A new extract of the plant Calendula officinalis produces a dual in vitro effect: cytotoxic anti-tumor activity and lymphocyte activation

BACKGROUND Phytopharmacological studies of different Calendula extracts have shown anti-inflammatory, anti-viral and anti-genotoxic properties of therapeutic interest. In this study, we evaluated the in vitro cytotoxic anti-tumor and immunomodulatory activities and in vivo anti-tumor effect of Laser Activated Calendula Extract (LACE), a novel extract of the plant Calendula Officinalis (Asteraceae). METHODS An aqueous extract of Calendula Officinalis was obtained by a novel extraction method in order to measure its anti-tumor and immunomodulatory activities in vitro. Tumor cell lines derived from leukemias, melanomas, fibrosarcomas and cancers of breast, prostate, cervix, lung, pancreas and colorectal were used and tumor cell proliferation in vitro was measured by BrdU incorporation and viable cell count. Effect of LACE on human peripheral blood lymphocyte (PBL) proliferation in vitro was also analyzed. Studies of cell cycle and apoptosis were performed in LACE-treated cells. In vivo anti-tumor activity was evaluated in nude mice bearing subcutaneously human Ando-2 melanoma cells. RESULTS The LACE extract showed a potent in vitro inhibition of tumor cell proliferation when tested on a wide variety of human and murine tumor cell lines. The inhibition ranged from 70 to 100%. Mechanisms of inhibition were identified as cell cycle arrest in G0/G1 phase and Caspase-3-induced apoptosis. Interestingly, the same extract showed an opposite effect when tested on PBLs and NKL cell line, in which in vitro induction of proliferation and activation of these cells was observed. The intraperitoneal injection or oral administration of LACE extract in nude mice inhibits in vivo tumor growth of Ando-2 melanoma cells and prolongs the survival day of the mice. CONCLUSION These results indicate that LACE aqueous extract has two complementary activities in vitro with potential anti-tumor therapeutic effect: cytotoxic tumor cell activity and lymphocyte activation. The LACE extract presented in vivo anti-tumoral activity in nude mice against tumor growth of Ando-2 melanoma cells.

In vitro activity of amphotericin B cochleates against Leishmania chagasi

Cochleate delivery vehicles are a novel lipid-based system with potential for delivery of amphotericin B (AmB). In this study, the efficacy of cochleates was evaluated by examining the in vitro activity of AmB cochleates (CAMB) against Leishmania chagasi in a macrophage model of infection. We demonstrate that CAMB is nontoxic to macrophages at concentrations as high as 2.5 μg/mL, whereas the conventional formulation, AmB deoxycholate, showed high toxicity at this concentration. The in vitro activity of CAMB against L. chagasi was found to be similar to that of the reference drug AmB deoxycholate, with ED50s of 0.017 μg/mL and 0.021 μg/mL, respectively. Considering that L. chagasi affects organs amenable to cochleate-mediated delivery of AmB, we hypothesize that CAMB will be an effective lipid system for the treatment of visceral leishmaniasis.

The in vitro leishmanicidal activity of hexadecylphosphocholine (miltefosine) against four medically relevant Leishmania species of Brazil

The in vitro leishmanicidal activity of miltefosine® (Zentaris GmbH) was assessed against four medically relevant Leishmania species of Brazil: Leishmania (Leishmania) amazonensis, Leishmania (Viannia) braziliensis, Leishmania (Viannia) guyanensis and Leishmania (Leishmania) chagasi. The activity of miltefosine against these New World species was compared to its activity against the Old World strain, Leishmania (Leishmania) donovani, which is known to be sensitive to the effects of miltefosine. The IC50 and IC90 results suggested the New World species harboured similar in vitro susceptibilities to miltefosine; however, miltefosine was approximately 20 times more active against the Old World L. (L.) donovani than against the New World L. (L.) chagasi species. The selectivity index varied from 17.2-28.9 for the New World Leishmania species and up to 420.0 for L. (L.) donovani. The differences in susceptibility to miltefosine suggest that future clinical trials with this drug should include a laboratory pre-evaluation and a dose-defining step.

