Antifungal Activity of Eugenol Derivatives against Botrytis Cinerea

Effect of eugenol on cytochrome P450 1A2, 2C9, 2D6, and 3A4 activity in human liver microsomes

This study aimed to provide an understanding of the influence of eugenol on CYP1A2, 2C9, 2D6, and 3A4 in human liver microsomes (HLM). Specific substrate for CYP1A2, 2C9, 2D6, and 3A4 were incubated in HLM with or without eugenol. The formation of their respective metabolites was assessed with HPLC analytical methods. Eugenol at 1, 10 and 100 µM levels inhibited the activity of CYP1A2 and CYP2C9 by 23.38 %, 23.57 %, 39.80 % and 62.82 %, 63.27 %, 67.70 % respectively. While, CYP2D6 and CYP3A4 activity was decreased by 40.70 %, 45.88 %, 62.68 % and 37.41 %, 42.58 % and 67.86 % at 1, 10 and 100 µM eugenol level respectively. The IC50 value of eugenol for CYP2D6 and CYP3A4 was calculated as 11.09 ± 3.49 µM and 13.48 ± 3.86 µM respectively. Potential herb-drug interactions was noted when eugenol is administered simultaneously with medications metabolized by these enzymes, most notably CYP2C9, CYP2D6 and CYP3A4.

Exogenous Eugenol Alleviates Salt Stress in Tobacco Seedlings by Regulating the Antioxidant System and Hormone Signaling

Salt stress seriously affects crop growth, leading to a decline in crop quality and yield. Application of exogenous substances to improve the salt tolerance of crops and promote their growth under salt stress has become a widespread and effective means. Eugenol is a small molecule of plant origin with medicinal properties such as antibacterial, antiviral, and antioxidant properties. In this study, tobacco seedlings were placed in Hoagland's solution containing NaCl in the presence or absence of eugenol, and physiological indices related to stress tolerance were measured along with transcriptome sequencing. The results showed that eugenol improved the growth of tobacco seedlings under salt stress. It promoted carbon and nitrogen metabolism, increased the activities of nitrate reductase (NR), sucrose synthase (SS), and glutamine synthetase (GS) by 31.03, 5.80, and 51.06%. It also activated the enzymatic and non-enzymatic antioxidant systems, reduced the accumulation of reactive oxygen species in the tobacco seedlings, and increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) by 24.38%, 18.22%, 21.60%, and 28.8%, respectively. The content of glutathione (GSH) was increased by 29.49%, and the content of superoxide anion (O2-) and malondialdehyde (MDA) were reduced by 29.83 and 33.86%, respectively. Promoted osmoregulation, the content of Na+ decreased by 34.34, K+ increased by 41.25%, and starch and soluble sugar increased by 7.72% and 25.42%, respectively. It coordinated hormone signaling in seedlings; the content of abscisic acid (ABA) and gibberellic acid 3 (GA3) increased by 51.93% and 266.28%, respectively. The transcriptome data indicated that the differentially expressed genes were mainly enriched in phenylpropanoid biosynthesis, the MAPK signaling pathway, and phytohormone signal transduction pathways. The results of this study revealed the novel role of eugenol in regulating plant resistance and provided a reference for the use of exogenous substances to alleviate salt stress.

Design and Synthesis of Eugenol Derivatives Bearing a 1,2,3-Triazole Moiety for Papaya Protection against Colletotrichum gloeosporioides

A series of 19 novel eugenol derivatives containing a 1,2,3-triazole moiety was synthesized via a two-step process, with the key step being a copper(I)-catalyzed azide-alkyne cycloaddition reaction. The compounds were assessed for their antifungal activities against Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. Triazoles 2k, 2m, 2l, and 2n, at 100 ppm, were the most effective, reducing mycelial growth by 88.3, 85.5, 82.4, and 81.4%, respectively. Molecular docking calculations allowed us to elucidate the binding mode of these derivatives in the catalytic pocket of C. gloeosporioides CYP51. The best-docked compounds bind closely to the heme cofactor and within the channel access of the lanosterol (LAN) substrate, with crucial interactions involving residues Tyr102, Ile355, Met485, and Phe486. From such studies, the antifungal activity is likely attributed to the prevention of substrate LAN entry by the 1,2,3-triazole derivatives. The triazoles derived from natural eugenol represent a novel lead in the search for environmentally safe agents for controlling C. gloeosporioides.

