Antimicrobial activity of the toxin VdTX-I from the spider Vitalius dubius (Araneae,Theraphosidae)

BackgroundCurrently there is an urgent need to develop new classes of antimicrobial agents with different mechanisms of action from conventionally antibiotics used for the control of pathogenic microorganisms. The acylpolyamine called VdTX-I was isolated from the venom of the tarantula Vitalius dubius, and first described with activity as an antagonist of nicotinic cholinergic receptors. The main objective of this study was to investigate the antimicrobial activity found in the venom of the spider, with emphasis on the toxin VdTX-I.MethodsAntimicrobial assays were performed in 96 well plates culture against 14 micro-organisms (fungi, yeasts and bacteria), which were tested concentrations from 0.19 to 100 μM of VdTX-I. After qualitative analysis, dose-response curve assays were performed in bacterial kill curve using MTT reagent and hemolytic assay.ResultsThe antimicrobial activity of the VdTX-I toxin was observed in 12 tested species of Candida, Trichosporiun, Staphylococcus and Micrococcus. The toxicity had a dose-response at 3.12 µM – 100 μM in Candida albicans, Candida guillermondii, Micrococcus luteus and Escherichia coli. VdTX-I took about 5 min to inhibit bacterial growth, which was faster than streptomycin. The toxin showed no hemolytic activity between 0.19 and 100 μM. At 2.5 µg/mL of toxin it was observed no growth inhibition against a mammalian cell lineage.ConclusionsThe VdTX-I toxin has a significant antimicrobial activity, with broad spectrum, and is experimentally inert to mammalian blood cells.General SignificanceThis paper explores the antimicrobial potential of the spider toxin VdTX-I, which can provide a new model to design new antimicrobial drugs.     

α-Linolenic acid attenuates pseudo-allergic reactions by inhibiting Lyn kinase activity

BackgroundPseudo-allergic reactions are potentially fatal hypersensitivity responses caused by mast cell activation. α-linolenic acid (ALA) is known for its anti-allergic properties. However, its potential anti-pseudo-allergic effects were not much investigated.PurposeTo investigate the inhibitory effects of ALA on IgE-independent allergy in vitro, and in vivo, as well as the mechanism underlying its effects.Methods/study designsThe anti-anaphylactoid activity of ALA was evaluated in passive cutaneous anaphylaxis reaction (PCA) and systemic anaphylaxis models. Calcium imaging was used to assess intracellular Ca²⁺ mobilization. The release of cytokines and chemokines was measured using enzyme immunoassay kits. Western blot analysis was conducted to investigate the molecules of Lyn-PLCγ-IP3R-Ca²⁺ and Lyn-p38/NF-κB signaling pathway.ResultsALA (0, 1.0, 2.0, and 4.0 mg/kg) dose-dependently reduced serum histamine, chemokine release, vasodilation, eosinophil infiltration, and the percentage of degranulated mast cells in C57BL/6 mice. In addition, ALA (0, 50, 100, and 200 μM) reduced Compound 48/80 (C48/80) (30 μg/ml)-or Substance P (SP) (4 μg/ml)-induced calcium influx, mast cell degranulation and cytokines and chemokine release in Laboratory of Allergic Disease 2 (LAD2) cells via Lyn-PLCγ-IP3R-Ca²⁺ and Lyn-p38/NF-κB signaling pathway. Moreover, ALA (0, 50, 100, and 200 μM) inhibited C48/80 (30 μg/ml)- and SP (4 μg/ml)-induced calcium influx in Mas-related G-protein coupled receptor member X2 (MrgX2)-HEK293 cells and in vitro kinase assays confirmed that ALA inhibited the activity of Lyn kinase. In response to 200 μM of ALA, the activity of Lyn kinase by (7.296 ± 0.03751) × 10⁻⁵ units/μl and decreased compared with C48/80 (30 μg/ml) by (8.572 ± 0.1365) ×10⁻⁵ units/μl.ConclusionOur results demonstrate that ALA might be a potential Lyn kinase inhibitor, which could be used to treat pseudo-allergic reaction-related diseases such as urticaria.     