Investigation into in vitro anti-leishmanial combinations of calcium channel blockers and current anti-leishmanial drugs

The need for drug combinations to treat visceral leishmaniasis (VL) arose because of resistance to antimonials, the toxicity of current treatments and the length of the course of therapy. Calcium channel blockers (CCBs) have shown anti-leishmanial activity; therefore their use in combination with standard drugs could provide new alternatives for the treatment of VL. In this work, in vitro isobolograms of Leishmania (Leishmania) chagasi using promastigotes or intracellular amastigotes were utilised to identify the interactions between five CCBs and the standard drugs pentamidine, amphotericin B and glucantime. The drug interactions were assessed with a fixed ratio isobologram method and the fractional inhibitory concentrations (FICs), sum of FICs (ΣFICs) and the overall mean ΣFIC were calculated for each combination. Graphical isobologram analysis showed that the combination of nimodipine and glucantime was the most promising in amastigotes with an overall mean ΣFIC value of 0.79. Interactions between CCBs and the anti-leishmanial drugs were classified as indifferent according to the overall mean ΣFIC and the isobologram graphic analysis.

Antibodies against the Plasmodium falciparum glutamate-rich protein from naturally exposed individuals living in a Brazilian malaria-endemic area can inhibit in vitro parasite growth

The glutamate-rich protein (GLURP) is an exoantigen expressed in all stages of the Plasmodium falciparum life cycle in humans. Anti-GLURP antibodies can inhibit parasite growth in the presence of monocytes via antibody-dependent cellular inhibition (ADCI), and a major parasite-inhibitory region has been found in the N-terminal R0 region of the protein. Herein, we describe the antiplasmodial activity of anti-GLURP antibodies present in the sera from individuals naturally exposed to malaria in a Brazilian malaria-endemic area. The anti-R0 antibodies showed a potent inhibitory effect on the growth of P. falciparum in vitro, both in the presence (ADCI) and absence (GI) of monocytes. The inhibitory effect on parasite growth was comparable to the effect of IgGs purified from pooled sera from hyperimmune African individuals. Interestingly, in the ADCI test, higher levels of tumour necrosis factor alpha (TNF-α) were observed in the supernatant from cultures with higher parasitemias. Our data suggest that the antibody response induced by GLURP-R0 in naturally exposed individuals may have an important role in controlling parasitemia because these antibodies are able to inhibit the in vitro growth of P. falciparum with or without the cooperation from monocytes. Our results also indicate that TNF-α may not be relevant for the inhibitory effect on P. falciparum in vitro growth.

Differential in vitro activity of the DNA topoisomerase inhibitor idarubicin against Trypanosoma rangeli and Trypanosoma cruzi

In this study the effect of eight DNA topoisomerase inhibitors on the growth Trypanosoma rangeli epimastigotes in cell culture was investigated. Among the eight compounds tested, idarubicin was the only compound that displayed promising trypanocidal activity with a half-maximal growth inhibition (GI50) value in the sub-micromolar range. Fluorescence-activated cell sorting analysis showed a reduction in DNA content in T. rangeli epimastigotes when treated with idarubicin. In contrast to T. rangeli, against Trypanosoma cruzi epimastigotes idarubicin was much less effective exhibiting a GI50 value in the mid-micromolar range. This result indicates that idarubicin displays differential toxic effects in T. rangeli and T. cruzi. Compared with African trypanosomes, it seems that American trypanosomes are generally less susceptible to DNA topoisomerase inhibitors.

The in vitro activity of fatty diamines and amino alcohols against mixed amastigote and trypomastigote Trypanosoma cruzi forms

Four diamines and three amino alcohols derived from 1-decanol, 1-dodecanol and 1,2-dodecanediol were evaluated in an in vitro assay against a mixture of trypomastigote and intracellular amastigote forms of Trypanosoma cruzi. Two of these compounds (6 and 7) showed better activity against both proliferative stages of T. cruzi than the positive control benznidazole, three were of similar potency (1, 2 and 5) and two were less active (3 and 4).

