Evolution of 1, 3, 5-trisubstituted bipyrazole scaffold based platinum(II) complexes as a biological active agent

Abstract

Square planar mononuclear platinum(II) complexes having general formula [Pt(Lⁿ)Cl₂], (where, Lⁿ?=?L^1–4) were synthesized with neutral bidentate heterocyclic 1,3,5-trisubstituted bipyrazole based ligands. The synthesized compounds were characterized by physicochemical method such as TGA, molar conductance, micro-elemental analysis and magnetic moment, and spectroscopic method such as, FT-IR, UV–vis, ¹H NMR, ¹³C NMR and mass spectrometry. Biological applications of the compounds were carried out using in vitro brine shrimp lethality bioassay, in vitro antimicrobial study against five different pathogens, and cellular level cytotoxicity against Schizosaccharomyces pombe (S. Pombe) cells. Pt(II) complexes were tested for DNA interaction activities using electronic absorption titration, viscosity measurements study, fluorescence quenching technique and molecular docking assay. Binding constants (K_b) of ligands and complexes were observed in the range of 0.23–1.07?×?10⁵?M^?1 and 0.51–3.13?×?10⁵?M^?1, respectively. Pt(II) complexes (I–IV) display an excellent binding tendency to biomolecule (DNA) and possess comparatively high binding constant (K_b) values than the ligands. The DNA binding study indicate partial intercalative mode of binding in complex-DNA. The gel electrophoresis activity was carried out to examine DNA nuclease property of pUC19 plasmid DNA.     

Identification and characterization of the mitochondrial membrane sorting signals in phosphatidylserine decarboxylase 1 from Saccharomyces cerevisiae

Phosphatidylserine decarboxylase 1 (Psd1p) catalyzes the formation of the majority of phosphatidylethanolamine (PE) in the yeast Saccharomyces cerevisiae. Psd1p is localized to mitochondria, anchored to the inner mitochondrial membrane (IMM) through membrane spanning domains and oriented towards the mitochondrial intermembrane space. We found that Psd1p harbors at least two inner membrane-associated domains, which we named IM1 and IM2. IM1 is important for proper orientation of Psd1p within the IMM (Horvath et al., J. Biol. Chem. 287 (2012) 36744–55), whereas it remained unclear whether IM2 is important for membrane-association of Psd1p. To discover the role of IM2 in Psd1p import, processing and assembly into the mitochondria, we constructed Psd1p variants with deletions in IM2. Removal of the complete IM2 led to an altered topology of the protein with the soluble domain exposed to the matrix and to decreased enzyme activity. Psd1p variants lacking portions of the N-terminal moiety of IM2 were inserted into IMM with an altered topology. Psd1p variants with deletions of C-terminal portions of IM2 accumulated at the outer mitochondrial membrane and lost their enzyme activity. In conclusion we showed that IM2 is essential for full enzymatic activity, maturation and correct integration of yeast Psd1p into the inner mitochondrial membrane.     

Overproduction of L-cysteine and L-cystine by expression of genes for feedback inhibition-insensitive serine acetyltransferase from Arabidopsis thaliana in Escherichia coli

Two cDNAs encoding feedback inhibition-insensitive serine acetyltransferases of Arabidopsis thaliana were expressed in the chromosomal serine acetyltransferase-deficient and L-cysteine non-utilizing Escherichia coli strain JM39-8. The transformants produced 1600 to 1700 mg l(-1) of L-cysteine and L-cystine from glucose. The amount of these amino acids produced per cell was 30 to 60% higher than that of an E. coli strain carrying mutant serine acetyltransferase less sensitive to feedback inhibition.     