Effect of Ottoman Viper (Montivipera xanthina (Gray, 1849)) Venom on Various Cancer Cells and on Microorganisms

Cytotoxic and antimicrobial effects of Montivipera xanthina venom against LNCaP, MCF-7, HT-29, Saos-2, Hep3B, Vero cells and antimicrobial activity against selected bacterial and fungal species: Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, E. coli O157H7, Enterococcus faecalis 29212, Enterococcus faecium DSM 13590, Staphylococcus epidermidis ATCC 12228, S. typhimirium CCM 5445, Proteus vulgaris ATCC 6957 and Candida albicans ATCC 10239 were studied for evaluating the potential medical benefit of this snake venom. Cytotoxicity of venom was determined using MTT assay. Snake venom cytotoxicity was expressed as the venom dose that killed 50 % of the cells (IC₅₀). The antimicrobial activity of venom was studied by minimal inhibitory concentration (MIC) and disc diffusion assay. MIC was determined using broth dilution method. The estimated IC₅₀ values of venom varied from 3.8 to 12.7 or from 1.9 to 7.2 μg/ml after treatment with crude venom for 24 or 48 h for LNCaP, MCF-7, HT-29 and Saos-2 cells. There was no observable cytotoxic effect on Hep3B and Vero cells. Venom exhibited the most potent activity against C. albicans (MIC, 7.8 μg/ml and minimal fungicidal concentration, 62.5 μg/ml) and S. aureus (MIC, 31.25 μg/ml). This study is the first report showing the potential of M. xanthina venom as an alternative therapeutic approach due to its cytotoxic and antimicrobial effects.     

Comparative assessment of biological activities of different parts of halophytic plant Tamarix articulata (T. articulata) growing in Saudi Arabia

Owing to extremely high salinity and harsh environmental conditions, T. articulata is one of the most abundant wild plants growing in the deserts of Saudi Arabia. Such plants may contain novel compounds to display promising biological activities. Here, in this study, we evaluate the biological activities of methanolic extracts of fresh leaves, dry leaves, stem, and roots of T. articulata. The antioxidant activity was determined by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and total phenolic and flavonoid content were determined using standard colorimetric methods. Whereas antimicrobial and ant-proliferative activities were determined by standard well-diffusion and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) methods, respectively. Our results demonstrate that all methanolic extracts of T. articulata showed antioxidant activity, however, the methanolic extract of dry leaves exhibits promising antioxidant effect with IC₅₀ value 49.08 ± 1.98, which was strongly supported by total phenolic (409.92 ± 6.03 mg GAE/g DW) and flavonoid (177.71 mg QE/g DW) content. Although, antimicrobial activity was also exhibited by all the methanolic extracts, however, methanolic extract of dry leaves exhibits promising antimicrobial activity in Gram-positive bacteria Staphylococcus epidemidis. Furthermore, MTT assay revealed that all methanolic extracts exhibit antiproliferative activity in MCF-7 (breast cancer) and RKO (colorectal cancer) cells with IC₅₀ values ranges from 219 ± 5.112 µg/ml to 253 ± 5.231 µg/ml and 220 ± 4.330 µg/ml to 325 ± 6.213 µg/ml, respectively. However, the most promising antiproliferative effect was displayed by methanolic extract of dry leaves with IC₅₀ values 219 ± 5.112 µg/ml and 220 ± 4.330 µg/ml, respectively. In summary, these findings provide evidence that T. articulata has promising biological activities and can be used for many pharmaceutical activities in the future.     