Comprehensive antifungal investigation of natural plant extracts against Neosartorya spp. (Aspergillus spp.) of agriculturally significant microbiological contaminants and shaping their metabolic profile

Fungi belonging to the genus Neosartorya (teleomorph of Aspergillus spp.) are of great concern in the production and storage of berries and fruit-based products, mainly due to the production of thermoresistant ascospores that cause food spoilage and possible secretion of mycotoxins. We initially tested the antifungal effect of six natural extracts against 20 isolates of Neosartorya spp. using a traditional inhibition test on Petri dishes. Tested isolates did not respond uniformly, creating 5 groups of descending sensitivity. Ten isolates best representing of the established sensitivity clusters were chosen for further investigation using a Biolog™ MT2 microplate assay with the same 6 natural extracts. Additionally, to test for metabolic profile changes, we used a Biolog™ FF microplate assay after pre-incubation with marigold extract. All natural extracts had an inhibitory effect on Neosartorya spp. growth and impacted its metabolism. Lavender and tea tree oil extracts at a concentration of 1000 µg mL-1 presented the strongest antifungal effect during the inhibition test, however all extracts exhibited inhibitory properties at even the lowest dose (5 µg mL-1). The fungal stress response in the presence of marigold extract was characterized by a decrease of amino acids and carbohydrates consumption and an uptake of carboxylic acids on the FF microplates, where the 10 studied isolates also presented differences in their innate resilience, creating 3 distinctive sensitivity groups of high, average and low sensitivity. The results confirm that natural plant extracts and essential oils inhibit and alter the growth and metabolism of Neosartorya spp. suggesting a possible future use in sustainable agriculture as an alternative to chemical fungicides used in traditional crop protection.

Eugenol improves salt tolerance via enhancing antioxidant capacity and regulating ionic balance in tobacco seedlings

Salt stress inhibits plant growth by disturbing plant intrinsic physiology. The application of exogenous plant growth regulators to improve the plant tolerance against salt stress has become one of the promising approaches to promote plant growth in saline environment. Eugenol (4-allyl-2- methoxyphenol) is the main ingredient in clove oil and it is known for its strong antioxidant and anti-microbial activities. Eugenol also has the ability of inhibiting several plant pathogens, implying the potential use of eugenol as an environmental friendly agrichemical. However, little is known about the possible role of eugenol in the regulation of plant tolerance against abiotic stress. Therefore, here we investigated the effectiveness of phytochemical eugenol in promoting salt tolerance in tobacco seedlings through physiological, histochemical, and biochemical method. The seedling roots were exposed to NaCl solution in the presence or absence of eugenol. Salt stress inhibited seedling growth, but eugenol supplementation effectively attenuated its effects in a dose-dependent manner, with an optimal effect at 20 µM. ROS (reactive oxygen species) accumulation was found in seedlings upon salt stress which was further resulted in the amelioration of lipid peroxidation, loss of membrane integrity, and cell death in salt-treated seedlings. Addition of eugenol highly suppressed ROS accumulation and reduced lipid peroxidation generation. Both enzymatic and non-enzymatic antioxidative systems were activated by eugenol treatment. AsA/DHA and GSH/GSSG were also enhanced upon eugenol treatment, which helped maintain redox homeostasis upon salinity. Eugenol treatment resulted in an increase in the content of osmoprotectants (e.g. proline, soluble sugar and starch) in salt-treated seedlings. Na+ levels decreased significantly in seedlings upon eugenol exposure. This may result from the upregulation of the expression of two ionic transporter genes, SOS1 (salt-hypersensitive 1) and NHX1 (Na+/H+ anti-transporter 1). Hierarchical cluster combined correlation analysis uncovered that eugenol induced salt tolerance was mediated by redox homeostasis and maintaining ionic balance in tobacco seedlings. This work reveals that eugenol plays a crucial role in regulating plant resistant physiology. This may extend its biological function as a novel biostimulant and opens up new possibilities for improving crop productivity in the saline agricultural environment.

Conformational Changes of Poly(Maleic Anhydride-alt-styrene) Modified with Amino Acids in an Aqueous Medium and Their Effect on Cytocompatibility and Hemolytic Response

The conformational changes of poly(maleic anhydride-alt-styrene) (PSMA) modified with different amino acids (PSMA-Aa) were studied in an aqueous medium as a function of ionic strength and pH. The specific viscosity of PSMA-Aa decreased with increasing salt concentration due to a more compact conformation. There was a decrease in surface tension with increasing concentrations of the modified polyelectrolyte having a greater effect for the PSMA modified with l-phenylalanine at pH 7.0, demonstrating a greater surface-active character. The conformational changes were also confirmed by molecular dynamics studies, indicating that PSMA-Aa exhibits a compact structure at pH 4.0 and a more extended structure at pH 7.0. On the other hand, the conformational changes of PSMA-Aa were related to its biological response, where the higher surface-active character of the PSMA modified with l-phenylalanine correlates very well with the higher hemolytic activity observed in red blood cells, in which the surface-active capacity supports lytic potency in erythrocytes. The cytocompatibility assays indicated that there were no significant cytotoxic effects of the PSMA-Aa. Additionally, in solvent-accessible surface area studies, it was shown that the carboxylate groups of the PSMA modified with l-phenylalanine are more exposed to the solvent at pH 7.0 and high salt concentrations, which correlates with lower fluorescence intensity, reflecting a loss of mitochondrial membrane potential. It is concluded that the study of the conformational changes in PE modified with amino acids is essential for their use as biomaterials and relevant to understanding the possible effects of PE modified with amino acids in biological systems.

