Minimum Lethal Concentration Research Articles

Evidence of self-resolution of feline trichomonosis in a pair of single household cats due to ronidazole-resistant Tritrichomonas foetus

Tritrichomonas foetus causes chronic large-bowel diarrhoea in cats, complicated not only by its chronicity but for its difficulty to treat, with few registered or effective products available, subsequently resulting in ronidazole frequently used off-label. The extent of T. foetus resistance to ronidazole is unknown. To demonstrate in vitro resistance of feline T. foetus to ronidazole and the self-resolution of the infection, we isolated novel T. foetus “feline” genotype strains from two cats in 2017 from the same household and monitored these cats over a three-year period. Axenic cultures of T. foetus from the cats were tested for in vitro resistance to metronidazole and ronidazole using anaerobic and aerobic culture assays. The minimum lethal concentration for the novel strains after incubation in aerobic conditions for 48 h were 50–100 μg/ml and 6.25–12.50 μg/ml for metronidazole and ronidazole, respectively. For susceptible T. foetus strains, the minimum lethal concentrations ranged from 1.56–12.50 μg/ml for metronidazole, and 0.39–3.13 μg/ml for ronidazole. The self-resolution of the infection was assessed using repeat diagnostic qPCR and culture. Whilst positive in 2018, the cat samples are no longer returning positive qPCR results in 2020 and 2021, indicating self-resolution over this period. This study demonstrated resistance to ronidazole for the first time in Australian cats and infection self-resolution without antimicrobial intervention is demonstrated. This study provides clinicians with the evidence to reduce the use of off-label ronidazole, and advice on the resolution timeframe for cats in single households.

PEGylation enhances the antibacterial and therapeutic potential of amphibian host defence peptides

Aurein 2.1, aurein 2.6 and aurein 3.1 are amphibian host defence peptides that kill bacteria via the use of lytic amphiphilic α-helical structures. The C-terminal PEGylation of these peptides led to decreased antibacterial activity (Minimum Lethal Concentration (MLCs) ↓ circa one and a half to threefold), reduced levels of amphiphilic α-helical structure in solvents (α-helicity ↓ circa 15.0%) and lower surface activity (Δπ ↓ > 1.5 mN m−1). This PEGylation of aureins also led to decreased levels of amphiphilic α-helical structure in the presence of anionic membranes and zwitterionic membranes (α-helicity↓ > 10.0%) as well as reduced levels of penetration (Δπ ↓ > 3.0 mN m−1) and lysis (lysis ↓ > 10.0%) of these membranes. Based on these data, it was proposed that the antibacterial action of PEGylated aureins involved the adoption of α-helical structures that promote the lysis of bacterial membranes, but with lower efficacy than their native counterparts. However, PEGylation also reduced the haemolytic activity of native aureins to negligible levels (haemolysis ↓ from circa 10% to 3% or less) and improved their relative therapeutic indices (RTIs ↑ circa three to sixfold). Based on these data, it is proposed that PEGylated aureins possess the potential for therapeutic development; for example, to combat infections due to multi-drug resistant strains of S. aureus, designated as high priority by the World Health Organization.

Acacia auriculiformis pericarp – a substitute of Mohua oil cake as piscicide in pre-stocking pond preparation

