Effects of Lipophilicity and Structural Features on the Antiherpes Activity of Digitalis Cardenolides and Derivatives.

There is growing interest in exploring Digitalis cardenolides as potential antiviral agents. Hence, we herein investigated the influence of structural features and lipophilicity on the antiherpes activity of 65 natural and semisynthetic cardenolides assayed in vitro against HSV-1. The presence of an α,ß-unsaturated lactone ring at C-17, a ß-hydroxy group at C-14 and C-3ß-OR substituents were considered essential requirements for this biological activity. Glycosides were more active than their genins, especially monoglycosides containing a rhamnose residue. The activity enhanced in derivatives bearing an aldehyde group at C-19 instead of a methyl group, whereas inserting a C-5ß-OH improved the antiherpes effect significantly. The cardenolides lipophilicity was accessed by measuring experimentally their log P values (n-octanol-water partition coefficient) and disclosed a range of lipophilicity (log P 0.75±0.25) associated with the optimal antiherpes activity. In silico studies were carried out and resulted in the establishment of two predictive models potentially useful to identify and/or optimize novel antiherpes cardenolides. The effectiveness of the models was confirmed by retrospective analysis of the studied compounds. This is the first SAR study addressing the antiherpes activity of cardenolides. The developed computational models were able to predict the active cardenolides and their log P values.

Drug discovery for chagas disease: A viewpoint.

Chagas disease is a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi. It is a significant public health problem, affecting millions of people worldwide. And although it was described 110 years ago, only two old nitroheterocyclic drugs, benznidazole and nifurtimox, are currently available for the treatment of Chagas disease and both have several limitations. Besides the clear unmet medical need, many challenges preclude the development of new treatments, some of them related to a lack of understanding of the pathophysiology of the disease and parasite-host interactions. New knowledge and tools are becoming available, but the number of new chemical entities progressing through the preclinical pipeline is inadequate. Therefore, it is still uncertain whether safe, effective and accessible new drugs will be available in the near future. The Chagas disease research community must commit to even greater collaboration to ensure that patients eventually benefit from better treatments.

Clinical and pharmacological profile of benznidazole for treatment of Chagas disease.

INTRODUCTION: Chagas disease (CD) is one of the most neglected public health problems in the Americas, where <1% of the estimated 6 million people with the infection have been diagnosed and treated. The goal of treatment is to eliminate the parasite, decrease the probability of cardiomyopathy and other complications during the chronic stage of infection, and interrupt the cycle of disease transmission by preventing congenital infection. Currently, only benznidazole (BZN) and nifurtimox are recognized by the World Health Organization as effective drugs for treatment of CD. In this paper, we provide an overview of the clinical pharmacology of BZN. Areas covered: This review covers the historical background, chemistry, mechanism of action, pharmacokinetics, preclinical research, resistance, clinical research, toxicology, adverse effects, and current regulatory status of BZN. Expert commentary: Ongoing investigations aim to optimize BZN therapy by adjusting the current standard regimen or by combining BZN with new chemical entities. These studies are assessing alternatives that improve safety while maintaining or increasing the efficacy of BZN. Timely diagnosis and antitrypanosomal treatment are critical components of programs to eliminate CD as a public health problem, and can dramatically reduce the heavy burden of morbidity and mortality caused by the disease.

Pharmacokinetics of Saquinavir Mesylate from Oral Self-Emulsifying Lipid-Based Delivery Systems.

