Insecticide susceptibility of Ephemera orientalis (Ephemeroptera: Ephemeridae) and two mosquito species,Anopheles sinensis and Culex pipiens in the Republic of Korea

Field-collected populations of mayflies, Ephemera orientalis were tested for susceptibility to 10 different insecticides using a direct-contact mortality bioassay. Ephemera orientalis subimagoes were susceptible to the insecticides chlorpyrifos, fenitrothion and chlorfenapyr with LD₅₀ values of 69.7, 78.8 and 81.9 μg/♀, and adults had LD₅₀ values of 71.9, 78.8 and 85.4 μg/♀, respectively. Susceptibility ratios (SRs) of subimagoes and adults of E. orientalis to the 10 insecticides were 1.0 to1.2 folds. The mayflies showed higher susceptibility to organophosphates than to pyrethroids. The SRs of Anopheles sinensis to E. orientalis were 514 to 1438 folds higher for organophosphates (LD₅₀ values of 0.05 to 0.23 μg/♀) and 62 to 1155 folds higher for pyrethroids (LD₅₀ values of 0.13 to 2.41 μg/♀). The SRs of Culex pipiens to E. orientalis were 606 to 3595 folds higher for organophosphates with LD₅₀ values of 0.02–0.17 μg/♀ and 81 to 1365 folds higher for pyrethroids with LD₅₀ values of 0.11–1.83 μg/♀. These results indicate that the use of ineffective insecticides will result in unsatisfactory control against field populations of the subimagoes and adults of E. orientalis.     

Drosophila as a model system for studying lifespan and neuroprotective activities of plant-derived compounds

The fruit fly, Drosophila melanogaster, has been intensively used as a genetic model system for basic and applied research on human neurological diseases because of advantages over mammalian model systems such as ease of laboratory maintenance and genetic manipulations. Disease-associated gene mutations, whether endogenous or transgenically-inserted, often cause phenotypes in vivo that are similar to the clinical features of the human disorder. The Drosophila genome is simpler than that of mammals, in terms of gene and chromosome number, but nonetheless demonstrates extraordinary phylogenetic conservation of gene structure and function, especially notable among the genes whose mutations cause neurodevelopmental, neuropsychiatric, or neurodegenerative disorders. In addition, its well-established neuroanatomical, developmental, and molecular genetic research techniques allow many laboratories worldwide to study complex biological and genetic processes. Based on these merits of the Drosophila model system, it has been used for screening lifespan expansion and neuroprotective activities of plant extracts or their secondary metabolites to counteract pathological events such as mitochondrial damage by oxidative stress, which may cause sporadic neurodegenerative diseases. In this review, we have summarized that the fruit fly can be used for early-stage drug discovery and development to identify novel plant-derived compounds to protect against neurodegeneration in Alzheimer's disease and Parkinson's disease, and other neurological disorders caused by oxidative stress. Thus, the Drosophila system can directly or indirectly contribute to translational research for new therapeutic strategies to prevent or ameliorate neurodegenerative diseases.     

Fungus mediated synthesis of gold nanoparticles and their conjugation with genomic DNA isolated from Escherichia coli and Staphylococcus aureus

Biological systems employing microorganisms have been used as an alternative to conventional chemical techniques for synthesizing gold nanoparticles. In the present study, gold nanoparticles have been synthesized from the supernatant broth (SB) and live cell filtrate (LCF) of the industrially important fungus Penicillium rugulosum. Additionally, potato dextrose broth (PDB) medium which is used for the growth of the fungus has also been able to synthesize gold nanoparticles. The size of the particles has been investigated by Bio-TEM before purification as well as after purification to find the difference in morphology pattern of the nanoparticles. Different characterization techniques like X-ray diffraction (XRD), infra-red (FTIR), X-ray photoelectron (XPS) and UV–vis spectroscopy have been used for analysis of the particles. SB of the fungus has yielded nanoparticles with better morphology and hence further optimization studies were conducted for controlling the size and shape of the above by altering pH and concentration of gold salt. A pH range of 4–6 has favored the synthesis process whereas increasing concentration of gold salt (beyond 2 mM) has resulted in the formation of bigger sized and aggregated nanoparticles. The optimized nanoparticles have been used to conjugate with isolated genomic DNA of bacteria Escherichia coli and Staphylococcus aureus. Visual observation of agarose gel electrophoresis images confirmed the binding of gold nanoparticles (4 μL and 6 μL) with isolated DNA (2 μL) fragments of both the organisms. The slight red shift of the surface plasmon (SP) band and minor aggregations noticed in Bio-TEM images for the DNA conjugated gold nanoparticles indicates that the genomic DNA could stabilize the particles against aggregation owing to negatively charged phosphate backbone.     

