Edyta Łukowska-Chojnacka

Synthesis of novel polybrominated benzimidazole derivatives-potential CK2 inhibitors with anticancer and proapoptotic activity.

The efficient method for the synthesis of novel cell permeable inhibitors of protein kinase CK2 with anticancer and proapoptotic activity has been developed. A series of polybrominated benzimiadazole derivatives substituted by various cyanoalkyl groups have been synthesized. Cyanoethyl derivatives were obtained by Michael type addition of 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi) and 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazole to acrylonitrile, whilst cyanomethyl, cyanopropyl and cyanobutyl analogs by N-alkylation of 4,5,6,7-tetrabromo-1H-benzimidazole and 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazole with appropriate cyanoalkyl halides. The inhibitory activity against protein kinase rhCK2α catalytic subunit and cytotoxicity against two human cancer cell lines: acute lymphocytic leukemia (CCRF-CEM) and breast (MCF-7) were evaluated for all newly synthesized compounds. Additionally, the proapoptotic activity toward leukemia cells and intracellular inhibition of CK2 for the most cytotoxic derivatives have been performed, demonstrating 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazole as a new selective inhibitor of rhCK2 with twenty-fold better proapoptotic activity than parental compound (TBBi).

Tetrazole activity against Candida albicans. The role of KEX2 mutations in the sensitivity to (±)-1-[5-(2-chlorophenyl)-2H-tetrazol-2-yl]propan-2-yl acetate

Series of 4-(5-aryl-2H-tetrazol-2-yl)butan-2-ol, 1-(5-aryl-2H-tetrazol-2-yl)propan-2-ol and their acetates have been screened against Candida albicans. Among the tested compounds, (±)-1-[5-(2-chlorophenyl)-2H-tetrazol-2-yl]propan-2-yl acetate (E5) proved to be the most effective inhibitor of fungal growth and was further evaluated against young (adhesion phase) and mature biofilm in vitro. The activity exhibited by the tested tetrazole derivatives against C. albicans associated with minor cytotoxicity towards Vero epithelial cells make us suggest that E5 could be a promising structure in the development of new antifungals. Serine protease Kex2 appeared essential for the resistance mechanism. Further investigations of in vivo activity, drug interactions, and E5 structure optimization are needed.

Synthesis of novel tetrazole derivatives and evaluation of their antifungal activity.

With the appearance of the antifungal resistance, novel antifungal agents need to be identified. In this context new 2,5-disubstituted tetrazole derivatives containing benzothiazole, benzoxazole or phenylsulfonyl moiety were synthesized by N-alkylation of aryltetrazole with 2-[(3-chloropropyl)sulfanyl]-1,3-benzothiazole or 2-[(3-chloropropyl)sulfanyl]-1,3-benzoxazole and Michael-type addition of aryltetrazole to phenyl vinyl sulfone. The chemical structures of the synthesized compounds were confirmed by means of 1H NMR, 13C NMR, IR and HRMS spectral data. The compounds were tested against the moulds: Fusarium sambucinum, Fusarium oxysporum, Colletotrichum coccodes, Aspergillus niger, and the yeast Candida albicans. The results showed that among the moulds only C. coccodes was significantly sensitive to all the structures examined. All the tetrazole derivatives acted at the same level against C. albicans and demonstrated a high cell growth inhibition (97-99%) at the concentrations ranging from 16 to 0.0313μg/mL. The mode of action of 2-({3-[5-(4-chlorophenyl)-2H-tetrazol-2-yl]propyl}sulfanyl)-1,3-benzoxazole (5c) and 2-({3-[5-(2-chlorophenyl)-2H-tetrazol-2-yl]propyl}sulfanyl)-1,3-benzoxazole (5d) was established by verifying fungal growth in the presence of osmotic protector-sorbitol. The effect of compound 5c or 5d combined with Fluconazole was determined using the checkerboard method. The calculated fractional inhibitory concentration index (FIC) indicated antagonism (FIC >1). Additionally, survival experiments with lepidopteran Galleria mellonella treated with compounds 5c and 5d were performed and demonstrated the lack of toxicity of these compounds.

Lipase‐Catalyzed Kinetic Resolution of Novel Antifungal N‐Substituted Benzimidazole Derivatives

A series of new N-substituted benzimidazole derivatives was synthesized and their antifungal activity against Candida albicans was evaluated. The chemical step included synthesis of appropriate ketones containing benzimidazole ring, reduction of ketones to the racemic alcohols, and acetylation of alcohols to the esters. All benzimidazole derivatives were obtained with satisfactory yields and in relatively short times. All synthesized compounds exhibit significant antifungal activity against Candida albicans 900028 ATCC (% cell inhibition at 0.25 μg concentration > 98%). Additionally, racemic mixtures of alcohols were separated by lipase-catalyzed kinetic resolution. In the enzymatic step a transesterification reaction was applied and the influence of a lipase type and solvent on the enantioselectivity of the reaction was studied. The most selective enzymes were Novozyme SP 435 and lipase Amano AK from Pseudomonas fluorescens (E > 100).

