Investigation of HMG-CoA reductase inhibitory and antioxidant effects of various hydroxycoumarin derivatives.

Cardiovascular diseases are one of the primary causes of deaths worldwide, and the development of atherosclerosis is closely related to hypercholesterolemia. As the reduction of the low-density lipoprotein cholesterol level is critical for treating these diseases, the inhibition of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase, which is essentially responsible for cholesterol biosynthesis, stands out as a key solution to lower plasma cholesterol levels. In this study, we synthesized several dihydroxycoumarins and investigated their antioxidant and in vitro HMG-CoA reductase inhibitory effects. Furthermore, we carried out in silico studies and examined the quantum-chemical properties of the coumarin derivatives. We also performed molecular docking experiments and analyzed the binding strength of each coumarin derivative. Our results revealed that compound IV displayed the highest HMG-CoA reductase inhibitory activity (IC50 = 42.0 µM) in vitro. Cupric-reducing antioxidant capacity and ferric-reducing antioxidant power assays demonstrated that coumarin derivatives exhibit potent antioxidant activities. Additionally, a close relationship was found between the lowest unoccupied molecular orbital energy levels and the antioxidant activities.

Discovery and evaluation of inhibitory activity and mechanism of arylcoumarin derivatives on Theileria annulata enolase by in vitro and molecular docking studies.

In this study, the inhibition potential of 3- and 4-arylcoumarin derivatives on Theileria annulata enolase (TaENO) was assessed for the first time in the literature. Firstly, protein stabilization analyses of TaENO were performed and it was found that the enzyme remains stable with the addition of 6 M ethylene glycol at + 4 °C. Inhibitor screening analyses were carried out using 25 coumarin derivatives on highly purified TaENO (> 95%), and four coumarin derivatives [4-(3,4-dimethoxyphenyl)-6,7-dihydroxy-2H-chromen-2-one (C8); 4-(3,4-dihydroxyphenyl)-7,8 dihydroxy-2H-chromen-2-one (C9); 4-(3,4-dihydroxyphenyl)-6,7-dihydroxy-2H-chromen-2 one (C21); and 3-(3,4-dihydroxyphenyl)-7,8-dihydroxy-2H-chromen-2-one (C23)] showed the highest inhibitory effects with the IC50 values of 10.450, 13.170, 8.871 and 10.863 µM, respectively. The kinetic results indicated that these compounds inhibited the enzyme by uncompetitive inhibition. In addition, the successful binding of the most potent inhibitor (C21) into TaENO was confirmed by using MALDI-TOF mass spectrophotometry. Molecular docking analyses have predicted that C8 and C21 coumarin derivatives which showed high inhibitory effects on TaENO were interacted with high affinity to the potential regions out of the active site. Taken together, these coumarin derivatives (C8, C9, C21 and C23) are first known potent, nonsubstrate, uncompetitive inhibitors of TaENO and these results will facilitate further in vitro and in vivo analysis toward structure-based drug design studies.

Inhibitory effects of arylcoumarin derivatives on Bacteroides fragilisd­lactate dehydrogenase.

Bacteroides fragilis is an anaerobic bacterium naturally hosted in the human colon flora. B. fragilisd­lactate dehydrogenase (Bfd­LDH) is an important enzyme which catalyzes the conversion of d­lactate to pyruvate and regulates anaerobic glycolysis. In this study Bfd­LDH has been targeted for structure based drug design. B. fragilisd­lactate dehydrogenase has been expressed, purified and inhibitory activities of 25 coumarin derivatives previously synthetize for their antioxidant activity were evaluated. Among the 25 coumarin derivatives, compound 6a, 5l, and 6b exhibited the highest inhibitory activity with IC50 values of 0,47 µM, 0,57 µM ve 0,057 µM, respectively. The results indicate that the mechanism by which 6a, 5l and 6b coumarin derivatives inhibit Bfd­LDH by reversible non-competitive inhibition. Docking experiments were carried out to further explain the results and compare the theoretical and experimental affinity of these compounds to the Bfd­LDH protein. According to docking results, all coumarins bind to the site occupied by pyruvate and the nicotinamide ring of NADH.

