A comparative study was conducted to assess the contact and fumigant toxicities of eleven monoterpenes on two important stored products insects--, Sitophilus oryzae, the rice weevil, and Tribolium ...castaneum, the rust red flour beetle. The monoterpenes included: camphene, (+)-camphor, (-)-carvone, 1-8-cineole, cuminaldehyde, (l)-fenchone, geraniol, (-)-limonene, (-)-linalool, (-)-menthol, and myrcene. The inhibitory effect of these compounds on acetylcholinesterase (AChE) activity also was examined to explore their possible mode(s) of toxic action. Although most of the compounds were toxic to S. oryzae and T. castaneum, their toxicity varied with insect species and with the bioassay test. In contact toxicity assays, (-)-carvone, geraniol, and cuminaldehyde showed the highest toxicity against S. oryzae with LC₅₀ values of 28.17, 28.76, and 42.08 μg/cm², respectively. (-)-Carvone (LC₅₀ = 19.80 μg/cm²) was the most effective compound against T. castaneum, followed by cuminaldehyde (LC₅₀ = 32.59 μg/cm²). In contrast, camphene, (+)-camphor, 1-8-cineole, and myrcene had weak activity against both insects (i.e., LC₅₀ values above 500 μg/cm²). In fumigant toxicity assays, 1-8-cineole was the most effective against S. oryzae and T. castaneum (LC₅₀ = 14.19 and 17.16 mg/l, respectively). Structure-toxicity investigations revealed that (-)-carvone--, a ketone--, had the highest contact toxicity against the both insects. 1-8-Cineole--, an ether--, was the most potent fumigant against both insects. In vitro inhibition studies of AChE from adults of S. oryzae showed that cuminaldehyde most effectively inhibited enzyme activity at the two tested concentrations (0.01 and 0.05 M) followed by 1-8-cineole, (-)-limonene, and (l)-fenchone. 1-8-Cineole was the most potent inhibitor of AChE activity from T. castaneum larvae followed by (-)-carvone and (-)-limonene. The results of the present study indicate that (-)-carvone, 1,8-cineole, cuminaldehyde, (l)-fenchone, and (-)-limonene could be effective biocontrol agents against S. oryzae and T. castaneum.
Analytical processes involving sample preparation, separation, and quantifying analytes in complex mixtures are indispensable in modern-day analysis. Each step is crucial to enriching correct and ...informative results. Therefore, sample preparation is the critical factor that determines both the accuracy and the time consumption of a sample analysis process. Recently, several promising sample preparation approaches have been made available with environmentally friendly technologies with high performance. As a result of its many advantages, solid-phase extraction (SPE) is practiced in many different fields in addition to the traditional methods. The SPE is an alternative method to liquid–liquid extraction (LLE), which eliminates several disadvantages, including many organic solvents, a lengthy operation time and numerous steps, potential sources of error, and high costs. SPE advanced sorbent technology reorients with various functions depending on the structure of extraction sorbents, including reversed-phase, normal-phase, cation exchange, anion exchange, and mixed-mode. In addition, the commercial SPE systems are disposable. Still, with the continual developments, the restricted access materials (RAM) and molecular imprinted polymers (MIP) are fabricated to be active reusable extraction cartridges. This review will discuss all the theoretical and practical principles of the SPE techniques, focusing on packing materials, different forms, and performing factors in recent and future advances. The information about novel methodological and instrumental solutions in relation to different variants of SPE techniques, solid-phase microextraction (SPME), in-tube solid-phase microextraction (IT-SPME), and magnetic solid-phase extraction (MSPE) is presented. The integration of SPE with analytical chromatographic techniques such as LC and GC is also indicated. Furthermore, the applications of these techniques are discussed in detail along with their advantages in analyzing pharmaceuticals, biological samples, natural compounds, pesticides, and environmental pollutants, as well as foods and beverages.
