Structure-based mapping of the histone-binding pocket of KDM4D using functionalized tetrazole and pyridine core compounds.

KDM4 histone demethylases became an exciting target for inhibitor development as the evidence linking them directly to tumorigenesis mounts. In this study, we set out to better understand the binding cavity using an X-ray crystallographic approach to provide a detailed landscape of possible interactions within the under-investigated region of KDM4. Our design strategy was based on utilizing known KDM binding motifs, such as nicotinic acid and tetrazolylhydrazides, as core motifs that we decided to enrich with flexible tails to map the distal histone binding site. The resulting X-ray structures of the novel compounds bound to KDM4D, a representative of the KDM4 family, revealed the interaction pattern with distal residues in the histone-binding site. The most prominent protein rearrangement detected upon ligand binding is the loop movement that blocks the accessibility to the histone binding site. Apart from providing new sites that potential inhibitors can target, the novel compounds may prove helpful in exploring the capacity of ligands to bind in sites distal to the cofactor-binding site of other KDMs or 2-oxoglutarate (2OG)-dependent oxygenases. The case study proves that combining a strong small binding motif with flexible tails to probe the binding pocket will facilitate lead discovery in classical drug-discovery campaigns, given the ease of accessing X-ray quality crystals.

Synthesis of Cycloartan-16ß-ol from 16ß 24R-Epoxy-Cycloartane and Their Cytotoxicity Evaluation Against Human Cancer Cell Lines.

It was found that Argentatins A and B triterpenoids make up approximately 20-30 % of the waste resin produced from the industrial processes to isolate rubber from P. argentatum. We have developed an efficient protocol for synthesizing cycloartane-16ß-ol derivatives by opening the oxepane ring of argentatin B acetate (2) with BF3-OEt2. Although three new cycloartenol derivatives showed high cytotoxicity against PC-3 and HCT-15 cancer cell lines, nevertheless, the best results were obtained for (16ß,24R) -(16,24-epoxy-cycloartan-2(1H)-ylidene) acetate (14), compound with intact oxepane ring. These results indicate that the substituents in the argentatin nucleus and a side chain account for the cytotoxic activity. However, according to the selectivity index (SI), 14 did not show selectivity activity to cancer cell lines over the HaCat noncancerous cell line. The compound 3ß,16ß-Dihydroxy-cycloartan-24-one (5), synthesized by oxepane opening, demonstrated high cytotoxic activity to cancer cell lines and showed a remarkable selectivity to cancer cell lines over the noncancerous ones. These results suggest that 5 could lead to the development of new anticancer compounds.

Design, synthesis and biological evaluation of 1,5-disubstituted α-amino tetrazole derivatives as non-covalent inflammasome-caspase-1 complex inhibitors with potential application against immune and inflammatory disorders.

Compounds targeting the inflammasome-caspase-1 pathway could be of use for the treatment of inflammation and inflammatory diseases. Previous caspase-1 inhibitors were in great majority covalent inhibitors and failed in clinical trials. Using a mixed modelling, computational screening, synthesis and in vitro testing approach, we identified a novel class of non-covalent caspase-1 non cytotoxic inhibitors which are able to inhibit IL-1ß release in activated macrophages in the low µM range, in line with the best activities observed for the known covalent inhibitors. Our compounds could form the basis of further optimization towards potent drugs for the treatment of inflammation and inflammatory disorders including also dysregulated inflammation in Covid 19.

A One-Pot Six-Component Reaction for the Synthesis of 1,5-Disubstituted Tetrazol-1,2,3-Triazole Hybrids and Their Cytotoxic Activity against the MCF-7 Cell Line.

A high-order multicomponent reaction involving a six-component reaction to obtain the novel linked 1,5-disubstituted tetrazole-1,2,3-triazole hybrids in low to moderate yield is described. This one-pot reaction is carried out under a cascade process consisting of three sequential reactions: Ugi-azide, bimolecular nucleophilic substitution (SN2), and copper-catalyzed alkyne-azide reaction (CuAAC), with high atom and step-economy due the formation of six new bonds (one C-C, four C-N, and one N-N). Thus, the protocol developed offers operational simplicity, mild reaction conditions, and structural diversity. Finally, to evaluate the antitumoral potential of the synthetized molecules, a proliferation study was performed in the breast cancer (BC) derived cell line MCF-7. The hybrid compounds showed several degrees of cell proliferation inhibition with a remarkable effect in those compounds with cyclohexane and halogens in their structures. These compounds represent potential drug candidates for breast cancer treatment. However, additionally assays are needed to elucidate their complete effect over the cellular hallmarks of cancer.