Blood shizonticidal activities of phenazines and naphthoquinoidal compounds against Plasmodium falciparum in vitro and in mice malaria studies

Due to the recent advances of atovaquone, a naphthoquinone, through clinical trials as treatment for malarial infection, 19 quinone derivatives with previously reported structures were also evaluated for blood schizonticide activity against the malaria parasite Plasmodium falciparum. These compounds include 2-hydroxy-3-methylamino naphthoquinones (2-9), lapachol (10), nor-lapachol (11), iso-lapachol (12), phthiocol (13) and phenazines (12-20). Their cytotoxicities were also evaluated against human hepatoma and normal monkey kidney cell lines. Compounds 2 and 5 showed the highest activity against P. falciparum chloroquine-resistant blood-stage parasites (clone W2), indicated by their low inhibitory concentration for 50% (IC50) of parasite growth. The therapeutic potential of the active compounds was evaluated according to the selectivity index, which is a ratio of the cytotoxicity minimum lethal dose which eliminates 50% of cells and the in vitro IC50. Naphthoquinones 2 and 5, with activities similar to the reference antimalarial chloroquine, were also active against malaria in mice and suppressed parasitaemia by more than 60% in contrast to compound 11 which was inactive. Based on their in vitro and in vivo activities, compounds 2 and 5 are considered promising molecules for antimalarial treatment and warrant further study.

The efficacy of 2-nitrovinylfuran derivatives againstLeishmania in vitro and in vivo

Despite recent advances in the treatment of some forms of leishmaniasis, the available drugs are still far from ideal due to inefficacy, parasite resistance, toxicity and cost. The wide-spectrum antimicrobial activity of 2-nitrovinylfuran compounds has been described, as has their activity against Trichomonas vaginalis and other protozoa. Thus, the aim of this study was to test the antileishmanial activities of six 2-nitrovinylfurans in vitro and in a murine model of leishmaniasis. Minimum parasiticide concentration (MPC) and 50% inhibitory concentration (IC50) values for these compounds against the promastigotes of Leishmania amazonensis, Leishmania infantum and Leishmania braziliensis were determined, as were the efficacies of two selected compounds in an experimental model of cutaneous leishmaniasis (CL) caused by L. amazonensis in BALB/c mice. All of the compounds were active against the promastigotes of the three Leishmania species tested. IC50 and MPC values were in the ranges of 0.8-4.7 µM and 1.7-32 µM, respectively. The compounds 2-bromo-5-(2-bromo-2-nitrovinyl)-furan (furvina) and 2-bromo-5-(2-methyl-2-nitrovinyl)-furan (UC245) also reduced lesion growth in vivo at a magnitude comparable to or higher than that achieved by amphotericin B treatment. The results demonstrate the potential of this class of compounds as antileishmanial agents and support the clinical testing of Dermofural(r) (a furvina-containing antifungal ointment) for the treatment of CL.

Estrogenic activity assessment of environmental chemicals using in vitro assays: identification of two new estrogenic compounds.