Graphical abstract
In the present work, quaternary chitosans as water-soluble compounds were prepared based on three-step process. Schiff bases were firstly synthesized by the reaction between the amino groups of ...chitosan with aliphatic aldehydes followed by a reduction with sodium borohydride (NaBH₄) to form N-(alkyl) chitosans. N,N,N-(dimethyl alkyl) chitosans were then obtained by a reaction of chitosan containing N-butyl, N-pentyl, N-hexyl, N-heptyl, and N-octyl substituents with methyl iodide. The compounds were characterized using IR and NMR spectroscopy. Subsequent experiments were conducted to test their antimicrobial activities against the most economic plant pathogenic bacteria of crown gall disease Agrobacterium tumefaciens, soft mold disease Erwinia carotovora, fungi of grey mold Botrytis cinerea, root rot disease Fusarium oxysporum, and damping off disease Pythium debaryanum. Quaternary chitosans enhanced the antibacterial activity and N,N,N-(dimethyl pentyl) chitosan was the most active one with Minimum Inhibitory Concentration (MIC) of 750 and 1225 mg/L against A. tumefaciens and E. carotovora, respectively. All quaternized chitosans gave stronger antifungal activities than chitosan where N,N,N-(dimethyl pentyl) chitosan and N,N,N-(dimethyl octyl) chitosan were significantly the highest in mycelial growth inhibiation against B. cinerea (EC₅₀ = 908 and 383 mg/L, respectively), F. oxysporum (EC₅₀ = 871 and 812 mg/L, respectively), and P. debaryanum (EC₅₀ = 624 and 440 mg/L, respectively). In addition, spore germination of B. cinerea and F. oxysporum was significantly affected with the compounds at the tested concentrations and the inhibition activity was increased with an increase in the chain length of the alkyl substituent.
•Quaternary N-(benzyl) chitosans were synthesized as antimicrobial agents.•Chemical structures were characterized by 1H-NMR, FT-IR and UV spectroscopy.•Derivatives exhibited promising activity ...against plant pathogenic bacteria and fungi.•Grafting benzyl or quaternization onto chitosan was successfully inhibiting pathogens.
Chemical modification of a biopolymer chitosan by introducing quaternary ammonium moieties into the polymer backbone enhances its antimicrobial activity. In the present study, a series of quaternary N-(benzyl) chitosan derivatives were synthesized and characterized by 1H-NMR, FT-IR and UV spectroscopic techniques. The antimicrobial activity against crop-threatening bacteria Agrobacterium tumefaciens and Erwinia carotovora and fungi Botrytis cinerea, Botryodiplodia theobromae, Fusarium oxysporum and Phytophthora infestans were evaluated. The results proved that the grafting of benzyl moiety or quaternization of the derivatives onto chitosan molecule was successful in inhibiting the microbial growth. Moreover, increase water-solubility of the compounds by quaternization significantly increased the activity against bacteria and fungi. Exocellular enzymes including polygalacturonase (PGase), pectin-lyase (PLase), polyphenol oxidase (PPOase) and cellulase were also affected at 1000mg/L. These compounds especially quaternary-based chitosan derivatives that have good inhibitory effect should be potentially used as antimicrobial agents in crop protection.
Gray mold caused by
Botrytis cinerea (Pers.) is the most economically important postharvest disease of fruit and vegetables at harvest and during storage. Therefore the current study was conducted to ...investigate the effectiveness of chitosan with different molecular weights on gray mold
in vitro and
in vivo in tomato fruit (
Solanum lycopersicum L. var.
lycopersicum) stored at different temperatures. In an
in vitro experiment, the results demonstrated that the antifungal activity increased as the chitosan molecular weight decreased. In an
in vivo study, chitosan treatments significantly reduced fungal decay and all compounds with concentrations of 2000 and 4000
mg/L showed complete control of the fungus in wound-inoculated fruit. Chitosan with a molecular weight of 5.7
×
10
4
g/mol was the most effective compound among those tested. The results also revealed that high chitosan concentrations correlated with low disease incidence regardless of storage conditions. In addition to the antifungal activity, chitosan had the potential for the elicitation of defense markers, including total soluble phenolic compounds, polyphenoloxidase (PPO) activity and total protein content. Chitosan treatment decreased the activity of PPO and enhanced total protein and phenolic compounds in wounded tomato fruit. These findings suggest that the effects of chitosan with different molecular weights on gray mold in tomato fruit may be associated with direct fungitoxic properties against the pathogen, and the elicitation of biochemical defense responses in fruit.