BACKGROUND AND OBJECTIVES: Although lipid-based drug delivery systems have gained much importance in recent years due to their ability to improve the solubility and bioavailability of poorly soluble drugs, compartmental pharmacokinetic analyses have not been extensively explored. The oral pharmacokinetics of commercial liquid formulation and a developed semisolid system containing saquinavir mesylate (SQVM) were compared in Beagle dogs. A compartmental analysis after intravenous bolus administration of this drug (1 mg/kg) was also performed. METHOD: Pharmacokinetic profiles were analyzed using both non-compartmental and compartmental approaches. Plasma concentration of the drug was determined by high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS). RESULTS: The disposition curve of SQVM given intravenously was better described by a three-compartment model. In contrast, plasma profiles obtained following the oral administration were fitted to a two-compartment model with lag time due to the fact that the distribution phase was masked by the absorption phase in these formulations. CONCLUSION: The proposed semisolid lipid system was found to be a promising formulation for commercial purposes given the similarity of SQVM absorption rate to that from the commercial liquid formulation.

In vitro intestinal permeability studies, pharmacokinetics and tissue distribution of 6-methylcoumarin after oral and intraperitoneal administration in Wistar rats

ABSTRACT 6-Methylcoumarin (6MC) is a semisynthetic coumarin with important in vitro and in vivo anti-inflammatory activity. In order to continue the pre-clinical characterization of this molecule, in vitro intestinal permeability, plasma profile and tissue distribution after oral administration in rats were studied. The permeability of 6MC was evaluated by the Caco-2 cellular model in both the apical-basal (A-B) and basal-apical (B-A) directions. The pharmacokinetics and biodistribution were evaluated in rats after oral and intraperitoneal administration at doses of 200 mg/kg. Transport experiments with Caco-2 cells showed that 6MC presented high permeability at all concentrations evaluated. This finding suggested that 6MC could be transported across the gut wall by passive diffusion. The plasma concentration-time curve showed that the maximum concentration (Cmax) was 17.13 ± 2.90 µg/mL at maximum time (Tmax) of 30 min for the oral route and Cmax 26.18 ± 2.47 µg/mL at 6.0 min for the intraperitoneal administration, with elimination constant of (Ke ) 0.0070 min-1 and a short life half time of (T1/2 ) lower that 120 min. The distribution study showed that 6MC has high accumulation in the liver, and widespread distribution in all the organs evaluated.

Anti-inflammatory Effect and Toxicology Analysis of Oral Delivery Quercetin Nanosized Emulsion in Rats.

PURPOSE: This study evaluates the advantage of the quercetin encapsulation in nanosized emulsion (QU-NE) administered orally in rats in order to demonstrate its anti-oedematous and antioxidant effects as well as its toxicity. METHODS: The nanocarriers were prepared using the hot solvent diffusion with the phase inversion temperature methods. The nanocarriers physicochemical properties were then investigated. The anti-edematous activity was tested using paw edema in rats. In addition, NF-kB expression in subcutaneous tissue of the paws was accessed by immunohistochemistry while the lipid peroxidation was analyzed in the liver by malondialdehyde reaction with thiobarbituric acid. Hematological, renal and hepatic toxicity as well as the genetic damage were also evaluated. RESULTS: The results demonstrated that QU-NE exhibited pronounced anti-oedematous property comparable to drug diclofenac. This effect was associated with NF-κB pathway inhibition. The lipid peroxidation was also only reduced in rats treated with QU-NE. Besides this, no genetic damage, hematological, renal or hepatic toxicities were observed after administration of QU-NE. CONCLUSIONS: These results suggest that quercetin nanosized emulsion exhibits anti-oedematous and antioxidant properties and does not demonstrate toxic effects. This indicates that it has a potential application in the treatment of inflammatory diseases.

Inclusion complexes of hydrochlorothiazide and ß-cyclodextrin: Physicochemical characteristics, in vitro and in vivo studies.