Mahua oil cake (MOC), a derivative of the seeds from Bassia latifolia is used as a piscicide in pre-stocking pond preparation for composite fish culture. However, for its nutritional potency MOC is used as a protein substitute in the formulated diets for fish, poultry and cattle. In present experiment piscicidal potency of Acacia pericarp preparation (APP) has been evaluated to get a substitute of MOC. LC-ESI-MS analysis of the methanolic extract of Acacia auriculiformis pericarp revealed seven triterpenoid saponins (acaciasides), twenty two flavonoids, eight tannins and a phenolic rich fraction- gallyl glucose. In the present experiment Minimum lethal concentration, LC50 and LC100 of APP were worked out through static bioassay and subsequent probit analyses putting trial upon nine potential predator fishes viz. Channa punctatus (Bloch), Channa gachua (Hamilton), Channa striata (Bloch), Clarias batrachus (Lin), Clarias gariepinus (Burchell), Heteropneustes fossilis (Bloch), Anabas testudineus (Bloch), Notopterus notopterus (Pallas) and Wallago attu (Bloch & Schneider). Among the native species C. striata exhibited its toxicological response with higher Minimum lethal concentration (70 ppm), LC50 (78.7 ppm) and LC100 (90 ppm). Toxicological response of the exotic species C. gariepinus however, were found to be with highest LC50 (98.4 ppm) and LC100 (130 ppm). On the basis of toxicological response of different predator species the piscicidal application concentration of APP has been recommended in reference to LC100 of C. striatus. However, if the exotic species C. gariepinus is present in the system, APP application should be made with reference to LC100 to this species. Kaplan-Meier analysis on survivality of fish under exposure was performed to justify the results of the bioassay experiments. APP has the least effect on non-target invertebrate organisms of the aquatic body. Application of APP results in improving soil nutrients such as NPK and organic carbon. The result of the study revealed that Acacia pericarp could be a better substitute of MOC as a piscicide.

Prevention of Saprolegniasis in rainbow trout (Oncorhynchus mykiss) eggs using oregano (Origanum onites) and laurel (Laurus nobilis) essential oils

The present study investigated the antifungal effects of essential oils of oregano (Origanum onites) and laurel (Laurus nobilis) on Saprolegniasis, a disease that occurs in rainbow trout eggs during the incubation period. Oregano and laurel were ground after drying, and essential oils were obtained by water distillation method using a Clevenger apparatus. The essential oils were added to potato dextrose agar (PDA) at the rates of 1-1000ppm, and the minimum inhibitory concentration (MIC) was determined as 250ppm whereas the minimum lethal concentration (MLC) was determined to be 500ppm for both plants. In the in vivo trials, fertilized eggs were treated with predetermined doses either by bathing during water hardening and incubation period or only during incubation period, and death rates were monitored during embryological development. The best larvae hatching rate was determined in 500ppm oregano and 500ppm laurel groups treated during water hardening plus daily as 82.11% and 79.87%, respectively. According to the results, it was determined that oregano and laurel essential oils exhibited better results in all doses compared with the negative control group, and 500ppm dose had a better effect than the positive control group treated with formalin.

DFT Study and Antiparasitic Activity of Some Azo Dyes Containing Uracil

In this study, for the first time, molecular modeling and antiparasitic activity studies were carried out on some azo dyes containing uracil, 6-amino-5-[(4-nitrophenyl) diazenyl] pyrimidine-2,4 (1H, 3H)-dione (dye I) and 6-amino-5-[(4-bromophenyl) diazenyl] pyrimidin-2,4 (1H, 3H)-dione (dye II), which were resynthesized using the same method in the literature and whose molecular structures were confirmed using FTIR and 1H-NMR methods. In molecular modeling study, all calculations were performed using DFT/B3LYP/6-311++G(d,p) method. The molecular structures of the possible tautomeric forms of dyes I and II were optimized, and their molecular total energies were calculated in the gas phase and DMSO solvent. IR and 1H-NMR spectral data of the possible tautomeric forms of dyes were obtained, and theoretical spectral data were compared with experimental ones. The evaluations show that, for both dyes, the spectral data of the imine-diketo-hydrazone form, which has the lowest energy and is hence determined to be the most stable form, are in agreement with the experimental ones. In antiparasitic activity study, dyes I and II were tested for the first time against parasites Leishmania infantum, Leishmania major, Leishmania tropica promastigotes, and Trichomonas vaginalis trophozoites. In vitro antileishmanial activities against Leishmania promastigotes were tested by microdilution broth assay with Alamar Blue in RPMI 1640 medium, and in vitro trichomonacidal activities against Trichomonas vaginalis parasite were tested using TYM medium. In tests, antileishmanial and trichomonacidal effects were determined by comparing the obtained minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) values with those obtained for standard drugs (amphotericin B and metronidazole, respectively).

