Structure–activity relationship study of thiosemicarbazones on an African trypanosome: Trypanosoma brucei brucei

Tripeptides conjugated with thiosemicarbazones: new inhibitors of tyrosinase for cosmeceutical use

The development of skin-care products is recently growing. Cosmetic formulas containing active ingredients with proven efficacy, namely cosmeceuticals, are based on various compounds, including peptides. Different whitening agents featuring anti-tyrosinase activity have been applied in the cosmeceutical field. Despite their availability, their applicability is often limited due to several drawbacks including toxicity, lack of stability, and other factors. In this work, we present the inhibitory effect on diphenolase activity of thiosemicarbazone (TSC)-peptide conjugates. Tripeptides FFY, FWY, and FYY were conjugated with three TSCs bearing one or two aromatic rings via amide bond formation in a solid phase. Compounds were then examined as tyrosinase and melanogenesis inhibitors in murine melanoma B16F0 cell line, followed by the cytotoxicity assays of these cells. In silico investigations explained the differences in the activity, observed among tested compounds. Mushroom tyrosinase was inhibited by TSC1-conjugates at micromolar level, with IC₅₀ lower than this for kojic acid, a widely used reference compound. Up to now, this is the first report regarding thiosemicarbazones conjugated with tripeptides, synthesised for the purpose of tyrosinase inhibition.

Monosubstituted Acetophenone Thiosemicarbazones as Potent Inhibitors of Tyrosinase: Synthesis, Inhibitory Studies, and Molecular Docking

A set of 12 monosubstituted acetophenone thiosemicarbazone derivatives (TSCs) were synthesized and their inhibitory properties toward tyrosinase activity were tested. Moreover, their ability to inhibit melanogenesis in the B16F10 murine melanoma cell line was studied. In order to investigate the nature of interactions between the enzyme and the inhibitors, molecular docking to the active site was performed. TSCs 5, 6, 8, and 9 revealed a half maximal inhibitory concentration (IC₅₀) below 1 µM. Compound 6 turned out to be the most potent tyrosinase inhibitor. All investigated compounds showed reversible inhibition of competitive or mixed type. The para-substituted TSCs had higher affinity for the enzyme as compared to their ortho- and meta-analogues. All investigated compounds inhibited melanin production in B16F10 cells at the micromolar level. Molecular docking showed that the sulfur atom of the thiourea moiety penetrates the active site and interacts with copper ions. The above outcomes might be helpful in the design of new tyrosinase inhibitors in the food and cosmetic industries.

Thiazolidinone/thiazole based hybrids - New class of antitrypanosomal agents

Different compounds have been investigated as potent drugs for trypanosomiasis treatment, but no new drug has been marketed in the past 3 decades. 4-Thiazolidinone/thiazole as privileged structures and thiosemicarbazides cyclic analogs are well known scaffolds in novel antitrypanosomal agent design. We present here the design and synthesis of new hybrid molecules bearing thiazolidinone/thiazole cores linked by the hydrazone group with various molecular fragments. Structure optimization led to compounds with phenyl-indole or phenyl-imidazo[2,1-b][1,3,4]thiadiazole moieties showing excellent antitrypanosomal activity towards Trypanosoma brucei brucei and Trypanosoma brucei gambiense. Biological study allowed identifying compounds with the submicromolar levels of IC₅₀, good selectivity indexes and relatively low cytotoxicity upon human primary fibroblasts as well as low acute toxicity.

Microwave-assisted synthesis and biological evaluation of thiazole-substituted dibenzofurans

New thiazole-substituted dibenzofurans 7a–j were synthesized from dibenzofuran derivatives 5a–b and substituted thiosemicarbazones 6a–h under conventional and microwave irradiation conditions. The structures of all products were established on the basis of analytical and spectral data. The synthesized compounds were evaluated for their in vitro antibacterial activity against Gram-positive and Gram-negative strains. Compounds 7b, 7d and 7h are active against Bacillus subtilis (+ve), and compound 7i displays good activity against Pseudomonas aeruginosa (-ve) strain. Compounds 7a–j were also evaluated for their in vitro antimycobacterial activity, and compound 7b shows antimycobacterial activity against Mycobacterium bovis strain.

Ex vivo trypanocidal activity of 1-(2-hydroxybenzylidene)thiosemicarbazide against Trypanosoma equiperdum

Trypanosoma equiperdum is the causative agent of dourine, a venereal disease in horses and donkeys. This parasite has a widely distribution, is found in Africa, Asia, Southern and Eastern Europe, Russia, Mexico and Venezuela. The T. equiperdum is morphologically indistinguishable to other Trypanozoon species, however differs from other mammalian trypanosomes due to the fact that it is primarily a tissue parasite, generating cutaneous plaques, swelling of genitalia and neurological signs. The aim of this study was to evaluate the trypanocidal effectiveness of a set of derivatives of thiosemicarbazones on a T. equiperdum ex vivo culture. All compounds appeared to have trypanocidal activity, however one of them shown better solubility and a dose-dependent effect. The median inhibitory concentration (IC₅₀) was 1.2μM. The selected compound exhibits a greater inhibitory activity than diminazene aceturate, a common drug for animal trypanosomosis treatment.