Chitosan, a hydrophilic biopolymer industrially obtained by N-deacetylation of chitin, can be applied as an antimicrobial agent. The current review of 129 references describes the biological activity ...of several chitosan derivatives and the modes of action that have been postulated in the literature. It highlights the applications of chitosan as an antimicrobial agent against fungi, bacteria, and viruses and as an elicitor of plant defense mechanisms.
The presence of calcium carbonate (CaCO
3
) in soil plays an essential role in regulating many processes whether chemical, physical, or biological. The effect of calcium carbonate content on the ...adsorption and desorption characteristics of insecticides (chlorantraniliprole, CAP, dinotefuran, DNF) and herbicides (bispyribac-sodium, BPS, metribuzin, MBZ) in calcareous soil has been studied. Adsorption and desorption isotherms of tested pesticides were quantified using the batch equilibration technique. The data were modeled with the Freundlich model to obtain the adsorption parameters. The results showed that the adsorption of DNF and BPS was the highest in intact calcareous soil (IS), while the adsorption of CAP and MBZ was the highest in calcium carbonate free calcareous soil (FS). The desorption from IS and FS was highest for MBZ, whereas it was lowest for BPS. Therefore, we demonstrate that the soil calcium carbonate could block the adsorption sites available for certain pesticides like CAP and MBZ, while it could be shared in the adsorption of other pesticides like DNF and BPS.
•Eighteen essential oils were isolated from Egyptian plants and their chemical composition was identified by GC/MS.•The isolated oils showed pronounced antibacterial and antifungal activities against ...plant pathogenic bacteria and fungi.•The relationship between chemical composition and antimicrobial activity was discussed.
The essential oils of eighteen Egyptian plants, namely, Artemisia judaica, A. monosperma, Callistemon viminals, Citrus aurantifolia, C. lemon, C. paradisi, C. sinensis, Cupressus macrocarpa, C. sempervirens, Myrtus communis, Origanum vulgare, Pelargonium graveolens, Rosmarinus officinalis, Syzygium cumini, Schinus molle, S. terebinthifolius, Thuja occidentalis and Vitex agnus-castus, were isolated by hydrodistillation. The chemical composition of the isolated oils was identified by gas chromatograph/mass spectrometer (GC/MS). The major constituents of the isolated oils were limonene (40.19%, 56.30%, 74.29% and 89.23% in C. aurantifolia, C. lemon, Citrus paradise and C. sinensis, respectively), α-pinene (37.88%, 35.49%, 26.16% and 17.26% in C. sempervirens, T. occidentalis, M. communis and S. cumini, respectively), 1,8-cineole (71.77% and 19.60% in C. viminals and R. officinalis), pulegone (77.45% in O. vulgare), β-thujone (49.83% in A. judaica), capillene (36.86% in A. monosperma), sabinene (14.93% in S. terebinthifolius), α-phellandrene (29.87% in S. molle), 4-terpeneol (20.29% in C. macrocarpa), trans-caryophyllene (15.19% in V. agnus-castus) and β-citronellol (35.92 in P. graveolens). The isolated oils were tested for their antimicrobial activity against the most economic plant pathogenic bacteria of Agrobacterium tumefaciens and Erwinia carotovora var. carotovora, and fungi of Alternaria alternata, Botrytis cinerea, Fusarium oxysporum and Fusarium solani. The isolated oils showed variable degree of antibacteabril activity against A. tumefaciens and E. carotovora var. carotovora. Based on minimum inhibitory concentration (MIC) values, the oils were more effective against E. carotovora var. carotovora than A. tumefaciens. The oil of T. occidentalis revealed the highest antibacterial activity among the tested oils showing the lowest MIC values of 400 and 350mg/L, on A. tumefaciens and E. carotovora var. carotovora, respectively. In mycelial growth inhibition assay, most of the essential oils showed pronounced effect and the oil of A. monosperma was the most potent inhibitor with EC50=54, 111, 106 and 148mg/L against A. alternata, B. cinerea, F. oxysporum and F. solani, respectively. On the other hand, the oils caused strong reduction in spore germination of fungi compared with control. The oils of A. judaica and A. monosperma caused the highest spore germination inhibition of F. oxysporum and their EC50 values were 69 and 62mg/L, respectively. Among the tested fungi, F. oxysporum was the most susceptible fungus to all of the tested oil except the oil of S. molle. The relationship between the antimicrobial activity and the chemical composition of the isolated oils was disclosed. The findings of the present study suggest that the isolated oils have a potential to be used as antimicrobial agents.
