Median Effective Concentration Research Articles

Estimation of median effective effect-site concentration (EC50) during target-controlled infusion of propofol for dilatation and curettage - A prospective observational study.

Background and Aims:Propofol is the drug of choice for sedation in daycare procedures due to its pharmacokinetic properties. Propofol delivery using target-controlled infusion (TCI) pump reduces adverse effects like hypotension and apnoea. In this study, we estimated the median effective effect-site concentration of propofol in patients undergoing dilatation and curettage.Methods:Patients of the American Society of Anesthesiologists physical status class I–III, aged 40–70 years, undergoing elective dilatation and curettage were recruited for the study. All patients received 1 μg/kg fentanyl and 20 mg lignocaine. The first patient received an effect-site concentration of propofol at 4 μg/mL with TCI Schneider pharmacokinetic model. Failure was defined as patient movement at any time during the procedure. According to the ‘BiasedCoin Design’ up-and-down sequential method, the response of the previous patient determined the effect-site concentration of propofol of the next patient. The study was terminated once forty patients completed the procedures successfully. Probit analysis was used to determine EC50.Results:Fifty-three patients were recruited for the study. The various effect-site concentrations of propofol EC50, EC90, and EC95 in providing sedation for dilatation and curettage were 3.38 μg/mL, 4.29 μg/mL, and 4.60 μg/mL, respectively. The incidence of hypotension and apnoea were comparable among the various concentrations of propofol. The mean duration of the propofol infusion was 20 ± 2.86 min. The time to recovery from propofol sedation was 6.97 ± 1.76 min.Conclusion:A median effective effect-site concentration of 3.38 μg/mL of propofol is required to prevent patient movement during uterine dilatation and curettage.

Identification, biological characteristics, and fungicide screening of pathogen of black spot in Aconitum carmichaelii

In Hezhang county, Guizhou province, black spot tends to occur to Aconitum carmichaelii in the hot rainy summer, with the incidence up to 50%-70%, seriously impacting the yield and quality of the medicinal material. Thus, this study aims to clarify the pathogen and the occurrence characteristics. To be specific, the pathogen was isolated and identified according to Koch's postulates and the pathogenicity and biological characteristics were determined. In addition, the sensitivity of the pathogen to four microbial fungicides, four botanical fungicides, and five chemical fungicides was determined with the mycelium growth rate method for the purpose of screening out optimal fungicides. The pathogen was identified as Alternaria alternate, as evidenced by the similar colony morphology and microscopic characteristics and 99.55%-100% similarity in sequences of rDNA-ITS, LSU, 18S, and TEF of the two. The optimum growth conditions for A. alternata were 28 ℃, pH 8, and continuous darkness. Bacillus subtilis had strong inhibitory effect on the pathogen, and the inhibition rate was more than 90% when the concentration was 1 mg·L~(-1). In addition, difenoconazole and quinoline copper can also control the pathogen, with median effective concentration(EC_(50)) of 2.92 and 9.02 mg·L~(-1), respectively. This study lays a theoretical basis for the field control of black spot in A. carmichaelii.

Toxicity of Nanoparticles of AgO, La₂O₃, CuO, AgO-Fe₃O₄, Ag-Graphene, and GO-Cu-AgO to the Fungus Moniliella wahieum Y12T Isolated from Degraded Biodiesel and the Bacterium Escherichia coli.