Introducing new method for the synthesis of polycyclic compounds containing [1,3]dithiine derivatives, with anticancer and antibacterial activities against common bacterial strains between aquatic and human

AbstractIn this study, glycerol:potassium carbonate used as a green deep eutectic solvent, for synthesis of polycyclic compounds containing [1,3]dithiine derivatives. The antimicrobial properties of the derivatives against Lactococcus garvieae and Edwardsiella tarda were tested as bacterial strains between aquatic and human based on the minimum inhibitory concentration (MIC), the minimum lethal concentration (MBC) and inhibition zone diameter (IZD). In addition to antimicrobial properties, cytotoxicity testing was performed against MCF‐7 breast cancer cells via MTT cell viability assay.

Toxicity assessment of green synthesized Cu nanoparticles by cell-free extract of Pseudomonas silesiensis as antitumor cancer and antimicrobial

Spherical homogeneous 32 nm, protein coated Pseudomonas silesiensis strain A3 CuNPs was investigated for their cytotoxicity effect as well as antimicrobial and antitumor activity. CuNPs cytotoxicity was estimated using human normal lung cell lines (Wi38) against CuNPs with concentrations ranging from 25 to 150 μg/mL using neutral red uptake assay. The cytotoxicity study revealed that the bacterial CuNPs had an impact on Wi38 cell viability at concentrations of 25, 50, 100 and 150 μg/mL CuNPs were 95.8, 91.1, 89.2 and 82.3%, respectively, with a strong correlation coefficient (r = 0.94) and a CuNPs IC50 value of 1057.0 μg/mL. CuNPs exhibit a broad-spectrum antimicrobial activity against various microorganism species, including fungi and Gram positive and negative bacteria using the agar-well diffusion method. The findings revealed that the most sensitive pathogens were Staphylococcus aureus ATCC5638 and Aspergillus flavus ATCC 9643 which tended to have a high inhibition zone diameter (50 and 47 mm, respectively). The minimum inhibitory concentration (MIC) of CuNPs was 50 μg/mL. The minimum lethal concentration (MLC) values were 50 and 75 μg/mL for S. aureus ATCC 5638 and A. flavus ATCC 9643, respectively. MLC/MIC ratio was ≤2, suggesting the CuNPs had a bactericidal or fungicidal effect on both pathogenic strains. Results also indicated that bacterial CuNPs at varying concentrations of 25, 50, 100 and 150 μg/mL were such a good antitumor agent against A549 lung carcinoma cell lines with an IC50 value of 137.5 μg/mL and a cell viability of 89.3, 79.6, 64.9 and 44.1%, respectively. The results also suggested that the biosynthesized-CuNPs were an antimicrobial and anticancer agent that could be used in future in food preservation, biomedicine and pharmaceutical fields.

Synergistic antimicrobial activities of plant essential oils against Listeria monocytogenes in organic tomato juice