Environmental chemicals with estrogenic activities have been suggested to be associated with deleterious effects in animals and humans. To characterize estrogenic chemicals and their mechanisms of action, we established in vitro and cell culture assays that detect human estrogen receptor [alpha] (hER[alpha])-mediated estrogenicity. First, we assayed chemicals to determine their ability to modulate direct interaction between the hER[alpha] and the steroid receptor coactivator-1 (SRC-1) and in a competition binding assay to displace 17ss-estradiol (E(2)). Second, we tested the chemicals for estrogen-associated transcriptional activity in the yeast estrogen screen and in the estrogen-responsive MCF-7 human breast cancer cell line. The chemicals investigated in this study were o,p'-DDT (racemic mixture and enantiomers), nonylphenol mixture (NPm), and two poorly analyzed compounds in the environment, namely, tris-4-(chlorophenyl)methane (Tris-H) and tris-4-(chlorophenyl)methanol (Tris-OH). In both yeast and MCF-7 cells, we determined estrogenic activity via the estrogen receptor (ER) for o,p'-DDT, NPm, and for the very first time, Tris-H and Tris-OH. However, unlike estrogens, none of these xenobiotics seemed to be able to induce ER/SRC-1 interactions, most likely because the conformation of the activated receptor would not allow direct contacts with this coactivator. However, these compounds were able to inhibit [(3)H]-E(2) binding to hER, which reveals a direct interaction with the receptor. In conclusion, the test compounds are estrogen mimics, but their molecular mechanism of action appears to be different from that of the natural hormone as revealed by the receptor/coactivator interaction analysis.

Assessment of the in vitro synergy of daptomycin plus linezolid against multidrug-resistant enterococci

The widespread incidence of enterococci resistant to ampicillin, vancomycin and aminoglycosides, the first-line anti-enterococcal antibiotics, has made the treatment of severe enterococcal infections difficult and alternatives should be explored. We investigated the activity of daptomycin combined with linezolid against three Enterococcus faecalis and four Enterococcus faecium strains resistant to standard drugs used for therapy. Minimum inhibitory concentrations (MICs) were determined by the broth dilution method. Drug interactions were assessed by the checkerboard and time-kill methods. Synergy was defined by a fractional inhibitory concentration index (FICI) of ≤0.5 or a ≥2 log10 CFU/mL killing at 24 h with the combination in comparison with killing by the most active single agent. Indifference was defined by a FICI > 0.5-4.0 or a 1-2 log10 CFU/mL killing compared with the most active single agent. MICs of daptomycin were 2-4 μg/mL for E. faecalis and 2-8 μg/mL for E. faecium. MICs of linezolid were 1-2 μg/mL for all bacteria. In the checkerboard assay, five isolates showed synergism (FICI < 0.5) and two showed indifference (FICIs of 0.53 and 2). Killing studies revealed synergy of daptomycin plus linezolid against four isolates (2.2-3.7 log10 CFU/mL kill) and indifference (1.1-1.6 log10 CFU/mL kill) for the other three strains. Antagonism was not observed. In conclusion, the combination of daptomycin and linezolid had a synergistic or indifferent effect against multidrug-resistant enterococci. Additional studies are needed to explore the potential of this combination for severe enterococcal infections when first-line antibiotic combinations cannot be used.

High activity of Fosfomycin and Rifampin against methicillin-resistant staphylococcus aureus biofilm in vitro and in an experimental foreign-body infection model.

Increasing antimicrobial resistance reduces treatment options for implant-associated infections caused by methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the activity of fosfomycin alone and in combination with vancomycin, daptomycin, rifampin, and tigecycline against MRSA (ATCC 43300) in a foreign-body (implantable cage) infection model. The MICs of the individual agents were as follows: fosfomycin, 1 μg/ml; daptomycin, 0.125 μg/ml; vancomycin, 1 μg/ml; rifampin, 0.04 μg/ml; and tigecycline, 0.125 μg/ml. Microcalorimetry showed synergistic activity of fosfomycin and rifampin at subinhibitory concentrations against planktonic and biofilm MRSA. In time-kill curves, fosfomycin exhibited time-dependent activity against MRSA with a reduction of 2.5 log10 CFU/ml at 128 × the MIC. In the animal model, planktonic bacteria in cage fluid were reduced by <1 log10 CFU/ml with fosfomycin and tigecycline, 1.7 log10 with daptomycin, 2.2 log10 with fosfomycin-tigecycline and fosfomycin-vancomycin, 3.8 log10 with fosfomycin-daptomycin, and >6.0 log10 with daptomycin-rifampin and fosfomycin-rifampin. Daptomycin-rifampin cured 67% of cage-associated infections and fosfomycin-rifampin cured 83%, whereas all single drugs (fosfomycin, daptomycin, and tigecycline) and rifampin-free fosfomycin combinations showed no cure of MRSA cage-associated infections. No emergence of fosfomycin resistance was observed in animals; however, a 4-fold increase in fosfomycin MIC (from 2 to 16 μg/ml) occurred in the fosfomycin-vancomycin group. In summary, the highest eradication of MRSA cage-associated infections was achieved with fosfomycin in combination with rifampin (83%). Fosfomycin may be used in combination with rifampin against MRSA implant-associated infections, but it cannot replace rifampin as an antibiofilm agent.