Formation of Thiazolidine-4-Carboxylic Acid Represents a Main Metabolic Pathway of 5-Hydroxytryptamine in Rat Brain

Incubation of 5-hydroxytryptamine (5-HT) with rat brain homogenate resulted in the formation of (4R)-2-[3'-(5'-hydroxyindolyl)-methyl]-1,3-thiazolidine-4-carboxyl ic acid (5'-HITCA) as the major metabolite. The substance represents the condensation product of 5-hydroxyindole-3-acetaldehyde with L-cysteine. The chemical structure was confirmed by chromatographic and chemical methods as well as by fast atom bombardment mass spectrometry. Incubation of 5-HT in the presence of L-cysteine yielded the thiazolidine as the main metabolite up to 4 h. Under these conditions, the concentration of 5-hydroxyindole-3-acetic acid (5-HIAA) amounted to about 20% and 57% of 5'-HITCA (0.5 h and 4 h, respectively). In contrast to these findings, indole-3-acetic acid (IAA) was identified as the major metabolite when tryptamine was incubated under similar conditions. (4R)-2-(3'-Indolylmethyl)-1,3-thiazolidine-4-carboxylic acid (ITCA) was found to be the main conversion product of tryptamine only during the first 30 min. To investigate the fate of the thiazolidines, radiolabelled and unlabelled ITCA was incubated with rat brain homogenate. The compound was degraded enzymatically and rapidly. Subcellular fractionation revealed that the enzyme activity was present mainly in the cytosolic fraction whereas the preparation of mitochondria showed less activity. The responsible enzyme is presumably a carbon-sulfur lyase (EC 4.4.1.-). The major metabolite was isolated by HPLC and identified by mass spectrometry as well as by comparison with reference compounds to be IAA.(ABSTRACT TRUNCATED AT 250 WORDS)     

微生物酶法合成L-半胱氨酸和L-胱氨酸

从土壤中分离到一株假单胞菌Pseudomonas sp.TS1138菌株,其胞内含有DL-2-氨基-Δ²-噻唑啉-4-羧酸(DL-2-Amino-Δ²-Thiazoling-4-Carboxylic Acid,缩写为DL-ATC)水解酶,以培养16h的细胞为酶源,可转化DL-ATC合成L-半胱氨酸。该菌株生长及产酶的最佳碳、氮源为葡萄糖和尿素,DL-ATC对酶的产生具有诱导作用。酶促反应后的产物经薄层层析、旋光度法和高效液相色谱鉴定为L-半胱氨酸。     

Polyamines and thiols in the cytoprotective effect of L-cysteine and L-methionine on carbon tetrachloride-induced hepatotoxicity

Summary. The relationship between cellular glutathione (GSH), protein-SH levels, and lactate dehydrogenase (LDH), with respect to the effect of polyamines on the cytoprotective ability of L-cysteine and L-methionine, the most important components in the sulfur amino acid metabolic pathway, in carbon tetrachloride (CCl₄)-induced toxicity in isolated rat hepatocytes was studied. CCl₄ induced a LDH release and decreased cellular thiols and polyamines levels but treatment with L-cysteine and L-methionine reversed these decreases. Treating with methylglyoxal bis-(guanylhydrazone), MGBG, an irreversible inhibitor of S-adenosylmethionine decarboxylase, which is a key enzyme in spermidine and spermine biosynthesis, and therefore used to deplete cellular polyamines, prevented the protective effect of L-cysteine and L-methionine, but the addition of exogenous polyamines inhibited the influence of MGBG. These results suggest that the cytoprotective effect of L-cysteine and L-methionine in CCl₄-induced toxicity were via maintenance of cellular polyamines, GSH and protein-SH concentrations and prevention of LDH leakage. Received September 1, 1999, Accepted January 11, 2000     

The physical basis of reflective communication between fish,with special reference to the horse mackerel,Trachurus trachurus

Some properties of reflecting structures in the external surfaces of Trachurus trachurus and some other fish are described. These are related to the hypothesis that such structures are useful, especially to schooling fish, for communicating information on relative positions, orientations, and movements between neighbours. In addition to the silvery layers on the main body surfaces, there are: (a) highly silvered patches on the tail, the pectoral fins and the jaws which, in the sea, will become much brighter or darker with any movement such as a tailbeat or mouth opening which changes their orientations in the ambient lightfield, and (b) structures such as the dorsal lateral line which, in the sea, will only appear bright from certain directions. To us, the colours of the ventral flanks change from bright red to blue with direction orientations and have special reflectivity curves close to those predicted by A.F. Huxley for interference reflectors which are ''ideal'' λ/4 stacks of guanine crystals and cytoplasm. The wavebands best reflected by such platelets move to shorter wavelengths with increasing angle of incidence, also in accord with these equations. At normal incidence, the outer layer of platelets reflects maximally for far-red light which penetrates only a short distance in the sea. Such layers can, however, be useful at oblique angles where they reflect maximally in the yellow and blue. The inner layer of reflectors reflects very strongly in the blue at normal incidence, but reflects in the ultra-violet at oblique angles. Some theoretical studies are made on the ways in which the patterns of reflectivity by single and superposed layers of λ/4 stacks could signal a fish''s movements or its position relative to its neighbours.     