The objective of this study was to identify combinations of plant essential oils (EOs) that have synergistic antilisterial effects in raw organic tomato juice. Among the EOs approved for addition to organic foods in the Republic of Korea, twenty-four EOs were screened for antilisterial activity using a well diffusion assay. Six EOs (cinnamon bark, lemon, lemongrass, oregano, peppermint, and thyme thymol) showed relatively strong inhibitory activities (diameter of zone of inhibition ≥ 35.0 mm) against Listeria monocytogenes. The minimal inhibitory concentrations (MICs) and minimal lethal concentrations (MLCs) of these EOs against L. monocytogenes in a laboratory medium were determined. Oregano and thyme thymol EOs had the lowest MIC (0.3125 μL/mL), and cinnamon bark, oregano, and thyme thymol EOs had the lowest MLC (0.6250 μL/mL). The synergistic antilisterial activities of combinations of EOs in a laboratory medium were determined using a modified checkerboard assay. Combinations of cinnamon bark and lemongrass EOs, cinnamon bark and thyme thymol EOs, and lemongrass and thyme thymol EOs showed synergistic antilisterial activities (fractional inhibitory concentration index = 0.5). A combination of cinnamon bark and thyme thymol EOs was tested for synergistic antilisterial activity in tomato juice incubated at 10 °C and 25 °C for up to 48 h. The number of L. monocytogenes in juice treated with combined EOs at a total concentration of 0.3125 μL/mL decreased significantly (P ≤ 0.05) compared to numbers in juice treated with 0.3125 μL/mL of either cinnamon bark EO or thyme thymol EO alone. These observations show the potential for using combinations of EOs for controlling L. monocytogenes in juice released from cut or bruised raw organic tomatoes intended for consumption in food service or home settings.

Origanum vulgare ssp. hirtum Essential Oil as a Natural Intrinsic Hurdle against Common Spoilage and Pathogenic Microbes of Concern in Tomato Juice

The aim of the present study was to assess the commercial potential of the Origanum vulgare ssp. hirtum essential oil (OEO) as a natural intrinsic hurdle against common spoilage and pathogenic microbes in tomato juice. The main volatile compounds of the OEO identified by gas chromatography mass spectrometry (GC/MS) analysis were thymol and carvacrol, accounting for approximately 48% and 27%, respectively. Its activity against common food spoilage and pathogenic microbes was confirmed and the minimum inhibitory concentration (MIC), non-inhibitory concentration (NIC), and minimum lethal concentration (MLC) values were determined. OEO effectiveness was further validated in commercial tomato juice. Supplementation of tomato juice with OEO at concentrations lower than the MIC (350 ppm) resulted in significant delay of food spoilage and extension of the product’s shelf-life, as well as in inhibition of Listeria monocytogenes, Clostridium difficile, Saccharomyces cerevisiae, and Aspergillus niger growth after deliberate inoculation in both room and refrigerated temperatures. In conclusion, the results suggested that OEO may be used as an efficient intrinsic inhibitor of food spoilage and growth of pathogenic microbes in tomato juice.

In vitro antibacterial activity of garlic (Allium sativum) and ginger (Zingiber officinale) aqueous extracts against isolates of Brucella abortus

Microbial resistance to antibiotics has become a problem plaguing the world. Currently, interest has been focused on exploring antimicrobial properties of plants and herbs. This work aim to evaluate the antibacterial activity of garlic (Allium sativum) bulbs and ginger (Zingiber officinale) rhizome on Brucella abortus isolates. Some concentrations of garlic and ginger extracts were tested for their antibacterial activity against B. abortus isolate brought from Central Veterinary Research Laboratory (CVRL), Soba, using well diffusion method. Moreover, minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) of garlic and ginger were tested using broth dilution method. Sensitivity pattern of the conventional antibacterial against common pathogenic bacteria was tested using disc diffusion method. Aqueous extract of ginger produced dose-dependent increase in the zone of inhibition at a concentration of 15% and higher, whereas the garlic extract produced inhibition zone at a concentration of 5% and higher, i.e. B. abortus isolate showed relatively high sensitivity toward garlic extract than ginger which required a more concentrated extract to kill or inhibit B. abortus isolate that brought from (CVRL), Soba, Khartoum, Sudan. Further studies are needed to find out the efficacy, safety, and kinetic data of their active ingredients.