Computational insight into the phthalocyanine-DNA binding via docking and molecular dynamics simulations.

Phthalocyanines are considered as good DNA binders, which makes them promising anti-tumor drug leads. The purpose of this study is to investigate the interactions between DNA and quaternary metallophthalocyanine derivatives (Q-MPc) possessing varying metals (M = Zn, Ni, Cu, Fe, Mg and Ca) by molecular docking since there seems to be a lack of information in the literature regarding this issue. In this direction, Autodock Vina and Molegro Virtual Docker programs were employed. Autodock Vina results reveal that each Q-MPc derivative binds to DNA strongly with similar binding energies and almost identical binding modes. They bind to the grooves of DNA by constituting favorable interactions between phosphate groups of DNA and Q-MPcs. Although changing the metal has no significant effect on binding, presence of quaternary amine substituents increases the binding constant Kb by about 2-fold comparing to the core Pc (ZnPc). Contrary to Autodock Vina, the calculated Molegro Virtual Docker binding scores have been more diverse indicating that the scoring function of Molegro is better in differentiating these metals. Despite the fact that Molegro is superior to Autodock Vina in terms of metal characterization, Autodock Vina and Molegro exhibit similar binding sites for the studied metallophthalocyanines. We propose that Q-MPc derivatives designed in this study are promising anti-tumor lead compounds since they tightly bind to DNA with considerably high Kb values. Cationic substituents and presence of metal have both positive effects on DNA binding which is critical for designing DNA-active drugs. Additional calculations employing molecular dynamics (MD) simulations verified the stability of Q-MPc-DNA complexes which remained in contact after 20 ns via attractive interactions mainly between DNA backbone and the Pc metal center.

Asymmetric synthesis, molecular modeling and biological evaluation of 5-methyl-3-aryloxazolidine-2,4-dione enantiomers as monoamine oxidase (MAO) inhibitors.

Single enantiomers of the new 5-methyl-3-aryloxazolidine-2,4-diones have been obtained either by an asymmetric synthesis using the chiral pool strategy or by a semipreparative resolution of the racemic compound by HPLC on an optically active stationary phase. The single enantiomers were assayed for their in vitro monoamine oxidase (hMAO) inhibitory activity and selectivity. The most potent inhibitor among the studied compounds has been found as (5R)-3-phenyl-5-methyl-2,4-oxazolidinedione (compound 1-R) which appeared to be a good antidepressant drug candidate since it inhibited hMAO-A selectively, competitively and reversibly with Ki values in the micromolar range (0.16 ±â€¯0.01 µM). To better understand the enzyme-inhibitor interaction and to explain the efficiency and selectivity of the compounds toward hMAOs, molecular modeling studies were carried out on new, high resolution hMAO-A and hMAO-B crystallographic structures. According to binding energies and inhibition constants obtained from molecular docking calculations, compound 1-R has been found as the most selective MAO-A inhibitor and its weak binding affinities to MAO-B (large Ki values) led to the enhancement in MAO-A selectivity. It bounded in close proximity to FAD in the active site of MAO-A and situated near the aromatic cage by means of π-alkyl interactions with Tyr407 and Phe352 whereas its position in MAO-B was 10 Šfar from FAD and it was situated outside the Ile199 gate of the active site. None of the studied compounds showed any cytototoxicity on HepG2 cells at 1 and 5 µM concentrations.

Preparation, characterization, and in vitro evaluation of isoniazid and rifampicin-loaded archaeosomes.