Enabling In Vivo Photocatalytic Activation of Rapid Bioorthogonal Chemistry by Repurposing Silicon-Rhodamine Fluorophores as Cytocompatible Far-Red Photocatalysts.

Chromophores that absorb in the tissue-penetrant far-red/near-infrared window have long served as photocatalysts to generate singlet oxygen for photodynamic therapy. However, the cytotoxicity and side reactions associated with singlet oxygen sensitization have posed a problem for using long-wavelength photocatalysis to initiate other types of chemical reactions in biological environments. Herein, silicon-Rhodamine compounds (SiRs) are described as photocatalysts for inducing rapid bioorthogonal chemistry using 660 nm light through the oxidation of a dihydrotetrazine to a tetrazine in the presence of trans-cyclooctene dienophiles. SiRs have been commonly used as fluorophores for bioimaging but have not been applied to catalyze chemical reactions. A series of SiR derivatives were evaluated, and the Janelia Fluor-SiR dyes were found to be especially effective in catalyzing photooxidation (typically 3%). A dihydrotetrazine/tetrazine pair is described that displays high stability in both oxidation states. A protein that was site-selectively modified by trans-cyclooctene was quantitatively conjugated upon exposure to 660 nm light and a dihydrotetrazine. By contrast, a previously described methylene blue catalyst was found to rapidly degrade the protein. SiR-red light photocatalysis was used to cross-link hyaluronic acid derivatives functionalized by dihydrotetrazine and trans-cyclooctenes, enabling 3D culture of human prostate cancer cells. Photoinducible hydrogel formation could also be carried out in live mice through subcutaneous injection of a Cy7-labeled hydrogel precursor solution, followed by brief irradiation to produce a stable hydrogel. This cytocompatible method for using red light photocatalysis to activate bioorthogonal chemistry is anticipated to find broad applications where spatiotemporal control is needed in biological environments.

Discovery of Encequidar, First-in-Class Intestine Specific P-glycoprotein Inhibitor.

Many chemotherapeutics, such as paclitaxel, are administered intravenously as they suffer from poor oral bioavailability, partly because of efflux mechanism of P-glycoprotein in the intestinal epithelium. To date, no drug has been approved by the U.S. Food and Drug Administration (FDA) that selectively blocks this efflux pump. We sought to identify a compound that selectively inhibits P-glycoprotein in the gastrointestinal mucosa with poor oral bioavailability, thus eliminating the issues such as bone marrow toxicity associated with systemic inhibition of P-glycoprotein. Here, we describe the discovery of highly potent, selective, and poorly orally bioavailable P-glycoprotein inhibitor 14 (encequidar). Clinically, encequidar was found to be well tolerated and minimally absorbed; and importantly, it enabled the oral delivery of paclitaxel.

Design, synthesis and biological evaluation of 1-Aryl-5-(4-arylpiperazine-1-carbonyl)-1H-tetrazols as novel microtubule destabilizers.

A series of 1-aryl-5-(4-arylpiperazine-1-carbonyl)-1H-tetrazols as microtubule destabilizers were designed, synthesised and evaluated for anticancer activity. Based on bioisosterism, we introduced the tetrazole moiety containing the hydrogen-bond acceptors as B-ring of XRP44X analogues. The key intermediates ethyl 1-aryl-1H-tetrazole-5-carboxylates 10 can be simply and efficiently prepared via a microwave-assisted continuous operation process. Among the compounds synthesised, compound 6-31 showed noteworthy potency against SGC-7901, A549 and HeLa cell lines. In mechanism studies, compound 6-31 inhibited tubulin polymerisation and disorganised microtubule in SGC-7901 cells by binding to tubulin. Moreover, compound 6-31 arrested SGC-7901cells in G2/M phase. This study provided a new perspective for development of antitumor agents that target tubulin.

Novel Antimalarial Tetrazoles and Amides Active against the Hemoglobin Degradation Pathway in Plasmodium falciparum.