Effect of Rhamnolipids on Pathogenicity Characteristics of Microorganisms in Organic Compost

Background: Rhamnolipids are hydrophilic glycolipids, often classified as biosurfactants. They are produced by different bacterial species. Rhamnolipids are extensively studied in biological research because of their interesting features like antimicrobial, antifungal, and antiviral activities. Materials and Methods: To study the antimicrobial effect of rhamnolipid, we conducted a crosssectional study on the eight different pathogenic bacterial strains from November 2019 to June 2020. These bacterial strains were isolated from the organic compost. Both disk diffusion and broth microdilution methods were used to evaluate the inhibitory effects of rhamnolipids on these pathogenic bacteria. Also, protease and amylase enzyme activities were evaluated in these eight bacterial isolates. Results: For Bacillus stearothermophilus, within the area of 31.5 mm, no growth was observed, hence proving the inhibitory effect of rhamnolipid. After calculating the minimum inhibitory (MIC) and minimum lethal concentrations (MLC) for each bacterial strain, it has been found that the studied bacteria were more susceptible to rhamnolipids than most of the antibiotics. Strains were also quantified for their enzymatic activity of proteases and amylases. The bacterial strains of Bacillus stearothermophilus, Brevibacillus brevis, Bacillus licheniformis, and Bordetella petrii showed maximum protease activity. Whereas Escherichia coli, Enterococcus faecalis, Enterobacter aerogenes, and Pseudomonas aeruginosa showed high amylase activity. Conclusion: Rhamnolipids can be used as a potential antimicrobial agent for treatment of infections.

Comparative pharmacokinetics of metronidazole in healthy and Trichomonas gallinae infected pigeons (Columba livia, var. domestica)

ABSTRACT 1. This study investigated the pharmacokinetics of metronidazole after intravenous (i.v.) and oral administration to healthy and experimentally Trichomonas gallinae-infected pigeons, and determined the in vitro antiprotozoal activity of metronidazole against T. gallinae. 2. Twelve pigeons which were experimentally infected to T. gallinae and twelve healthy pigeons received metronidazole at the dose of 25 mg/kg by oral or i.v. administration. Serial blood sampling was used for pharmacokinetic analysis. The metronidazole minimum lethal concentration (MLC) and the concentration killing 50% of the trophozoites (LC50) in the culture media were determined. 3. In vitro data showed that the 24 h LC50 and MLC of metronidazole were 0.31 and 25 µg/ml, respectively. In vivo results showed no statistical differences between pharmacokinetics in infected and non-infected pigeons for both routes of administration. The area under the curve was statistically higher after the i.v. administration in both infected and healthy pigeons. The mean oral bioavailability was similar in the infected (83.8%) and the healthy (81.5%) birds. 4. In conclusion, the pharmacokinetics of metronidazole in pigeons was not affected by experimentally-induced trichomoniasis. Despite in vitro susceptibility testing, which showed probable resistance of the isolated T. gallinae to metronidazole, five-day oral treatment of infected pigeons with 25 mg/kg metronidazole twice a day resulted in total eradication of trophozoites recovered in crop lavage of infected birds.

Optimization for biogenic microbial synthesis of silver nanoparticles through response surface methodology, characterization, their antimicrobial, antioxidant, and catalytic potential

Silver is a poisonous but precious heavy metal that has widespread application in various biomedical and environmental divisions. Wide-ranging usage of the metal has twisted severe environmental apprehensions. Henceforth there is a cumulative call for the progress of modest, low-cost and, the ecological method for remediation of silver. In the present study, Bacillus cereus was isolated from contaminated soil. Various experimental factors like the amount of AgNO3, inoculum size, temperature, time, and pH were improved by using central composite design (CCD) grounded on response surface methodology (RSM). Optimized values for AgNO3 (1 mM) 10 ml, inoculum size (Bacillus cereus) 8.7 ml, temperature 48.5 °C, time 69 h, and pH 9 showed in the form of optimized ramps. The formed nanoparticles stayed characterized by UV–visible spectrophotometer, Scanning Electron Microscopy, Fourier transform infra-red spectrometry, particle size analyzer, and X-ray diffraction. The particle size ranges from 5 to 7.06 nm with spherical form. The antimicrobial effectiveness of synthesized nanoparticles was tested contrary to five multidrug resistant microbial strains, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Salmonella enterica, Porteus mirabilis by disc diffusion method. The minimum inhibitory concentrations and minimum lethal concentrations were detected by the broth macro dilution method. 2,2-diphenyl-1-picrylhydrazyl-hydrate (DPPH) was used to check the free radical scavenging ability of biogenic silver nanoparticles. Similarly, anti-radical activity was checked by 2,2′-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid (ABTS) with varying time intervals. Catalytic potential of biosynthesized silver nanoparticles was also investigated.

Anti-parasitic effect of lacquer tree Rhus verniciflua Stokes lignum against Miamiensis avidus (Ciliophora: Scuticociliatida)

Scuticociliatosis is a disease in marine fishes worldwide, especially in olive flounder (Paralichthys olivaceus), and is caused by the ciliate Miamiensis avidus (syn. Philasterides dicentrarchi). To find an effective preventive measure against M. avidus, the usefulness of lignum extract from Rhus verniciflua Stokes (RVS; lacquer tree) was investigated. The maximum anti-parasitic activity and extraction yield for RVS lignum were optimised using response surface methodology with the three-factor–three-level Box–Behnken design model (BBD). The optimised extract (OE) contained major active compounds of gallic acid, fustin, and fisetin at concentrations of 3.07 ± 0.06%, 19.77 ± 0.42%, and 2.52 ± 0.02%, respectively. An in vitro parasite killing study showed that the minimum lethal concentration of OE was 225 ppm, whereas that of individual compounds was 100 ppm for gallic acid, 500 ppm for fustin, and 1000 ppm for fisetin. The in vivo experimental results showed that fish that were fed OE-incorporated feed at 100 mg/kg body weight/day for 1–2 weeks had significant preventive efficacy against M. avidus without any toxic effect. Thus, the OE of RVS lignum can act as an effective and safe natural therapeutic agent to control M. avidus in cultured olive flounder.

The lampricide 3-trifluoromethyl-4-nitrophenol causes temporary metabolic disturbances in juvenile lake sturgeon (Acipenser fulvescens): implications for sea lamprey control and fish conservation.

The pesticide 3-trifluoromethyl-4-nitrophenol (TFM) is applied to rivers and streams draining into the Laurentian Great Lakes to control populations of invasive sea lamprey (Petromyzon marinus), which are ongoing threats to fisheries during the lamprey’s hematophagous, parasitic juvenile life stage. While TFM targets larval sea lamprey during treatments, threatened populations of juvenile lake sturgeon (Acipenser fulvescens), particularly young-of-the-year (<100 mm in length), may be adversely affected by TFM when their habitats overlap with larval sea lamprey. Exposure to TFM causes marked reductions in tissue glycogen and high energy phosphagens in lamprey and rainbow trout (Oncorhynchus mykiss) by interfering with oxidative ATP production in the mitochondria. To test that environmentally relevant concentrations of TFM would similarly affect juvenile lake sturgeon, we exposed them to the larval sea lamprey minimum lethal concentration (9-h LC99.9), which mimicked concentrations of a typical lampricide application and quantified energy stores and metabolites in the carcass, liver and brain. Exposure to TFM reduced brain ATP, PCr and glycogen by 50–60%, while lactate increased by 45–50% at 6 and 9 h. A rapid and sustained depletion of liver glucose and glycogen of more than 50% was also observed, whereas the respective concentrations of ATP and glycogen were reduced by 60% and 80% after 9 h, along with higher lactate and a slight metabolic acidosis (~0.1 pH unit). We conclude that exposure to environmentally relevant concentrations of TFM causes metabolic disturbances in lake sturgeon that can lead to impaired physiological performance and, in some cases, mortality. Our observations support practices such as delaying TFM treatments to late summer/fall or using alternative TFM application strategies to mitigate non-target effects in waters where lake sturgeon are present. These actions would help to conserve this historically and culturally significant species in the Great Lakes.

Antifungal efficacy of isavuconazole and liposomal amphotericin B in a rabbit model of Exserohilum rostratum meningoencephalitis: A preclinical paradigm for management of CNS phaeohyphomycosis.

Treatment options for Exserohilum rostratum meningoencephalitis and other causes of phaeohyphomycosis of the central nervous system (CNS) are limited, while mortality and morbidity remain high. We therefore evaluated isavuconazole, a new antifungal triazole in comparison to liposomal amphotericin B (LAMB), in vitro and in the rabbit model of Exserohilum rostratum meningoencephalitis. We hypothesized that isavuconazole alone or in combination with LAMB or micafungin may be alternative options for treatment of CNS phaeohyphomycosis. We therefore investigated the in vitro antifungal activity of isavuconazole alone or in combination with amphotericin B deoxycholate (DAMB) or micafungin and efficacy of treatment with isavuconazole and LAMB in a rabbit model of experimental E. rostratum meningoencephalitis. Combination checkerboard plates were used to determine the minimum inhibitory concentrations, minimal lethal concentrations, fractional inhibitory concentration indices, and Bliss surface analysis of isavuconazole and amphotericin B deoxycholate (DAMB), either alone or in combination. As there were no in vitro synergistic or antagonistic interactions for either combination of antifungal agents against the E. rostratum isolates, in vivo studies were conducted with isavuconazole and LAMB as monotherapies. Rabbits were divided in following groups: treated with isavuconazole at 60 mg/kg/d (ISAV60), LAMB at 5.0 (LAMB5), 7.5 (LAMB7.5), and 10 mg/kg/d (LAMB10), and untreated controls (UC). In ISAV60-, LAMB5-, LAMB7.5-, and LAMB10-treated rabbits, significant reductions of fungal burden of E. rostratum in cerebral, cerebellar, and spinal cord tissues (P < 0.01) were demonstrated in comparison to those of UC. These antifungal effects correlated with significant reduction of CSF (1→3)-β-D-glucan levels vs UC (P < 0.05). These data establish new translational insights into treatment of CNS phaeohyphomycosis.

Chemical composition and larvicidal activity of essential oils from Zingiber montanum (J. Koenig) Link ex. A. Dietr. against three mosquito vectors

The chemical composition and larvicidal activity of essential oils derived from the leaves and rhizomes of Zingiber montanum (J. Koenig) Link ex. A. Dietr. were reported. The main compounds in the leaf oil were -pinene (13.8%), -phellandrene (11.3%) and -pinene (7.3%) while the rhizome oil was dominated by sabinene (41.1%), terpinen-4-ol (22.7%) and (E)-nerolidol (14.3%). The minimum lethal concentration (larvicidal activity) LC50 of the rhizome oil at 24 h against Aedes albopictus was 35.17 μg/mL, while LC50 values of 32.20 μg/mL and 31.12 μg/mL were obtained against Aedes aegypti and Culex quinquefasciatus respectively. At 48 h the oil displayed larvicidal action with LC50 values of 23.18 μg/mL, 25.58 μg/mL and 18.99 μg/mL respectively towards Ae. albopictus, Ae. Aegypti and Cx. quinquefasciatus. The leaf oil did not exhibit significant mortality and larvicidal action. The results indicate the potential of rhizome essential oil of Z. montanum as a source of larvicidal agent.

Detection of genes responsible for cetuximab sensitization in colorectal cancer cells using CRISPR-Cas9.