Enzymatic Hydrolysis of Esters Containing a Tetrazole Ring

The lipase-catalyzed enantioselective hydrolysis of acetates containing tetrazole moiety was studied. Among all tested lipases, Novozyme SP 435 allowed to obtain optically active 4-(5-aryl-2H-tetrazol-2yl)butan-2-ol and 1-(5-aryl-2H-tetrazol-2yl)-propan-2-ol and their acetates with the highest optical purities (ee = 95%-99%) and excellent enantioselectivity (E>100). Some of the synthesized tetrazole derivatives were screened for their antifungal activity. Racemic mixtures of 4-[5-(4-chlorophenyl)-2H-tetrazol-2-yl)butan-2-ol as well as pure enantiomers of this compound showed promising antifungal activity against F. sambucinum, F. oxysporum, C. coccodes, and A. niger.

Synthesis of polybrominated benzimidazole and benzotriazole derivatives containing a tetrazole ring and their cytotoxic activity

A series of new benzimidazole and benzotriazole derivatives containing a tetrazole moiety was synthesized by N-alkylation of 5-aryltetrazole with 4,5,6,7-tetrabromo-1-(3-chloropropyl)-1H-benzimidazole and 4,5,6,7-tetrabromo-2-(3-chloropropyl)-2H-benzotriazole. The reaction was regioselective and mostly 2,5-disubstituted tetrazole derivatives were obtained. The effect of all synthesized compounds on human recombinant casein kinase 2alpha subunit (rhCK2α) and cytotoxicity against human T-cell lymphoblast (CCRF-CEM) and breast adenocarcinoma (MCF-7) cell lines were evaluated. The results have shown that many of the synthesized compounds exhibit significant cytotoxicity at micromolar concentration.Graphical abstract

Biological properties and structural study of new aminoalkyl derivatives of benzimidazole and benzotriazole, dual inhibitors of CK2 and PIM1 kinases.

The new aminoalkyl-substituted derivatives of known CK2 inhibitors 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi) and 4,5,6,7-tetrabromo-1H-benzotriazole (TBBt) were synthesized, and their influence on the activity of recombinant human CK2 α, CK2 holoenzyme and PIM1 kinases was evaluated. All derivatives inhibited the activity of studied kinases and the most efficient were aminopropyl-derivatives 8b and 14b. These compounds also exerted inhibition of cancer cell lines - CCRF-CEM (acute lymphoblastoid leukemia), MCF-7 (human breast cancer), and PC-3 (prostate cancer) proliferation and their EC50 is comparable with the value for clinically studied CK2 inhibitor CX-4945. Preliminary structure activity relationship analysis indicated that the spacer length affected antitumor potency, and two to three methylene units were more favorable. The complex of CK2 α1-335/8b was crystallized, both under high-salt conditions and under low-salt conditions giving crystals which diffracted X-rays to about 2.4 Å resolution, what enabled the determination of the corresponding 3D-structures.

Effect of Simultaneous Inhibition of Protein Kinase CK2 and Thymidylate Synthase in Leukemia and Breast Cancer Cells

Background/Aim: Protein kinase CK2 was recently identified as a promising therapeutic target for combination therapy. Our study aims to investigate the anticancer effect of a simultaneous inhibition of thymidylate synthase (TS) and CK2 in MCF-7 breast cancer and CCRF-CEM leukemia cells. Materials and Methods: The type of interaction between CK2 inhibitors: CX-4945, 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi), or recently obtained 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazol-1-yl)acetonitrile (2b) and TS-directed anticancer drug, 5-fluorouracil (5-FU) was determined using the MTT assay and a combination index method. The influence of the combined treatment on apoptosis in leukemia cells, as well as on cell-cycle progression and the levels of TS, CK2α and P-Ser529-p65 were determined in both cell lines, using flow cytometry and western blot analysis, respectively. Results: The best synergistic effect was observed in CCRF-CEM cell line with the combination of 5-FU and 2b which correlated with a decrease in the endocellular CK2 activity and enhancement of the pro-apoptotic effect. Conclusion: The obtained results demonstrate the ability of CK2 inhibitors to enhance the efficacy of 5-FU in anticancer treatment, indicating a different molecular mechanism of the studied CK2 inhibitors interaction with 5-FU.

Simple Synthesis of β-Acetoxy Thiocyanates from Oxiranes

Abstract A convenient and simple method for the preparation of previously unknown β-acetoxy thiocyanates by regioselective ring opening of the corresponding oxiranes with thiocyanate anion followed by acetylation is described. The shorter reaction times, better yields of the products, and easy workup are the advantages of this methodology.