The ability of Archaea to adapt their membrane lipid compositions to extreme environments has brought in archaeosomes into consideration for the development of drug delivery systems overcoming the physical, biological blockades that the body exhibits against drug therapies. In this study, we prepared unilamellar archaeosomes, from the polar lipid fraction extracted from Haloarcula 2TK2 strain, and explored its potential as a drug delivery vehicle. Rifampicin and isoniazid which are conventional drugs in tuberculosis medication were loaded separately and together in the same archaeosome formulation for the benefits of the combined therapy. Particle size and zeta potential of archaeosomes were measured by photon correlation spectroscopy, and the morphology was assessed by with an atomic force microscope. Encapsulation efficiency and loading capacities of the drugs were determined, and in vitro drug releases were monitored spectrophotometrically. Our study demonstrates that rifampicin and isoniazid could be successfully loaded separately and together in archaeosomes with reasonable drug-loading and desired vesicle-specific characters. Both of the drugs had greater affinity for archaeosomes than a conventional liposome formulation. The results imply that archaeosomes prepared from extremely halophilic archaeon were compatible with the liposomes for the development of stable and sustained release of antituberculosis drugs.

Comprehensive structural analysis of the open and closed conformations of Theileria annulata enolase by molecular modelling and docking.

Theileria annulata is an apicomplexan parasite which is responsible for tropical theileriosis in cattle. Due to resistance of T. annulata against commonly used antitheilerial drug, new drug candidates should be identified urgently. Enolase might be a druggable protein candidate which has an important role in glycolysis, and could also be related to several cellular functions as a moonlight protein. In this study; we have described three-dimensional models of open and closed conformations of T. annulata enolase by homology modeling method for the first time with the comprehensive domain, active site and docking analyses. Our results show that the enolase has similar folding patterns within enolase superfamily with conserved catalytic loops and active site residues. We have described specific insertions, possible plasminogen binding sites, electrostatic potential surfaces and positively charged pockets as druggable regions in T. annulata enolase.

Proteomic changes in the cortex membrane fraction of genetic absence epilepsy rats from Strasbourg.

Epilepsy is a serious neurodegenerative disorder with a high incidence and a variety of presentations and causes. Studies on brain from various animal models including chronic models: Genetic Absence Epilepsy Rats from Strasbourg (GAERS) are very useful for understanding the fundamental mechanisms associated with human epilepsy. Individual regions of the brain have different protein composition in different conditions. Therefore, proteomic analyses of the brain compartments are preferred for the development of new therapeutic targets in different pathophysiological conditions like neurodegenerative disorders. In this study, we describe a proteomic profiling of membrane fraction of cortex tissue from epileptic GAERS and non-epileptic Wistar rat brain by two-dimensional gel electrophoresis coupled with matrix-assisted laser desorption/ionization mass spectroscopy. Comparing the optical density of spots between groups, we found that one protein expression was significantly down-regulated (guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1) and one protein expression was significantly up-regulated (14-3-3 protein epsilon isoform) in GAERS group. Our results indicate that these proteins might have played a significant role in epilepsy and may be considered as valuable therapeutic targets in the absence of epilepsy.

Synthesis of 3-amino-4-hydroxy coumarin and dihydroxy-phenyl coumarins as novel anticoagulants.

Natural and synthetic coumarin derivatives have been shown to possess several beneficial pharmacological effects. The anticoagulation and antithrombotic activities of the 4-hydroxy coumarin derivatives are well known. In this study, besides the 4-hydroxy substituent phenyl and p-methylphenyl derivatives were synthesized and confirmed on the basis of their spectral data. 3-Amino-4-hydroxy coumarin, 5,7-dihydroxy-4-phenyl coumarin and 7,8-dihydroxy-3-(4-methylphenyl)coumarin were tested in rats to determine whether they had any effect on vitamin K inhibition by investigating the prothrombin time (PT). PT values of coumarin derivatives were compared with those of warfarin (CAS 81-81-2), which is the most commonly used anticoagulant. 7,8-Dihydroxy-3-(4-methylphenyl)coumarin increased PT when compared to saline treated control group and other coumarins synthesized, 3-amino-4-hydroxy coumarin and 5,7-dihydroxy-4-phenyl coumarin.