Inflammatory breast cancer (IBC) is a rare, but aggressive entity of breast carcinoma with rapid dermal lymphatic invasion in young females. It is either poorly or misdiagnosed as mastitis because of ...the absence of a distinct lump. Small extracellular vesicles (sEVs) circulating in liquid biopsies are a novel class of minimally invasive diagnostic alternative to invasive tissue biopsies. They modulate cancer progression via shuttling their encapsulated cargo including microRNAs (miRNAs) into recipient cells to either trigger signaling or induce malignant transformation of targeted cells. Plasma sEVs < 200 nm were isolated using a modified cost-effective polyethylene glycol (PEG)-based precipitation method and compared to standard methods, namely ultracentrifugation and a commercial kit, where the successful isolation was verified by different approaches. We evaluated the expression levels of selected sEV-derived miR-181b-5p, miR-222-3p and let-7a-5p using quantitative real PCR (qPCR). Relative to non-IBC, our qPCR data showed that sEV-derived miR-181b-5p and miR-222-3p were significantly upregulated, whereas let-7a-5p was downregulated in IBC patients. Interestingly, receiver operating characteristic (ROC) curves analysis revealed that diagnostic accuracy of let-7a-5p alone was the highest for IBC with an area under curve (AUC) value of 0.9188, and when combined with miR-222-3p the AUC was improved to 0.973. Further, 38 hub genes were identified using bioinformatics analysis. Together, circulating sEV-derived miR-181b-5p, miR-222-3p and let-7a-5p serve as promising non-invasive diagnostic biomarkers for IBC.
The present work describes the antimicrobial action of 25 monoterpenes (six hydrocarbons, five ketones, two aldehydes, six alcohols and six acetate analogues) against Gram-negative Escherichia coli ...and Gram-positive Staphylococcus aureus and antifungal activity against Aspergillus flavus. The antibacterial activity was evaluated by broth microdilution technique as a minimum inhibitory concentration (MIC) and the antifungal activity was performed by mycelia radial growth technique as the effective concentration causing 50% inhibition of the mycelial growth (EC50). The results showed that thymol and α-terpineol were the most potent against E. coli (MIC = 45 and 55 mg/L, respectively) and S. aureus (MIC = 135 and 225 mg/L, respectively). The results also showed that thymol displayed the maximum antifungal action against A. flavus with EC50 20 mg/L. Furthermore, the antioxidant activity was determined using N,N-dimethyl-1,4-phenylenediamine (DMPD) and the results showed that geraniol were the most potent compound (IC50 = 19 mg/L). Molecular docking studies indicated that the compounds displayed different binding interactions with the amino acid residues at the catalytic sites of N5-carboxyaminoimidazole synthetase and oxysterol binding protein Osh4 enzymes. Non-covalent interactions including van der Waals, hydrogen bonding as well as hydrophobic were observed between the compounds and the enzymes. A significant relationship was found between the docking score and the biological activity of the tested monoterpenes compared to the ceftriaxone and carbendazim as standard bactericide and fungicide, respectively. In silico ADMET properties were also performed and displayed potential for the development of promising antimicrobial agents. For these reasons, these compounds may be considered as potential ecofriendly alternatives in food preservation to delay or prevent the microbial infection and prolong the shelf life of food products.
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•Twenty five monoterpenes were evaluated against Escherichia coli, Staphylococcus aureus and Aspergillus flavus.•The compounds exhibited varying degrees of antimicrobial potency against bacteria and fungus.•Thymol and α-terpineol were the most potent against E. coli and S. aureus.•Thymol displayed the maximum antifungal action against A. flavus.•In silico studies include molecular docking and ADMET properties were demonstrated to elucidate the mechanism of action.
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