Moniliella wahieum Y12T (M. wahieum Y12T), a fungal isolated from biodiesel caused serious biodiesel contamination and resulting in biofouling and corrosion, especially during storage. Nanoparticles (NPs) composed of silver, copper, iron, and graphene or their binary mixtures were examined as environmental inhibitors against the fungus Moniliella wahieum Y12T, a biodiesel contaminant. Exposure of M. wahieum Y12T and Escherichia coli (E. coli) to low concentrations of Ag-based nanoparticles (from 0.01 to 0.05 mg mL-1) resulted in excellent growth inhibition. The half-maximal inhibitory concentration (IC50) of M. wahieum Y12T by La₂O₃ NPs was 138 times greater when compared with silver (AgO). The median effective concentration (EC50) of La₂O₃ NPs on E. coli was 379 times more than M. wahieum Y12T. At this same concentration, E. coli was uninhibited after exposure to the NPs. However, a fluorescein diacetate analysis showed the Ag-based NPs (including AgO, AgO-Fe₃O₄ and GO-Cu-AgO) significantly reduced the metabolic activity for both of the compared organisms. Compared with other metal oxide NPs, AgO and AgO-Fe₃O₄ NPs display strong bactericidal effect with higher stability and dispersibility, with the zeta potential of -22.27 mV and poly-dispersity index (PDI) values of 0.36. These results demonstrate the broad-spectrum biological inhibition that occurs with both Ag-based bimetallic and graphene oxide nanoparticles and the combined utilization of Ag-based NPs paves a new way for inhibits the biodegradation of biodiesel.

Molecular Mechanisms Associated with the Resistance of Rhizoctonia solani AG-4 Isolates to the Succinate Dehydrogenase Inhibitor Thifluzamide

Thifluzamide, a succinate dehydrogenase (SDH) inhibitor, possesses high activity against Rhizoctonia. In this study, 144 Rhizoctonia solani AG-4 (4HGI, 4HGII, and 4HGIII) isolates, the predominate pathogen associated with sugar beet seedling damping-off, were demonstrated to be sensitive to thifluzamide with a calculated mean median effective concentration of 0.0682 ± 0.0025 μg/ml. Thifluzamide-resistant isolates were generated using fungicide-amended media, resulting in four AG-4HGI isolates and eight AG-4HGII isolates with stable resistance and almost no loss in fitness. Evaluation of cross-resistance of the 12 thifluzamide-resistant isolates and their corresponding parental-sensitive isolates revealed a moderately positive correlation between thifluzamide resistance and the level of resistance to eight other fungicides from three groups, the exception being fludioxonil. An active efflux of fungicide through ATP-binding cassette and major facilitator superfamily transporters was found to be correlated to the resistance of R. solani AG-4HGII isolates to thifluzamide based on RNA-sequencing and quantitative reverse transcription-PCR analyses. Sequence analysis of sdhA, sdhB, sdhC, and sdhD revealed replacement of isoleucine by phenylalanine at position 61 in SDHC in 9 of the 12 generated thifluzamide-resistant isolates. No other mutations were found in any of the other genes. Collectively, the data indicate that the active efflux of fungicide and a point mutation in sdhC may contribute to the resistance of R. solani AG-4HGI and AG-4HGII isolates to thifluzamide invitro. This is the first characterization of the potential molecular mechanism associated with the resistance of R. solani AG-4 isolates to thifluzamide and provides practical guidance for the use of this fungicide.

Synergistic toxicity to the toxigenic Microcystis and enhanced microcystin release exposed to polycyclic aromatic hydrocarbon mixtures

With the continued influx and accumulation of polycyclic aromatic hydrocarbons (PAHs) in eutrophic waters, the effects of PAHs on cyanobacteria bloom need to be clarified. PAHs usually existed as mixtures in aquatic environments, but the combined toxicity of PAH mixtures to toxigenic cyanobacteria remained unknown. This study investigated the effects of phenanthrene (Phe) and benzo [a]pyrene (BaP), alone or in combination, on the growth and physiology of Microcystis aeruginosa. The results showed that a hormesis effect on growth at low doses of the single Phe (≤1 mg/L) or PAH mixtures (≤0.279 mg/L) was observed, whereas the single BaP induced significant growth inhibitions at all concentrations (≥0.2 mg/L). The median effective concentrations (96 h) for Phe, BaP and their mixtures were 4.29, 1.29 and 1.07 mg/L, respectively. Mixture toxicity models showed that Phe and BaP elicited a synergistic interaction on M. aeruginosa. The synergy may be ascribed to the excessive oxidative stress induced by PAH mixtures, which further led to membrane structure damages, photosynthesis inhibitions and decreased metabolic activity. Moreover, the microcystins (MCs) release significantly increased by 25.3% and 31.9% upon exposure to 0.558 and 1.116 mg/L of PAH mixtures. In all, this study suggested that the enhanced release of MCs by PAH mixtures might exacerbate potential risks to the aquatic environment.