Crystal structures of (E)-4-[1-(2-carbamo-thio-yl-hydrazinyl-idene)eth-yl]phenyl acetate and (E)-4-[1-(2-carbamo-thio-ylhydrazinyl-idene)eth-yl]phenyl benzoate

In the title compounds, C11H13N3O2S, (I), and C16H15N3O2S, (II), the thio-semicarbazone group adopts an extended conformation. The acetate ester (I) crystallizes with two independent mol-ecules in the asymmetric unit. In the benzoate ester (II), the planes of the two aryl rings are inclined to one another by 46.70 (7)°. In both compounds, there is a short intra-molecular N-H⋯N contact present, forming an S(5) ring motif. In the crystals of both compounds, mol-ecules are linked via pairs of N-H⋯S hydrogen bonds, forming dimers with R22(8) ring motifs. The dimers are linked by N-H⋯S and N-H⋯O hydrogen bonds, forming slabs parallel to (01-1). In (I), there are N-H⋯π and C-H⋯π inter-actions present within the slabs, while in (II), there are only N-H⋯π inter-actions present.

Substituted N-aminothioglycolurils containing thiosemicarbazone moiety and their cytotoxic activity in vitro

A library of hybrid molecules bearing thioglycoluril and (hetero)aromatic aldehyde thiosemicarbazone moieties was synthesized via a tandem hydrazone formation-ring contraction reaction of 5,7-dialkyl-3-thioxoperhydroimidazo[4,5-e]-1,2,4-triazin-6-ones with (hetero)aromatic aldehydes. All synthesized compounds were tested for their cytotoxic activity against rhabdomyosarcoma, A549, and MS human cancer cell lines by MTT-assay. Among the derivatives, (E)-4-benzylideneamino-1,3-dimethyl-5-thioxohexahydroimidazo[4,5-d]imidazol-2(1H)-one 1f was found to have the most marked antiproliferative activity toward the tested cell lines (1f: IC[Formula: see text] 23.7, and 6.4 [Formula: see text]M, respectively). The IC[Formula: see text] value of thioglycoluril 1f against normal human embryonic kidney cells HEK293 was 72.5 [Formula: see text]M, which appeared to be 3-11-fold higher than IC[Formula: see text] values of 1f against human cancer cells.

Synthesis of a DNA-targeting nickel (II) complex with testosterone thiosemicarbazone which exhibits selective cytotoxicity towards human prostate cancer cells (LNCaP)

Testosterone thiosemicarbazone, L and its nickel (II) complex 1 were synthesized and characterized by using FTIR, CHN, (1)H NMR, and X-ray crystallography. X-ray diffraction study confirmed the formation of L from condensation of testosterone and thiosemicarbazide. Mononuclear complex 1 is coordinated to two Schiff base ligands via two imine nitrogens and two tautomeric thiol sulfurs. The cytotoxicity of both compounds was investigated via MTT assay with cisplatin as positive reference standard. L is more potent towards androgen-dependent LNCaP (prostate) and HCT 116 (colon). On the other hand, complex 1, which is in a distorted square planar environment with L acting as a bidentate NS-donor ligand, is capable of inhibiting the growth of all the cancer cell lines tested, including PC-3 (prostate). It is noteworthy that both compounds are less toxic towards human colon cell CCD-18Co. The intrinsic DNA binding constant (Kb) of both compounds were evaluated via UV-Vis spectrophotometry. Both compounds showed Kb values which are comparable to the reported Kb value of typical classical intercalator such as ethidium bromide. The binding constant of the complex is almost double compared with ligand L. Both compounds were unable to inhibit the action topoisomerase I, which is the common target in cancer treatment (especially colon cancer). This suggest a topoisomerase I independent-cell death mechanism.

A novel series of thiosemicarbazone drugs: from synthesis to structure

A new series of thiosemicarbazones (TSCs) and their 1,3,4-thiadiazolines (TDZs) containing acetamide group have been synthesized from thiosemicarbazide compounds by the reaction of TSCs with cyclic ketones as well as aromatic aldehydes. The structures of newly synthesized 1,3,4-thiadiazole derivatives obtained by heterocyclization of the TSCs with acetic anhydride were experimentally characterized by spectral methods using IR, (1)H NMR, (13)C NMR and mass spectroscopic methods. Furthermore, the structural, thermodynamic, and electronic properties of the studied compounds were also studied theoretically by performing Density Functional Theory (DFT) to access reliable results to the experimental values. The molecular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and Mulliken atomic charges of the studied compounds have been calculated at the B3LYP method and standard 6-31+G(d,p) basis set starting from optimized geometry. The theoretical (13)C chemical shift results were also calculated using the gauge independent atomic orbital (GIAO) approach and their respective linear correlations were obtained.

Synthesis and structures of 5-nitro-salicylaldehyde thiosemicarb-azonates of copper(ii): molecular spectroscopy, ESI-mass studies, antimicrobial activity and cytotoxicity

Salicylaldehyde thiosemicarbazonates of copper(ii) have shown significant growth inhibitory activity againstS. aureus, MRSA,K. pneumonia,S. flexneri,P. aeruginosaandC. albicansand are bactericidal in nature with low cytotoxicity.

Crystal structure of (E)-4-{1-[2-(car-bamo-thio-yl)hydrazin-1-yl-idene]ethyl}phenyl 4-methyl-benzoate

The asymmetric unit of the title compound, C₁₇H₁₇N₃O₂S, consists of two independent mol­ecules, A and B, with different conformations: in mol­ecule A, the dihedral angles between the central benzene ring and the pendant tolyl and carbamo­thio­ylhydrazono groups are 71.12 (9) and 5.95 (8)°, respectively. The corresponding angles in mol­ecule B are 50.56 (12) and 26.43 (11)°, respectively. Both mol­ecules feature an intra­molecular N—H⋯N hydrogen bond, which closes an S(5) ring. In the crystal, mol­ecules are linked by N—H⋯O, N—H⋯S and C—H⋯O hydrogen bonds, generating a three-dimensional network.