Design and synthesis of novel coumarin-benzimidazole hybrids as human galectin-1 inhibitors.

Aim: To develop novel non-carbohydrate inhibitors of human galectin-1 (GAL-1), we have designed a series of coumarin-benzimidazole hybrids. Methods: We synthesized and characterized the coumarin-benzimidazole hybrids and further evaluated them using an in vitro GAL-1 enzyme-linked immunosorbent assay and in silico methods. Results: Among all, the compounds 6p and 6q were found to be potent, with GAL-1 inhibition of 37.61 and 36.92%, respectively, at 10 µM in GAL-1-expressed cell culture supernatant of MCF-7 cells. These two compounds are feasible for fluorine-18 radiolabeling to develop GAL-1 selective PET radiotracers. Computational studies revealed strong binding interactions of GAL-1 with these novel coumarin-benzimidazole hybrids. Conclusion: Coumarin-benzimidazole hybrids can serve as potential leads to develop selective non-carbohydrate GAL-1 inhibitors for cancer therapy.

Coumarin and Piperazine Conjugates as Selective Inhibitors of the Tumor-associated Carbonic Anhydrase IX and XII Isoforms.

BACKGROUND: Carbonic Anhydrases (CAs) are a family of metalloenzymes that catalyze the reversible interconversion of CO2 and water to bicarbonate and proton. CA isoforms I, II, IX, and XII are considered physiologically and pharmacologically relevant. OBJECTIVE: The objective of this study is to synthesize potent and selective tumor-associated CA IX and XII inhibitors. METHODS: A library of 17 coumarin derivatives clubbed with piperazine and benzyl moiety was designed, synthesized and evaluated for its inhibitory effects and selectivity profile towards physiologically and pharmacologically relevant CA isoforms I, II, IX, and XII. RESULTS: All the derivatives were found to be active against the tumor-associated isoforms IX and XII. The most active compound against hCA (human Carbonic Anhydrase) IX was found to possess a Ki of 229 nM, while the one against hCA XII had a Ki of 294.2 nM. Additionally, two of the compounds were found to have exquisite selectivity towards the off-target hCA I and II isoforms. Moreover, they were found to be approximately 20-fold more selective towards hCA IX than XII. The selectivity of the compounds was further investigated via molecular modeling techniques. CONCLUSION: Coumarin-piperazine hybrids were identified as potent and selective CA IX and XII inhibitors. Molecular modeling techniques provided interesting cues pertaining to observed selectivity.

An updated patent review of galectin-1 and galectin-3 inhibitors and their potential therapeutic applications (2016-present).

INTRODUCTION: Galectins are ubiquitous in nature. They have established themselves as a protein family of high therapeutic potential and play a role in a wide variety of diseases like cancer, fibrosis, and Alzheimer's. Within the galectin family, galectin- 1 and galectin- 3 have been widely studied and their roles and functions have now been well established. AREAS COVERED: In this review, we discuss the important advancements in the development of galectin-1 & 3 inhibitors. All patents filed detailing the divergent strategies to inhibit galectin-1 & 3 from 2016 to present have been covered and discussed. EXPERT OPINION: Over the past couple of decades, distinct galectin inhibitors have been synthesized, reported and studied. Among all, the mono and disaccharide-based antagonists have been found to be considerably successful. However, the cumbersome synthetic route followed to develop this class of inhibitors, in addition to complexity involved in making selective modifications within these molecules has posed a significant challenge. Recently, there have been numerous reports on heterocyclic-based galectin inhibitors. If these are established as potent galectin inhibitors, their ease of synthesis and tunability could overcome the potential drawbacks of carbohydrate-based inhibitors and could thus be exploited to develop efficient and highly specific galectin inhibitors.

Synthesis and biological evaluation of novel 4,7-disubstituted coumarins as selective tumor-associated carbonic anhydrase IX and XII inhibitors.

With an aim to develop novel potential anti-cancer agents we have designed a series of novel 4,7-disubstituted coumarin hybrids synthesis and evaluated for their inhibitory activity against the human carbonic anhydrase isoforms namely CA I, CA II, CA IX and CA XII. The results of CA inhibition clearly showed that the novel 4, 7-disubstituted coumarin hybrids (7a-i & 8a-j) exhibited selective inhibition towards tumor associated isoforms, CA IX and CA XII without inhibiting CA I and CA II isoforms. Among all the compound 8b showed a significant inhibition against hCA IX with a Ki of 0.58 µM whereas, the compound 7c showed a significant inhibition against hCA XII with a Ki of 0.36 µM respectively. All other compounds have shown a good inhibition against hCA IX and hCA XII over hCA I and hCA II within the range of 0.46 to 9.35 µM. Therefore, compound 8b and 7c would be the potential leads for developing selective cytotoxic agents targeting hCA IX and XII.

