Nutraceuticals - An Emerging Era in the Treatment and Prevention of Cardiovascular Diseases

Foods and nutrients play a vital role in normal functioning of the body. They are helpful in maintaining the health of the individual and in reducing the risk of various diseases. Worldwide acceptance of this fact formed a recognition link between "nutrition" and "health" and the concept of "nutraceuticals" was evolved. Nutraceuticals are medicinal foods that play a role in maintaining well being, enhancing health, modulating immunity and thereby preventing as well as treating specific diseases. Thus the field of nutraceuticals can be envisioned as one of the missing blocks in the health benefit of an individual. More than any other disease, the etiology of cardiovascular disease reveals many risk factors that are amenable to nutraceutical intervention. The scientific literature shows that several ingredients marketed for use in dietary supplements address each of these. The ability of nutraceuticals to positively influence cardiovascular risk factors should be recognized as an enormous opportunity in the treatment of a highly prevalent disease. Nutraceuticals hold promise in clinical therapy as they have the potential to significantly reduce the risk of side effects associated with chemotherapy along with reducing the global health care cost. In this review, an attempt has been made to summarize some of the recent research findings on garlic, omega-3-fatty acids, soy products, dietary fibres, vitamins, antioxidants, plant sterols, flavonoids, prebiotics and probiotics that have beneficial effects on the heart, in order to update the practising clinician on the benefit of using nutraceuticals for the management of cardiovascular diseases.

Power of two: combination of therapeutic approaches involving glucose transporter (GLUT) inhibitors to combat cancer

Cancer research of the Warburg effect, a hallmark metabolic alteration in tumors, focused attention on glucose metabolism whose targeting uncovered several agents with promising anticancer effects at the preclinical level. These agents' monotherapy points to their potential as adjuvant combination therapy to existing standard chemotherapy in human trials. Accordingly, several studies on combining glucose transporter (GLUT) inhibitors with chemotherapeutic agents, such as doxorubicin, paclitaxel, and cytarabine, showed synergistic or additive anticancer effects, reduced chemo-, radio-, and immuno-resistance, and reduced toxicity due to lowering the therapeutic doses required for desired chemotherapeutic effects, as compared with monotherapy. The combinations have been specifically effective in treating cancer glycolytic phenotypes, such as pancreatic and breast cancers. Even combining GLUT inhibitors with other glycolytic inhibitors and energy restriction mimetics seems worthwhile. Though combination clinical trials are in the early phase, initial results are intriguing. The various types of GLUTs, their role in cancer progression, GLUT inhibitors, and their anticancer mechanism of action have been reviewed several times. However, utilizing GLUT inhibitors as combination therapeutics has received little attention. We consider GLUT inhibitors agents that directly affect glucose transporters by binding to them or indirectly alter glucose transport by changing the transporters' expression level. This review mainly focuses on summarizing the effects of various combinations of GLUT inhibitors with other anticancer agents and providing a perspective on the current status.

Discovery of novel N-substituted thiazolidinediones (TZDs) as HDAC8 inhibitors: in-silico studies, synthesis, and biological evaluation

Epigenetics plays a fundamental role in cancer progression, and developing agents that regulate epigenetics is crucial for cancer management. Among Class I and Class II HDACs, HDAC8 is one of the essential epigenetic players in cancer progression. Therefore, we designed, synthesized, purified, and structurally characterized novel compounds containing N-substituted TZD (P1-P25). Cell viability assay of all compounds on leukemic cell lines (CEM, K562, and KCL22) showed the cytotoxic potential of P8, P9, P10, P12, P19, and P25. In-vitro screening of different HDACs isoforms revealed that P19 was the most potent and selective inhibitor for HDAC8 (IC50 - 9.3 μM). Thermal shift analysis (TSA) confirmed the binding of P19 to HDAC8. In-vitro screening of all compounds on the transport activity of GLUT1, GLUT4, and GLUT5 indicated that P19 inhibited GLUT1 (IC50 - 28.2 μM). P10 and P19 induced apoptotic cell death in CEM cells (55.19% and 60.97% respectively) and P19 was less cytotoxic on normal WBCs (CC50 - 104.2 μM) and human fibroblasts (HS27) (CC50 - 105.0 μM). Thus, among this novel series of TZD derivatives, compound P19 was most promising HDAC8 inhibitor and cytotoxic on leukemic cells. Thus, P19 could serve as a lead for further development of optimized molecules with enhanced selectivity and potency.

Structure guided design and synthesis of furyl thiazolidinedione derivatives as inhibitors of GLUT 1 and GLUT 4, and evaluation of their anti-leukemic potential

Cancer cells increase their glucose uptake and glycolytic activity to meet the high energy requirements of proliferation. Glucose transporters (GLUTs), which facilitate the transport of glucose and related hexoses across the cell membrane, play a vital role in tumor cell survival and are overexpressed in various cancers. GLUT1, the most overexpressed GLUT in many cancers, is emerging as a promising anti-cancer target. To develop GLUT1 inhibitors, we rationally designed, synthesized, structurally characterized, and biologically evaluated in-vitro and in-vivo a novel series of furyl-2-methylene thiazolidinediones (TZDs). Among 25 TZDs tested, F18 and F19 inhibited GLUT1 most potently (IC50 11.4 and 14.7 μM, respectively). F18 was equally selective for GLUT4 (IC50 6.8 μM), while F19 was specific for GLUT1 (IC50 152 μM in GLUT4). In-silico ligand docking studies showed that F18 interacted with conserved residues in GLUT1 and GLUT4, while F19 had slightly different interactions with the transporters. In in-vitro antiproliferative screening of leukemic/lymphoid cells, F18 was most lethal to CEM cells (CC50 of 1.7 μM). Flow cytometry analysis indicated that F18 arrested cell cycle growth in the subG0-G1 phase and lead to cell death due to necrosis and apoptosis. Western blot analysis exhibited alterations in cell signaling proteins, consistent with cell growth arrest and death. In-vivo xenograft study in a CEM model showed that F18 impaired tumor growth significantly.

Pharmacophore hybridization approach to discover novel pyrazoline-based hydantoin analogs with anti-tumor efficacy

In search for new and safer anti-cancer agents, a structurally guided pharmacophore hybridization strategy of two privileged scaffolds, namely diaryl pyrazolines and imidazolidine-2,4-dione (hydantoin), was adopted resulting in a newfangled series of compounds (H1-H22). Herein, a bio-isosteric replacement of "pyrrolidine-2,5-dione" moiety of our recently reported antitumor hybrid incorporating diaryl pyrazoline and pyrrolidine-2,5-dione scaffolds with "imidazoline-2,4-dione" moiety has been incorporated. Complete biological studies revealed the most potent analog among all i.e. compound H13, which was at-least 10-fold more potent compared to the corresponding pyrrolidine-2,5-dione, in colon and breast cancer cells. In-vitro studies showed activation of caspases, arrest of G0/G1 phase of cell cycle, decrease in the expression of anti-apoptotic protein (Bcl-2) and increased DNA damage. In-vivo assay on HT-29 (human colorectal adenocarcinoma) animal xenograft model unveiled the significant anti-tumor efficacy along with oral bioavailability with maximum TGI 36% (i.p.) and 44% (per os) at 50 mg/kg dose. These findings confirm the suitability of hybridized pyrazoline and imidazolidine-2,4-dione analog H13 for its anti-cancer potential and starting-point for the development of more efficacious analogs.

Double-edged Swords: Diaryl pyrazoline thiazolidinediones synchronously targeting cancer epigenetics and angiogenesis

In the present study, two novel series of compounds incorporating naphthyl and pyridyl linker were synthesized and biological assays revealed 5-((6-(2-(5-(2-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethoxy) naphthalene-2-yl)methylene)thiazolidine-2,4-dione (14b) as the most potent dual inhibitors of vascular endothelial growth factors receptor-2 (VEGFR-2) and histone deacetylase 4 (HDAC4). Compounds 13b, 14b, 17f, and 21f were found to stabilize HDAC4; where, pyridyl linker swords were endowed with higher stabilization effects than naphthyl linker. Also, 13b and 14b showed best inhibitory activity on VEGFR-2 as compared to others. Compound 14b was most potent as evident by in-vitro and in-vivo biological assessments. It displayed anti-angiogenic potential by inhibiting endothelial cell proliferation, migration, tube formation and also suppressed new capillary formation in the growing chick chorioallantoic membranes (CAMs). It showed selectivity and potency towards HDAC4 as compared to other HDAC isoforms. Compound 14b (25 mg/kg, i.p.) also indicated exceptional antitumor efficacy on in-vivo animal xenograft model of human colorectal adenocarcinoma (HT-29). The mechanism of action of 14b was also confirmed by western blot.

Synthesis and Biological Evaluation of Pyrazoline and Pyrrolidine-2,5-dione Hybrids as Potential Antitumor Agents

In search of novel and effective antitumor agents, pyrazoline-substituted pyrrolidine-2,5-dione hybrids were designed, synthesized and evaluated in silico, in vitro and in vivo for anticancer efficacy. All the compounds exhibited remarkable cytotoxic effects in MCF7 and HT29 cells. The excellent antiproliferative activity toward MCF7 (IC₅₀ =0.78±0.01 μM), HT29 (IC₅₀ =0.92±0.15 μM) and K562 (IC₅₀ =47.25±1.24 μM) cell lines, prompted us to further investigate the antitumor effects of the best compound S2 (1-(2-(3-(4-fluorophenyl)-5-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethyl)pyrrolidine-2,5-dione). In cell-cycle analysis, S2 was found to disrupt the growth phases with increased cell population in G₁ /G₀ phase and decreased cell population in G₂ /M phase. The excellent in vitro effects were also supported by inhibition of anti-apoptotic protein Bcl-2. In vivo tumor regression studies of S2 in HT29 xenograft nude mice, exhibited equivalent and promising tumor regression with maximum TGI, 66 % (i. p. route) and 60 % (oral route) at 50 mg kg^-1 dose by both the routes, indicating oral bioavailability and antitumor efficacy. These findings advocate that hybridization of pyrazoline and pyrrolidine-2,5-dioes holds promise for the development of more potent and less toxic anticancer agents.

Assorted Applications of N-substituted-2,4-thiazolidinediones in Various Pathological Conditions

Thiazolidine-2,4-dione (TZD) is one of the most frequently encountered heterocyclic rings which has been implicated in design and synthesis of entities for various pathogenic conditions including cancer. Since its discovery various substitutions at 5th position have been carried out and reviewed. Various substitutions at 5th position have led to generation of glitazones, whose target peroxisome proliferating activated receptor γ (PPARγ) was found decade after their discovery. Acidic hydrogen (-NH) of TZD is a prime pharmacophoric requirement for the activation of PPARγ. However, advanced in-silico techniques have helped to design compounds bearing substitutions at both methylene and -NH group of TZD, targeting range of enzymes involved in various pathological conditions viz., diabetes, hyperlipidemia, infectious disease, inflammation and cancer. The promising activities shown by methylene and N-substituted TZDs in above mentioned therapeutic areas, prompted us to collate the information which would help researchers to alter the structure of existing ligands and to design new TZD derivatives with better safety and efficacy profiles.

A novel series of di-fluorinated propanedione derivatives synergistically augment paclitaxel mediated caspase 3 activation in ovarian cancer cells

BACKGROUND

Both chronic and acute inflammatory circuits are known to be associated with malignancy and drug resistance indicating that many antiinflammatory agents can potentially act as chemotherapeutic drugs. A series of new class of propanediones with good antiinflammatory activity were shown to possess moderate cytotoxic activities.

AIM

The aim of the study was to evaluate this new series of 1-(2',4'-difluorophenyl)-3-(substituted phenyl)-1,3 propanediones (PR 1-7) for their caspase dependent apoptotic activity by using a reporter gene mediated caspase-3 sensor in chemo sensitive and paclitaxel resistant ovarian cancer cells.

MATERIALS AND METHODS

A cellular model of paclitaxel resistance was developed in OAW42 cells stably expressing the caspase 3 sensor. The activity of caspase 3 after single and combinatorial drug treatments was determined using western blot and luciferase activity. Cell viability and cell cycle analysis were determined by MTT 3 (4,5- dimethyl thiazol-2 yl-2,5- diphenyl tetrazolium bromide (MTT) and Flow cytometric analysis (FACS) analysis. High Performance Liquid Chromatography (HPLC) analysis was performed to assess cellular uptake of the propanediones.

RESULTS

Both nitro/methoxy (Group I) and halogen substituted propandiones at ortho, meta and para positions (Group II) showed a moderate increase in caspase-3 activity by 1.5- to 3.3-fold as compared with controls. However, no noticeable change in apoptotic cells percentage was observed. Increased intracellular uptake of Paclitaxel was observed during combinatorial treatment with one of the propanediones (PR2). Intriguingly, PR2 alone or in combination with Paclitaxel could induce a 2.5- to 2.9-fold increase in caspase-3 activity in Paclitaxel resistant cells.

CONCLUSION

Our study reports a new class of propanediones that can augment the cytotoxic effect of Paclitaxel, and potentially can be used for treating Paclitaxel-resistant cancers.

Hypoglycemic and Hypolipidemic Swords: Synthesis and In-vivo Biological Assessment of 5-benzylidene-2,4-thiazolidinediones

Thiazolidinedione (TZD), being a privileged scaffold, has been known as a significant structural moiety of antidiabetic drugs. TZD has been known to improve glycaemic control in type 2 diabetes mellitus (T2DM) by increasing insulin sensitivity in the body. A novel series of 5-benzylidene 2,4-thiazolidinedione derivatives were designed, synthesized (V1-V28), and structurally confirmed by different spectroscopic techniques such as FTIR, ¹H NMR, ¹³C NMR, and Mass spectrometry. Upon the safety assessment of the synthesized molecules in non-transformed hepatocytes by MTT reduction assay, these were found non-toxic. These derivatives were then further evaluated for their antihyperglycemic and antihyperlipidemic properties in a high-fat diet and low dose of streptozotocin-induced diabetic rats. Altogether, seven biochemical parameters were analyzed, namely blood glucose, triglycerides, cholesterol, creatinine, blood urea nitrogen, HDL-cholesterol, and glycosylated hemoglobin in serum by standard methods. Four synthetic molecules (V2, V4, V5, and V20) possessed significant hypoglycaemic and hypolipidemic activity as compared to the positive control pioglitazone. Moreover, the histopathological studies of the heart and liver revealed no significant toxicity. Two representative compounds V2 and V4, were evaluated for their PPARγ activation potential, demonstrating that they were partial PPARγ agonists, thus confirming our designing hypothesis. Based on the results obtained, we assume that these compounds have the potential to be developed as future antidiabetic agents.