A large-scale genetic validation study coupled with in vitro analyses reveal a role for vitamin Dsignaling in the pathogenesis and response to treatment of hepatitis C virus infection

Background and Aims: Vitamin D is an important modulatorof numerous cellular processes. Some of us recently observedan association of the 1a-hydroxylase promoter polymorphismCYP27B1-1260 rs10877012 with sustained virologic response (SVR)in a relatively small number of German patients with chronichepatitis C. In the present study, we aimed to validate thisassociation in a large and well characterized patient cohort, theSwiss Hepatitis C Cohort Study (SCCS). In addition, we examinedthe effect of vitamin D on the hepatitis C virus (HCV) life cyclein vitro.Methods: CYP27B1-1260 rs10877012 and IL28B rs12979860 singlenucleotide polymorphisms (SNPs) were genotyped in 1049 patientswith chronic hepatitis C from the SCCS, of whom 698 were treatedwith pegylated interferon-a (PEG-IFN-a) and ribavirin. In addition,112 patients with spontaneous clearance of HCV were examined.SNPs were correlated with variables reflecting the natural courseand treatment outcome of chronic hepatitis C. The effect of1,25-(OH)2D3 (calcitriol) on HCV replication and viral particleproduction was investigated in vitro using human hepatoma celllines (Huh-7.5) harbouring subgenomic replicons and cell culturederivedHCV.Results: The CYP27B1-1260 rs10877012 genotype was notassociated with SVR in patients with the good-response IL28Brs1279860 CC genotype. However, in patients with poor-responseIL28B rs1279860 genotype CT and TT, CYP27B1-1260 rs10877012was a significant independent predictor of SVR (15% difference inSVR between rs10877012 genotype AA vs. CC, p = 0.030, OR = 1.495,95% CI = 1.038-2.152). The CYPB27-1260 rs10877012 genotype wasneither associated with spontaneous clearance of HCV, nor withliver fibrosis progression rate, inflammatory activity of chronichepatitis C, or HCV viral load. Physiological doses of 1,25-(OH)2D3did not significantly affect HCVRNA replication or infectiousparticle production in vitro.Conclusions: The results of this large-scale genetic validationstudy reveal a role of vitamin D metabolism in the responseto treatment in chronic hepatitis C, but 1,25-(OH)2D3 does notexhibit a significant direct inhibitory antiviral effect. Thus, theability of vitamin D to modulate immunity against HCV shouldbe investigated.

In Vitro Activity of Gentamicin-Loaded Bioabsorbable Beads against Different Microorganisms

Abstract: Osteomyelitis is responsible for high treatment costs, long hospital stays, and results in substantial morbidity. Treatment with surgical debridement and antibiotic-impregnated Polymethylmetacrylate (PMMA) beads is the standard of care, providing high local but low serum antibiotic concentrations, thereby avoiding systemic toxicity. However, for several reasons, the beads require surgical removal. Alternative antibiotic delivery systems should improve the treatment of bone infection, actively encourage bone healing and require no additional surgery for removal. We investigated the activity of gentamicin-loaded bioabsorbable beads against different microorganisms (Staphylococcus epidermidis, S. aureus, Escherichia coli, Enterococcus faecalis, Candida albicans) commonly causing surgical site bone infection, by microcalorimetry. Calcium sulphate beads containing gentamicin were incubated in microcalorimetry ampoules containing different concentrations of the corresponding microorganism. Growth medium with each germ and unloaded beads was used as positive control, growth medium with loaded beads alone as negative control. Bacterial growth-related heat production at 37 °C was measured for 24 h. Cultures without gentamicin-loaded beads produced heat-flow peaks corresponding to the exponential growth of the corresponding microorganisms in nutrient-rich medium. In contrast, cultures with gentamicin-loaded beads completely suppressed heat production during 24 h, demonstrating their antibiotic activity. Gentamicin-loaded beads effectively inhibited growth of susceptible microorganisms, under the described in vitro conditions.

