Multi-step synthesis, spectroscopic studies of biological active steroidal thiosemicarbazones and their palladium (II) complex as macromolecules

Transition Metal Complexes of Thiosemicarbazides, Thiocarbohydrazides, and Their Corresponding Carbazones with Cu(I), Cu(II), Co(II), Ni(II), Pd(II), and Ag(I)-A Review

This review focuses on some interesting and recent applications of transition metals towards the complexation of thiosemicarbazides, thiocarbohydrazides, and their corresponding carbazones. We started the review with a description of the chosen five metals, including Cu[Cu(I), Cu(II], Co(II), Ni(II), Pd(II), and Ag(I) and their electronic configurations. The stability of the assigned complexes was also discussed. We shed light on different routes describing the synthesis of these ligands. We also reported on different examples of the synthesis of Cu(I), Cu(II), Co(II), Ni(II), Ag(I), and Pd(II) of thiosemicarbazide and thiocarbohydrazide complexes (until 2022). This review also deals with a summary of the fruitful use of metal complexes of thiosemicarbazones and thiocarbazones ligands in the field of catalysis. Finally, this recent review focuses on the applications of these complexes related to their biological importance.

An efficient turn-on fluorescence chemosensor system for Zn(II) ions detection and imaging in mitochondria

Mitochondria-targetable fluorescent chemosensors, Rhodamine-B and rhodamine 6G bearing syringaldehyde based receptors were designed and synthesized for efficient chemosensing of Zinc(II) ions. The probes showed the very selective naked eye color change to pink from colorless upon addition of Zinc(II) ions, further these probes showing turn-on fluorescence enhancement with Zn(II) ions by opening of rhodamine spirolactam. The probes are very sensitive towards Zn(II) ions among other ions. These probes RBS and R6S will be applicable to detect zinc ions upto the low level concentration 0.18 and 0.19 nano molar respectively. The affinity of these sensors RBS and R6S for Zinc (II) ions was found to be in the range of 1.12 × 10⁴ M^-1 and 7.28 × 10⁴ M^-1 respectively. ¹H-nmr titrations of the probes with Zn(II) ions clearly indicating the spiroring opening of the spirolactam. DFT calculations supporting that the perceived photophysical changes of the probes on appendage of the zinc ions. Probes RBS and R6S are useable for selective staining mitochondria. Both of the probes are applicable to reveal labile Zn(II) in live Hela and MCF-7 cells via fluorescence imaging. RBS and R6S are also finding application on quantification of Zinc(II) ions inside mitochondria via fluorescence imaging.

Anticancer, Antibacterial, Antioxidant, and DNA-Binding Study of Metal-Phenalenyl Complexes

Phenalenyl (PLY)-based metal complexes are a new addition to the metal complex family. Various applications of metal-based phenalenyl complexes (metal-PLY) have been reported, such as catalyst, quantum spin simulators, spin electronic devices, and molecular conductors, but the biological significance of metal-PLY (metal = Co(II), Mn(III), Ni(II), Fe(III), and Al(III)) systems has yet to be explored. In this study, the anticancer properties of such complexes were investigated in ovarian cancer cells (SKOV3 and HEY A8), and the cytotoxicity was comparable to that of other platinum-based drugs. Antibacterial activity of the metal-PLY complexes against both gram-negative (E. coli) and gram-positive (S. aureus) bacteria was studied using a disk diffusion test and minimum inhibitory concentration (MIC) methods. All five metal-PLY complexes showed significant antibacterial activity against both bacterial strains. The antioxidant properties of metal-PLY complexes were evaluated following the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging method and were acceptable. The DNA-binding properties of these metal-PLY complexes were investigated using absorption spectroscopy, fluorescence spectroscopy, viscosity measurements, and thermal denaturation methods. Experimental evidence revealed that the complexes bind to DNA through intercalation, and the molecular docking study supported this conclusion.

Synthesis, “turn-on” fluorescence signals towards Zn2+ and Hg2+ and monoamine oxidase A inhibitory activity using a molecular docking approach of morpholine analogue Schiff base linked organosilanes

A new set of morpholine analogue Schiff base linked organosilanes (5a–5c) was prepared.