Toxicity and accumulation of lead and cadmium in the land snail, Archachatina papyracea, in a tropical Alfisol from Southwestern Nigeria.

Snails are an important link in the transfer of contaminants, especially metals in the food chain. Yet, few studies have examined the toxicity and accumulation of metals in snails in the tropics. This study assessed the toxicity and accumulation of two non-essential metals (cadmium and lead) to the tropical snail Archachatina papyracea. Specimens of the snail A. papyracea were exposed in a loamy soil collected from Ile-Ife, Nigeria and spiked with varying concentrations of Cd and Pb over 28days. Survival and weight change of snails were monitored weekly, while tissue accumulation was assessed at the end of the 28-day period. Survival was a more sensitive endpoint than the weight change of snails. The Cd median lethal concentration (LC50) value was 93 ± 4.4mg/kg, while the median effect concentration (EC50) for snail weight change was 131 ± 41mg/kg. For Pb, LC50 value was 1121 ± 457mg/kg, while the EC50 value for weight change was higher at 4541 ± 1180mg/kg. Therefore, Cd was a factor of about 10 to 30 × more toxic than Pb, consistent with findings on the relative toxicity of Cd and Pb to other soil organisms, including earthworms, springtails, and mites. Although not included initially as an endpoint, egg production in the snails decreased with increasing Cd and Pb concentrations in the substrate. Metal analysis of the foot and visceral mass of surviving snails showed progressive accumulation of Cd and Pb as concentration increased, showing the tendency to use body residue of A. papyracea as an indicator of metal pollution. It further suggests the role of this snail species in above-ground metal transfer in the food chain and highlights the potential danger for human consumption.

TOXIC EFFECTS OF ESTER BASED POLYMERS ON DAPHNIA MAGNA: A LABORATORY MICROCOSM STUDY

This study aims to determine toxic effects of polyester-based polymers (polycarbonate (PC), polyethylene terephthalate (PET) and, polybutylene terephthalate (PBT)) depending on physiological change in life cycle of Daphnia magna Straus (1820) (Cladocera, Crustacea). As a result of acute toxicity test, it was observed that although the rates of immobilized/dead organisms were low, damage started occurring in organisms. According to the results of 72th, the median effective concentration (EC50) values of PC, PET and PBT were determined as 2.604 mg L-1, 4.694 mg L-1 and >100 mg L-1, respectively. In consequence of chronic toxicity test, in the experiment set in which the water where daphnids were cultivated was used, it was observed that there was a high rate of deformation on daphnids which were exposed to ester-based polymers. The possible effect of polyester-based polymers on the daphnids deformation might be consequence of reaction between urea and ester groups of PC, PET, and PBT. Especially in the sets where microalgae existed and the natural conditions were simulated, it was determined that the toxicity response of daphnids varied in accordance with different microplastic types in terms of their chemical structure.