Piper crocatum Ruiz & Pav. ameliorates wound healing through p53, E-cadherin and SOD1 pathways on wounded hyperglycemia fibroblasts

IntroductionPiper crocatum Ruiz & Pav (P. crocatum) has been reported to accelerate the diabetic wound healing process empirically. Some studies showed the benefits of P. crocatum in treating various diseases but its mechanisms in diabetic wound healing have never been reported. In the present study we investigated the diabetic wound healing activity of the active fraction of P. crocatum on wounded hyperglycemia fibroblasts (wHFs).MethodsBioassay-guided fractionation was performed to get the most active fraction. The selected active fraction was applied to wHFs within 72 h incubation. Mimicking a diabetic condition was done using basal glucose media containing an additional 17 mMol/L D-glucose. A wound was simulated via the scratch assay. The collagen deposition was measured using Picro-Sirius Red and wound closure was measured using scratch wound assay. Underlying mechanisms through p53, αSMA, SOD1 and E-cadherin were measured using western blotting.ResultsWe reported that F_IV is the most active fraction of P. crocatum. We confirmed that F_IV\(7.81 µg/ml, 15.62 µg/ml, 31.25 µg/ml, 62.5 µg/ml, and 125 µg/ml) induced the collagen deposition and wound closure of wHFs. Furthermore, F_IV treatment (7.81 µg/ml, 15.62 µg/ml, 31.25 µg/ml) down-regulated the protein expression level of p53 and up-regulated the protein expression levels of αSMA, E-cadherin, and SOD1.Discussion/conclusionsOur findings suggest that ameliorating collagen deposition and wound closure through protein regulation of p53, αSMA, E-cadherin, and SOD1 are some of the mechanisms by which F_IV of P. crocatum is involved in diabetic wound healing therapy.     

New antimicrobial anthraquinone 6,61-bis (1,5,7-trihydroxy-3-hydroxymethylanthraquinone) isolated from Streptomyces sp. isolate ERI-26

The present report is about Streptomyces sp. isolate ERI-26 isolated from the soil sample of Nilgiri forest, Western Ghats. The methanol extract of ERI-26 showed good antimicrobial activity against tested microbes. The antimicrobial novel anthraquinones were purified by bioactivity-guided fractionation using a silica gel column and preparative HPLC. The compound was characterized and identified by UV, IR, NMR and MASS spectral data. The compound named as 6,6¹-bis (1,5,7-trihydroxy-3-hydroxymethylanthraquinone), showed significant antimicrobial activities against tested microbes. The isolated compound inhibited the tested bacterial growth, Staphylococcus aureus at 62.5 μg/ml, Staphylococcus epidermidis at 15.62 μg/m, Bacillus subtilis at 62.5 μg/ml, fungi; Trichophyton mentagrophytes at 15.62 μg/m Trichophyton simii at 15.62 μg/ml, Aspergillus niger at. 7.81 μg/ml, Aspergiller flavus at 3.90 μg/ml, Trichophyton rubrum 296 at 62.5 μg/ml, T. rubrum 57/01 at 7.81 μg/ml, Magnaporthe grisea at 15.62 μg/ml. and Botrytis cinerea at 3.90 μg/ml. Isolated anthraquinone compound and its antimicrobial activity were newly reported.     

Ebselen and analogs as inhibitors of Bacillus anthracis thioredoxin reductase and bactericidal antibacterials targeting Bacillus species,Staphylococcus aureus and Mycobacterium tuberculosis

