Synthesis and Antiplasmodial Activity of Betulinic Acid and Ursolic Acid Analogues

More than 40% of the World population is at risk of contracting malaria, which affects primarily poor populations in tropical and subtropical areas. Antimalarial pharmacotherapy has utilised plant-derived products such as quinine and artemisinin as well as their derivatives. However, worldwide use of these antimalarials has caused the spread of resistant parasites, resulting in increased malaria morbidity and mortality. Considering that the literature has demonstrated the antimalarial potential of triterpenes, specially betulinic acid (1) and ursolic acid (2), this study investigated the antimalarial activity against P. falciparum chloroquine-sensitive 3D7 strain of some new derivatives of 1 and 2 with modifications at C-3 and C-28. The antiplasmodial study employed flow cytometry and spectrofluorimetric analyses using YOYO-1, dihydroethidium and Fluo4/AM for staining. Among the six analogues obtained, compounds 1c and 2c showed excellent activity (IC50 = 220 and 175 nM, respectively) while 1a and b demonstrated good activity ( IC50 = 4 and 5 mu M, respectively). After cytotoxicity evaluation against HEK293T cells, 1a was not toxic, while 1c and 2c showed IC50 of 4 mu M and a selectivity index (SI) value of 18 and 23, respectively. Moreover, compound 2c, which presents the best antiplasmodial activity, is involved in the calcium-regulated pathway(s).

Synthesis and properties of cyclic gomesin and analogues

Gomesin (Gm) was the first antimicrobial peptide (AMP) isolated from the hemocytes of a spider, the Brazilian mygalomorph Acanthoscurria gomesiana. We have been studying the properties of this interesting AMP, which also displays anticancer, antimalarial, anticryptococcal and anti-Leishmania activities. In the present study, the total syntheses of backbone-cyclized analogues of Gm (two disulfide bonds), [Cys(Acm)2,15]-Gm (one disulfide bond) and [Thr2,6,11,15,d-Pro9]-Gm (no disulfide bonds) were accomplished, and the impact of cyclization on their properties was examined. The consequence of simultaneous deletion of pGlu1 and Arg16-Glu-Arg18-NH2 on Gm antimicrobial activity and structure was also analyzed. The results obtained showed that the synthetic route that includes peptide backbone cyclization on resin was advantageous and that a combination of 20% DMSO/NMP, EDC/HOBt, 60?degrees C and conventional heating appears to be particularly suitable for backbone cyclization of bioactive peptides. The biological properties of the Gm analogues clearly revealed that the N-terminal amino acid pGlu1 and the amidated C-terminal tripeptide Arg16-Glu-Arg18-NH2 play a major role in the interaction of Gm with the target membranes. Moreover, backbone cyclization practically did not affect the stability of the peptides in human serum; it also did not affect or enhanced hemolytic activity, but induced selectivity and, in some cases, discrete enhancements of antimicrobial activity and salt tolerance. Because of its high therapeutic index, easy synthesis and lower cost, the [Thr2,6,11,15,d-Pro9]-Gm analogue remains the best active Gm-derived AMP developed so far; nevertheless, its elevated instability in human serum may limit its therapeutic potential. Copyright (c) 2012 European Peptide Society and John Wiley & Sons, Ltd.

Dillapiole as Antileishmanial Agent: Discovery, Cytotoxic Activity and Preliminary SAR Studies of Dillapiole Analogues

In this paper, the isolation of dillapiole (1) from Piper aduncum was reported as well as the semi-synthesis of two phenylpropanoid derivatives [di-hydrodillapiole (2), isodillapiole (3)], via reduction and isomerization reactions. Also, the compounds' molecular properties (structural, electronic, hydrophobic, and steric) were calculated and investigated to establish some preliminary structureactivity relationships (SAR). Compounds were evaluated for in vitro antileishmanial activity and cytotoxic effects on fibroblast cells. Compound 1 presented inhibitory activity against Leishmania amazonensis (IC50?=?69.3 mu M) and Leishmania brasiliensis (IC50?=?59.4 mu M) and induced cytotoxic effects on fibroblast cells mainly in high concentrations. Compounds 2 (IC50?=?99.9 mu M for L. amazonensis and IC50?=?90.5 mu M for L. braziliensis) and 3 (IC50?=?122.9 mu M for L. amazonensis and IC50?=?109.8 mu M for L. brasiliensis) were less active than dillapiole (1). Regarding the molecular properties, the conformational arrangement of the side chain, electronic features, and the hydrophilic/hydrophobic balance seem to be relevant for explaining the antileishmanial activity of dillapiole and its analogues.