Impacts of di-(2-ethylhexyl) phthalate on Folsomia candida (Collembola) assessed with a multi-biomarker approach

Di-(2-ethylhexyl) phthalate (DEHP) is extensively used as an additive to produce plastics, but it may damage non-target organisms in soil. In this study, the effects of DEHP on Folsomia candida in terms of survival, reproduction, enzyme activities, and DNA damage were investigated in spiked artificial soil using a multi-biomarker strategy. The 7-day LC50 (median lethal concentration) and 28-day EC50 (median effect concentration) values of DEHP were 1256.25 and 19.72 mg a.i. (active ingredient) kg-1 dry soil, respectively. Biomarkers involved in antioxidant defense including catalase (CAT-catalase), glutathione S-transferases (GST), detoxifying enzymes including acetylcholinesterase (AChE), Cytochrome P450 (CYP450), and peroxidative damage (LPO-lipid peroxide) were also measured (EC10, EC20, and EC50) after exposure for 2, 4, 7, and 14 days. The Comet assay was also applied to assess the level of genetic damage. The activity of CAT and LPO was drastically enhanced by the highest dose (EC50) of DEHP on day two. The activities of GST and AChE in DEHP treatment groups were found to be blocked. In contrast, the activity of CYP450 was significantly enhanced compared to the respective control groups during the first four days of incubation. The Comet assay in F.candida demonstrated that DEHP (EC50) could induce DNA damage. The obtained multi-biomarker data were analyzed using an integrated biomarker response (IBR) index, indicating that limited-time exposure triggered higher stress than long-term exposure at low concentrations of DEHP. These results demonstrate that DEHP may cause biochemical and genetic toxicity to F. candida, which illustrated the potential risks of DEHP in the soil environment and might affect soil ecosystem processes. Further studies are necessary to elucidate the toxic mechanisms of DEHP on other non-target organisms in soil.

Newly Hatched Stage I American Lobster (Homarus americanus) Survival Following Exposure to Physically and Chemically Dispersed Crude Oil

Standard model species are commonly used in toxicity tests due to their biological and technical advantages but studying native species increases the specificity and relevance of results generated for the potential risk assessment to an ecosystem. Accounting for intraspecies variability and other factors, such as chemical and physical characterization of test medium, is necessary to develop a reproducible bioassay for toxicity testing with native species. In this study, larval stage I American lobster (Homarus americanus), a commercially important and native species of Atlantic Canada, was used as the test species. Toxicity tests were first conducted by exposing lobster larvae to a reference toxicant of copper sulphate (CuSO4) and then to physically and chemically (using Corexit 9500A) dispersed oil (WAF and CEWAF, respectively). The effect on larval survival was estimated by calculating the 24-h median effect concentration (24-h EC50), and there was no difference between WAF or CEWAF exposure when the results are reported on a total petroleum hydrocarbon (TPH) basis. The 24-h EC50s ranged from 2.54 to 9.73 mg TPH/L when all trials (n = 19) are considered together. The HC5 (hazardous concentration for 5 per cent of the population) value was 2.52 mg TPH/L and similar to the EC50 value when all trials were pooled. To evaluate the reproducibility of the lobster toxicity tests, inter-trial variability was determined, and the resultant coefficients of variation (%CV) were compared to those reported for two standard test species, mysid shrimp (Americamysis bahia) and inland silverside (Menidia beryillina). This comparison showed that the %CV for the lobster toxicity tests were lower than those for the standard species tests indicating that the described larval lobster toxicity bioassay produces reliable and repeatable results.

The Median Effective Concentration (EC50) of Epidural Ropivacaine With Different Doses of Oxycodone During Limb Surgery in Elderly Patients

