statistical analysis. Significant improvement was observed in all 4 lipid profile components. Following zinc supplementation, a significant decrease was observed in TC (weighted mean difference [WMD]: -16.16; 95% confidence interval [CI]: -26.43, -5.89; P = 0.002), LDL (WMD: -6.18; 95% CI: -9.35, -3.02; P < 0.001), and TG (WMD: -13.08; 95% CI: -21.83, -4.34; P = 0.003). After analyzing 13 studies reporting HDL, a significant increase was seen (WMD: 3.76; 95% CI: 1.30, 6.22; P = 0.003). In a nonlinear dose-response analysis, a significant inverse association was observed between <12 wk zinc supplementation and TC, LDL, and TG (TC: WMD: -5, Pnonlinearity < 0.001; LDL: WMD: -5, Pnonlinearity = 0.07, TG: WMD: -16.5, Pnonlinearity = 0.006). Nonlinear dose-response analysis shows that the optimum elemental zinc dosage for the best response to the supplementation for TC, LDL, and TG are 120, 100, and 140 mg/d, respectively (TC: WMD: -5, Pnonlinearity < 0.001; LDL: WMD: -10, Pnonlinearity = 0.006, TG: WMD: -50, Pnonlinearity = 0.031). In conclusion, we found significant changes in all 4 components of the lipid profile through zinc supplementation in T2DM patients. Based on our findings, zinc supplementation may have profound favorable consequences on the lipid profile of T2DM patients, especially in the zinc-deficient group.

In vitro biological activity of cobalt(II) complexes with salicylaldimine ligands in microbial and cancer cells

Background: More studies using cobalt complexes as drugs are needed. Results: The drug action of two cobalt salicylaldimines was determined. The complexes and amphotericin B (20 mg/ml) inhibited Candida albicans at 9-15 and 21 mm. This concentration of both ligands inhibited Staphylococcus aureus at 10 mm and one ligand inhibited Escherichia coli at 9 mm, but the complexes and ampicillin inhibited four bacteria at 9-20 and 21-26 mm. The ligands were inactive against cancer and normal cells, but the complexes and doxorubicin provided IC50 values of 28.18-54.19 and 9.66 μM against MCF-7 cells and 15.76-20.49 and 36.42 μM against BHK cells. Conclusion: The ligands' activity was much improved by complexation, although they remained substandard.

Zinc Complexes with Nitrogen Donor Ligands as Anticancer Agents

The search for anticancer metal-based drugs alternative to platinum derivatives could not exclude zinc derivatives due to the importance of this metal for the correct functioning of the human body. Zinc, the second most abundant trace element in the human body, is one of the most important micro-elements essential for human physiology. Its ubiquity in thousands of proteins and enzymes is related to its chemical features, in particular its lack of redox activity and its ability to support different coordination geometries and to promote fast ligands exchange. Analogously to other trace elements, the impairment of its homeostasis can lead to various diseases and in some cases can be also related to cancer development. However, in addition to its physiological role, zinc can have beneficial therapeutic and preventive effects on infectious diseases and, compared to other metal-based drugs, Zn(II) complexes generally exert lower toxicity and offer few side effects. Zinc derivatives have been proposed as antitumor agents and, among the great number of zinc coordination complexes which have been described so far, this review focuses on the design, synthesis and biological studies of zinc complexes comprising N-donor ligands and that have been reported within the last five years.

Enhancement Effect of Zn-Arsenazo III Complex for G-quadruplex DNA Stability of Proto-oncogene Promoter Telomeres

Background:

Controlling the structure of proto-oncogene telomeres is very important in antitumor therapy. There are relationships between G-quadruplex DNA and the growth of tumor cell.