BackgroundBacillus anthracis is the causative agent of anthrax, a disease associated with a very high mortality rate in its invasive forms.MethodsWe studied a number of ebselen analogs as inhibitors of B. anthracis thioredoxin reductase and their antibacterial activity on Bacillus subtilis, Staphylococcus aureus, Bacillus cereus and Mycobacterium tuberculosis.ResultsThe most potent compounds in the series gave IC50 values down to 70 nM for the pure enzyme and minimal inhibitory concentrations (MICs) down to 0.4 μM (0.12 μg/ml) for B. subtilis, 1.5 μM (0.64 μg/ml) for S. aureus, 2 μM (0.86 μg/ml) for B. cereus and 10 μg/ml for M. tuberculosis. Minimal bactericidal concentrations (MBCs) were found at 1–1.5 times the MIC, indicating a general, class-dependent, bactericidal mode of action. The combined bacteriological and enzymological data were used to construct a preliminary structure–activity-relationship for the benzoisoselenazol class of compounds. When S. aureus and B. subtilis were exposed to ebselen, we were unable to isolate resistant mutants on both solid and in liquid medium suggesting a high resistance barrier.ConclusionsThese results suggest that ebselen and analogs thereof could be developed into a novel antibiotic class, useful for the treatment of infections caused by B. anthracis, S. aureus, M. tuberculosis and other clinically important bacteria. Furthermore, the high barrier against resistance development is encouraging for further drug development.General significanceWe have characterized the thioredoxin system from B. anthracis as a novel drug target and ebselen and analogs thereof as a potential new class of antibiotics targeting several important human pathogens.     

Toxic copper level increases erythrocyte glycolytic rate,glutathione production and alters electrolyte balance in male Wistar rats

BackgroundCopper is a micronutrient vital to several cellular energy metabolic processes and drives erythropoiesis. However, it disrupts cellular biological activities and causes oxidative damage when in excess of cellular needs. This study investigated the effects of copper toxicity on erythrocyte energy metabolism in male Wistar rats.MethodsTen Wistar rats (150–170 g) were randomly divided into 2 groups: control (given 0.1 ml distilled water) and copper toxic (given 100 mg/kg copper sulphate). Rats were orally treated for 30 days. Blood, collected retro-orbitally after sodium thiopentone anaesthesia (50 mg/kg i.p.) into fluoride oxalate and EDTA bottles, was subjected to blood lactate assay and extraction of red blood cell respectively. Red blood cell nitric oxide (RBC NO), glutathione (RBC GSH), adenosine triphosphate (RBC ATP) levels, RBC hexokinase, glucose-6-phosphate (RBC G6P), glucose-6-phosphate dehydrogenase (RBC G6PDH), and lactate dehydrogenase (RBC LDH) activity was estimated spectrophotometrically. Values (Mean±SEM, n = 5) were compared by Student’s unpaired T-test at p < 0.05.Results and conclusionCopper toxicity significantly increased RBC hexokinase (23.41 ± 2.80 µM), G6P (0.48 ± 0.03 µM), G6PDH (71.03 ± 4.76nmol/min/ml) activities, ATP (624.70 ± 57.36 µmol/gHb) and GSH (3.08 ± 0.37 µM) level compared to control (15.28 ± 1.37 µM, 0.35 ± 0.02 µM, 330.30 ± 49.58 µmol/gHb, 54.41 ± 3.01nmol/min/ml and 2.05 ± 0.14 µM respectively, p < 0.05). Also, RBC LDH activity (145.00 ± 19.88mU/ml), NO (3.45 ± 0.25 µM) and blood lactate (31.64 ± 0.91 mg/dl) level were lowered significantly compared to control (467.90 ± 94.23mU/ml, 4.48 ± 0.18 µM and 36.12 ± 1.06 mg/dl respectively). This study shows that copper toxicity increases erythrocyte glycolytic rate and glutathione production. This increase could be connected to a compensatory mechanism for cellular hypoxia and increased free radical generation.     