BackgroundOxycodone can be used both intravenously and epidurally in elderly patients because of its strong analgesic effect and more slight respiratory inhibition compared with other opioids at the same effect. In this study, we determined the median effective concentration (EC50) of epidural ropivacaine required for great saphenous vein surgery in elderly patients in order to describe its pharmacodynamic interaction with oxycodone.MethodsOne hundred forty-one elderly patients scheduled for high ligation and stripping of the great saphenous vein surgery were allocated into three groups in a randomized, double-blinded manner as follows: Q2.5 group (2.5 mg oxycodone), Q5.0 group (5.0 mg oxycodone), and C group (normal saline). Anesthesia, was achieved with epidural ropivacaine and oxycodone. The EC50 of ropivacaine for surgery with different doses of oxycodone was adjusted by using an up-and-down sequential methods with an adjacent concentration gradient at a factor of 0.9 to inhibit analgesia. Anesthesia associated adverse events and recovery, characteristics were also recorded.ResultsThe EC50 of ropivacaine for the great saphenous vein surgery in elderly patients was 0.399% (95% CI, 0.371–0.430%) in the Q2.5 group, 0.396% (95% CI, 0.355–0.441%) in the Q5.0 group, and 0.487% (95% CI, 0.510–0.465%) in the C group, respectively (P < 0.05). Specially, the EC50 of ropivacaine in the Q2.5 and Q5.0 groups was lower than that in the C group (P < 0.01), But the difference between the Q2.5 group and the Q5.0 group was not significant (P > 0.05). There was no significant difference in the Bromage score from the motor block examination, heart rate (HR) or mean arterial pressure (MAP) at each observation time point after epidural administration among the three groups (P > 0.05). No serious adverse reactions occurred in any of the three groups.ConclusionOxycodone combined with ropivacaine epidural anesthesia can reduce the EC50 of ropivacaine required for elderly patients undergoing the great saphenous vein surgery. There was no significant difference in anesthesia associated adverse events among the three groups. The recommended dose of oxycodone is 2.5 mg.

Sensitivity of Meloidogyne enterolobii and M. incognita to fluorinated nematicides.

Meloidogyne enterolobii (Yang and Eisenback) was recently introduced into Louisiana on contaminated sweetpotato planting material. Given the known variation in sensitivity to nematicides within the genus Meloidogyne, there is question as to whether fluorinated nematicides will be as efficacious toward M. enterolobii as they are with M. incognita (Chitwood). Using a series of in vitro and growth cabinet experiments, this study compared the sensitivity of M. enterolobii and M. incognita to four synthetic non-fumigant nematicides (fluopyram, fluensulfone, fluazaindolizine, and oxamyl). Meloidogyne enterolobii had lower sensitivity to nematicides than M. incognita in the majority of the in vitro exposure assays. Similar levels of reduction in root infectivity were observed after nematicide exposure among both nematode species. Fluopyram showed high hatching inhibition for both Meloidogyne species at low concentrations [median effective concentration (EC50 ) values of 0.273 to 0.018 mg L-1 ], whereas fluensulfone showed high root penetration inhibition at low concentrations (EC50 values of 0.151 to 0.065 mg L-1 ) relative to that of other evaluated nematicides. For both Meloidogyne species, each of the four non-fumigant nematicides reduced root galling (58-96% reduction for M. enterolobii, 71-100% reduction for M. incognita) and egg production (63-99% reduction for M. enterolobii, 58-96% reduction for M. incognita) on sweetpotato when applied at the label recommended rate. Fluorinated nematicides and oxamyl show capacity to suppress M. enterolobii on sweetpotato. © 2021 Society of Chemical Industry.

Chemical Profile, Antimicrobial and Antioxidant Activity Assessment of the Crude Extract and Its Main Flavonoids from Tartary Buckwheat Sprouts.