A Combined Study Using Ligand-Based Design, Synthesis, and Pharmacological Evaluation of Analogues of the Acetaminophen Ortho-Regioisomer with Potent Analgesic Activity

A ligand-based drug design study was performed to acetaminophen regioisomers as analgesic candidates employing quantum chemical calculations at the DFT/B3LYP level of theory and the 6-31G* basis set. To do so, many molecular descriptors were used such as highest occupied molecular orbital, ionization potential, HO bond dissociation energies, and spin densities, which might be related to quench reactivity of the tyrosyl radical to give N-acetyl-p-benzosemiquinone-imine through an initial electron withdrawing or hydrogen atom abstraction. Based on this in silico work, the most promising molecule, orthobenzamol, was synthesized and tested. The results expected from the theoretical prediction were confirmed in vivo using mouse models of nociception such as writhing, paw licking, and hot plate tests. All biological results suggested an antinociceptive activity mediated by opioid receptors. Furthermore, at 90 and 120 min, this new compound had an effect that was comparable to morphine, the standard drug for this test. Finally, the pharmacophore model is discussed according to the electronic properties derived from quantum chemistry calculations.

Cyclic Voltammetry and Computational Chemistry Studies on the Evaluation of the Redox Behavior of Parabens and other Analogues

Parabens are antimicrobial preservatives widely used in pharmaceutical, cosmetic and food industries. The alkyl chain connected to the ester group defines some important physicochemical characteristics of these compounds, including the partition coefficient and redox properties. The voltammetric and computational analyses were carried out in order to evaluate the redox behavior of these compounds and other phenolic analogues. A strong correlation between chemical substituents inductive effects of parabens with redox potentials was observed. Using cyclic voltammetry and glassy carbon working electrode, only one irreversible anodic peak was observed around 0.8 V for methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), benzylparaben (BzP) and p-substituted phenolic analogues. The electrodonating inductive effect of alkyl groups was demonstrated by the anodic oxidation potential shift to lower values as the carbon number increases and, therefore the parabens (and other phenolic analogues) oxidation processes to the quinonoidic forms showed great dependence on the substituent pattern.

Populene D Analogues: Design, Concise Synthesis and Antiproliferative Activity

An efficient and concise synthesis of nine populene D analogues was performed using an iodine-catalyzed Prins cyclization as the key transformation. The antiproliferative activity of these new pyrans against several cancer cell lines was then investigated. Among them, an isochromene with moderate activity (mean logGI(50) = 0.91) was found. Additionally, compounds with selectivity toward the tumor cell lines NCI-ADR/RES, OVCAR-3, and HT29 were discovered.

Insulin analogues in the treatment of diabetes in pregnancy

Pregnancy affects both maternal and fetal metabolism, and even in non-diabetic women, it exerts a diabetogenic effect. Among pregnant women, 2% to 14% develop gestational diabetes. Pregnancy can also occur in women with preexisting diabetes, which may predispose the fetus to many alterations in organogenesis, restrict growth, and the mother, to some diabetes-related complications, such as retinopathy and nephropathy, or to acceleration of the course of these complications, if they are already present. Women with gestational diabetes generally start their treatment with diet and lifestyle changes; when these changes are not enough for optimal glycemic control, insulin therapy must then be considered. Women with type 2 diabetes using oral hypoglycemic agents are advised to change to insulin therapy. Those with preexisting type 1 diabetes should start intensive glycemic control. As basal insulin analogues have frequently been used off-label in pregnant women, there is a need to evaluate their safety and efficacy. The aim of this review is to report the use of both short- and long-acting insulin analogues during pregnancy and to enable clinicians, obstetricians, and endocrinologists to choose the best insulin treatment for their patients.

Cyclic voltammetry and computational chemistry studies on the evaluation of the redox behavior of parabens and other analogues

Parabens are antimicrobial preservatives widely used in pharmaceutical, cosmetic and food industries. The alkyl chain connected to the ester group defines some important physicochemical characteristics of these compounds, including the partition coefficient and redox properties. The voltammetric and computational analyses were carried out in order to evaluate the redox behavior of these compounds and other phenolic analogues. A strong correlation between chemical substituents inductive effects of parabens with redox potentials was observed. Using cyclic voltammetry and glassy carbon working electrode, only one irreversible anodic peak was observed around 0.8 V for methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), benzylparaben (BzP) and p-substituted phenolic analogues. The electrodonating inductive effect of alkyl groups was demonstrated by the anodic oxidation potential shift to lower values as the carbon number increases and, therefore the parabens (and other phenolic analogues) oxidation processes to the quinonoidic forms showed great dependence on the substituent pattern.