Design and synthesis of diosgenin derivatives as apoptosis inducers through mitochondria-related pathways

Diosgenin (DSG) has attracted attention recently as a potential anticancer therapeutic agent due to its profound antitumor activity. To better utilize DSG as an antitumor compound, two series of DSG-amino acid ester derivatives (3a-3g and 7a-7g) were designed and synthesized, and their cytotoxic activities against six human cancer cell lines (K562, T24, MNK45, HepG2, A549, and MCF-7) were evaluated. The results obtained showed that a majority of derivatives exhibited cytotoxic activities against these six human tumor cells. Structure-activity relationship analysis revealed that the introduction of l-tryptophan to the C-3 position of DSG and the C-26 position of derivative 5 was the preferred option for these compounds to display significant cytotoxic activities. Among them, compound 7g exhibited significant cytotoxicity against the K562 cell line (IC₅₀ = 4.41 μM) and was 6.8-fold more potent than diosgenin (IC₅₀ = 30.04 μM). Further cellular mechanism studies in K562 cells elucidated that compound 7g triggered mitochondrial-related apoptosis by increasing the generation of intracellular reactive oxygen species (ROS) and decreasing mitochondrial membrane potential (MMP), which was associated with upregulation of the gene and protein expression levels of Bax, downregulation of the gene and protein expression levels of Bcl-2 and activation of the caspase cascade. The above results suggested that compound 7g might be considered a promising scaffold for further modification of more potent anticancer agents.

Synthesis, Spectroscopic Characterization, Structural Studies, and In Vitro Antitumor Activities of Pyridine-3-carbaldehyde Thiosemicarbazone Derivatives

Eight new thiosemicarbazone derivatives, 6-(1-trifluoroethoxy)pyridine-3-carbaldehyde thiosemicarbazone (1), 6-(4′-fluorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (2), 5-chloro-pyridine-3-carbaldehyde thiosemicarbazone (3), 2-chloro-5-bromo-pyridine-3-carbaldehyde thiosemicarbazone (4), 6-(3′,4′-dimethoxyphenyl)pyridine-3-carbaldehyde thiosemicarbazone (5), 2-chloro-5-fluor-pyridine-3-carbaldehyde thiosemicarbazone, (6), 5-iodo-pyridine-3-carbaldehyde thiosemicarbazone (7), and 6-(3′,5′-dichlorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (8) were synthesized, from the reaction of the corresponding pyridine-3-carbaldehyde with thiosemicarbazide. The synthesized compounds were characterized by ESI-Mass, UV-Vis, IR, and NMR (1H, 13C, 19F) spectroscopic techniques. Molar mass values and spectroscopic data are consistent with the proposed structural formulas. The molecular structure of 7 has been also confirmed by single crystal X-ray diffraction. In the solid state 7 exists in the E conformation about the N2-N3 bond; 7 also presents the E conformation in solution, as evidenced by 1H NMR spectroscopy. The in vitro antitumor activity of the synthesized compounds was studied on six human tumor cell lines: H460 (lung large cell carcinoma), HuTu80 (duodenum adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), M-14 (amelanotic melanoma), and HT-29 (colon adenocarcinoma). Furthermore, toxicity studies in 3T3 normal cells were carried out for the prepared compounds. The results were expressed as IC50 and the selectivity index (SI) was calculated. Biological studies revealed that 1 (IC50 = 3.36 to 21.35 μM) displayed the highest antiproliferative activity, as compared to the other tested thiosemicarbazones (IC50 = 40.00 to >582.26 μM) against different types of human tumor cell lines. 1 was found to be about twice as cytotoxic (SI = 1.82) than 5-fluorouracile (5-FU) against the M14 cell line, indicating its efficiency in inhibiting the cell growth even at low concentrations. A slightly less efficient activity was shown by 1 towards the HuTu80 and MCF7 tumor cell lines, as compared to that of 5-FU. Therefore, 1 can be considered as a promising candidate to be used as a pharmacological agent, since it presents significant activity and was found to be more innocuous than the 5-FU anticancer drug against the 3T3 mouse embryo fibroblast cells.