Methods:

In this study, spectroscopic, cyclic voltammetry and viscosity methods were employed to investigate the interaction between Zn-Arsenazo Ⅲ complex and G-quadruplex DNA by using 4S Green Plus Nucleic Acid Stain as a spectral probe in PBS buffer. The binding ratios were n Arsenazo Ⅲ : n Zn(Ⅱ) = 5:1 for Zn-Arsenazo Ⅲ complex and n Zn- Arsenazo Ⅲ : n G-quadruplex DNA = 8:1 for Zn-Arsenazo Ⅲ-G-quadruplex DNA. The bonding constants (Kθ 298.15K=4.44x105 L·mol-1, Kθ 308.15K= 1.00x105 L·mol-1, Kθ 318.15K= 1.04x106 L·mol-1) were obtained by double reciprocal method at different temperatures, Which was found that the interaction between Zn-Arsenazo Ⅲ complex and Gquadruplex DNA was driven by enthalpy. Furthermore, the research further confirmed that the interaction mode between Zn-Arsenazo Ⅲ complex and G-quadruplex DNA was a mixed binding which involved intercalation and non-intercalation interaction.

Results and Conclusion:

Together these findings also have corroborated the application of stabilizing ligands and intervening with their function for target G-quadruplexes in a cellular context.

Nutritional Effects of Zinc on Metabolic Syndrome and Type 2 Diabetes: Mechanisms and Main Findings in Human Studies

Zinc (Zn) plays crucial roles in mammalian metabolism. There is increasing interest about the potential beneficial effects of Zn on the prevention or treatment of non-communicable diseases. This review critically analyzes the information related to the role of Zn on the metabolic syndrome (MetS) as well as type 2 diabetes (T2D), and summarizes the biological basis of these potential effects of Zn. There are several mechanisms by which Zn may help to prevent the development or progression of MetS and T2D, respectively. Zn is involved in both insulin secretion and action in peripheral tissues. Specifically, Zn has insulin-mimetic properties that increase the activity of the insulin signaling pathway. Zn modulates long-chain polyunsaturated fatty acids levels through its action on the absorption of essential fatty acids in the intestine and its subsequent desaturation. Zn is also involved in both the assembly of chylomicrons and lipoproteins as well as their clearance, and thus, plays a role in lipolysis regulation. Finally, Zn has been found to play a role in redox metabolism, and in turn, on blood pressure. The evidence related to the association between Zn status and occurrence of MetS is inconsistent. Although there are several studies reporting an inverse relationship between Zn status or dietary Zn intake and MetS prevalence, others found a direct relationship between Zn status and MetS prevalence. Intervention studies also provide confusing information about this issue, making it hard to reach firm conclusions. Zn as part of the treatment for patients with T2D has been shown to have positive responses in terms of glucose control outcomes, but only among those with Zn deficiency.

Exploring the Scope of Photo-Induced Electron Transfer-Chelation-Enhanced Fluorescence-Fluorescence Resonance Energy Transfer Processes for Recognition and Discrimination of Zn2+, Cd2+, Hg2+, and Al3+ in a Ratiometric Manner: Application to Sea Fish Analysis

A rhodamine-based smart probe (RHES) has been developed for trace-level detection and discrimination of multiple cations, viz. Al³⁺, Zn²⁺, Cd²⁺, and Hg²⁺ in a ratiometric manner involving photo-induced electron transfer-chelation-enhanced fluorescence-fluorescence resonance energy transfer processes. The method being very fast and highly selective allows their bare eye visualization at a physiological pH. The optimized geometry and spectral properties of RHES and its cation adducts have been analyzed by time-dependent density functional theory calculations. RHES detects as low as 1.5 × 10^-9 M Al³⁺, 1.2 × 10^-9 M Zn²⁺, 6.7 × 10^-9 M Cd²⁺, and 1.7 × 10^-10 M Hg²⁺, whereas the respective association constants are 1.33 × 10⁵ M^-1, 2.11 × 10⁴ M^-1, 1.35 × 10⁵ M^-1, and 4.09 × 10⁵ M^-1. The other common ions do not interfere. The probe is useful for intracellular imaging of Zn²⁺, Cd²⁺, and Hg²⁺ in squamous epithelial cells. RHES is useful for the determination of the ions in sea fish and real samples.