The purpose of this study was to investigate the major flavonoids content and bioactivities of Tartary buckwheat sprouts. The crude methanol extract (ME) of Tartary buckwheat sprouts was abundant in flavonoids, and six major flavonoids, including isoorientin, vitexin, isovitexin, rutin, quercetin, and kaemferol were successfully determined from the sprouts by the high-performance liquid chromatography (HPLC) method. Generally, the flavonoid content of buckwheat sprouts was in the order of rutin > quercetin > isovitexin > vitexin> isoorientin > kaemferol. The highest rutin content of the ME and sprout cultures was 89.81 mg/g and 31.50 mg/g, respectively. Antibacterial activity results indicated the ME displayed notable inhibitory activity against the five tested bacteria, and its minimum inhibitory concentration (MIC) values ranged from 0.8 mg/mL to 3.2 mg/mL. Among the six flavonoids, quercetin was the most active compound, which exhibited strong activity against all tested bacteria except for E. coli and S. epidermidis, with its MIC values ranging from 0.2 mg/mL to 0.4 mg/mL. For the antifungal activity assay, the ME of Tartary buckwheat sprouts and four flavonoids could significantly inhibit the spore germination of two pathogenic fungi, and their inhibitory efficiency was concentration dependent. Quercetin was the most active one, which significantly inhibited the spore germination of F. oxysporum f. sp. vasinfectum and F. oxysporum f. sp. cucumerinum, and its median effective inhibitory concentration (IC50) value was 42.36 and 32.85 µg/mL, respectively. The antioxidant activity results showed that quercetin, kaemferol, and rutin displayed excellent antioxidant activity in the DPPH radical scavenging test, and their IC50 value was calculated as 5.60, 16.23, and 27.95 µg/mL, respectively. This is the first report on the antimicrobial activity of the crude extract of Tartary buckwheat sprouts. These results indicated that the methanol extract of Tartary buckwheat sprouts could be used as a potential antimicrobial or antioxidant agent in the future.

Solar photoreactor: application in the recalcitrance and toxicity reduction of old leachate by photo-Fenton

This research evaluated the applicability of a solar photoreator using the photo-Fenton process to reduce the old leachate recalcitrance from the biological treatment system of the Metropolitan Sanitary Landfill of João Pessoa, Brazil. The operational variables, such as flow rate and reaction time were initially investigated in the photoreactor. Then, the test was carried out under defined conditions: pH (2.8), [Fe2+] (0.257 g.L-1), [H2O2] (9.42 g.L-1), volumetric flow rate (35 L.s-1) and reaction time (60 minutes). The results showed high colour removal (94.4%), COD (81.7%), aromatic compounds, in terms of absorbance at 254 nm (87.1%) and 280 nm (87.74%), as well as a threefold increase in biodegradability (BOD5/COD) of the phototreated effluent. The phytotoxicity of the leachate in the Lactuca sativa (lettuce), in terms of median effective concentration (EC50) was reduced by 76%. It can be concluded that photoreactor was efficient using the solar photo-Fenton process, being available alternative for the leachate post-treatment.

Orbitides and free polyamines have similarly limited fungicidal activity against three common pathogens of flax in vitro

Fusarium oxysporum f. sp. lini and Septoria linicola are causes of fusarium wilt and pasmo in flax ( Linum usitatissimum). Members of a third fungal genus, Alternaria spp., have also been found in fiber and linseed varieties of flax, and are a source of post-harvest spoilage and mycotoxins in a wide range of crops. We performed a microdilution assay and calculated the median effective concentration (EC50) to compare the potency of cyclolinopeptides (CLPs), two polyamines (spermidine and spermine), and the fungicide carbendazimin in the control of three fungi that have potential pathogenic activity ( F. oxysporum, S. linicola, and Alternaria spp), of which the first two are particulary significant causes of disease in flax. For carbendazim, all EC50 values were &lt;0.6 μg/mL. The observed EC50 ranged from 111 to 340 μg/mL for a mixture of six unique CLPs, 109 to 778 μg/mL for spermine, and 21 to 272 μg/mL for spermidine. Spermidine was most effective against Alternaria sp., with an EC50 of 21 μg/mL. The results presented here showed that polyamines and CLPs possess limited antifungal activities against several fungi, with spermidines the most effective naturally occurring compound tested. Our findings do not support the hypothesis that CLPs act as potent antifungals against the three species of pathogens tested.

