Synthesis, Docking, Computational Studies, and Antimicrobial Evaluations of New Dipeptide Derivatives Based on Nicotinoylglycylglycine Hydrazide.

Within a series of dipeptide derivatives (5-11), compound 4 was refluxed with d-glucose, d-xylose, acetylacetone, diethylmalonate, carbon disulfide, ethyl cyanoacetate, and ethyl acetoacetate which yielded 5-11, respectively. The candidates 5-11 were characterized and their biological activities were evaluated where they showed different anti-microbial inhibitory activities based on the type of pathogenic microorganisms. Moreover, to understand modes of binding, molecular docking was used of Nicotinoylglycine derivatives with the active site of the penicillin-binding protein 3 (PBP3) and sterol 14-alpha demethylase's (CYP51), and the results, which were achieved via covalent and non-covalent docking, were harmonized with the biological activity results. Therefore, it was extrapolated that compounds 4, 7, 8, 9, and 10 had good potential to inhibit sterol 14-alpha demethylase and penicillin-binding protein 3; consequently, these compounds are possibly suitable for the development of a novel antibacterial and antifungal therapeutic drug. In addition, in silico properties of absorption, distribution, metabolism, and excretion (ADME) indicated drug likeness with low to very low oral absorption in most compounds, and undefined blood-brain barrier permeability in all compounds. Furthermore, toxicity (TOPKAT) prediction showed probability values for all carcinogenicity models were medium to pretty low for all compounds.

Discovery of Novel Fungal Lanosterol 14α-Demethylase (CYP51)/Histone Deacetylase Dual Inhibitors to Treat Azole-Resistant Candidiasis.

Invasive fungal infections (particularly candidiasis) are emerging as severe infectious diseases worldwide. Because of serious antifungal drug resistance, therapeutic efficacy of the current treatment for candidiasis is limited and associated with high mortality. However, it is highly challenging to develop novel strategies and effective therapeutic agents to combat drug resistance. Herein, the first generation of lanosterol 14α-demethylase (CYP51)-histone deacetylase (HDAC) dual inhibitors was designed, which exhibited potent antifungal activity against azole-resistant clinical isolates. In particular, compounds 12h and 15j were highly active both in vitro and in vivo to treat azole-resistant candidiasis. Antifungal mechanism studies revealed that they acted by blocking ergosterol biosynthesis and HDAC catalytic activity in fungus, suppressing the function of efflux pump, yeast-to-hypha morphological transition, and biofilm formation. Therefore, CYP51-HDAC dual inhibitors represent a promising strategy to develop novel antifungal agents against azole-resistant candidiasis.

Design, synthesis and in silico study of pyridine based 1,3,4-oxadiazole embedded hydrazinecarbothioamide derivatives as potent anti-tubercular agent.

Development of novel, safe and effective drug candidates combating the emerging drug resistance has remained a major focus in the mainstream of anti-tuberculosis research. Here, we inspired to design and synthesize series of new pyridin-4-yl-1,3,4-oxadiazol-2-yl-thio-ethylidene-hydrazinecarbothioamide derivatives as potential anti-tubercular agents. The anti-tubercular bioactive assay demonstrated that the synthesized compounds exhibit potent anti-tubercular activity (MIC = 3.9-7.81 µg/mL) in comparison with reference drugs Rifampicin and Isoniazid.We employed pharmacophore probing approach for the identification of CYP51 as a possible drug target for the synthesized compounds. To understand the preferable binding mode, the synthesized molecules were docked onto the active site of Sterol 14 α-demethylases (CYP51) target. From the binding free energy of the docking results it was revealed that the compounds were effective CYP51 inhibitors and acts as antitubercular agent.

Promising antileishmanial activity of novel imidazole antifungal drug luliconazole against Leishmania major: In vitro and in silico studies.