In vitro activity of gentamicin-loaded bioabsorbable beads against different microorganisms

Grâce à la prophylaxie antibiotique per-opératoire, à l'amélioration des techniques chirurgicales et au flux laminaire dans les blocs opératoires le taux d'infections postopératoires a pu être diminué dans les interventions chirurgicales orthopédiques. Il stagne néanmoins à environ 0,5- 2% dans les fractures fermées ainsi que dans les interventions orthopédiques électives, et peut monter jusqu'à 30% dans les fractures ouvertes stade III. L'ostéomyelite et la pseudarthrose infectée, qui peuvent en découler, sont responsables de séjours hospitaliers prolongés, engendrent des coûts de traitement élevés, et conduisent souvent à une morbidité substantielle. Le traitement de l'ostéomyelite combine le débridement chirurgical et l'administration d'antibiotiques. Cependant l'administration systémique d'antibiotiques à hautes doses est problématique en raison de leur toxicité systémique et de leur faible pénétration dans les tissus ischémiques et nécrotiques, souvent présents dans l'ostéomyelite. Pour ces raisons, le traitement standard actuel consiste, après débridement chirurgical, en la mise en place de billes de Polyrnéthylmétacrylate (PMMA) imprégnées d'antibiotique, qui fournissent des concentrations locales élevées mais systémiques basses. Malheureusement, ces billes doivent être enlevées une fois l'infection guérie, ce qui nécessite une nouvelle intervention chirurgicale. Des systèmes de libération antibiotique alternatifs devraient non seulement guérir l'infection osseuse, mais également encourager activement la consolidation osseuse et ne pas nécessiter de nouvelle chirurgie pour leur ablation. Nous avons investigué l'activité de billes résorbables chargées en gentamicine contre différents microorganismes (Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Candida albicans), des germes communément responsables d'infections osseuses, par microcalorimétrie, une méthode novice basée sur la mesure de la chaleur produite par des microorganismes qui se répliquent dans une culture. Des billes composées essentiellement de sulfate de calcium et chargées en gentamicine ont été incubées dans des ampoules microcalorimétriques contenant différentes concentrations du germe correspondant. Les bouillons de culture avec chaque germe et billes non-chargées ont été utilisés comme contrôle positif, le bouillon de culture avec bille chargée mais sans germe comme contrôle négatif. La production de chaleur provenant de la croissance bactérienne à 37°C a été mesurée pendant 24 heures. Les cultures ne contenant pas de billes chargées en gentamicine ont. produit des pics de chaleur équivalents à la croissance exponentielle du microorganisme correspondant en milieu riche. Par contre, les germes susceptibles à la gentamicine incubés avec les billes chargées ont complètement supprimé leur production de chaleur pendant 24 heures, démontrant ainsi l'activité antibiotique des billes chargées en gentamicine contre ces germes. Les billes résorbables chargées en gentamicine inhibent donc de façon effective la croissance des germes susceptibles sous les conditions in vitro décrites. Des études sur animaux sont maintenant nécessaires pour déterminer la cinétique d'élution et l'effet antimicrobien de la gentamicine sous conditions in vivo. Finalement des études cliniques devront démontrer que l'utilisation de ces billes est effectivement une bonne option thérapeutique dans le traitement des infections osseuses.