Diethylpropion produces psychostimulant and reward effects

Diethylpropion (DEP) is a stimulant drug widely used for weight control in Brazil and other American countries. However, its effects on behavior and addiction potential are not yet well known. Data suggest that sensitization resulting from pre-exposure to psychostimulants could be a possible risk factor in subsequent drug addiction. The purpose of this investigation was to verify whether pre-exposure to DEP would sensitize rats to the motor activating effect and to the rewarding value of DEP. Two experiments were conducted. In both experiments rats were pre-exposed to DEP (20 mg/kg) or vehicle for 7 consecutive days. The acute effect of DEP (0.0, 1.0, 2.5 or 5.0 mg/kg) on motor activity (Experiment 1) and induction of Conditioned Place Preference-CPP (Experiment 2) were then measured. Results from Experiment 1 showed that 2.5 and 5.0 mg/kg DEP increased motor activity. Sensitization of this motor effect was observed. In Experiment 2, the doses of 2.5 and 5.0 mg/kg DEP induced CPP, indicating their rewarding value. However, no sensitization effect was observed. The results suggest that DEP at low doses has psychostimulant and rewarding properties. It is recommended that more effort should be dedicated to elucidating DEP abuse Potential. (c) 2008 Elsevier Inc. All rights reserved.

Conjunctival inflammation in patients under topical glaucoma treatment with indication to surgery

PURPOSE: To compare the frequency of conjunctival HLA-DR expression (a surrogate marker for inflammation) in eyes treated with topical prostaglandin analogues versus eyes treated with other topical antiglaucomatous drugs. METHODS: Patients diagnosed with primary open-angle glaucoma presenting indication for trabeculectomy were divided in groups according to the use or not of prostaglandin analogues. All subjects were treated with the maximum tolerated dose of antiglaucomatous drugs until the date of the surgery. At the beginning of the surgical procedure, a 5 x 5 mm biopsy of the bulbar conjunctiva was collected, incubated with monoclonal anti-HLA-DR antibody and processed for histological analysis. RESULTS: Of the 31 eyes included (31 patients), 25 were under topical prostaglandin analogues (Group 1) and six under other topical pharmacological agents (Group 2). Fourteen eyes of Group 1 (56%) and three of Group 2 (50 %) were positive for the inflammatory marker HLA-DR (P=1.0). The percentage of stained cells ranged from 15.49 to 48.09% (median: 27.61) in Group 1, and from 18.35 to 28 (median: 20.71) in Group 2, with no differences statistically significant (p=0.33). CONCLUSION: The use of prostaglandin analogues did not increase conjunctival expression of HLA-DR compared to other topical antiglaucomatous agents.

Capillary bioreactors based on human purine nucleoside phosphorylase: A new approach for ligands identification and characterization

The enzyme purine nucleoside phosphorylase (PNP) is a target for the discovery of new lead compounds employed on the treatment severe T-cell mediated disorders. Within this context, the development of new, direct, and reliable methods for ligands screening is an important task. This paper describes the preparation of fused silica capillaries human PNP (HsPNP) immobilized enzyme reactor (IMER). The activity of the obtained IMER is monitored on line in a multidimensional liquid chromatography system, by the quantification of the product formed throughout the enzymatic reaction. The Km value for the immobilized enzyme was about twofold higher than that measured for the enzyme in solution (255 +/- 29.2 mu M and 133 +/- 114.9 mu M, respectively). A new fourth-generation immucillin derivative (DI4G: IC50 = 40.6 +/- 0.36 nM), previously identified and characterized in HsPNP free enzyme assays, was used to validate the IMER as a screening method for HsPNP ligands. The validated method was also used for mechanistic studies with this inhibitor. This new approach is a valuable tool to PNP ligand screening, since it directly measures the hypoxanthine released by inosine phosphorolysis, thus furnishing more reliable results than those one used in a coupled enzymatic spectrophotometric assay. (C) 2011 Elsevier B.V. All rights reserved.

INVESTIGAÇÃO ELETROQUÍMICA E CALORIMÉTRICA DA INTERAÇÃO DE NOVOS AGENTES ANTITUMORAIS BISCATIÔNICOS COM DNA

ELECTROCHEMICAL AND CALORIMETRIC INVESTIGATION OF INTERACTION OF NOVEL BISCATIONIC ANTICANCER AGENTS WITH DNA. Biscationic amidines bind in the DNA minor groove and present biological activity against a range of infectious diseases. Two new biscationic compounds (bis-alpha,omega-S-thioureido, amino and sulfide analogues) were synthesized in good yields and fully characterized, and their interaction with DNA was also investigated. Isothermal titration calorimetry (ITC) was used to measure the thermodynamic properties of binding interactions between DNA and these ligands. A double stranded calf thymus DNA immobilized on an electrode surface was used to study the possible DNA-interacting abilities of these compounds towards dsDNA in situ. A remarkable interaction of these compounds with DNA was demonstrated and their potential application as anticancer agents was furthered.