Hydrochlorothiazide is a thiazide diuretic widely used in clinics to treat arterial hypertension. It is a class IV drug according to the Biopharmaceutical Classification System, that is, it presents low solubility and low permeability and, consequently, low absorption in the gastrointestinal tract. As a strategy to improve stability and biopharmaceutical properties of hydrochlorothiazide, the use of cyclodextrins to produce inclusion complexes, applying different methods, was investigated. In the phase solubility studies, ß-cyclodextrin was identified as the cyclodextrin which provided the most promising results in terms of the solubilization of the drug. The thermal analysis verified the interaction between hydrochlorothiazide and ß-cyclodextrin, indicating the formation of inclusion complexes, and the thermal stability varied according to the preparation technique. The physicochemical characterization showed that in the inclusion complexes obtained by co-evaporation, kneading followed by freeze-drying and kneading followed by spray-drying the hydrochlorothiazide complexation mostly occurred with different degrees of amorphization and the drug solubility was improved. These three inclusion complexes presented better in vitro characteristics and the inclusion complex obtained by kneading followed by freeze-drying increased the in vivo diuretic activity of the drug accompanied by significant effects on natriuresis, kaliuresis and chloriuresis. The inclusion complex formation was effective in improving the biopharmaceutical properties of hydrochlorothiazide and protecting the drug from hydrolysis. This paper describes an important alternative approach to the development of liquid pharmaceutical formulations to pediatric administration, a real need of the current pharmaceutical market.

Synergistic Antiproliferative Effects of a New Cucurbitacin B Derivative and Chemotherapy Drugs on Lung Cancer Cell Line A549.

Nonsmall cell lung cancer (NSCLC) represents an important cause of mortality worldwide due to its aggressiveness and growing resistance to currently available therapy. Cucurbitacins have emerged as novel potential anticancer agents showing strong antiproliferative effects and can be promising candidates for combined treatments with clinically used anticancer agents. This study investigates the synergistic antiproliferative effects of a new semisynthetic derivative of cucurbitacin B (DACE) with three chemotherapy drugs: cisplatin (CIS), irinotecan (IRI), and paclitaxel (PAC) on A549 cells. The most effective combinations were selected for studies of the mechanism of action. Using an in silico tool, DACE seems to act by a different mechanism of action when compared with that of different classes of drugs already used in clinical settings. DACE also showed potent synergic effects with drugs, and the most potent combinations induced G2/M cell cycle arrest by modulating survivin and p53 expression, disruption of F-actin cytoskeleton, and cell death by apoptosis. These treatments completely inhibited the clonogenic potential and did not reduce the proliferation of nontumoral lung cells (MRC-5). DACE also showed relevant antimigratory and anti-invasive effects, and combined treatments modulated cell migration signaling pathways evolved with metastasis progression. The effects of DACE associated with drugs was potentiated by the oxidant agent l-buthionine-sulfoximine (BSO), and attenuated by N-acetilcysteine (NAC), an antioxidant agent. The antiproliferative effects induced by combined treatments were attenuated by a pan-caspase inhibitor, indicating that the effects of these treatments are dependent on caspase activity. Our data highlight the therapeutic potential of DACE used in combination with known chemotherapy drugs and offer important insights for the development of more effective and selective therapies against lung cancer.

Ball-milled solid dispersions of BCS Class IV drugs: Impact on the dissolution rate and intestinal permeability of acyclovir.

Acyclovir, an analog of 2'-deoxyguanosine, is one of the most important drugs in the current approved antiviral treatment. However, it's biopharmaceutical properties, contribute to acyclovir's poor oral bioavailability, which restricts the clinical use of the drug. In this view, the aim of this work was to improve the dissolution rate and intestinal permeability of acyclovir through the development of ball milling solid dispersions with the hydrophilic carriers Pluronic F68®, hydroxypropylmethyl cellulose K100M® and chitosan. Solid dispersions were obtained and completely characterized through different solid state techniques. The solid state data demonstrated a decrease in the crystallinity (amorphous phase and defects) and the presence of hydrogen bonds for SD HPMC and SD CTS. The enhancement of dissolution rates was observed for all SDs developed. In addition, no detrimental effects over the in vitro antiviral activity were detected. The solid dispersions with Pluronic F68® significantly improved the intestinal permeability of acyclovir across Caco-2 cells. In summary, the SDs developed in this study could be considered as potential systems for solid dosage forms containing acyclovir with superior biopharmaceutical properties.

Antiherpetic mechanism of a sulfated derivative of Agaricus brasiliensis fruiting bodies polysaccharide.

OBJECTIVE: To study the anti-herpes simplex virus (HSV) activity of a (1→6)-(1→3)-ß-D-glucan isolated from Agaricus brasiliensis fruiting bodies (FR) as well as its chemically sulfated derivative (FR-S). METHODS: The antiherpetic activity and mechanism of action was studied by viral plaque assay applying different methodological strategies. RESULTS: Although FR presented no in vitro antiherpetic action at 1 mg/ml, FR-S displayed promising anti-HSV-1 and anti-HSV-2 activities in both simultaneous and postinfection treatments, resulting in selectivity indices (CC50/EC50) higher than 393. FR-S had no virucidal effect, but significantly suppressed HSV-1 (EC50 = 0.32 µg/ml) and HSV-2 (EC50 = 0.10 µg/ml) adsorption. FR-S was less effective on adsorption inhibition of mutant virus strains devoid of gC (HSV-1 gC⁻39 and HSV-2 gCneg1), indicating a possible interaction with this glycoprotein. The reduction of viral adsorption upon cell pretreatment with FR-S also suggests its interaction with cellular components. FR-S inhibited HSV-1 (EC50 = 8.39 µg/ml) and HSV-2 (EC50 = 2.86 µg/ml) penetration more efficiently than heparin. FR-S reduced HSV-1 and HSV-2 cell-to-cell spread. A synergic effect between FR-S and acyclovir was also detected. CONCLUSIONS: FR-S displays an interesting mechanism of antiviral action and represents a promising candidate for the treatment and/or prevention of herpetic infections, to be used as a single therapeutic agent or in combination with acyclovir.

Anti-HSV-1 and anti-HIV-1 activity of gallic acid and pentyl gallate.

The synthetic n-alkyl esters of gallic acid (GA), also known as gallates, especially propyl, octyl and dodecyl gallates, are widely employed as antioxidants by food and pharmaceutical industries. The inhibitory effects of GA and 15 gallates on Herpes Simplex Virus type 1 (HSV-1) and Human Immunodeficiency Virus (HIV-1) replication were investigated here. After a preliminary screening of these compounds, GA and pentyl gallate (PG) seemed to be the most active compounds against HSV-1 replication and their mode of action was characterized through a set of assays, which attempted to localize the step of the viral multiplication cycle where impairment occurred. The detected anti-HSV-1 activity was mediated by the inhibition of virus attachment to and penetration into cells, and by virucidal properties. Furthermore, an anti-HIV-1 activity was also found, to different degrees. In summary, our results suggest that both compounds could be regarded as promising candidates for the development of topical anti-HSV-1 agents, and further studies concerning the anti-HIV-1 activity of this group of molecules are merited.

Anti-HSV-1 and anti-HIV-1 activity of gallic acid and pentyl gallate

The synthetic n-alkyl esters of gallic acid (GA), also known as gallates, especially propyl, octyl and dodecyl gallates, are widely employed as antioxidants by food and pharmaceutical industries. The inhibitory effects of GA and 15 gallates on Herpes Simplex Virus type 1 (HSV-1) and Human Immunodeficiency Virus (HIV-1) replication were investigated here. After a preliminary screening of these compounds, GA and pentyl gallate (PG) seemed to be the most active compounds against HSV-1 replication and their mode of action was characterized through a set of assays, which attempted to localize the step of the viral multiplication cycle where impairment occurred. The detected anti-HSV-1 activity was mediated by the inhibition of virus attachment to and penetration into cells, and by virucidal properties. Furthermore, an anti-HIV-1 activity was also found, to different degrees. In summary, our results suggest that both compounds could be regarded as promising candidates for the development of topical anti-HSV-1 agents, and further studies concerning the anti-HIV-1 activity of this group of molecules are merited.

Evaluation of anti-HSV-2 activity of gallic acid and pentyl gallate.

The synthetic n-alkyl esters of gallic acid, also known as gallates, are widely employed as antioxidants by food and pharmaceutical industries. Besides the antioxidant activity, other biological activities have been described for this group of molecules, mainly anticancer, antibacterial and antifungal properties. In the present study, the anti-herpes simplex virus (HSV)-2 activity of gallic acid and pentyl gallate was evaluated followed by the determination of the site of antiviral activity of these compounds. Our results demonstrated that both compounds reduced HSV-2 replication in a concentration-dependent manner when either incubated with the virus prior to the addition of the mixture to cells, or added to and incubated with cells after their infection. In summary, the anti-HSV-2 activity of gallic acid and pentyl gallate was ascribed to their virucidal effect on virus particles, a change that was likely accompanied by partial inhibition of the virus attachment to cells and its subsequent cell-to-cell spread activity. This suggests that these compounds can be regarded as promising candidates for development as topical anti-HSV-2 agents.

In vitro antiviral activity of antimicrobial peptides against herpes simplex virus 1, adenovirus, and rotavirus.

Peptides with broad-spectrum antimicrobial activity, known as antimicrobial peptides, have been isolated from distinct organisms. This paper describes the in vitro evaluation of the cytotoxicity and antiviral activity of nine peptides with different structures and origins against herpes simplex virus type 1, human adenovirus respiratory strain, and rotavirus SA11. Most of the evaluated peptides presented antiviral activity but they were only active near cytotoxic concentrations. Nevertheless, these results seem promising, and further modifications on the peptide's structures may improve their selectivity and reduce their cytotoxicity.

In vitro antiviral activity of antimicrobial peptides against herpes simplex virus 1, adenovirus, and rotavirus

Peptides with broad-spectrum antimicrobial activity, known as antimicrobial peptides, have been isolated from distinct organisms. This paper describes the in vitro evaluation of the cytotoxicity and antiviral activity of nine peptides with different structures and origins against herpes simplex virus type 1, human adenovirus respiratory strain, and rotavirus SA11. Most of the evaluated peptides presented antiviral activity but they were only active near cytotoxic concentrations. Nevertheless, these results seem promising, and further modifications on the peptide's structures may improve their selectivity and reduce their cytotoxicity.

In vitro antiviral activity of marine sponges collected off Brazilian coast.

This paper describes the in vitro antiviral evaluation of 27 different marine sponges (Porifera) collected off Brazilian coastline in the search for novel drug leads. With these sponges aqueous and organic extracts were prepared and tested for anti-herpetic (HSV-1, KOS strain), anti-adenovirus (human AdV serotype 5) and anti-rotavirus (simian RV SA11) activities. The evaluation of the cytotoxicity and potential antiviral activity of these extracts were performed by using MTT assay. Results were expressed as 50% cytotoxicity (CC50) and 50% effective (EC50) concentrations, respectively, in order to calculate the selectivity indices (SI=CC50/EC50) of each extract. From the 40 sponge extracts tested, 17 extracts showed antiviral action in different degrees. The results concerning the antiviral activity were obtained by using three different strategies: (1) simultaneous assay, when sponge extracts were added to the cells at the same time of the viruses; (2) pre treatment assay, when sponge extracts were added to the cells 15 h prior to the viruses infection; and (3) post treatment assay, when the viruses were added to the cells and remained during 2 h prior to the addition of sponge extracts. The antiviral assays with HSV-1/KOS and AdV-5 showed more promising results when the pre treatment test was employed. In relation to the RV-SA11 virus, only the simultaneous assay showed antiviral activity. The extracts presenting the most promising results were the aqueous extracts of Cliona sp., Agelas sp.2, Tethya sp., Axinella aff corrugata, Polymastia janeirensis and Protosuberites sp., and these extracts deserve special attention in further studies.