Improving diagnostic strategies for ovarian cancer in Filipino women using ultrasound imaging and a multivariate index assay

ObjectiveTo evaluate the clinical performance and overall utility of imaging and biomarker assays in discriminating between benign and malignant ovarian masses in a Filipino population.MethodsThis is a prospective cohort study among Filipino women undergoing assessment for an ovarian mass in a tertiary center. All included patients underwent a physical examination before level III specialist ultrasonographic and Doppler evaluation, multivariate index assay (MIA2G), and surgery for an adnexal mass. Ovarian tumors were classified as high-risk for malignancy based on the International Ovarian Tumour Analysis (IOTA) – Logistic Regression 2 (LR2) score. The ovarian imaging and biomarker results were correlated with the reference standard: histological findings.ResultsAmong the 379 women with adnexal masses enrolled in this study, 291 were evaluable with ultrasound imaging, biomarker assays, and histopathological results. The risk of malignancy was higher for women classified as high-risk based on IOTA-LR2 (≥10%). The sensitivity, specificity, and diagnostic accuracy for the prediction of malignancy were 81.2%, 81%, and 0.81 (95% CI: 0.77–0.86) for IOTA-LR2; 77.5%, 66.7%, and 0.72 (95% CI: 0.67–0.77) for CA-125; and 91.3%, 41.2%, and 0.66 (95% CI: 0.62–0.71) for MIA2G. A combination of IOTA-LR2 and MIA2G significantly influenced the diagnostic performance and the result. When MIA2G was combined with IOTA-LR2 in parallel, the sensitivity (94.2%) and NPV (87.7%) increased, but the specificity (37.3%) decreased. When combined with IOTA-LR2 in series, there were fewer false positives, which resulted in improved specificity (85%).ConclusionThis study determined the utility of ovarian imaging and a second-generation multivariate index assay in predicting the risk of ovarian malignancy. IOTA-LR2 and MIA2G were useful in classifying patients with a high risk for ovarian malignancy.     

Investigation of intermolecular hydrogen bond interactions in crystalline l-Cysteine by DFT calculations of the oxygen-17, nitrogen-14, and hydrogen-2 EFG tensors and AIM analysis

A systematic computational study is carried out to investigate hydrogen bond (HB) interactions in the real crystalline structures of l-Cysteine at 30 and 298 K by density functional theory (DFT) calculations of electric field gradient (EFG) tensors at the sites of O-17, N-14, and H-2 nuclei. One-molecule (monomer) and nine-molecule (cluster) models of l-Cysteine are created by available crystal coordinates at both temperatures and the EFG tensors are calculated for both models to indicate the effect of HB interactions on the tensors. The calculated EFG tensors at the level of B3LYP and B3PW91 DFT methods and 6-311++G?? and cc-pVTZ basis sets are converted to those experimentally measurable nuclear quadrupole resonance (NQR) parameters i.e. quadrupole coupling constants (qcc) and asymmetry parameters (η_Q). The evaluated NQR parameters reveal that the EFG tensors of ¹⁷O, ¹⁴N, and ²H are influenced and show particular trends from monomer to the target molecule in the cluster due to the contribution of target molecule to classic N–H…O, and non-classic S–H…O and S–H…S types of HB interactions. On the other hand, atoms in molecules (AIM) analyses confirm the presence of HB interactions and rationalize the observed EFG trends. The results indicate different contribution of various nuclei to HB interactions in the cluster where O2 and N1 have major contributions. The EFG tensors as well as AIM analysis at the H6 site show that the N1-H6…O2 HB undergoes a significant change from 30 to 298 K where changes in other N–H…O interactions are almost negligible. There is a good agreement between the calculated ¹⁴N NQR parameters and reported experimental data.