Caco-2 cells cytotoxicity of nifuroxazide derivatives with potential activity against Methicillin-resistant Staphylococcus aureus (MRSA)

It is important to determine the toxicity of compounds and co-solvents that are used in cell monolayer permeability studies to increase confidence in the results obtained from these in vitro experiments. This study was designed to evaluate the cytotoxicity of new nifuroxazide derivatives with potential activity against Methicillin-resistant Staphylococcus aureus (MRSA) in Caco-2 cells to select analogues for further in vitro permeability analyses. In this study, nitrofurantoin and nifuroxazide, in addition to 6 furanic and 6 thiophenic nifuroxazide derivatives were tested at 2, 4, 6, 8 and 10 mu g/mL. In vitro cytotoxicity assays were performed according to the MTT (methyl tetrazolium) assay protocol described in ISO 10993-5. The viability of treated Caco-2 cells was greater than 83% for all tested nitrofurantoin concentrations, while those treated with nifuroxazide at 2, 4 and 6 mu g/mL had viabilities greater than 70%. Treatment with the nifuroxazide analogues resulted in viability values greater than 70% at 2 and 4 mu g/mL with the exception of the thiophenic methyl-substituted derivative, which resulted in cell viabilities below 70% at all tested concentrations. Caco-2 cells demonstrated reasonable viability for all nifuroxazide derivatives, except the thiophenic methyl-substituted compound. The former were selected for further permeability studies using Caco-2 cells. (C) 2012 Elsevier Ltd. All rights reserved.

Total synthesis of (-)-indolizidine 167B via an unusual Wolff rearrangement from an alpha,beta-unsaturated diazoketone

A concise synthesis of the (-)-indolizidine alkaloid 167B and two formal syntheses of (-)-indolizidine 209D and (-)-coniceine are described in just three steps from an alpha,beta-unsaturated diazoketone, via an unusual photochemical Wolff rearrangement. Preparation of the unsaturated diazoketone is straightforward from N-Cbz-prolinal and a 3-diazo-2-oxopropylphosphonate, employing a Horner-Wadsworth-Emmons reaction. The strategy should be feasible and easily adaptable to the synthesis of other indolizidine alkaloids and analogues. (C) 2011 Elsevier Ltd. All rights reserved.

Insights into Phosphate Cooperativity and Influence of Substrate Modifications on Binding and Catalysis of Hexameric Purine Nucleoside Phosphorylases

The hexameric purine nucleoside phosphorylase from Bacillus subtilis (BsPNP233) displays great potential to produce nucleoside analogues in industry and can be exploited in the development of new anti-tumor gene therapies. In order to provide structural basis for enzyme and substrates rational optimization, aiming at those applications, the present work shows a thorough and detailed structural description of the binding mode of substrates and nucleoside analogues to the active site of the hexameric BsPNP233. Here we report the crystal structure of BsPNP233 in the apo form and in complex with 11 ligands, including clinically relevant compounds. The crystal structure of six ligands (adenine, 2'deoxyguanosine, aciclovir, ganciclovir, 8-bromoguanosine, 6-chloroguanosine) in complex with a hexameric PNP are presented for the first time. Our data showed that free bases adopt alternative conformations in the BsPNP233 active site and indicated that binding of the co-substrate (2'deoxy) ribose 1-phosphate might contribute for stabilizing the bases in a favorable orientation for catalysis. The BsPNP233-adenosine complex revealed that a hydrogen bond between the 5' hydroxyl group of adenosine and Arg(43*) side chain contributes for the ribosyl radical to adopt an unusual C3'-endo conformation. The structures with 6-chloroguanosine and 8-bromoguanosine pointed out that the Cl-6 and Br-8 substrate modifications seem to be detrimental for catalysis and can be explored in the design of inhibitors for hexameric PNPs from pathogens. Our data also corroborated the competitive inhibition mechanism of hexameric PNPs by tubercidin and suggested that the acyclic nucleoside ganciclovir is a better inhibitor for hexameric PNPs than aciclovir. Furthermore, comparative structural analyses indicated that the replacement of Ser(90) by a threonine in the B. cereus hexameric adenosine phosphorylase (Thr(91)) is responsible for the lack of negative cooperativity of phosphate binding in this enzyme.