Malaria control programs continue to be threatened by drug resistance. To identify new antimalarials, we conducted a phenotypic screen and identified a novel tetrazole-based series that shows fast-kill kinetics and a relatively low propensity to develop high-level resistance. Preliminary structure-activity relationships were established including identification of a subseries of related amides with antiplasmodial activity. Assaying parasites with resistance to antimalarials led us to test whether the series had a similar mechanism of action to chloroquine (CQ). Treatment of synchronized Plasmodium falciparum parasites with active analogues revealed a pattern of intracellular inhibition of hemozoin (Hz) formation reminiscent of CQ's action. Drug selections yielded only modest resistance that was associated with amplification of the multidrug resistance gene 1 (pfmdr1). Thus, we have identified a novel chemical series that targets the historically druggable heme polymerization pathway and that can form the basis of future optimization efforts to develop a new malaria treatment.

An efficient synthesis tetrazole and oxadiazole analogues of novel 2'-deoxy-C-nucleosides and their antitumor activity.

Various tetrazole and oxadiazole C-nucleoside analogues were synthesized starting from pure α- or ß-glycosyl-cyanide. The synthesis of glycosyl-cyanide as key precursor was optimized on gram-scale to furnish crystalline starting material for the assembly of C-nucleosides. Oxadizole C-nucleosides were synthesized via two independent routes. First,  the glycosyl-cyanide was converted into an amidoxime which upon ring closure offered an alternative pathway for the assembly of 1,2,4-oxadizoles in an efficient manner. Second, both anomers of glycosyl-cyanide were transformed into tetrazole nucleosides followed by acylative rearrangement to furnish 1,3,4-oxadiazoles in high yields. These protocols offer an easy access to otherwise difficult to synthesize C-nucleosides in good yield and protecting group compatibility. These C-nucleosides were evaluated for their antitumor activity. This work paves a path for facile assembly of library of new chemical entities useful for drug discovery.

Synthesis, Cytotoxic Analysis, and Molecular Docking Studies of Tetrazole Derivatives via N-Mannich Base Condensation as Potential Antimicrobials.

PURPOSE: A new series of tetrazole derivatives, which are renowned antimicrobials possessing a five-membered aromatic heterocyclic group, are synthesized herein and subjected to antimicrobial and cytotoxicity screening. METHODS: The tetrazole derivatives were synthesized via ultrasonication using Mannich base condensation. Structural verification of the products was performed using IR, 1H NMR, and 13C NMR spectroscopy, as well as mass spectroscopic and elemental analyses. The compounds were then screened for antimicrobial and cytotoxic activity against HepG2 (liver), MCF-7 (breast), and HeLa (cervical) cell lines. Inter- and intra-molecular binding interactions were determined using molecular docking studies. The exact binding mode between the most active tetrazole derivatives (ie, 1b, 2a, and 2b) and the proteins (ie, 4OR7, 1AI9, and 4FM9) was established using Autodock Vina 1.1.2 software and compared to the binding mode of the reference compounds (ie, cefazolin, clotrimazole, and fluorouracil). RESULTS: Compound 1b was extremely active against Enterococcus faecalis relative to the positive control cefazolin. Compounds 1b and 1e were active against Candida albicans and Microsporum audouinii compared to the positive control clotrimazole in antifungal screening. The HepG2 (liver) and MCF-7 (breast) cancer cell lines were particularly susceptible to the synthesized compounds. Compared to the control compound fluorouracil, 2a and 2b were extremely active against all three cancer cell lines. Molecular docking studies showed that 2b exhibited higher binding affinity (-7.8 kcal/mol) to the 4OR7 protein than the control cefazolin (-7.2 kcal/mol). CONCLUSION: Generally, 1b, 2a, and 2b exhibited impressive inhibitory capabilities in antibacterial, antifungal, and cytotoxic screenings relative to the reference compounds. The results of the molecular docking studies and both the microbial and anticancer screenings indicate that these novel derivatives could be developed into potential therapeutic agents for medical applications.

Novel tetrazole-based selective COX-2 inhibitors: Design, synthesis, anti-inflammatory activity, evaluation of PGE2, TNF-α, IL-6 and histopathological study.

To search for effective and selective COX-2 inhibitors, four novel series of tetrazole derivatives were designed based on bioisosteric replacement of SO2NH2 in celecoxib with tetrazole ring incorporating different central moieties as chalcone (2a-f), isoxazole (3a-c) or pyrazole (4a-c & 5a-c). Target tetrazoles were synthesized and their structures were confirmed by spectroscopic techniques and elemental analyses. All target compounds were more selective for COX-2 isozyme than COX-1 when compared to standard drugs indomethacin and celecoxib. Compounds 3b, 3c, 4b, 4c, 5b and 5c exhibited potent in vitro COX-2 inhibitory activity (IC50 = 0.039-0.065 µM). Trimethoxy derivatives 3c, 4c and 5c acquired superior COX-2 selectivity index values (SI = 297.67-317.95) and were 1.1 fold higher than celecoxib (SI = 282.22). The most active six compounds were evaluated for their in vivo anti-inflammatory activity and serum levels of PGE2, TNF-α and IL-6 in addition to their ulcerogenic liability and histopathological profile. At a dose of 50 mg/Kg, compounds 3c and 5c showed better anti-inflammatory activity (% edema inhibition = 29.209-42.643) than celecoxib (% edema inhibition = 28.694-40.114) at different time intervals and were less ulcerogenic (UI = 0.123 and 0.11 in sequent) than celecoxib (UI = 0.167). Also, they displayed potent inhibitory effect on the production of PGE2 (% inhibition = 81.042 and 82.724 in sequent) greater than celecoxib (% inhibition = 79.666). Compound 5c decreased rat serum concentrations of both TNF-α (% inhibition = 55.349) and IL-6 (% inhibition = 61.561) in a comparable or better activity to celecoxib as reference drug. Finally, docking poses of the most active compounds showed strong binding interactions and effective overall docking energy scores explaining their remarkable COX-2 inhibitory activity.

Multicomponent Synthesis, Binding Mode, and Structure-Activity Relationship of Selective Histone Deacetylase 6 (HDAC6) Inhibitors with Bifurcated Capping Groups.

Histone deacetylase 6 (HDAC6) is an emerging target for the treatment of cancer, neurodegenerative diseases, inflammation, and other diseases. Here, we present the multicomponent synthesis and structure-activity relationship of a series of tetrazole-based HDAC6 inhibitors. We discovered the hit compound NR-160 by investigating the inhibition of recombinant HDAC enzymes and protein acetylation. A cocrystal structure of HDAC6 complexed with NR-160 disclosed that the steric complementarity of the bifurcated capping group of NR-160 to the L1 and L2 loop pockets may be responsible for its HDAC6-selective inhibition. While NR-160 displayed only low cytotoxicity as a single agent against leukemia cell lines, it augmented the apoptosis induction of the proteasome inhibitor bortezomib in combination experiments significantly. Furthermore, a combinatorial high-throughput drug screen revealed significantly enhanced cytotoxicity when NR-160 was used in combination with epirubicin and daunorubicin. The synergistic effect in combination with bortezomib and anthracyclines highlights the potential of NR-160 in combination therapies.

Tetrazoles as anticancer agents: A review on synthetic strategies, mechanism of action and SAR studies.

Cancer is a leading cause of death worldwide. Even after the availability of numerous drugs and treatments in the market, scientists and researchers are focusing on new therapies because of their resistance and toxicity issues. The newly synthesized drug candidates are able to demonstrate in vitro activity but are unable to reach clinical trials due to their rapid metabolism and low bioavailability. Therefore there is an imperative requisite to expand novel anticancer negotiators with tremendous activity as well as in vivo efficacy. Tetrazole is a promising pharmacophore which is metabolically more stable and acts as a bioisosteric analogue for many functional groups. Tetrazole fragment is often castoff with other pharmacophores in the expansion of novel anticancer drugs. This is the first systematic review that emphasizes on contemporary strategies used for the inclusion of tetrazole moiety, mechanistic targets along with comprehensive structural activity relationship studies to provide perspective into the rational design of high-efficiency tetrazole-based anticancer drug candidates.

Antiamoebic activity of synthetic tetrazoles against Acanthamoeba castellanii belonging to T4 genotype and effects of conjugation with silver nanoparticles.

Acanthamoeba causes diseases such as Acanthamoeba keratitis (AK) which leads to permanent blindness and granulomatous Acanthamoeba encephalitis (GAE) where there is formation of granulomas in the brain. Current treatments such as chlorhexidine, diamidines, and azoles either exhibit undesirable side effects or require immediate and prolonged treatment for the drug to be effective or prevent relapse. Previously, antifungal drugs amphotericin B, nystatin, and fluconazole-conjugated silver with nanoparticles have shown significantly increased activity against Acanthamoeba castellanii. In this study, two functionally diverse tetrazoles were synthesized, namely 5-(3-4-dimethoxyphenyl)-1H-tetrazole and 1-(3-methoxyphenyl)-5-phenoxy-1H-tetrazole, denoted by T1 and T2 respectively. These compounds were evaluated for anti-Acanthamoeba effects at different concentrations ranging from 5 to 50 µM. Furthermore, these compounds were conjugated with silver nanoparticles (AgNPs) to enhance their efficacy. Particle size analysis showed that T1-AgNPs and T2-AgNPs had an average size of 52 and 70 nm respectively. After the successful synthesis and characterization of tetrazoles and tetrazole-conjugated AgNPs, they were subjected to anti-Acanthamoeba studies. Amoebicidal assay showed that at concentration 10 µM and above, T2 showed promising antiamoebic activities between the two compounds while encystation and excystation assays reveal that both T1 and T2 have inhibited differentiation activity against Acanthamoeba castellanii. Conjugation of T1 and T2 to AgNP also increased efficacy of tetrazoles as anti-Acanthamoeba agents. This may be due to the increased bioavailability as AgNP allows better delivery of treatment compounds to A. castellanii. Human cell cytotoxicity assay revealed that tetrazoles and AgNPs are significantly less toxic towards human cells compared with chlorhexidine which is known to cause undesirable side effects. Cytopathogenicity assay also revealed that T2 conjugated with AgNPs significantly reduced cytopathogenicity of A. castellanii compared with T2 alone, suggesting that T2-conjugated AgNP is an effective and safe anti-Acanthamoeba agent. The use of a synthetic azole compound conjugated with AgNPs can be an alternative strategy for drug development against A. castellanii. However, mechanistic and in vivo studies are needed to explore further translational values.

A New Synthesis of Poly Heterocyclic Compounds Containing [1,2,4]triazolo and [1,2,3,4]tetrazolo Moieties and their DFT Study as Expected Anti-cancer Reagents.

BACKGROUND: 2-amino-3-cyanopyridines are good starting reagents that have been used in synthesis of many heterocyclic compounds such as pyridopyrimidines, [1,2,4]triazolo and [1,2,3,4] tetrazolo derivatives which have biological activities as anti-microbial and cytotoxic activities. Meanwhile [1,2,4]triazolo and [1,2,3,4]tetrazolo derivatives are well known to possess many physiological activities, such as anticancer , antifungal, muscle relaxant, hypnotic, anti-inflammatory, diuretic and antihypertensive activities. A broad class of heterocyclic compounds has been studied to demonstrate their biological activity on the structures of DNA and RNA. Several of important functions make Tankyrases acts as targets in potential drug. OBJECTIVE: The article focuses on synthesis of [1,2,4]triazolo and [1,2,3,4]tetrazolo derivatives and their theoretical calculations that suggest they are anti-cancer substances. MATERIALS AND METHODS: DFT and computational studies were performed on the structural properties of experimental molecules experimentally, and significant theoretical calculations were performed based on density functional theory (DFT) with Becke's three-parameter exchange function21-22 of correlation functional Lee Yang Parr (B3LYP) with the basis set 6-31G (d,p) using Gaussian 03 software23. Geometrical parameters of the optimized structures were calculated and also the charge on each atom (Mulliken charge). Chemcraft program24 was used to visualize the optimized structure and ChemBio3D ultra 12.0 was used to visualize the highest occupied and lowest unoccupied molecular orbitals. RESULTS: Preliminary screening in five studied ligands acts as inhibitors for different active sites along the target. The molecular docking study also revealed that the compound 6c was the most effective compounds in inhibiting Tankyrase I enzyme (2rf5), this result can help strongly in inhibition of carcinogenic cells and cancer treatment. CONCLUSION: We have described a new practical cyclocondensation synthesis for a series of [1,2,4]triazolo[4,3- c]pyrido[3,2-e] pyrimidine and pyrido[2',3':4,5] pyrimido[6,1-c][1,2,4] triazine from 2-amino-3-cyano-4.6- diarylpyridines. Also polyheterocyclic compounds containing [1,2,4]triazolo and [1,2,3,4]tetrazolo moieties were also synthesized through the reactions of 3-hydrazino-8,10-diaryl [1,2,4]triazolo[4,3-c]pyrido[3,2- e]pyrimidine with both formic acid and the formation of diazonuim salt respectively. Newly synthesized heterocycles structures were confirmed using elemental analysis, IR, 1H-NMR, 13C-NMR and mass spectral data. DFT and computational studies were carried out on five of the synthesized poly heterocyclic compounds to show their structural and geometrical parameters involved in the study. Molecular docking using Tankyrase I enzyme as a target showed how the studied heterocyclic compounds act as a ligand interacting most of active sites on Tankyrase I with a type of interactions specified for H-bonding and VDW. We investigated that the five studied ligands act as inhibitors for different active sites along the target. The molecular docking study also revealed that the compound 6c was the most effective compounds in inhibiting Tankyrase I enzyme (2rf5), this result can help strongly in inhibition of carcinogenic cells and cancer treatment.

The architecture of hydrogen and sulfur σ-hole interactions explain differences in the inhibitory potency of C-ß-d-glucopyranosyl thiazoles, imidazoles and an N-ß-d glucopyranosyl tetrazole for human liver glycogen phosphorylase and offer new insights to structure-based design.

C-Glucopyranosyl imidazoles, thiazoles, and an N-glucopyranosyl tetrazole were assessed in vitro and ex vivo for their inhibitory efficiency against isoforms of glycogen phosphorylase (GP; a validated pharmacological target for the development of anti-hyperglycaemic agents). Imidazoles proved to be more potent inhibitors than the corresponding thiazoles or the tetrazole. The most potent derivative has a 2-naphthyl substituent, a Ki value of 3.2 µM for hepatic glycogen phosphorylase, displaying also 60% inhibition of GP activity in HepG2 cells, compared to control vehicle treated cells, at 100 µM. X-Ray crystallography studies of the protein - inhibitor complexes revealed the importance of the architecture of inhibitor associated hydrogen bonds or sulfur σ-hole bond interactions to Asn284 OD1, offering new insights to structure-based design efforts. Moreover, while the 2-glucopyranosyl-tetrazole seems to bind differently from the corresponding 1,2,3-triazole compound, the two inhibitors are equipotent.

Development of (4-methoxyphenyl)-1H-tetrazol-5-amine regioisomers as a new class of selective antitubercular agents.

A series of halogenated (4-methoxyphenyl)-1H-tetrazol-5-amine regioisomers (1a-9a, 1b-9b) were synthesized from their corresponding thiourea analogues (1-9). The synthesis pathway was confirmed by an X-ray crystallographic studies of 1a, 1b and 5a. Title derivatives were tested for their in vitro antitubercular activity against standard, "wild-type" and atypical mycobacteria. The highest therapeutic potential was attributed to isomeric N-(bromophenyl)tetrazoles 8a and 9a. Their growth-inhibitory effect against multidrug-resistant Mycobacterium tuberculosis Spec. 210 was 8-16-fold stronger than that of the first-line tuberculostatics. Other new tetrazole-derived compounds were also more or equally effective towards that pathogen comparing to the established pharmaceuticals. Among non-tuberculous strains, Mycobacterium scrofulaceum was the most susceptible to the presence of the majority of tetrazole derivatives. The synergistic interaction was found between 9a and streptomycin, as well as the additivity of both 8a and 9a in pairs with isoniazid, rifampicin and ethambutol. None of the studied compounds displayed antibacterial or cytotoxic properties against normal and cancer cell lines, which indicated their highly selective antimycobacterial effects.

In vitro nephrotoxicity and anticancer potency of newly synthesized cadmium complexes.

Complexes based on heavy metals have great potential for the treatment of a wide variety of cancers but their use is often limited due to toxic side effects. Here we describe the synthesis of two new cadmium complexes using N(4)-phenyl-2-formylpyridine thiosemicarbazone (L1) and 5-aminotetrazole (L2) as organic ligands and the evaluation of their anti-cancer and nephrotoxic potential in vitro. The complexes were characterized by Single-crystal X-ray data diffraction, 1HNMR, FT-IR, LC/MS spectrometry and CHN elemental analysis. Next, cytotoxicity of these cadmium complexes was evaluated in several cancer cell lines, including MCF-7 (breast), Caco-2 (colorectal) and cisplatin-resistant A549 (lung) cancer cell lines, as well as in conditionally-immortalized renal proximal tubule epithelial cell lines for evaluating nephrotoxicity compared to cisplatin. We found that both compounds were toxic to the cancer cell lines in a cell-cycle dependent manner and induced caspase-mediated apoptosis and caspase-independent cell death. Nephrotoxicity of these compounds was compared to cisplatin, a known nephrotoxic drug, in vitro. Our results demonstrate that compound {2}, but not compound {1}, exerts increased cytotoxicity in MCF-7 and A549 cell lines, combined with reduced nephrotoxic potential compared to cisplatin. Together these data make compound {2} a likely candidate for further development in cancer treatment.

Structure-Based Screening of Tetrazolylhydrazide Inhibitors versus KDM4 Histone Demethylases.

Human histone demethylases are known to play an important role in the development of several tumor types. Consequently, they have emerged as important medical targets for the treatment of human cancer. Herein, structural studies on tetrazolylhydrazide inhibitors as a new scaffold for a certain class of histone demethylases, the JmjC proteins, are reported. A series of compounds are structurally described and their respective binding modes to the KDM4D protein, which serves as a high-resolution model to represent the KDM4 subfamily in crystallographic studies, are examined. Similar to previously reported inhibitors, the compounds described herein are competitors for the natural KDM4 cofactor, 2-oxoglutarate. The tetrazolylhydrazide scaffold fills an important gap in KDM4 inhibition and newly described, detailed interactions of inhibitor moieties pave the way to the development of compounds with high target-binding affinity and increased membrane permeability, at the same time.

Synthesis and biological evaluation of tetrazole derivatives as TNF-α, IL-6 and COX-2 inhibitors with antimicrobial activity: Computational analysis, molecular modeling study and region-specific cyclization using 2D NMR tools.

A group of tetrazole bearing compounds were synthesized and evaluated for their in vitro cyclooxygenase (COX) isozymes (COX-1/COX-2) inhibitory activity, in vitro anti-inflammatory activity through measuring levels of expression of IL-6 and TNF-α and antimicrobial activity. Cyclization of pyridine derivative 5b was confirmed using 2D NMR such as NOESY and HMBC experiments. Within the synthesized compounds, compound 7c was identified as effective and selective COX-2 inhibitors (COX-2 IC50 = 0.23 uM; COX-2 selectivity index = 16.91). Moreover 7c was the most effective derivative on TNF-α (37.6 pg/ml). While, the most active compound on IL-6 was isoxazole derivative 6 (42.8 pg/ml). Dual inhibitory activity on both IL-6 and TNF-α was exhibited by compounds 2 and 3 (IL-6 = 47.5 and 82.7 pg/ml, respectively) and (TNF-α = 31.7 and 33.8 pg/ml, sequentially). Additionally, compound 7a, showed broad spectrum antimicrobial activity against Gram positive cocci, Gram positive rods and yeast fungus (inhibition zone = 20 and 19 mm). None of the test compounds exhibited activity against Gram negative rods. Compounds 3 and 7c exhibited good antifungal activity at MIC equal to 64.5 µg/ml. While compound 6 showed antibacterial activities against Micrococcus lysodicticus and Bacillus subtilis at MIC = 32.25 and 64.5 µg/ml, respectively. Computational analysis was used to predict molecular properties and bioactivity of the target compounds. To confirm the mode of action of the synthesized compounds as anti-inflammatory agents, molecular docking was done. Appreciable binding interactions were observed for compound 7c containing COX-2 pharmacophore (SO2NH2), with binding energy -10.6652 Kcal/mol, forming two hydrogen bonding interactions with His90 and Tyr355 amino acids. It was fully fitted within COX-2 active site having the highest COX-2 selectivity index between all the test compounds (S.I. = 16.91).