Inhibitory effects of the essential oils α-longipinene and linalool on biofilm formation and hyphal growth of Candida albicans

Candida albicans is one of the most common fungal pathogens, and causes systemic and invasive infections in humans. C. albicans biofilms are composed of yeast and hyphal and pseudohyphal elements, and the transition of yeast to the hyphal stage could be a virulence factor. In this study, diverse essential oils were initially investigated for anti-biofilm activity against C. albicans strains, and cascarilla bark oil and helichrysum oil and their components α-longipinene (a major constituent of both) and linalool were found to markedly inhibit biofilm formation without affecting planktonic cell growth. Moreover, α-longipinene and linalool were found to synergistically reduce biofilm formation. Notably, treatments with cascarilla bark oil, helichrysum oil, α-longipinene, or linalool clearly inhibited hyphal formation, and this appeared to be largely responsible for their anti-biofilm effect. Furthermore, the two essential oils, α-longipinene and linalool, reduced C. albicans virulence in Caenorhabditis elegans.     

Microbial synthesis of gold nanoparticles using the fungus <Emphasis Type="Italic">Penicillium brevicompactum</Emphasis> and their cytotoxic effects against mouse mayo blast cancer C<Subscript>2</Subscript>C<Subscript>12</Subscript> cells

Microorganisms, their cell filtrates, and live biomass have been utilized for synthesizing various gold nanoparticles. The shape, size, stability as well as the purity of the bio synthesized nanoparticles become very essential for application purpose. In the present study, gold nanoparticles have been synthesized from the supernatant, live cell filtrate, and biomass of the fungus Penicillium brevicompactum. The fungus has been grown in potato dextrose broth which is also found to synthesize gold nanoparticles. The size of the particles has been investigated by Bio-TEM before purification, following purification and after storing the particles for 3 months under refrigerated condition. Different characterization techniques like X-ray diffraction, Fourier transform infrared spectroscopy, and UV–visible spectroscopy have been used for analysis of the particles. The effect of reaction parameters such as pH and concentration of gold salt have also been monitored to optimize the morphology and dispersity of the synthesized gold nanoparticles. A pH range of 5 to 8 has favored the synthesis process whereas increasing concentration of gold salt (beyond 2 mM) has resulted in the formation of bigger sized and aggregated nanoparticles. Additionally, the cytotoxic nature of prepared nanoparticles has been analyzed using mouse mayo blast cancer C₂C₁₂ cells at different time intervals (24, 48, and 72 h) of incubation period. The cells are cultivated in Dulbecco’s modified Eagle’s medium supplemented with fetal bovine serum with antibiotics (streptopenicillin) at 37°C in a 5% humidified environment of CO₂. The medium has been replenished every other day, and the cells are subcultured after reaching the confluence. The viability of the cells is analyzed with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide method.     

Plant extract-mediated biogenic synthesis of silver,manganese dioxide,silver-doped manganese dioxide nanoparticles and their antibacterial activity against food- and water-borne pathogens

Silver nanoparticles (AgNPs), manganese dioxide nanoparticles (MnO₂NPs) and silver-doped manganese dioxide nanoparticles (Ag-doped MnO₂NPs) were synthesized by simultaneous green chemistry reduction approach. Aqueous extract from the leaves of medicinally important plant Cucurbita pepo was used as reducing and capping agents. Various characterization techniques were carried out to affirm the formation of nanoparticles. HR-TEM analysis confirmed the size of nanoparticles in the range of 15–70 nm and also metal doping was confirmed through XRD and EDS analyses. FT-IR analysis confirmed that the presence of biomolecules in the aqueous leaves extract was responsible for nanoparticles synthesis. Further, the concentration of metals and their doping in the reaction mixture was achieved by ICP–MS. The growth curve and well diffusion study of synthesized nanoparticles were performed against food- and water-borne Gram-positive and Gram-negative bacterial pathogens. The mode of interaction of nanoparticles on bacterial cells was demonstrated through Bio-TEM analysis. Interestingly, AgNPs and Ag-doped MnO₂ NPs showed better antibacterial activity against all the tested bacterial pathogens; however, MnO₂NPs alone did not show any antibacterial properties. Hence, AgNPs and Ag-doped MnO₂ NPs synthesized from aqueous plant leaves extract may have important role in controlling various food spoilage caused by bacteria.     

Toxicity and repellency of origanum essential oil and its components against Tribolium castaneum (Coleoptera: Tenebrionidae) adults

The components of Origanum vulgare L. essential oil showing insecticidal activity and repellency against red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae), adults were analysed by GC-MS. All constituents were identified, and the main components were carvacrol (67.2%), p-cymene (16.2%), γ-terpinene (5.5%), thymol (4.9%), and linalool (2.1%). In a vapor phase fumigant assay, the origanum oil was more effective in closed conditions (LD₅₀ = 0.055 mg/cm³) than in open conditions (LD₅₀ > 0.353 mg/cm³). This suggests that toxicity is exerted largely in the vapor phase. Based on 24-h LD₅₀ values, the toxicity of caryophyllene oxide (0.00018 mg/cm³) was comparable with that of dichlorvos (0.00007 mg/cm³). In addition, thymol, camphene, α-pinene, p-cymene, and γ-terpinene showed good insecticidal activity (LD₅₀ = 0.012–0.195 mg/cm³). In repellency tests using 9 constituents of origanum oil, caryophyllene oxide showed complete repellency at 0.03 mg/cm². Hydrogenated monoterpenoids, such as thymol, α-pinene, carvacrol, and myrcene, elicited strong repellency at 0.03 and 0.006 mg/cm². Repellency depended on both time and concentration. These results indicate that origanum oil and its components could be potential candidates as a fumigant and repellent for managing T. castaneum adults.     