Novel benzimidazole-triazole hybrids as apoptosis inducing agents in lung cancer: Design, synthesis, 18F-radiolabeling & galectin-1 inhibition studies.

In this study, we have synthesized a new series of benzimidazole-triazole hybrids as galectin-1 (gal-1) mediated apoptosis-inducing agents, and evaluated for their potential anticancer activity against a panel of human cancer cell lines viz. breast cancer (MCF-7 and MDA-MB-231) lung cancer (A-549 and NCI-H460), and human keratinocyte cancer (HaCaT), using MTT assay. The target compound 7c exhibited an excellent growth inhibition against lung cancer (A-549 and NCI-H460) cells with an IC50 value of 0.63 ± 0.21 µM, and 0.99 ± 0.01 µM respectively. The target compound 7c also showed a significant growth inhibition against breast cancer (MCF-7 and MDA-MB-23) with an IC50 value of 1.3 ± 0.18 µM, and 0.94 ± 0.02 µM respectively. In addition, the radiochemical synthesis has been performed using fluorine-18 radionuclide in the GE Tracer-lab FX2N module to prove the target compound 7c as a PET imaging agent. In the final stage, the 18F-7c target compound was successfully purified with 60% ethanol in water. The radiochemical purity was achieved >95% using HPLC, and the residual solvent DMF limit was around 78 ± 3 ppm confirmed by GC analysis. Further, the apoptosis induction by 7c in lung cancer (A-549) cells was confirmed as a result of the decrease in MMP levels, increased percentage of apoptotic cells, and sub G1 phase arrest by JC-1 staining, DAPI staining, annexin V-FITC/PI, and flow cytometric analysis. In addition, the target compound 7c significantly reduced the gal-1 protein levels in a dose-dependent manner as confirmed by ELISA studies. The protein binding studies like Surface Plasmon Resonance (SPR) and Fluorescence Spectroscopy (FS) studies indicated that the target compound 7c is capable of binding to gal-1 with an equilibrium constant (KD) value of 1.19E-06 M, and binding constant (Ka) of 9.5 × 103 M-1 respectively. The in-silico computational studies also revealed possible interactions and pharmacokinetic properties (ADMET) of compound 7c with the binding domain of gal-1. Therefore, the novel benzimidazole-triazole hybrids as apoptosis-inducing agents in lung cancer would be potential cytotoxic and PET imaging agents via gal-1.

Synthesis, 18F-radiolabeling and apoptosis inducing studies of novel 4, 7-disubstituted coumarins.

In present study, a new series of 4, 7-disubstituted coumarin derivatives (7a-y) have been synthesized as galectin-1 targeting apoptosis inducing agents and evaluated for their in vitro cytotoxic potentials against a panel of selected human cancer cell lines namely, Brest (MCF7), Ovarian (SKOV3), Prostate (PC-3 & DU145) and normal embryonic kidney (HEK293T) cells, using MTT assay. Most of the compounds exhibited potent growth inhibitory action against the treated cancer cell lines with an IC50 range of 10-30 µM. Compound 7q exhibited a significant growth inhibition against prostate cancer (PC-3 & DU145) cell lines with an IC50 value of 7.45 ± 0.03 µM, 8.95 ± 0.17 µM respectively. Further, the target compound 7q was radiolabeled with fluorine-18 [18F] to be used as a novel PET radiotracer for imaging of tumors via targeting galectin-1, using appropriate reaction conditions in the GE Tracer-lab FX2N synthesis module. The purification of the [18F] radiolabeled compound [18F]-7q was successfully achieved with 60% ethanol. The radiochemical purity was>85% and residual solvent limits of DMF was 65 ± 3 ppm as analysed by HPLC, TLC & GC analytical methods. The apoptosis studies confirm the inhibition of cell proliferation with morphological changes like cell shrinkage, blebbing and cell wall deformation, increasing the ROS levels, and loss of mitochondrial membrane potential by Acridine orange/Ethidium bromide staining, Hoechst-33342 staining, H2DCFDA staining, annexin V-FITC/PI, and JC-1 staining methods. In flow cytometric analysis, 7q selectively arrested the sub-G1 phase of the cell cycle in a dose-dependent manner. In Gal-1 ELISA studies, compound 7q efficiently reduced the levels of Gal-1 protein in dose-dependent manner with an IC50 value of 100 µM. The binding constant (Ka) of 7q with Gal-1 was observed as 1.3 × 104 M-1 by fluorescence spectroscopy. The molecular docking studies clearly showed possible interactions and the pharmacokinetic (ADMET) properties of compound 7q with Gal-1. Hence, the novel 4, 7-disubstituted coumarins could be a potential cytotoxic and PET imaging agents via Gal-1.

Synthesis and biological evaluation of morpholines linked coumarin-triazole hybrids as anticancer agents.

A series of novel morpholines linked coumarin-triazole hybrids (6a-6v) has been synthesized and evaluated for their anti-proliferative potential on a panel of five human cancer cell lines, namely bone (MG-63), lung (A549), breast (MDA-MB-231), colon (HCT-15) and liver (HepG2), using MTT assay. Among all, the compound 6n {7-((1-(2,4-dichlorobenzyl)-1H-1,2,3-triazol-4-yl) methoxy)-4-((2,6-dimethylmorpholino) methyl)-2H-chromen-2-one} showed significant growth inhibition against MG-63 cells with an IC50 value of 0.80 ± 0.22 µM. Further, induction of apoptosis by 6n of MG-63 cells confirmed as a result of morphological changes, the sub-G1 phase arrest, increased percentage of apoptotic cells, and decrease in mitochondrial membrane potential and increase in reactive oxygen species levels. The in vitro Gal-1 expression in cell culture supernatant of MG-63 cells treated with compound 6n showed dose-dependent reduction. The binding constant (Ka ) of 6n with Gal-1 was calculated from the intercept value which was observed as 3.0 × 105  M-1 by fluorescence spectroscopy. Surface plasmon resonance showed that 6n binds to Gal-1 with binding constant (Ka ) of 1.29E+04 1/Ms and equilibrium constant KD value of 7.54E-07 M, respectively. Molecular docking studies revealed the binding interactions of 6n with Gal-1.

Synthesis of 1-benzyl-1H-benzimidazoles as galectin-1 mediated anticancer agents.

In our pursuit to develop novel non-carbohydrate small molecule Galectin-1 Inhibitors, we have designed a series of 1-benzyl-1H-benzimidazole derivatives and demonstrated their anticancer activity. The compound 6g, 4-(1-benzyl-5-chloro-1H-benzo[d]imidazol-2-yl)-N-(4-hydroxyphenyl) benzamide was found to be most potent with an IC50 of 7.01 ±â€¯0.20 µM and arresting MCF-7 cell growth at G2/M phase and S phase. Induction of apoptosis was confirmed by morphological changes like cell shrinkage, blebbing and cell wall deformation, dose dependent increase in the mitochondrial membrane potential (ΔΨm) and ROS levels. Further, dose dependent decrease in Gal-1 protein levels proves Gal-1 mediated apoptosis by 6g. Molecular docking studies were performed to understand the Gal-1 interaction with compound 6g. In addition, RP-HPLC studies showed 85.44% of 6g binding to Gal-1. Binding affinity studies by fluorescence spectroscopy and Surface Plasmon Resonance (SPR) showed that 6g binds to Gal-1 with binding constant (Ka) of 1.2 × 104 M-1 and equilibrium constant KD value of 5.76 × 10-4 M respectively.

Human Galectin-1 and Its Inhibitors: Privileged Target for Cancer and HIV.

Galectin 1(Gal-1), a ß-galactoside binding mammalian lectin of 14KDa, is implicated in many signalling pathways, immune responses associated with cancer progression and immune disorders. Inhibition of human Gal-1 has been regarded as one of the potential therapeutic approaches for the treatment of cancer, as it plays a major role in tumour development and metastasis by modulating various biological functions viz. apoptosis, angiogenesis, migration, cell immune escape. Gal-1 is considered as a biomarker in diagnosis, prognosis and treatment condition. The overexpression of Gal-1 is well established and seen in many types of cancer progression like osteosarcoma, breast, lung, prostate, melanoma, etc. Gal-1 greatly accelerates the binding kinetics of HIV-1 to susceptible cells, leading to faster viral entry and a more robust viral replication by specific binding of CD4 cells. Hence, the Gal-1 is considered a promising molecular target for the development of new therapeutic drugs for cancer and HIV. The present review laid emphasis on structural insights and functional role of Gal-1 in the disease, current Gal-1 inhibitors and future prospects in the design of specific Gal-1 inhibitors.

Synthesis and Biological Evaluation of Novel Heterocyclic Imines Linked Coumarin- Thiazole Hybrids as Anticancer Agents.

BACKGROUND: Human Galectin-1, a protein of lectin family showing affinity towards ß-galactosides has emerged as a critical regulator of tumor progression and metastasis, by modulating diverse biological events including homotypic cell aggregation, migration, apoptosis, angiogenesis and immune escape. Therefore, galectin-1 inhibitors might represent novel therapeutic agents for cancer. METHODS: A new series of heterocyclic imines linked coumarin-thiazole hybrids (6a-6r) was synthesized and evaluated for its cytotoxic potential against a panel of six human cancer cell lines namely, lung (A549), prostate (DU-145), breast (MCF-7 & MDA-MB-231), colon (HCT-15 & HT-29) using MTT assay. Characteristic apoptotic assays like DAPI staining, cell cycle, annexin V and Mitochondrial membrane potential studies were performed for the most active compound. Furthermore, Gal-1 inhibition was confirmed by ELISA and fluorescence spectroscopy. RESULTS: Among all, compound 6g {3-(2-(2-(pyridin-2-ylmethylene) hydrazineyl) thiazol-4-yl)-2H-chromen-2- one} exhibited promising growth inhibition against HCT-15 colorectal cancer cells with an IC50 value of 1.28 ± 0.14 µM. The characteristic apoptotic morphological features like chromatin condensation, membrane blebbing and apoptotic body formation were clearly observed with compound 6g on HCT-15 cells using DAPI staining studies. Further, annexin V-FITC/PI assay confirmed effective early apoptosis induction by treatment with compound 6g. Loss of mitochondrial membrane potential and enhanced ROS generation were confirmed with JC-1 and DCFDA staining method, respectively by treatment with compound 6g, suggesting a possible mechanism for inducing apoptosis. Moreover, flow cytometric analysis revealed that compound 6g blocked G0/G1 phase of the cell cycle in a dose-dependent manner. Compound 6g effectively reduced the levels of Gal-1 protein in a dose-dependent manner. The binding constant (Ka) of 6g with Gal-1 was calculated from the intercept value which was observed as 1.9 x 107 M-1 by Fluorescence spectroscopy. Molecular docking studies showed strong interactions of compound 6g with Gal-1 protein. CONCLUSION: Our studies demonstrate the anticancer potential and Gal-1 inhibition of heterocyclic imines linked coumarin-thiazole hybrids.

Bioenhancing effects of naringin on atorvastatin.

Naringin (CAS no: 10236-47-2) is a flavonone glycoside obtained from Citrus paradisi (grapefruit), a natural bioenhancer and reported to enhance the bioavailability of drugs by inhibiting cytochrome P450 and P-glycoprotein (P-gp). The aim of the present study was to investigate the effect of naringin on antihyperlipidemic properties of atorvastatin (AST) in tyloxapol induced hyperlipidemic rats and the effects were supported with measurement of plasma concentrations of AST by HPLC method. Animals received AST along with naringin (15 and 30 mg/kg) shown higher percent reduction in both cholesterol and triglycerides levels, when compared to animals received AST alone at dose of 25 and 50 mg/kg and it was found that the higher percent reduction in cholesterol and triglycerides was proportional to increase in plasma concentration of AST. From the results it is evident that the co-administration of naringin along with AST increased the plasma concentration of AST. The findings of the present study confirmed that naringin could be used as bioenhancer. The co-administration of AST and the diet with naringin (grapefruit) to the patients may potentiate the therapeutic efficacy of AST.

Antimicrobial Peptides: A Promising Therapeutic Strategy in Tackling Antimicrobial Resistance.

BACKGROUND: Antimicrobial resistance (AMR) has posed a serious threat to global public health and it requires immediate action, preferably long term. Current drug therapies have failed to curb this menace due to the ability of microbes to circumvent the mechanisms through which the drugs act. From the drug discovery point of view, the majority of drugs currently employed for antimicrobial therapy are small molecules. Recent trends reveal a surge in the use of peptides as drug candidates as they offer remarkable advantages over small molecules. METHODS: Newer synthetic strategies like organometalic complexes, Peptide-polymer conjugates, solid phase, liquid phase and recombinant DNA technology encouraging the use of peptides as therapeutic agents with a host of chemical functions, and tailored for specific applications. In the last decade, many peptide based drugs have been successfully approved by the Food and Drug Administration (FDA). This success can be attributed to their high specificity, selectivity and efficacy, high penetrability into the tissues, less immunogenicity and less tissue accumulation. Considering the enormity of AMR, the use of Antimicrobial Peptides (AMPs) can be a viable alternative to current therapeutics strategies. AMPs are naturally abundant allowing synthetic chemists to develop semi-synthetics peptide molecules. AMPs have a broad spectrum of activity towards microbes and they possess the ability to bypass the resistance induction mechanisms of microbes. RESULT: The present review focuses on the potential applications of AMPs against various microbial disorders and their future prospects. Several resistance mechanisms and their strategies have also been discussed to highlight the importance in the current scenario. CONCLUSION: Breakthroughs in AMP designing, peptide synthesis and biotechnology have shown promise in tackling this challenge and has revived the interest of using AMPs as an important weapon in fighting AMR.

Evaluation of glucose utilization capacity of bioactivity-guided fractions of Barleria prionitis Linn and Hyptis suaveolens (L.) Poit in isolated rat hemidiaphragm.

INTRODUCTION: Diabetes mellitus (DM) is a chronic disease characterized by high blood glucose levels due to absolute or relative circulating insulin levels. Plants represent a major potential source of drugs for treating diabetes. The study of plants having antidiabetic activity may give a new approach in the treatment of DM. AIM: This study was aimed to investigate the glucose utilization capacity of bioactivity-guided fractions of Barleria prionitis and Hyptis suaveolens. MATERIALS AND METHODS: The dried coarse powdered plant material was extracted in aqueous ethanol by cold maceration; further, ethanolic extracts were fractionated using solvents of varying polarity and were investigated in isolated rat hemidiaphragm using 0.1% and 0.2% concentrations of plant extracts. RESULTS: The tested fractions of both plants showed significant and dose-dependent increased glucose uptake capacity and was found to be maximum with petroleum ether and aqueous ethanolic extracts of both plants; 0.2% concentration of both plant extracts is superior in activity when compared to 0.1% of the test extracts. H. suaveolens has produced more glucose utilization capacity when compared to B. prionitis. CONCLUSION: The activity of H. suaveolens is comparable to standard insulin (P < 0.01). Both the plant materials have some extra pancreatic mechanism like glucose uptake by peripheral tissue.

Scientific evidence for traditional claim of anti-obesity activity of Tecomella undulata bark.

ETHNOPHARMACOLOGICAL RELEVANCE: The bark of Tecomella undulata is traditionally claimed in the treatment of various disease ailments including obesity and cancer. Till now there are no studies about anti-obesity activity of Tecomella undulata bark. AIM OF THE STUDY: The present study was aimed to establish a scientific evidence for anti-obesity efficiency of ethyl acetate extract of Tecomella undulata bark (EATUB). Further to standardize the active fractions of EATUB using different biomarkers. MATERIALS AND METHODS: We investigated activity of EATUB fractions (F1-F7) using 3T3-L1 fibroblasts. Further, F1-mediated effects were characterized by determining mRNA and protein levels of SIRT1, one of the key targets for the treatment of obesity, using semi-quantitative RT-PCR (sqRT-PCR) and western blot analysis. The consequences of modulation of SIRT1 on mRNA and protein levels of various adipogenesis mediators like PPARγ, C/EBPα, E2F1, leptin, adiponectin and LPL were also studied. In vivo studies were performed using High Fat Diet (HFD) obese mice. RESULTS: Our data showed that compared to controls, preadipocytes and adipocytes incubated with F1 exhibited a significant decrease in adipogenesis and lipogenesis. In addition, sqRT-PCR and western blot analysis showed significant increase in SIRT1 and adiponectin levels and decrease in PPARγ, C/EBPα, E2F1, leptin and LPL levels in preadipocytes and adipocytes. In vivo studies of F1 in HFD induced obese mice showed significant improvement in lipid profile and glucose levels. The bioactive fraction (F1) was determined to possess 4.95% of ferulic acid. CONCLUSION: Thus, our findings signified the beneficial effects of Tecomella undulata bark in pharmacologic interventions related to obesity and metabolic disorders. Ferulic acid and rutin are being reported and quantified for the first time from the bark of Tecomella undulata.

Synthesis and in vitro antiproliferative activity of 2-methyl-3-(2-piperazin-1-yl-ethyl)-pyrido[1,2-a]pyrimidin-4-one derivatives against human cancer cell lines.

A series of new 2-methyl-3-(2-piperazin-1-yl-ethyl)-pyrido[1,2-a]pyrimidin-4-one derivatives 6a-j were synthesized by a nucleophilic substitution reaction of 2-methyl-3-(2-piperazin-1-ylethyl)-pyrido[1,2-a]pyrimidin-4-one with various sulfonyl chlorides. The compounds were characterized by different spectral studies. All the compounds were evaluated for their antiproliferative effect using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay method against four human cancer cell lines (K562, Colo-205, MDA-MB 231, IMR-32) for the time period of 24 h. Among the series, compounds 6d, 6e and 6i showed good activity on all cell lines except K562, whereas the other compounds in the series exhibited moderate activity. Compound 6d could be a potential anticancer agent and therefore deserves further research.