OBJECTIVES: Pentavalent antimonials have been used for the treatment of leishmaniasis for over 70 years, however they are limited by their toxicity. Unfortunately, the efficacy of first-line drugs for the treatment of leishmaniasis has decreased and resistance is noticeable. Luliconazole is a new azole with unique effects on fungi that has not yet been tested on Leishmania parasites. METHODS: In this study, the cytotoxicity and antileishmanial activity of luliconazole were evaluated in vitro against promastigotes and intracellular amastigotes of Leishmania major. The docking simulation with the target enzyme, sterol 14α-demethylase (CYP51) was performed using AutoDock 4.2 program. RESULTS: The IC50 (concentration of test compound required for 50% inhibition) against promastigotes revealed that luliconazole (IC50=0.19µM) has greater potency than ketoconazole (KET), meglumine antimoniate (MA) and amphotericin B (AmB) (IC50 values of 135, 538 and 2.52µM, respectively). Against the amastigote stage, luliconazole at a concentration of 0.07µM decreased the mean infection rate and the mean number of amastigotes per macrophage more effectively than MA (P<0.004) and KET (P<0.043), but there was no difference compared with AmB (P>0.05). A docking study of luliconazole with the cytochrome P450 enzyme sterol 14α-demethylase (CYP51) revealed that this azole drug can properly interact with the target enzyme in Leishmania mainly via coordination with heme and multiple hydrophobic interactions. CONCLUSION: These results show the potent activity of luliconazole at extremely low concentrations against L. major. It may therefore be considered as a new candidate for treatment of leishmaniasis in the near future.

Molecular Modeling and Structural Stability of Wild-Type and Mutant CYP51 from Leishmania major: In Vitro and In Silico Analysis of a Laboratory Strain.

Cutaneous leishmaniasis is a neglected tropical disease and a major public health in the most countries. Leishmania major is the most common cause of cutaneous leishmaniasis. In the Leishmania parasites, sterol 14α-demethylase (CYP51), which is involved in the biosynthesis of sterols, has been identified as an attractive target for development of new therapeutic agents. In this study, the sequence and structure of CYP51 in a laboratory strain (MRHO/IR/75/ER) of L. major were determined and compared to the wild-type strain. The results showed 19 mutations including seven non-synonymous and 12 synonymous ones in the CYP51 sequence of strain MRHO/IR/75/ER. Importantly, an arginine to lysine substitution at position of 474 resulted in destabilization of CYP51 (ΔΔG = 1.17 kcal/mol) in the laboratory strain; however, when the overall effects of all substitutions were evaluated by 100 ns molecular dynamics simulation, the final structure did not show any significant changes (p-value < 0.05) in stability parameter of the strain MRHO/IR/75/ER compared to the wild-type protein. The energy level for the CYP51 of wild-type and MRHO/IR/75/ER strain were -40,027.1 and -39,706.48 Kcal/mol respectively. The overall Root-mean-square deviation (RMSD) deviation between two proteins was less than 1 Å throughout the simulation and Root-mean-square fluctuation (RMSF) plot also showed no substantial differences between amino acids fluctuation of the both protein. The results also showed that, these mutations were located on the protein periphery that neither interferes with protein folding nor with substrate/inhibitor binding. Therefore, L. major strain MRHO/IR/75/ER is suggested as a suitable laboratory model for studying biological role of CYP51 and inhibitory effects of sterol 14α-demethylase inhibitors.

Synthesis and fungicidal activity of novel imidazole-based ketene dithioacetals.

Novel imidazole-based ketene dithioacetals show impressive in planta activity against the economically important plant pathogens Alternaria solani, Botryotinia fuckeliana, Erysiphe necator and Zymoseptoria tritici. Especially derivatives of the topical antifungal lanoconazole, which bear an alkynyloxy or a heteroaryl group in the para-position of the phenyl ring, exhibit excellent control of the mentioned phytopathogens. These compounds inhibit 14α -demethylase in the sterol biosynthesis pathway of the fungi. Synthesis routes starting from either benzaldehydes or acetophenones as well as structure-activity relationships are discussed in detail.