Size-specific sensitivity of cladocerans to freshwater salinization: Evidences from the changes in life history and population dynamics

The salinization of the global freshwater system caused by various human activities and climate change has become a common problem threatening freshwater biodiversity and resources, which may affect a variety of species of cladocerans at individual and population levels. In order to comprehensively evaluate the impact of salinization on different-sized cladocerans at individual and population levels, we exposed two species of cladocerans with obvious body size difference, Daphnia magna and Moina macrocopa, to seven salinities (0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12 M), recorded individual life history traits and population growth dynamics, and used multiple mechanistic models to fit the data. At the individual level, the median effect concentration of survival time, total offspring per female, and number of broods of D. magna were significantly higher than those of M. macrocopa. At the population level, the decrease in carrying capacity of D. magna with increasing salinity was significantly less than that of M. macrocopa. At the same salinity treatment, the integrated biomarker response indexes value of M. macrocopa is higher than that of D. magna. Therefore, it was further inferred that the sensitivity of small-sized species M. macrocopa to salinity stress is significantly higher than that of big-sized species D. magna. Thus, freshwater salinization may result in the replacement of smaller salt-intolerant cladocerans with larger salt-tolerant cladocerans, which may have dramatic effects on freshwater communities and ecosystems. Additionally, the increase of salinity had a greater impact on the population level of D. magna and M. macrocopa than on the individual level, indicating that population level of cladocerans was more susceptible to salinity stress. Experiments only based on individuals may underestimate the ecologically related changes in populations and communities, thus understanding the impact of salinization on freshwater systems needs to consider multiple ecological levels.

Potential application of an eco-friendly amine oxide collector in flotation separation of quartz from hematite

The development of eco-friendly collectors is an essential issue of much concern in mineral flotation processes. In this work, an eco-friendly amine oxide, N,N-Dimethyl aminopropyl dodecylamide oxide (LAO), was introduced as the collector in flotation separation of hematite and quartz. Compared with conventional amine collector dodecylamine (DDA), LAO with low toxicity has better flotation performance and superior selectivity in the natural slurry. With 10 mg/L LAO, the recovery of quartz and hematite is respectively 94.72% and 10.50%, while using the same dosage of DDA, the quartz recovery is only around 40% and the hematite recovery is 23%. The median effective inhibition concentration (EC50) of LAO for Daphnia magna is 328.44 mg/L, indicating LAO is a nontoxic compound to aquatic organisms. Therefore, LAO is a promising eco-friendly collector to apply in the separation of quartz from hematite.

Activity of terpenes derived from essential oils against Sarcoptes scabiei eggs

BackgroundThe limited ovicidal activity of currently available acaricides is a significant obstacle to efficacious scabies treatment. Several essential oils or their respective components have proved to be active against the eggs of arthropods, mainly lice and ticks. Information on the activity of these oils and/or components against the eggs of mites remains very limited. The aim of this study was to assess the activity of six terpenes (carvacrol, eugenol, geraniol, citral, terpinen-4-ol and linalool) commonly found in essential oils against the eggs of Sarcoptes scabiei.MethodsSarcoptes eggs were exposed to paraffin oil containing 1, 2.5, or 5% of each terpene tested. After a 12-h exposure period, the eggs were washed and placed in paraffin oil for hatching. Embryonic development following treatment was assessed every day to determine the stage of developmental arrest.ResultsThe median effective concentration to obtain 50% egg mortality (EC50) was 0.5, 0.9, 2.0, 4.8, 5.1 and 9.8% for carvacrol, eugenol, geraniol, citral, terpinen-4-ol and linalool, respectively. The microscopic images of eggs after each treatment indicated that these six terpenes may act by penetrating through the aeropyles on the egg surface.ConclusionsIn conclusion, carvacrol, eugenol and geraniol possess significant ovicidal activities, which should be considered as promising ovicidal agents for the treatment of scabies.Graphical

Comparative evaluation of the mechanisms of toxicity of graphene oxide and graphene oxide quantum dots to blue-green algae Microcystis aeruginosa in the aquatic environment