Synthesis and larvicidal activity of indole derivatives against Aedes aegypti (Diptera: Culicidae)

In light of the challenges to control Aedes aegypti and the critical role that it plays as arbovirus vector, it is imperative to adopt strategies that provide fast, efficient and environmentally safe control of the insect population. In the present study, we synthesized six indole derivatives (C1‐C6) and examined their larvicidal activity and persistence against Ae. aegypti larvae, as well as their toxicity towards Raw 264.7 macrophages, Vero cells, Chlorella vulgaris BR017, Scenedesmus obliquus BR003, Caenorhabditis elegans N2 and Galleria mellonella. Among the bioactive compounds (C1, C2, C4 and C5), C2 exerted the strongest larvicidal activity against Ae. aegypti, with LC50 = 1.5 μg/ml (5.88 µM) and LC90 = 2.4 μg/ml (9.50 µM), indicating that the presence of chlorine or bromine groups in the aromatic ring improved the larvicidal activity of the indole derivatives. C1, C2, C4 and C5 did not reduce viability of RAW 264.7 macrophages, Vero cells, C. elegans N2 and G. mellonella. Compounds C1, C2 and C5 did not affect the growth of C. vulgaris BR017 and S. obliquus BR003. Analysis of larvicidal persistence under laboratory conditions revealed that the effect of compounds C1, C2, C4 and C5 lasted for 30 days and caused 100% of larvae mortality within few hours. Altogether, our findings demonstrate that the indole derivatives C1, C2, C4 and C5 effectively control Ae. aegypti larvae population, without clear signs of toxicity to mammalian cells, algae, C. elegans and G. mellonella.     

The antimicrobial effects of deglycyrrhizinated licorice root extract on Streptococcus mutans UA159 in both planktonic and biofilm cultures

The objective of the study was to investigate the antimicrobial effects of deglycyrrhizinated licorice root extracts (DG-LRE) against Streptococcus mutans UA159 in both the planktonic and biofilm phases by determining the minimum inhibitory concentration and minimum bactericidal concentration, and by performing time-kill kinetic, growth, adhesion, and biofilm assays. The cell toxicity of DG-LRE on normal human gingival fibroblast (NHGF) cells was tested using a methyl thiazolyl tetrazolium assay. This study showed that DG-LRE had strong antimicrobial activity against S. mutans in the planktonic phase with little cytotoxic effect on NHGF cells. In addition, DG-LRE significantly inhibited biofilm formation by S. mutans UA159 at concentrations over 4 μg/ml for glucose or 16 μg/ml for sucrose, respectively, regardless of the presence of saliva-coating. To the best of our knowledge, this is the first report to provide evidence that DG-LRE demonstrates antimicrobial activity against S. mutans. These results suggest that DG-LRE can be used in developing oral hygiene products, such as gargling solution and dentifrice to prevent human dental caries.     

Cytotoxicity of a naturally occurring furoquinoline alkaloid and four acridone alkaloids towards multi-factorial drug-resistant cancer cells

IntroductionChemotherapy is one of the preferred mode of treatment of malignancies, but is complicated by the expression of diverse resistance mechanisms of cancer cells.MethodsIn the present study, we investigated the cytotoxicity of five alkaloids including a furoquinoline montrofoline (1) and four acridones namely 1-hydroxy-4-methoxy-10-methylacridone (2), norevoxanthine (3), evoxanthine (4), 1,3-dimethoxy-10-methylacridone (5) against 9 drug-sensitive and multidrug-resistant (MDR) cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle, mitochondrial membrane potential (MMP) and levels of reactive oxygen species (ROS) were all analyzed via flow cytometry.ResultsFuroquinoline 1 as well as the acridone alkaloids 2–5 displayed cytotoxic effects with IC₅₀ values below 138 µM on all the 9 tested cancer cell lines. The IC₅₀ values ranged from 41.56 µM (towards hepatocarinoma HepG2 cells) to 90.66 µM [towards colon carcinoma HCT116 (p53^−/−) cells] for 1, from 6.78 µM [towards HCT116 (p53^−/−) cells) to 106.47 µM [towards breast adenocarcinoma MDA-MB-231-pcDNA cells] for 2, from 5.72 µM (towards gliobastoma U87MG.ΔEGFR cells) to 137.62 µM (towards leukemia CCRF-CEM cells] for 3, from 6.11 µM [towards HCT116 (p53^+/+) cells] to 80.99 µM (towards HepG2 cells] for 4, from 3.38 µM (towards MDA-MB-231-BCRP cells) to 58.10 µM (towards leukemia CEM/ADR5000 cells] for 5 and from 0.20 µM (against CCRF-CEM cells) to 195.12 µM (against CEM/ADR5000 cells) for doxorubicin. Acridone alkaloid 5 induced apoptosis in CCRF-CEM leukemia cells, mediated by increased ROS production.ConclusionsThe five tested alkaloids and mostly acridone 5 are potential cytotoxic natural products that deserve more investigations to develop novel cytotoxic compounds against multifactorial drug-resistant cancers.     

Constituents of Leonotis leonurus flowering tops

Phytochemical investigation of flowering tops of Leonotis leonurus, yielded a new diterpene ester, 1,2,3-trihydroxy-3,7,11,15-tetramethylhexadecan-1-yl-palmitate along with five known metabolites. The structures of all compounds were determined by spectroscopic methods including 1D- and 2D NMR spectroscopy. All the isolated compounds were evaluated for antimalarial, cytotoxicity and for antimicrobial activities. Antimalarial activity for luteolin 7-O-β-d-glucopyranoside (4) (IC₅₀ = 2.2 μg/mL for the D6 clone and 1.8 μg/mL for the W2 clone) was observed. Chloroquine and artemisinin were used as positive controls which showed IC₅₀ of 0.016 and 0.0048 μg/mL for the D6 clone, respectively, and IC₅₀ of 0.14 and 0.0047 μg/mL for the W2 clone, respectively. None of the compounds were cytotoxic to Vero cells up to a concentration of 4.76 μg/mL.     

Cytotoxicity and antioxidant activity of 5-(2,4-dimethylbenzyl)pyrrolidin-2-one extracted from marine Streptomyces VITSVK5 spp.

The aim of the present study was to evaluate the cytotoxicity and antioxidant activity of 5-(2,4-dimethylbenzyl)pyrrolidin-2-one (DMBPO) extracted from marine Streptomyces VITSVK5 spp. The strain was isolated from sediment samples collected at the Marakkanam coast of Bay of Bengal, India. Systematic screening of isolates for anti-Aspergillus activity resulted in the identification of Streptomyces species designated as Streptomyces VITSVK5 spp. Bioactivity guided extraction and purification yielded a compound 5-(2,4-dimethylbenzyl)pyrrolidin-2-one (DMBPO) and was tested for cytotoxicity and antioxidant activity. The structure of the extracted compound was established by spectroscopic studies and identified as 5-(2,4-dimethylbenzyl)pyrrolidin-2-one (DMBPO). DMBPO exhibited cytotoxic activity on HEP 2 and Hep G2 cell lines with the IC₅₀ value of 2.8 μg/ml and 8.3 μg/ml, respectively, as compared to Vero cell line (22.6). DMBPO showed the hemolytic EC₅₀ value of 288 μg/ml on human erythrocytes. DMBPO treatment showed fewer (31.7%) aberrations, gaps and chromatid breaks as compared to untreated controls (27.8%) of human chromosomes. DMBPO also exhibited significant (44.13% at 5 μg/ml DMBPO) DPPH radical scavenging activity and total antioxidant activity (50.10% at 5 μg/ml DMBPO). The results of this study showed that DMBPO is cytotoxic to cancer cells and possesses antioxidant property.     

Identification of a bioactive compound isolated from Brazilian propolis type 6

A prenylated benzophenone, hyperibone A, was isolated from the hexane fraction of Brazilian propolis type 6. Its structure was determined by spectral analysis including 2D NMR. This compound exhibited cytotoxic activity against HeLa tumor cells (IC₅₀ = 0.1756 μM), strong antimicrobial activity (MIC range—0.73–6.6 μg/mL; MBC range—2.92–106 μg/mL) against Streptococcus mutans, Streptococcus sobrinus, Streptococcus oralis, Staphylococcus aureus, and Actinomyces naeslundii, and the results of its cytotoxic and antimicrobial activities were considered good.     

Primer caso de fungemia asociada a catéter por Candida nivariensis en la Península Ibérica

BackgroundIn recent years the incidence of candidemia caused by non-albicans Candida species has been increasing. Two cryptic species have been described within the Candida glabrata complex, Candida nivariensis and Candida bracarensis, which may be troublesome in laboratory identification and have lower susceptibility to fluconazole.AimsTo describe the first isolation of C. nivariensis in the Iberian Peninsula from a patient suffering from a catheter-related fungemia.Case reportAn 81-year-old man was hospitalized for surgical treatment of an intestinal fistula that was associated to a severe malnutrition. Cultures of the patient's central venous catheter tip and blood yielded white colonies in BD CHROMagar Candida^® medium, which could not be identified by conventional microbiological methods. Although intravenous fluconazole was administered, blood cultures continued being positive 5 days later. The MIC values of the isolate were as follows: 1 μg/ml for amphotericin B, 0.015 μg/ml for anidulafungin, 0.125 μg/ml for caspofungin, 0.015 μg/ml for micafungin, 4 μg/ml for fluconazole, 0.25 μg/ml for itraconazole, 0.25 μg/ml for posaconazole, and 0.03 μg/ml for voriconazole. Antifungal treatment was changed to intravenous caspofungin for 2 weeks. The intestinal fistula was surgically treated. There was no evidence of relapse during the following month, and the patient was discharged. The isolate was identified as C. nivariensis based on DNA sequencing of the ITS regions of rRNA.ConclusionsC. nivariensis should be regarded as an emerging pathogen which requires molecular methods for a definitive identification. Our patient was successfully treated with caspofungin.     

Cytotoxicity of three naturally occurring flavonoid derived compounds (artocarpesin,cycloartocarpesin and isobavachalcone) towards multi-factorial drug-resistant cancer cells

IntroductionCancer remains an aggressive deadly disease, if drug resistance develops. This problem is aggravated by the fact that multiple rather than single mechanisms are involved in resistance and that multidrug resistance (MDR) phenomena cause inefficacy of many clinical established anticancer drugs. We are seeking for novel cytotoxic phytochemicals to combat drug-resistant tumour cells.MethodsIn the present study, we investigated the cytotoxicity of three naturally occurring flavonoids including two flavones artocarpesin (1) and cycloartocarpesin (2) and one chalcone, isobavachalcone (3) against 9 drug-sensitive and MDR cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle, mitochondrial membrane potential (MMP) and levels of reactive oxygen species (ROS) were all analysed via flow cytometry.ResultsFlavones 1 and 2 as well as chalcone 3 displayed cytotoxic effects at various extent on all the 9 tested cancer cell lines with IC₅₀ values respectively below 106 µM, 50 µM and 25 µM. The IC₅₀ values for the three investigational flavonoids ranged from 23.95 µM (towards hepatocarcinoma HepG2 cells) to 105 µM [towards colon carcinoma HCT116 (p53^−/−) cells] for 1, from 15.51 µM (towards leukemia CCRF-CEM cells) to 49.83 µM [towards glioblastoma U87MG.ΔEGFR cells] for 2 and from 2.30 µM (towards CCRF-CEM cells) to 23.80 µM [towards colon carcinoma HCT116 (p53^+/+) cells] for 3 and from 0.20 µM (towards CCRF-CEM cells) to 195.12 µM (towards leukemia CEM/ADR5000 cells) for doxorubicin. Compounds 2 and 3 induced apoptosis in CCRF-CEM leukemia cells, mediated by caspase activation and the disruption of MMP.ConclusionsThe three tested flavonoids and mostly chalcone 3 are potential cytotoxic natural products that deserve more investigations to develop novel antineoplastic drugs against multifactorial drug-resistant cancers.     

Cytotoxicity of compounds from Xylopia aethiopica towards multi-factorial drug-resistant cancer cells

IntroductionMultidrug resistance (MDR) in cancer represent a major hurdle in chemotherapy. Previously, the methanol extract of the medicinal spice Xylopia aethiopica displayed considerable cytotoxicity against multidrug resistant (MDR) cancer cell lines.MethodsThe present study was designed to assess the cytotoxicity of compounds, 16α-hydroxy-ent-kauran-19-oic acid (2), 3,4′,5-trihydroxy-6″,6″-dimethylpyrano[2,3-g]flavone (3), isotetrandrine (5) and trans-tiliroside (6) derived from the methanol crude extract of Xylopia aethiopica against 9 drug-sensitive and -resistant cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle, mitochondrial membrane potential (MMP) and levels of reactive oxygen species (ROS) were all analyzed via flow cytometry.ResultsFlavonoid 3 and alkaloid 5 also displayed IC₅₀ values ranging from 2.61 µM (towards leukemia CCRF-CEM cells) to 18.60 µM (towards gliobastoma multiforme U87MG.ΔEGFR cells) and from 1.45 µM (towards HepG2 cells) to 7.28 µM (towards MDA-MB-231-pcDNA cells), respectively. IC₅₀ values ranged from 0.20 µM (against CCRF-CEM cells) to 195.12 µM (against CEM/ADR5000 cells) for doxorubicin. Compound 3 induced apoptosis in leukemia CCRF-CEM cells mediated by the disruption of the MMP, whilst 5 induced apoptosis mediated by ROS production.ConclusionsCompounds 2 and 5 represent potential cytotoxic phytochemicals that deserve more investigations to develop novel antineoplastic drugs against multifactorial drug-resistant cancers.     

In vitro susceptibility of human Blastocystis subtypes to simeprevir

Introduction and aimBlastocystis is a common enteric parasite, having a worldwide distribution. Many antimicrobial agents are effective against it, yet side effects and drug resistance have been reported. Thus, ongoing trials are being conducted for exploring anti-Blastocystis alternatives. Proteases are attractive anti-protozoal drug targets, having documented roles in Blastocystis. Serine proteases are present in both hepatitis C virus and Blastocystis. Since drug repositioning is quite trendy, the in vitro efficacy of simeprevir (SMV), an anti-hepatitis serine protease inhibitor, against Blastocystis was investigated in the current study.MethodsStool samples were collected from patients, Alexandria, Egypt. Concentrated stools were screened using direct smears, trichrome, and modified Ziehl-Neelsen stains to exclude parasitic co-infections. Positive stool isolates were cultivated, molecularly subtyped for assessing the efficacy of three SMV doses (100,150, and 200 μg/ml) along 72 hours (h), on the most common subtype, through monitoring parasite growth, viability, re-culture, and also via ultrastructure verification. The most efficient dose and duration were later tested on other subtypes.ResultsResults revealed that Blastocystis was detected in 54.17% of examined samples. Molecularly, ST3 predominated (62%), followed by ST1 (8.6%) and ST2 (3.4%). Ascending concentrations of SMV progressively inhibited growth, viability, and re-culture of treated Blastocystis, with a non-statistically significant difference when compared to the therapeutic control metronidazole (MTZ). The most efficient dose and duration against ST3 was 150 µg/ml for 72 h. This dose inhibited the growth of ST3, ST1, and ST2 with percentages of 95.19%, 94.83%, and 94.74%, successively and viability with percentages of 98.30%, 98.09%, and 97.96%, successively. This dose abolished Blastocystis upon re-culturing. Ultra-structurally, SMV induced rupture of Blastocystis cell membrane leading to necrotic death, versus the reported apoptotic death caused by MTZ. In conclusion, 150 µg/ml SMV for 72 h proved its efficacy against ST1, ST2, and ST3 Blastocystis, thus sparing the need for pre-treatment molecular subtyping in developing countries.