Synthesis, Molecular Docking, and Antimycotic Evaluation of Some 3-Acyl Imidazo[1,2-a]pyrimidines.

A series of 3-benzoyl imidazo[1,2-a]pyrimidines, obtained from N-heteroarylformamidines in good yields, was tested in silico and in vitro for binding and inhibition of seven Candida species (Candida albicans (ATCC 10231), Candida dubliniensis (CD36), Candida glabrata (CBS138), Candida guilliermondii (ATCC 6260), Candida kefyr, Candida krusei (ATCC 6358) and Candida tropicalis (MYA-3404)). To predict binding mode and energy, each compound was docked in the active site of the lanosterol 14α-demethylase enzyme (CYP51), essential for fungal growth of Candida species. Antimycotic activity was evaluated as the 50% minimum inhibitory concentration (MIC50) for the test compounds and two reference drugs, ketoconazole and fluconazole. All test compounds had a better binding energy (range: -6.11 to -9.43 kcal/mol) than that found for the reference drugs (range: 48.93 to -6.16 kcal/mol). In general, the test compounds showed greater inhibitory activity of yeast growth than the reference drugs. Compounds 4j and 4f were the most active, indicating an important role in biological activity for the benzene ring with electron-withdrawing substituents. These compounds show the best MIC50 against C. guilliermondii and C. glabrata, respectively. The current findings suggest that the 3-benzoyl imidazo[1,2-a]pyrimidine derivatives, herein synthesized by an accessible methodology, are potential antifungal drugs.

Comparison and analysis of the structures and binding modes of antifungal SE and CYP51 inhibitors.

With the abuse of clinical broad-spectrum antimicrobial agents, immunosuppressive agents, chemotherapy drugs, the emergence of pathogenic fungi resistance is more and more frequent. However, there is still no effective treatment for the fungal resistance. Squalenee epoxidase (SE) and 14 α-demethylase (CYP51) are important antifungal drug targets. In order to achieve a deeper insight into the structural characteristics and the action modes of SE and CYP51inhibitors, the homology model of SE (Candida albicans) was constructed using monooxygenase of Pseudomonas aeruginosa as template, and the reliability of model was confirmed by Ramachandran plots and Verify 3D. Subsequently, the molecular superimposition and molecular docking were performed, and the pharmacophore model based on the CYP51 receptor structure was constructed. The results indicate that SE and CYP51 inhibitors have common structural feature with two parts of essential fragments, which are mainly composed of aromatic groups. In addition, the fragment structures of inhibitors are combined in the similar hydrophobic pockets through the hydrophobic forces. The present study provides a deeper perspective to understand the characteristics and docking modes of SE and CYP51 inhibitors. It can be used to guide the optimization and design of SE and CYP51 inhibitors. In addition, it also provides the oretical support for the development of dual target antifungal inhibitors (SE and CYP51), which can help us solve the problem of fungi resistance.

Evaluation of the combination mode of azoles antifungal inhibitors with CACYP51 and the influence of Site-directed mutation.

14α-demethylase (CYP51) is an essential metabolic enzyme for fungal survival and has been considered as an interesting target for the development of new antifungal inhibitors. Azoles antifungal inhibitors in the treatment of fungal diseases are good candidates via the interaction with the target enzyme CYP51 of fungus. In the study, we constructed the homology model for Candida albicans CYP51 (CACYP51) and analyzed the active site. In order to better understand the structural characteristics of azoles inhibitors and combination mode, the common feature pharmacophore model and the molecular docking were performed. The results suggest that the azoles inhibitors consist of three chemical features: the aromatic groups, phenyl groups and the azoles groups. The aromatic groups of inhibitors occupy the upper of active pocket, the phenyl groups and azoles groups occupy the bottom of active pocket. Further validation studies found these amino acid residues Tyr118, His310 and Ser378 play an important role in the substrate binding, and these amino acid residues with site-directed mutation will weaken the combining ability of the inhibitors.