Due to the diverse applications, graphene-family nanomaterials (GFNs) have a high probability of release into the aquatic system, potentially posing risks to the aquatic environment. The acute effects on single-celled Microcystis aeruginosa by graphene oxide (GO) or graphene oxide quantum dots (GOQDs) were compared in the present study. GOQDs dispersed more effectively in water than GO at all pH values tested. The 96-hour median effective concentration (EC50) of GO and GOQDs were determined to be 49.32 and 22.46 mg/L, respectively. Both GO and GOQDs were internalized by heteroagglomeration and envelopment processes, with GOQDs inducing stronger upregulation of cell permeability, plasmolysis and lipid bodies than GO. Cracking of thylakoid layers, disappearance of nucleoid, and disintegration of cell infrastructure were observed at higher concentrations. In comparison to GO, GOQDs induced higher reactive oxygen species (ROS) and malondialdehyde (MDA) and disrupted antioxidant enzymes, leading to the inhibition of cellular contents such as chlorophyll a and proteins. Furthermore, both GO and GOQDs adsorbed nutrients from the algal medium, resulting in nutrient depletion-induced indirect toxicity, with GOQDs depleting more nutrients than GO. The current study provides new understanding of nanotoxicity of GO and GOQD and aids in the potential risks of nanomaterials in aquatic environments.

Synthesis, antibacterial evaluation, and safety assessment of CuS NPs against Pectobacterium carotovorum subsp. carotovorum.

Copper agents have been widely used in crop protection because of their unique mechanism against resistant pathogenic bacteria; however, their application brings environmental pollution and biosafety problems. Therefore, environmentally friendly copper agents have attracted attention. In this study, copper sulfide nanoparticles (CuS NPs) were prepared, characterized, analyzed for antibacterial activity and safety. Characterization results showed that the prepared pure CuS NPs have flake nanostructures, hexagonal crystal system, and size range from 40 to 60 nm. These CuS NPs exerted excellent antibacterial effects [median effective concentration (EC50 ) = 17 mg L-1 ] against Pectobacterium carotovorum subsp. carotovorum (Pcc) in vitro and can effectively delay and reduce bacterial infection in vivo. Antibacterial mechanism analysis revealed that CuS NPs can increase the levels of reactive oxygen species (ROS) and lipid peroxidation and destroy the structure of bacterial cells as observed through scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy. These NPs can also inhibit the motility of Pcc. At 7 and 14 days, the 50% lethal concentrations (LC50 ) of CuS NPs against earthworms were 1136 and 783 mg kg-1 , respectively, indicating their low acute toxicity to earthworms and environmental friendliness. Furthermore, the cells (L02) treated by CuS NPs showed relatively high cell viability (> 96%) and low apoptosis rate (only 5.2%), proving that CuS NPs had low cytotoxicity. Compared with commercial dicopper chloride trihydroxide (Cu2 (OH)3 Cl), CuS NPs could be used as a highly effective, lowly toxic, and environmentally friendly antibacterial agent. © 2021 Society of Chemical Industry.

The Antioxidant Guaiacol Exerts Fungicidal Activity Against Fungal Growth and Deoxynivalenol Production in Fusarium graminearum.

The main component of creosote obtained from dry wood distillation—guaiacol—is a natural antioxidant that has been widely used in pharmaceutical and food preservation applications. However, the antifungal mechanism of guaiacol against phytopathogens remains unclear. In this study, we found that guaiacol exerts inhibitory effects against mycelial growth, conidial formation and germination, and deoxynivalenol (DON) biosynthesis in Fusarium graminearum in a dose-dependent manner. The median effective concentration (EC50) value of guaiacol for the standard F. graminearum strain PH-1 was 1.838 mM. Guaiacol strongly inhibited conidial production and germination. The antifungal effects of guaiacol may be attributed to its capability to cause damage to the cell membrane by disrupting Ca2+ transport channels. In addition, the decreased malondialdehyde (MDA) levels and catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activity by guaiacol treatment indicate that guaiacol displays activity against DON production by modulating the oxidative response in F. graminearum. Taken together, this study revealed the potentials of antioxidant in inhibiting mycotoxins in F. graminearum.