Removal of Hexane in Biofilters Packed with Perlite and a Peat–Perlite Mixture

Removal of hexane from air–hexane mixtures in biofilters packed with different solid media under nitrogen supplementation was performed for 70 days. Two columns containing Perlite or a mixture of peat and Perlite, were used. The solid media were supplemented with nitrogen source up to 1 kg/m³ per week for high nutrient supplementation and 0.2 kg/m³ per month for low nutrient supplementation. A high rate of hexane removal: 95 g/m³ h was achieved under high nutrient supplementation, high air flow rate and high hexane concentration. However, the percentage of hexane removal decreased with increasing air flow rate and hexane inlet concentration. For high nutrient supplementation the type of solid medium did not significantly affect the biodegradation capacity. With low nutrient supplementation, the highest removal rate was achieved in the column containing the peat–perlite mixture. The column containing perlite had a significantly lower pressure drop (20 Pa/m) than the 2400–2930 Pa/m observed for the column containing the mixture. Perlite offers an opportunity of running a biofiltration process at a lower and stable pressure drop if the nutrient supplementation is managed properly.     

Antibacterial activity of ZnO nanoparticles prepared via non-hydrolytic solution route

The antibacterial activity of ZnO nanoparticles has been investigated and presented in this paper. Nanoparticles were prepared via non-hydrolytic solution process using zinc acetate di-hydrate (Zn(CH₃COO)₂·2H₂O) and aniline (C₆H₅NH₂) in 6 h refluxing at ∼65 °C. In the presence of four pathogens such as Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae, the antibacterial study of zinc oxide nanoparticles were observed. The antibacterial activity of ZnO nanoparticles (ZnO-NPs) were studied by spectroscopic method taking different concentrations (5–45 μg/ml) of ZnO-NPs. Our investigation reveals that the lowest concentration of ZnO-NPs solution inhibiting the growth of microbial strain is found to be 5 μg/ml for K. pneumoniae, whereas for E. coli, S. aureus, and S. typhimurium, it was calculated to be 15 μg/ml. The diameter of each ZnO-NPs lies between “20 and 30 nm” as observed from FESEM and transmission electron microscopy images. The composition of synthesized material was analyzed by the Fourier transform infrared spectroscopy, and it shows the band of ZnO at 441 cm⁻¹. Additionally, on the basis of morphological and chemical observations, the chemical reaction mechanism of ZnO-NPs was also proposed.     

Interaction of silver and gold nanoparticles in mammalian cancer: as real topical bullet for wound healing— A comparative study

The present study evaluates in vitro cytotoxic effects and the mode of interaction of biologically synthesized Ag and Au nanoparticles (NPs) using Brassica oleracea L. var. capitata f. rubra (BOL) against HT-1080 cancer cells and bacterial cells as well as their wound healing efficacy using a mouse model. UV–visible spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis have ascertained the formation of nano-sized Ag and Au particles. Fourier transform infrared analysis has confirmed that polyphenol and amide groups in BOL act as capping as well as reducing agents. The free radical scavenging activity under in vitro conditions is found to be higher for the Ag NPs when compared to the Au NPs. Acridine orange–ethidium bromide dual staining and comet assay have indicated that the cytotoxic effects are mediated through nuclear morphological changes and DNA damage. The intracellular localization of Ag and Au NPs in HT-1080 cells and their subsequent effect on apoptosis and necrosis were analyzed by flow cytometry while the mode of interaction was established by scanning electron microscopy under field emission mode and by bio-transmission electron microscopy. These methods of analysis clearly revealed that the Ag and Au NPs have easily entered and accumulated into the cytosol and nucleus, resulting in activation of inflammatory and apoptosis pathways, which in turn cause damage in DNA. Further, mRNA and protein expression of caspase-3 and caspase-7, TNF-α, and NF-κB have provided sufficient clues for induction of intrinsic and extrinsic apoptosis and inflammatory pathways in Ag NP- and Au NP-treated cells. Evaluation of wound healing properties of Ag and Au NPs using a mouse model indicates rapid healing of wounds. In addition, no clear toxic effects and no nuclear abnormalities in peripheral blood cells are observed. Ag NPs appear to be a better anticancer therapeutic agent than Au NPs. Nonetheless, both Ag NPs and Au NPs show potential for promoting topical wound healing without any toxic effects.

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Graphical abstract Schematic representation of biological synthesis of Ag and Au NPs and its application on cancer and wound healing: