Bisindole-based small molecules as transmembrane anion transporters and potential anticancer agents.

Few synthetic ion transporters have been reported incorporating indole as the core moiety. We have developed a novel bisindole-based transporter capable of efficient transmembrane anion antiport. This system induced cytotoxicity in MCF-7 breast cancer cells via chloride ion homeostasis disruption and the associated ROS generation, mitochondrial membrane depolarization, and lysosomal deacidification.

Identification of potential serum biomarkers associated with HbA1c levels in Indian type 2 diabetic subjects using NMR-based metabolomics.

BACKGROUND: The prevalence of type 2 diabetes mellitus (T2DM), a progressive metabolic disorder characterized by chronic hyperglycemia and the development of insulin resistance, has increased globally, with worrying statistics coming from children, adolescents, and young adults from developing countries like India. Here, we investigated unique circulating metabolic signatures associated with prediabetes and T2DM in an Indian cohort using NMR-based metabolomics. MATERIALS AND METHODS: The study subjects included healthy volunteers (N = 101), prediabetic subjects (N = 75), and T2DM patients (N = 108). Serum metabolic profiling was performed using 1H NMR spectroscopy and major perturbed metabolites were identified by multivariate analysis and receiver operating characteristic (ROC) modules. RESULTS: Of the 36 aqueous abundant metabolites, 24 showed a statistically significant difference between healthy volunteers, prediabetics, and established T2DM subjects. On performing multivariate ROC curve analysis with 5 commonly dysregulated metabolites (namely, glucose, pyroglutamate, o-phosphocholine, serine, and methionine) in prediabetes and T2DM, AUC values obtained were 0.96 (95 % confidence interval (CI) = 0.93, 0.98) for T2DM; and 0.88 (95 % CI = 0.81, 0.93) for prediabetic subjects, respectively. CONCLUSION: We propose that the identified metabolite panel can be used in the future as a biomarker for clinical diagnosis, patient surveillance, and for predicting individuals at risk for developing diabetes.

Molybdenum-maltolate as a molybdopterin mimic for bioinspired oxidation reaction.

A novel cis-dioxomolybdenum(VI)-maltolate [MoO2(Mal)2] (1) is prepared as a stable molybdopterin model for the biomimetic catalysis of the oxidation of hypoxanthine in acetonitrile-water at room temperature. Compound 1 efficiently catalyzes the oxidation reaction of toluene, diphenylmethane, and styrene. Cyto- and oral-toxicity studies suggest its tremendous potential for application as a molybdenum supplement.

Dual Functional Microcapsule based on Monodisperse Short PEG Amphiphile for Drug Encapsulation and Protein Affinity Controlled Release.

A short monodisperse poly(ethylene glycol) (PEG) and a neutral organic rotamer conjugate TEG-BTA-2 amphiphile was designed for the construction of a stimuli-responsive switchable self-assembled structure for drug encapsulation by noncovalent interaction and targeted controlled delivery. A short PEG, tetraethylene glycol (TEG) was covalently attached with a neutral organic rotamer benzothiazole dye (BTA-2) affording the neutral TEG-BTA-2 (<500 D). The TEG-BTA-2 is self-assembled into a microsphere in an aqueous medium, but remarkably undergoes morphology change switching to a rice-like microcapsule for curcumin encapsulation. Curcumin-loaded microcapsules were stable in an aqueous solution, however, were noticed disintegrating upon the addition of BSA protein. This is possibly due to an interaction with BSA protein leading to a protein affinity-controlled curcumin release in a neutral PBS buffer. Moreover, cell internalization of the neutral amphiphile TEG-BTA-2 into A549 cells was observed by fluorescence microscopy, providing an opportunity for application as a molecular vehicle for targeted drug delivery and monitoring.

Tetrahydropalmatine from medicinal plants activates human glucokinase to regulate glucose homeostasis.

Many synthetic glucokinase activators (GKAs), modulating glucokinase (GK), an important therapeutic target in diabetes have failed to clear clinical trials. In this study, an in silico structural similarity search with differing scaffolds of reference GKAs have been used to identify derivatives from natural product databases. Ten molecules with good binding score and similar interactions to that in the co-crystallized GK as well good activation against recombinant human GK experimentally were identified. Tetrahydropalmatine, an alkaloid present in formulations and drugs from medicinal plants, has not been explored as an antidiabetic agent and no information regarding its mechanism of action or GK activation exists. Tetrahydropalmatine activates GK with EC50 value of 71.7 ± 17.9 µM while lowering the S0.5 (7.1 mM) and increasing Vmax (9.22 µM/min) as compared to control without activator (S0.5 = 10.37 mM; Vmax = 4.8 µM/min). Kinetic data (α and ß values) suggests it to act as mixed, nonessential type activator. Using microscale thermophoresis, Kd values of 3.8 µM suggests a good affinity for GK. In HepG2 cell line, the compound potentiated the uptake of glucose and maintained glucose homeostasis by increasing the expression of GK, glycogen synthase, and insulin receptor genes and lowering the expression of glucokinase regulatory protein (GKRP) and glucagon. Tetrahydropalmatine at low concentrations could elicit a good response by reducing expression of GKRP, increasing expression of GK while also activating it. Thus, it could be used alone or in combination as therapeutic drug as it could effectively modulate GK and alter glucose homeostasis.

Mapping metabolic perturbations induced by glutathione activatable synthetic ion channels in human breast cancer cells.

Ion channels and transporters play key roles in various biological processes, including cell proliferation and programmed cell death. Recently, we reported that 2,4-dinitrobenzene-sulfonyl-protected N1,N3-dihexy-2-hydroxyisophthalamide (1) forms ion channels upon activation by glutathione (GSH) and results in the induction of apoptosis by depleting the intracellular GSH reservoir in cancer cells. However, the detailed molecular events leading to the induction of apoptosis by these synthetic transport systems in cancer cells still need to be uncovered. Along these lines, we investigated the alterations in cellular metabolites and the associated metabolic pathways by performing untargeted global metabolic profiling of breast cancer cells - MCF-7 - using 1H NMR-based metabolomics. The evaluation of spectral profiles from MCF-7 cells exposed to 1 and their comparison with those corresponding to untreated (control) cells identified 14 significantly perturbed signature metabolites. These metabolites belonged mostly to antioxidant defence, energy metabolism, amino acid biosynthesis, and lipid metabolism pathways and included GSH, o-phosphocholine, malate, and aspartate, to name a few. These results would help us gain deeper insights into the molecular mechanism underlying 1-mediated cytotoxicity of MCF-7 cells and eventually help identify potential novel therapeutic targets for more effective cancer management.

NAD(P)H:Quinone Acceptor Oxidoreductase 1 (NQO1) Activatable Salicylamide H+ /Cl- Transporters.

NAD(P)H:quinone acceptor oxidoreductase 1 (NQO1), a detoxifying enzyme overexpressed in tumors, plays a key role in protecting cancer cells against oxidative stress and thus has been considered an attractive candidate for activating prodrug(s). Herein, we report the first use of NQO1 for the selective activation of 'protransporter' systems in cancer cells leading to the induction of apoptosis. Salicylamides, easily synthesizable small molecules, have been effectively used for efficient H+ /Cl- symport across lipid membranes. The ion transport activity of salicylamides was efficiently abated by caging the OH group with NQO1 activatable quinones via either ether or ester linkage. The release of active transporters, following the reduction of quinone caged 'protransporters' by NQO1, was verified. Both the transporters and protransporters exhibited significant toxicity towards the MCF-7 breast cancer line, mediated via the induction of oxidative stress, mitochondrial membrane depolarization, and lysosomal deacidification. Induction of cell death via intrinsic apoptotic pathway was verified by monitoring PARP1 cleavage.

Dissecting the Interrelationship between COVID-19 and Diabetes Mellitus.

COVID-19 disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to enormous morbidity and mortality worldwide. After gaining entry into the human host, the virus initially infects the upper and lower respiratory tract, subsequently invading multiple organs, including the pancreas. While on one hand, diabetes mellitus (DM) is a significant risk factor for severe COVID-19 infection and associated death, recent reports have shown the onset of DM in COVID-19-recovered patients. SARS-CoV-2 infiltrates the pancreatic islets and activates stress response and inflammatory signaling pathways, impairs glucose metabolism, and consequently leads to their death. Indeed, the pancreatic autopsy samples of COVID-19 patients reveal the presence of SARS-CoV-2 particles in ß-cells. The current review describes how the virus enters the host cells and activates an immunological response. Further, it takes a closer look into the interrelationship between COVID-19 and DM with the aim to provide mechanistic insights into the process by which SARS-CoV-2 infects the pancreas and mediates dysfunction and death of endocrine islets. The effects of known anti-diabetic interventions for COVID-19 management are also discussed. The application of mesenchymal stem cells (MSCs) as a future therapy for pancreatic ß-cells damage to reverse COVID-19-induced DM is also emphasized.

A Benzohydrazide-Based Artificial Ion Channel that Modulates Chloride Ion Concentration in Cancer Cells and Induces Apoptosis by Disruption of Autophagy.

Fluctuations in the intracellular chloride ion concentration, mediated by synthetic ion transporters, have been known to induce cytotoxicity in cells by disrupting ionic homeostasis. However, the activity of these transporters in modulating autophagy remains largely unexplored. Here, we report a benzoylbenzohydrazide (1c) that self-assembles to form a supramolecular nanochannel lumen that allows selective and efficient transport of chloride ions across the cell membranes, disrupts ion homeostasis, and thus leads to the induction of apoptosis in cancer cells. It is important to note that the transporter was relatively nontoxic to cells of noncancerous origin. 1c was also shown to induce the deacidification of lysosomes, thereby disrupting autophagy in cancer cells. Taken together, these findings provide a rare example of an artificial ion channel that specifically targets cancer cells by induction of apoptosis via disruption of autophagy.

Human islet amyloid polypeptide: A therapeutic target for the management of type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) and other metabolic disorders are often silent and go unnoticed in patients because of the lack of suitable prognostic and diagnostic markers. The current therapeutic regimens available for managing T2DM do not reverse diabetes; instead, they delay the progression of diabetes. Their efficacy (in principle) may be significantly improved if implemented at earlier stages. The misfolding and aggregation of human islet amyloid polypeptide (hIAPP) or amylin has been associated with a gradual decrease in pancreatic ß-cell function and mass in patients with T2DM. Hence, hIAPP has been recognized as a therapeutic target for managing T2DM. This review summarizes hIAPP's role in mediating dysfunction and apoptosis in pancreatic ß-cells via induction of endoplasmic reticulum stress, oxidative stress, mitochondrial dysfunction, inflammatory cytokine secretion, autophagy blockade, etc. Furthermore, it explores the possibility of using intermediates of the hIAPP aggregation pathway as potential drug targets for T2DM management. Finally, the effects of common antidiabetic molecules and repurposed drugs; other hIAPP mimetics and peptides; small organic molecules and natural compounds; nanoparticles, nanobodies, and quantum dots; metals and metal complexes; and chaperones that have demonstrated potential to inhibit and/or reverse hIAPP aggregation and can, therefore, be further developed for managing T2DM have been discussed.

Chloride Transport across Liposomes and Cells by Nontoxic 3-(1H-1,2,3-Triazol-1-yl)benzamides.

Synthetic anion transmembrane transporters are adding new aspirations for treating channelopathies by replacing defective ion channels. The availability of such suitable candidates is still infrequent due to the associated toxicity. Here, we report 3-(1H-1,2,3-triazol-1-yl)benzamides as transmembrane anion carriers, nontoxic to cells. The selective and electrogenic chloride transport activity was established by fluorescence and ion selective electrode-based assays. MQAE assay confirmed the chloride uptake into the cells by the nontoxic compounds.

A robotic pill for oral delivery of biotherapeutics: safety, tolerability, and performance in healthy subjects.

Biotherapeutics are highly efficacious, but the pain and inconvenience of chronic injections lead to poor patient compliance and compromise effective disease management. Despite innumerable attempts, oral delivery of biotherapeutics remains unsuccessful due to their degradation in the gastrointestinal (GI) environment and poor intestinal absorption. We have developed an orally ingestible robotic pill (RP) for drug delivery, which protects the biotherapeutic drug payload from digestion in the GI tract and auto-injects it into the wall of the small intestine as a safe, pain-free injection since the intestines are insensate to sharp stimuli. The payload is delivered upon inflation of a balloon folded within the RP, which deflates immediately after drug delivery. Here we present results from two clinical studies demonstrating the safety, tolerability and performance of the RP in healthy humans. In the first study, three versions of the RP (A, B and C) were evaluated, which were identical in all respects except for the diameter of the balloon. The RP successfully delivered a biotherapeutic (octreotide) in 3 out of 12 subjects in group A, 10 out of 20 subjects in group B and 16 out of 20 subjects in group C, with a mean bioavailability of 65 ± 9% (based on successful drug deliveries in groups A and B). Thus,  reliability of drug delivery with the RP ranged from 25 to 80%, with success rate directly related to balloon size. In a separate study, the deployment of the RP was unaffected by fed or fasting conditions suggesting that the RP may be taken with or without food. These promising clinical data suggest that biotherapeutics currently administered parenterally may be safely and reliably delivered via this versatile, orally ingestible drug delivery platform.

Human islet amyloid polypeptide:A therapeutic target for the management of type 2 diabetes mellitus / 药物分析学报

Type 2 diabetes mellitus(T2DM)and other metabolic disorders are often silent and go unnoticed in patients because of the lack of suitable prognostic and diagnostic markers.The current therapeutic regimens available for managing T2DM do not reverse diabetes;instead,they delay the progression of diabetes.Their efficacy(in principle)may be significantly improved if implemented at earlier stages.The misfolding and aggregation of human islet amyloid polypeptide(hIAPP)or amylin has been associated with a gradual decrease in pancreatic β-cell function and mass in patients with T2DM.Hence,hIAPP has been recognized as a therapeutic target for managing T2DM.This review summarizes hIAPP's role in mediating dysfunction and apoptosis in pancreatic β-cells via induction of endoplasmic reticulum stress,oxidative stress,mitochondrial dysfunction,inflammatory cytokine secretion,autophagy blockade,etc.Furthermore,it explores the possibility of using intermediates of the hIAPP aggregation pathway as potential drug targets for T2DM management.Finally,the effects of common antidiabetic molecules and repurposed drugs;other hIAPP mimetics and peptides;small organic molecules and natural compounds;nanoparticles,nanobodies,and quantum dots;metals and metal complexes;and chaperones that have demonstrated potential to inhibit and/or reverse hIAPP aggregation and can,therefore,be further developed for managing T2DM have been discussed.

A Pyridyl-Linked Benzimidazolyl Tautomer Facilitates Prodigious H+/Cl- Symport through a Cooperative Protonation and Chloride Ion Recognition.

We report two pyridyl-linked benzimidazolyl hydrazones as HCl cotransporters that are 5 and 2 times superior to prodigiosin, a natural product whose transport efficiency has never been routed by synthetic molecules. These hydrazones provide a suitable HCl binding site through a cooperative protonation and chloride ion recognition. HCl transport by the most active compound induces lysosome deacidification. Viability assays confirmed that the compounds induce cytotoxicity toward human breast cancer MCF-7 cells but are relatively nontoxic toward noncancerous HEK293T cells.

Myricetin protects pancreatic ß-cells from human islet amyloid polypeptide (hIAPP) induced cytotoxicity and restores islet function.

The aberrant misfolding and self-assembly of human islet amyloid polypeptide (hIAPP)-a hormone that is co-secreted with insulin from pancreatic ß-cells-into toxic oligomers, protofibrils and fibrils has been observed in type 2 diabetes mellitus (T2DM). The formation of these insoluble aggregates has been linked with the death and dysfunction of ß-cells. Therefore, hIAPP aggregation has been identified as a therapeutic target for T2DM management. Several natural products are now being investigated for their potential to inhibit hIAPP aggregation and/or disaggregate preformed aggregates. In this study, we attempt to identify the anti-amyloidogenic potential of Myricetin (MYR)- a polyphenolic flavanoid, commonly found in fruits (like Syzygium cumini). Our results from biophysical studies indicated that MYR supplementation inhibits hIAPP aggregation and disaggregates preformed fibrils into non-toxic species. This protection was accompanied by inhibition of oxidative stress, reduction in lipid peroxidation and the associated membrane damage and restoration of mitochondrial membrane potential in INS-1E cells. MYR supplementation also reversed the loss of functionality in hIAPP exposed pancreatic islets via restoration of glucose-stimulated insulin secretion. Molecular dynamics simulation studies suggested that MYR molecules interact with the hIAPP pentameric fibril model at the amyloidogenic core region and thus prevents aggregation and distort the fibrils.

Human islet amyloid polypeptide (hIAPP) - a curse in type II diabetes mellitus: insights from structure and toxicity studies.

The human islet amyloid polypeptide (hIAPP) or amylin, a neuroendocrine peptide hormone, is known to misfold and form amyloidogenic aggregates that have been observed in the pancreas of 90% subjects with Type 2 Diabetes Mellitus (T2DM). Under normal physiological conditions, hIAPP is co-stored and co-secreted with insulin; however, under chronic hyperglycemic conditions associated with T2DM, the overexpression of hIAPP occurs that has been associated with the formation of amyloid deposits; as well as the death and dysfunction of pancreatic ß-islets in T2DM. Hitherto, various biophysical and structural studies have shown that during this process of aggregation, the peptide conformation changes from random structure to helix, then to ß-sheet, subsequently to cross ß-sheets, which finally form left-handed helical aggregates. The intermediates, formed during this process, have been shown to induce higher cytotoxicity in the ß-cells by inducing cell membrane disruption, endoplasmic reticulum stress, mitochondrial dysfunction, oxidative stress, islet inflammation, and DNA damage. As a result, several research groups have attempted to target both hIAPP aggregation phenomenon and the destabilization of preformed fibrils as a therapeutic intervention for T2DM management. In this review, we have summarized structural aspects of various forms of hIAPP viz. monomer, oligomers, proto-filaments, and fibrils of hIAPP. Subsequently, cellular toxicity caused by toxic conformations of hIAPP has been elaborated upon. Finally, the need for performing structural and toxicity studies in vivo to fill in the gap between the structural and cellular aspects has been discussed.

Cold storage reveals distinct metabolic perturbations in processing and non-processing cultivars of potato (Solanum tuberosum L.).

Cold-induced sweetening (CIS) causes considerable losses to the potato processing industry wherein the selection of potato genotypes using biochemical information has found to be advantageous. Here, 1H NMR spectroscopy was performed to identify metabolic perturbations from tubers of five potato cultivars (Atlantic, Frito Lay-1533, Kufri Jyoti, Kufri Pukhraj, and PU1) differing in their CIS ability and processing characteristics at harvest and after cold storage (4 °C). Thirty-nine water-soluble metabolites were detected wherein significantly affected metabolites after cold storage were categorized into sugars, sugar alcohols, amino acids, and organic acids. Multivariate statistical analysis indicated significant differences in the metabolic profiles among the potato cultivars. Pathway enrichment analysis revealed that carbohydrates, amino acids, and organic acids are the key players in CIS. Interestingly, one of the processing cultivars, FL-1533, exhibited a unique combination of metabolites represented by low levels of glucose, fructose, and asparagine accompanied by high citrate levels. Conversely, non-processing cultivars (Kufri Pukhraj and Kufri Jyoti) showed elevated glucose, fructose, and malate levels. Our results indicate that metabolites such as glucose, fructose, sucrose, asparagine, glutamine, citrate, malate, proline, 4-aminobutyrate can be potentially utilized for the prediction, selection, and development of potato cultivars for long-term storage, nutritional, as well as processing attributes.

A Glutathione Activatable Ion Channel Induces Apoptosis in Cancer Cells by Depleting Intracellular Glutathione Levels.

Cancer cells use elevated glutathione (GSH) levels as an inner line of defense to evade apoptosis and develop drug resistance. In this study, we describe a novel 2,4-nitrobenzenesulfonyl (DNS) protected 2-hydroxyisophthalamide system that exploits GSH for its activation into free 2-hydroxyisophthalamide forming supramolecular M+ /Cl- channels. Better permeation of the DNS protected compound into MCF-7 cells compared to the free 2-hydroxyisophthalamide and GSH-activatable ion transport resulted in higher cytotoxicity, which was associated with increased oxidative stress that further reduced the intracellular GSH levels and altered mitochondrial membrane permeability leading to the induction of the intrinsic apoptosis pathway. The GSH-activatable transport-mediated cell death was further validated in rat insulinoma cells (INS-1E); wherein the intracellular GSH levels showed a direct correlation to the resulting cytotoxicity. Lastly, the active compound was found to restrict the growth and proliferation of 3D spheroids of MCF-7 cells with efficiency similar to that of the anticancer drug doxorubicin.

Metabolic signatures suggest o-phosphocholine to UDP-N-acetylglucosamine ratio as a potential biomarker for high-glucose and/or palmitate exposure in pancreatic ß-cells.

INTRODUCTION: Chronic exposure to high-glucose and free fatty acids (FFA) alone/or in combination; and the resulting gluco-, lipo- and glucolipo-toxic conditions, respectively, have been known to induce dysfunction and apoptosis of ß-cells in Diabetes. The molecular mechanisms and the development of biomarkers that can be used to predict similarities and differences behind these conditions would help in easier and earlier diagnosis of Diabetes. OBJECTIVES: This study aims to use metabolomics to gain insight into the mechanisms by which ß-cells respond to excess-nutrient stress and identify associated biomarkers. METHODS: INS-1E cells were cultured in high-glucose, palmitate alone/or in combination for 24 h to mimic gluco-, lipo- and glucolipo-toxic conditions, respectively. Biochemical and cellular experiments were performed to confirm the establishment of these conditions. To gain molecular insights, abundant metabolites were identified and quantified using 1H-NMR. RESULTS: No loss of cellular viability was observed in high-glucose while exposure to FFA alone/in combination with high-glucose was associated with increased ROS levels, membrane damage, lipid accumulation, and DNA double-strand breaks. Forty-nine abundant metabolites were identified and quantified using 1H-NMR. Chemometric pair-wise analysis in glucotoxic and lipotoxic conditions, when compared with glucolipotoxic conditions, revealed partial overlap in the dysregulated metabolites; however, the dysregulation was more significant under glucolipotoxic conditions. CONCLUSION: The current study compared gluco-, lipo- and glucolipotoxic conditions in parallel and elucidated differences in metabolic pathways that play major roles in Diabetes. o-phosphocholine and UDP-N-acetylglucosamine were identified as common dysregulated metabolites and their ratio was proposed as a potential biomarker for these conditions.

Azadirachtin inhibits amyloid formation, disaggregates pre-formed fibrils and protects pancreatic ß-cells from human islet amyloid polypeptide/amylin-induced cytotoxicity.

The human islet amyloid polypeptide (hIAPP) or amylin is the major constituent of amyloidogenic aggregates found in pancreatic islets of type 2 diabetic patients that have been associated with ß-cell dysfunction and/or death associated with type 2 diabetes mellitus (T2DM). Therefore, developing and/or identifying inhibitors of hIAPP aggregation pathway and/or compound that can mediate disaggregation of preformed aggregates holds promise as a medical intervention for T2DM management. In the current study, the anti-amyloidogenic potential of Azadirachtin (AZD)-a secondary metabolite isolated from traditional medicinal plant Neem (Azadirachta indica)-was investigated by using a combination of biophysical and cellular assays. Our results indicate that AZD supplementation not only inhibits hIAPP aggregation but also disaggregates pre-existing hIAPP fibrils by forming amorphous aggregates that are non-toxic to pancreatic ß-cells. Furthermore, AZD supplementation in pancreatic ß-cells (INS-1E) resulted in inhibition of oxidative stress; along with restoration of the DNA damage, lipid peroxidation and the associated membrane damage, endoplasmic reticulum stress and mitochondrial membrane potential. AZD treatment also restored glucose-stimulated insulin secretion from pancreatic islets exposed to hIAPP. All-atom molecular dynamics simulation studies on full-length hIAPP pentamer with AZD suggested that AZD interacted with four possible binding sites in the amyloidogenic region of hIAPP. In summary, our results suggest AZD to be a promising candidate for combating T2DM and related amyloidogenic disorders.