Colorectal cancer (CRC) is a common malignant tumor in digestive tract with highly invasive and metastatic capacity. Drug sensitivity remains a significant obstacle to successful chemotherapy in CRC patients. The present study aimed to explore genes related to cetuximab (CTX) sensitivity in CRC by clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9. Celigo image cytometer was used to detect suitable cells and optimal dosage of CTX. Inhibition rate of CTX on Caco-2 cells was evaluated by cell counting kit-8 (CCK-8) method before and after transfection. 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) was performed to explore suitable concentration of puromycin and multiplicity of infection (MOI). CRISPR-Cas9, sequencing data quality analysis and cell viability test were used for the selection of genes related to CTX sensitivity in CRC cells. Finally, the selected genes associated with CTX sensitivity in CRC cells were further validated by colony formation and CCK-8 assays. In the present study, Caco-2 cells had a better prolificacy, and CTX 100 μg/ml exhibited a good inhibition trend on the 7th and 14th days of infection. MTT assay indicated that the minimum lethal concentration of puromycin was 2.5 μg/ml. Forty-six candidate genes were preliminarily screened via sequencing data quality analysis. Subsequently, we found that knockout of any of the four genes (MMP15, MRPL48, CALN1 and HADHB) could enhance CTX sensitivity in Caco-2 cells, which was further confirmed by colony formation assay. In summary, MMP15, MRPL48, CALN1 and HADHB genes are related to the mediation of CTX sensitivity in CRC.

Antimicrobial Properties of Composites of Chitosan-Silver Doped Zeolites

The antimicrobial functionality of composites constituted by chitosan with silver-doped zeolites was developed and characterized. A composite with chitosan particles and silver-doped zeolites was synthesized using an ionic gelation process with sodium tripolyphosphate. The chitosan silver-doped zeolites composite obtained presented sizes up to 5 μm, while the silver-doped zeolites had an average size between 0.5 μm and 3.3 μm. The synthesized chitosan silver-doped zeolites composites, as well as the silver-doped zeolites and the chitosan dissolution, were characterized through X-ray diffraction, Fourier Transform Infrared spectroscopy and scanning electron microscopy. The electro kinetic behaviour of chitosan, silver-doped zeolites and chitosan silver-doped zeolites composite was evaluated under different pH conditions. The antimicrobial activity of the composites was evaluated in terms of minimum inhibitory concentrations and minimum lethal concentrations and the results suggest that the chitosan silver-doped zeolites composites show antimicrobial activity against gram-negative and gram-positive bacteria, Escherichia coli and Staphylococcus aureus, respectively and against Candida albicans. The results here presented support the potential application of the composite of chitosan with silver-doped zeolites in the functionalization of textiles with antimicrobial properties.

Identification and validation of novel and more effective choline kinase inhibitors against Streptococcus pneumoniae

Streptococcus pneumoniae choline kinase (sChoK) has previously been proposed as a drug target, yet the effectiveness of the first and only known inhibitor of sChoK, HC-3, is in the millimolar range. The aim of this study was thus to further validate sChoK as a potential therapeutic target by discovering more powerful sChoK inhibitors. LDH/PK and colorimetric enzymatic assays revealed two promising sChoK inhibitor leads RSM-932A and MN58b that were discovered with IC50 of 0.5 and 150 μM, respectively, and were shown to be 2–4 magnitudes more potent than the previously discovered inhibitor HC-3. Culture assays showed that the minimum inhibitory concentration (MIC) of RSM-932A and MN58b for S. pneumoniae was 0.4 μM and 10 μM, respectively, and the minimum lethal concentration (MLC) was 1.6 μM and 20 μM, respectively. Western blot monitoring of teichoic acid production revealed differential patterns in response to each inhibitor. In addition, both inhibitors possessed a bacteriostatic mechanism of action, and neither interfered with the autolytic effects of vancomycin. Cells treated with MN58b but not RSM-932A were more sensitive to a phosphate induced autolysis with respect to the untreated cells. SEM studies revealed that MN58b distorted the cell wall, a result consistent with the apparent teichoic acid changes. Two novel and more highly potent putative inhibitors of sChoK, MN58b and RSM-932A, were characterized in this study. However, the effects of sChoK inhibitors can vary at the cellular level. sChoK inhibition is a promising avenue to follow in the development of therapeutics for treatment of S. pneumoniae.