Novel Steroidal 5α,8α-Endoperoxide Derivatives with Semicarbazone/Thiosemicarbazone Side-chain as Apoptotic Inducers through an Intrinsic Apoptosis Pathway: Design, Synthesis and Biological Studies

A series of novel steroidal 5α,8α-endoperoxide derivatives bearing semicarbazone (7a–g) or thiosemicarbazone (7h–k) side chain were designed, synthesized and evaluated for their cytotoxicities in four human cancer cell lines (HepG2, HCT-116, MCF-7, and A549) using the MTT assay in vitro. The results showed that compound 7j exhibited significant cytotoxic activity against HepG2 cells (IC₅₀ = 3.52 μM), being more potent than ergosterol peroxide. Further cellular mechanism studies in HepG2 cells indicated that compound 7j triggered the mitochondrial-mediated apoptosis by decreasing mitochondrial membrane potential (MMP), which was associated with up-regulation of Bax, down-regulation of Bcl-2, activation levels of the caspase cascade, and formation of reactive oxygen species (ROS). The above findings indicated that compound 7j may be used as a promising skeleton for antitumor agents with improved efficacy.

Engineering of 3-ketosteroid-∆1-dehydrogenase based site-directed saturation mutagenesis for efficient biotransformation of steroidal substrates

Background

Biosynthesis of steroidal drugs is of great benefit in pharmaceutical manufacturing as the process involves efficient enzymatic catalysis at ambient temperature and atmospheric pressure compared to chemical synthesis. 3-ketosteroid-∆¹-dehydrogenase from Arthrobacter simplex (KsdD3) catalyzes 1,2-desaturation of steroidal substrates with FAD as a cofactor.

Results

Recombinant KsdD3 exhibited organic solvent tolerance. W117, F296, W299, et al., which were located in substrate-binding cavity, were predicted to form hydrophobic interaction with the substrate. Structure-based site-directed saturation mutagenesis of KsdD3 was performed with W299 mutants, which resulted in improved catalytic activities toward various steroidal substrates. W299A showed the highest increase in catalytic efficiency (k_cat/K_m) compared with the wild-type enzyme. Homology modelling revealed that the mutants enlarged the active site cavity and relieved the steric interference facilitating recognition of C17 hydroxyl/carbonyl steroidal substrates. Steered molecular dynamics simulations revealed that W299A/G decreased the potential energy barrier of association of substrates and dissociation of the corresponding products. The biotransformation of AD with enzymatic catalysis and resting cells harbouring KsdD3 WT/mutants revealed that W299A catalyzed the maximum ADD yields of 71 and 95% by enzymatic catalysis and resting cell conversion respectively, compared with the wild type (38 and 75%, respectively).

Conclusions

The successful rational design of functional KsdD3 greatly advanced our understanding of KsdD family enzymes. Structure-based site-directed saturation mutagenesis and biochemical data were used to design KsdD3 mutants with a higher catalytic activity and broader selectivity.

Electronic supplementary material

The online version of this article (10.1186/s12934-018-0981-0) contains supplementary material, which is available to authorized users.

3-Methyl-1-{(E)-[1-(4-methyl-pyridin-2-yl)ethyl-idene]amino}-thio-urea: crystal structure and Hirshfeld surface analysis

The title disubstituted thio-urea derivative, C10H14N4S, features an almost planar imine (E configuration, C3N) core flanked by thio-urea (CN2S) and methyl-pyridyl (C5N) residues (each plane has a r.m.s. deviation of the respective fitted atoms of 0.0066 Å). The dihedral angles between the core and the thio-urea and pyridyl residues are 20.25 (8) and 7.60 (9)°, respectively, indicating twists in the mol-ecule; the dihedral angle between the outer planes is 13.62 (7)°. There is an anti-disposition of the amine-N-H atoms which allows for the formation of an intra-molecular amine-N-H⋯N(imine) hydrogen bond that closes an S(5) loop. In the crystal, amine-N-H⋯N(pyrid-yl) hydrogen bonds lead to zigzag (glide symmetry) supra-molecular chains along the c-axis direction. These are connected into a supra-molecular layer propagating in the bc plane by thio-amide-N-H⋯S(thione) hydrogen bonds via eight-membered thio-amide {⋯HNCS}2 synthons.