The beneficial effects of Zn on Akt-mediated insulin and cell survival signaling pathways in diabetes

Zinc is one of the essential trace elements and participates in numerous physiological processes. Abnormalities in zinc homeostasis often result in the pathogenesis of various chronic metabolic disorders, such as diabetes and its complications. Zinc has insulin-mimetic and anti-diabetic effects and deficiency has been shown to aggravate diabetes-induced oxidative stress and tissue injury in diabetic rodent models and human subjects with diabetes. Akt signaling pathway plays a central role in insulin-stimulated glucose metabolism and cell survival. Anti-diabetic effects of zinc are largely dependent on the activation of Akt signaling. Zn is also an inducer of metallothionein that plays important role in anti-oxidative stress and damage. However, the exact molecular mechanisms underlying zinc-induced activation of Akt signaling pathway remains to be elucidated. This review summarizes the recent advances in deciphering the possible mechanisms of zinc on Akt-mediated insulin and cell survival signaling pathways in diabetes conditions. Insights into the effects of zinc on epigenetic regulation and autophagy in diabetic nephropathy are also discussed in the latter part of this review.

Effect of the Zinc Oxide Nanoparticles and Thiamine for the Management of Diabetes in Alloxan-Induced Mice: a Stereological and Biochemical Study

This research was carried out to evaluate the antidiabetic effects of zinc oxide nanoparticles (ZnO NPs) and thiamine following experimental diabetes. Fifty-six 6-week-old female mice were used and divided into seven groups of eight animals. Diabetes was induced in fasted mice by using intraperitoneal (IP) injection of alloxan (180 mg/kg). Groups included (I) non-diabetic control, (II) thiamine (30 mg/l, IP), (III) alloxan-induced diabetic mice, (IV) diabetes + ZnO NPs (0.1 mg/kg IP), (V) diabetes + ZnO NPs (0.5 mg/kg IP), (VI) diabetes + ZnO NPs (0.1 mg/kg IP) + thiamine (30 mg/l, IP), and (VII) diabetes + ZnO NPs (0.5 mg/kg IP) + thiamine (30 mg/l, IP). Coincident with pancreas recovery, in diabetic treated mice (groups IV to VII), the mean islet volume, islets per square micrometer, and volume density of the pancreas had increased than in alloxan-induced diabetic mice. ZnO NPs and thiamine induced a decreasing blood glucose, lower serum triglyceride (TG), LDL, and total cholesterol (TC) levels in alloxan-induced diabetic mice treated with ZnO NPs and thiamine, simultaneously increasing HDL as well. In conclusion, ZnO NPs and thiamine are potent antidiabetic factors, and that, these compound supplementation possesses hypoglycemic properties and have effect on serum lipid parameters in diabetes mice.

A zinc Schiff base complex inhibits cancer progression both in vivo and in vitro by inducing apoptosis

Cancer chemotherapy suffers from selectivity and undesired toxicity of the drugs. Since zinc is a biocompatible tracer element and cysteine derivatives are used in cancer chemoprevention, we intend to develop a complex of zinc and cysteine-derivatives as potent, non-toxic anticancer agents. Herein, we synthesized and characterized cysteine based ligand, 2-[(2-Hydroxy-3-methoxy-benzylidene)-amino]-3-mercapto-propionic acid and its Zn-complex, which are found to be non-toxic towards normal human PBMC. Data also revealed that only Zn-complex exhibited remarkable apoptosis in drug-sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 cancer cells as assessed by MTT, Cell cycle and AnnexinV binding assay. Moreover, Zn-complex altered ROS and GSH level of the respective cell lines. Finally, treatment of Zn-complex in Swiss albino mice did not show any systemic toxicity in preliminary trials in normal mice and remarkably increased the life-span of EAC bearing mice. In conclusion, the synthesized Zn-complex may be developed for efficacious, multidrug resistance reversal, non-toxic chemotherapeutic agents in future.

Zinc Supplementation Improves Glucose Homeostasis in High Fat-Fed Mice by Enhancing Pancreatic β-Cell Function

Zinc is an essential component of the insulin granule and it possibly modulates insulin secretion and signaling. Since insulin resistance is a hallmark in the development of type 2 diabetes mellitus, this study aimed at investigating if zinc supplementation is able to improve glucose tolerance and β-cell function in a model of insulin resistance. Male C57BL/6 mice were distributed in four groups according to the diet: normal fat (NF); normal fat supplemented with ZnCl₂ (NFZ); high-fat (HF); and, high-fat chow supplemented with ZnCl₂ (HFZ). Intraperitoneal glucose (ipGTT) and insulin (ipITT) tolerance, glycemia, insulinemia, HOMA-IR, and HOMA-β were determined after 15 weeks in each diet. Glucose-stimulated insulin secretion (GSIS) was investigated in isolated islets. The insulin effect on glucose uptake, metabolism, and signaling was investigated in soleus muscle. ZnCl₂ did not affect body mass or insulin sensitivity as assessed by ipITT, HOMA-IR, muscle glucose metabolism, and Akt and GSK3-β phosphorylation. However, glucose tolerance, HOMA-β, and GSIS were significantly improved by ZnCl₂ supplementation. Therefore, ZnCl₂ supplementation improves glucose homeostasis in high fat-fed mice by a mechanism that enhances β-cell function, rather than whole-body or muscle insulin sensitivity.

In vitro studies on the pleotropic antidiabetic effects of zinc oxide nanoparticles

Aim: Our earlier study demonstrated antidiabetic activity of zinc oxide nanoparticles (ZON) in diabetic rats. The present study was performed to elucidate its mechanism of antidiabetic action. Methods: Protein tyrosine phosphatase 1B, protein kinase B and hormone sensitive lipase phosphorylation; glucose transporter 4 translocation and glucose uptake; glucose 6 phosphatase, phosphoenol pyruvate carboxykinase and glucokinase expression; and pancreatic beta cell proliferation were evaluated after ZON treatment to cells. Result: ZON treatment resulted in PKB activation, protein tyrosine phosphatase 1B inactivation, increased glucose transporter 4 translocation and enhanced glucose uptake, decreased glucose 6 phosphatase and phosphoenol pyruvate carboxykinase expression, hormone sensitive lipase inactivation and pancreatic beta cell proliferation. Conclusion: To the best of our knowledge, we report for the first time, pleiotropic antidiabetic effects of ZON viz. improved insulin signaling, enhanced glucose uptake, decreased hepatic glucose output, decreased lipolysis and enhanced pancreatic beta cell mass.

Synthesis, characterization, in vitro cytotoxicity, in silico ADMET analysis and interaction studies of 5-dithiocarbamato-1,3,4-thiadiazole-2-thiol and its zinc(ii) complex with human serum albumin: combined spectroscopy and molecular docking investigations

The binding site of new complex Zn(ii) of 5-dithiocarbamato-1,3,4-thiadiazole-2-thiol and HAS.

Zinc and diabetes mellitus: understanding molecular mechanisms and clinical implications

Background

Diabetes mellitus is a leading cause of morbidity and mortality worldwide. Studies have shown that Zinc has numerous beneficial effects in both type-1 and type-2 diabetes. We aim to evaluate the literature on the mechanisms and molecular level effects of Zinc on glycaemic control, β-cell function, pathogenesis of diabetes and its complications.

Methods

A review of published studies reporting mechanisms of action of Zinc in diabetes was undertaken in PubMed and SciVerse Scopus medical databases using the following search terms in article title, abstract or keywords; (“Zinc” or “Zn”) and (“mechanism” or “mechanism of action” or “action” or “effect” or “pathogenesis” or “pathology” or “physiology” or “metabolism”) and (“diabetes” or “prediabetes” or “sugar” or “glucose” or “insulin”).

Results

The literature search identified the following number of articles in the two databases; PubMed (n = 1799) and SciVerse Scopus (n = 1879). After removing duplicates the total number of articles included in the present review is 111. Our results show that Zinc plays an important role in β-cell function, insulin action, glucose homeostasis and the pathogenesis of diabetes and its complications.

Conclusion

Numerous in-vitro and in-vivo studies have shown that Zinc has beneficial effects in both type-1 and type-2 diabetes. However further randomized double-blinded placebo-controlled clinical trials conducted for an adequate duration, are required to establish therapeutic safety in humans.

Electronic supplementary material

The online version of this article (doi:10.1186/s40199-015-0127-4) contains supplementary material, which is available to authorized users.

Jasada bhasma, a Zinc-Based Ayurvedic Preparation: Contemporary Evidence of Antidiabetic Activity Inspires Development of a Nanomedicine

The roles of metals in human physiology are well established. It is also known that many metals are required in trace amounts for normal metabolism and their deficiency leads to diseases. In Ayurveda, metal-based preparations, that is, bhasmas, are indicated for the treatment of several diseases. Standard textbooks of Ayurveda recommend Jasada bhasma (zinc based bhasma) as the treatment of choice for diabetes. Modern medicine also recognizes the important role of zinc in glucose homeostasis. Yet, studies that validate the use of Jasada bhasma are few and uncomprehensive. There is an imminent need for a systematic study on physicochemical characterization, pharmacological efficacy, and toxicity assessment of several bhasma preparations to generate scientific evidence of their utility and safety. Interestingly, recent studies suggest that bhasmas comprise submicronic particles or nanoparticles. Thus a bhasma-inspired new drug discovery approach could emerge in which several metal based nanomedicines could be developed. This would help in utilizing the age old, time-tested wisdom of Ayurveda in modern medicine. One such study on antidiabetic activity of Jasada bhasma and the corresponding new drug, namely, zinc oxide nanoparticles, is briefly discussed, as an example.

Zn(ii) and Cu(ii) complexes containing bioactive O,O-chelated ligands: homoleptic and heteroleptic metal-based biomolecules

Zn(ii) or Cu(ii) highly stable complexes with chelated O,O-donor ligands from natural extractions give rise to drug delivery systems, new biologically active complexes and potential diagnostic agents due to their intrinsic spectroscopic properties.

Differentially selective chemosensor with fluorescence off-on responses on Cu(2+) and Zn(2+) ions in aqueous media and applications in pyrophosphate sensing, live cell imaging, and cytotoxicity

A new benzoyl hydrazone based chemosensor R is synthesized by Schiff base condensation of 2,6-diformyl-4-methylphenol and phenyl carbohydrazide and acts as a highly selective fluorescence sensor for Cu(2+) and Zn(2+) ions in aqueous media. The reaction of R with CuCl2 or ZnCl2 forms the corresponding dimeric dicopper(II) [Cu2(R)(CH3O)(NO3)]2(CH3O)2 (R-Cu(2+)) and dizinc(II) [Zn2(R)2](NO3)2 (R-Zn(2+)) complexes, which are characterized, as R, by conventional techniques including single-crystal X-ray analysis. Electronic absorption and fluorescence titration studies of R with different metal cations in a CH3CN/0.02 M HEPES buffer medium (pH = 7.3) show a highly selective binding affinity only toward Cu(2+)and Zn(2+) ions even in the presence of other commonly coexisting ions such as Na(+), K(+), Mg(2+), Ca(2+), Mn(2+), Fe(2+), Fe(3+), Co(2+), Ni(2+), Cd(2+), and Hg(2+). Quantification of the fluorescence titration analysis shows that the chemosensor R can indicate the presence of Cu(2+)and Zn(2+) even at very low concentrations of 17.3 and 16.5 ppb, respectively. R-Zn(2+) acts as a selective metal-based fluorescent sensor for inorganic pyrophosphate ion (PPi) even in the presence of other common anions such as F(-), Cl(-), Br(-), I(-), CH3COO(-), CO3(2-), HCO3(-), N3(-), SO4(2-), PPi, AMP, ADP, and ATP in an aqueous medium. The propensity of R as a bioimaging fluorescent probe to detect Cu(2+) and Zn(2+) ions in human cervical HeLa cancer cell lines and their cytotoxicity against human cervical (HeLa), breast cancer (MCF7), and noncancer breast epithelial (MCF10a) cells have also been investigated. R-Cu(2+) shows better cytotoxicity and sensitivity toward cancer cells over noncancer cells than R and R-Zn(2+) under identical conditions, with the appearance of apoptotic bodies.

Zinc oxide nanoparticles show antidiabetic activity in streptozotocin-induced Type 1 and 2 diabetic rats

Aim: The correlation of diabetes and an imbalance in zinc homeostasis makes zinc-based therapy an attractive proposition. In this study, zinc oxide nanoparticles were evaluated for antidiabetic effects and safety. Materials & methods: Zinc oxide nanoparticles (1, 3 and 10 mg/kg) were tested for antidiabetic activity in streptozotocin-induced Type 1 and 2 diabetic rats. A single-dose pharmacokinetic study, cytotoxicity, hemolysis, acute and subacute toxicity tests, and mechanism-of-action studies were performed. Results: Oral administration of zinc oxide nanoparticles resulted in significant antidiabetic effects – that is, improved glucose tolerance, higher serum insulin (70%), reduced blood glucose (29%), reduced nonesterified fatty acids (40%) and reduced triglycerides (48%). Nanoparticles were systemically absorbed resulting in elevated zinc levels in the liver, adipose tissue and pancreas. Increased insulin secretion and superoxide dismutase activity were also seen in rat insulinoma (RIN-5F) cells. Nanoparticles were safe up to a 300 mg/kg dose in rats. Conclusion: Zinc oxide nanoparticles are a promising antidiabetic agent warranting further studies.

Original submitted 9 July 2012; Revised submitted 27 November 2012; Published online 21 February 2013

Development of new zinc dithiosemicarbazone complex for use as oral antidiabetic agent

The increasing prevalence of diabetes mellitus (DM) worldwide has underscored the urgency of developing an efficient therapeutic agent. Recently, Zn complexes have been attracting attention due to their antidiabetic activity. In this study, we designed and synthesized a new Zn complex, Zn-3,4-heptanedione-bis(N (4)-methylthiosemicarbazonato) (Zn-HTSM), characterized its physicochemical properties, and examined its antidiabetic activity in KK-A(y) type 2 DM model mice. It was demonstrated that Zn-HTSM has adequate lipophilicity for the cellular permeability, shows potent hypoglycemic activity, and improves glucose intolerance in KK-A(y) mice. We also analyzed the levels of serum adipokines after continuous oral administration of Zn-HTSM. The level of serum leptin of KK-A(y) mice is significantly reduced by the treatment of Zn-HTSM. Nevertheless, the levels of serum insulin and adiponectin were not improved. These data suggested that the Zn-HTSM acts on the leptin metabolism. Our present studies indicate that Zn-HTSM is a candidate oral antidiabetic agent for the treatment of type 2 DM.

Identification of a potent activator of Akt phosphorylation from a novel series of phenolic, picolinic, pyridino, and hydroxamic zinc(II) complexes

The discovery of small-molecule modulators of signaling pathways is currently a particularly active area of research. We aimed at developing unprecedented metal-based activators of Akt signaling which can potentially find applications as tools for regulating glucose metabolism downstream of Akt or serve as lead structures for developing antidiabetic drugs. In this context, a highly diverse library of 11 new zinc(II) complexes with phenolic, picolinic, pyridino, and hydroxamic ligands, all containing features beneficial for medicinal purposes, was prepared and screened in an assay that detected levels of phospho-Akt in lysates from NIH3T3 cells after treatment with the compounds. The complexes featuring hydroxamic ligands were found to be the most prominent activators of Akt among the molecules prepared, with the most efficient compound acting at submicromolar concentrations. Further characterization revealed that this compound induces phosphorylation of the Akt downstream effector glycogen synthase kinase 3β, but does not act as an inhibitor of tyrosine phosphatases or PTEN.