Health from Brazilian Amazon food wastes: Bioactive compounds, antioxidants, antimicrobials, and potentials against cancer and oral diseases

Brazilian Amazon contains over 30,000 plant species and foods rich in bioactive compounds such as terpenes, phenolic acids, alkaloids, and flavonoids, of potential health benefits (antioxidant, antimicrobial, antiparasitic, anticancer, gastroprotection, prebiotic effects, among others). The existence of residues from non-edible parts of plants (leaves, roots, stems, branches, barks) or fruit wastes (peel, bagasse, seeds) in the agri-food industry and its supply chain is an important challenge in food loss and waste management. In this critical review several Amazon species, focusing on extracts/essential oils from nonedible parts or wastes, were analyzed in terms of phytochemicals, biological activity, and underlying mechanisms. We hope this review emphasizes the importance of Amazon's sustainability initiatives on population health due to the potential shown against cancer, infectious diseases, and prevention of oral diseases. It is urgent to think about the conversion of amazon food wastes and co-products into high-added-value raw materials to develop novel drugs, food packaging systems, or nutraceutical foods.

Iron and copper on Botrytis cinerea: new inputs in the cellular characterization of their inhibitory effect

Certain metals play key roles in infection by the gray mold fungus, Botrytis cinerea. Among them, copper and iron are necessary for redox and catalytic activity of enzymes and metalloproteins, but at high concentrations they are toxic. Understanding the mechanism requires more cell characterization studies for developing new, targeted metal-based fungicides to control fungal diseases on food crops. This study aims to characterize the inhibitory effect of copper and iron on B. cinerea by evaluating mycelial growth, sensitivity to cell wall perturbing agents (congo red and calcofluor white), membrane integrity, adhesion, conidial germination, and virulence. Tests of copper over the range of 2 to 8 mM and iron at 2 to 20 mM revealed that the concentration capable of reducing mycelial growth by 50% (IC50) was 2.87 mM and 9.08 mM for copper and iron, respectively. When mixed at equimolar amounts there was a significant inhibitory effect mostly attributable to copper. The effect of Cu50, Fe50, and Cu50-Fe50 was also studied on the mycelial growth of three wild B. cinerea strains, which were more sensitive to metallic inhibitors. A significant inhibition of conidial germination was correlated with adhesion capacity, indicating potential usefulness in controlling disease at early stages of crop growth. Comparisons of the effects of disruptive agents on the cell wall showed that Cu, Fe, and Cu-Fe did not exert their antifungal effect on the cell wall of B. cinerea. However, a relevant effect was observed on plasma membrane integrity. The pathogenicity test confirmed that virulence was correlated with the individual presence of Cu and Fe. Our results represent an important contribution that could be used to formulate and test metal-based fungicides targeted at early prevention or control of B. cinerea.

Production of nanocellulose from corn husk for the development of antimicrobial biodegradable packaging film

Packaging is a potential way of keeping food products safe from various environmental pollutants, and biological, chemical, & physical deterioration. Hence, the demand for an effective antimicrobial active packaging material is increasing tremendously to improve the shelf-life of food products. Thus, we extracted nanocellulose from corn husks and developed a eugenol-incorporated biodegradable antimicrobial active packaging film. The extracted nanocellulose showed a particle size of 149.67 ± 3.56 nm and an overall surface charge of -20.2 mV ± 0.76 V. The film casting method is one of the promising methods to fabricate biodegradable films using plant-based biopolymers. Therefore, different concentrations of eugenol (0.5-5 % v/v) were incorporated to formulate the functional film (FF0.5-FF5) by employing the casting process. FF exhibited comparable tensile strength as compared to the control film (CF), however, FF5 showed the least tensile strength (85 MPa). Based on the mechanical characterization, the FF3 film sample was further selected for characterization. The morphological evaluation revealed that the surface of the film was smooth and non-porous with reduced moisture content and density. The film exhibited high thermal stability as the degradation occurred above 400 °C, indicating the strong hydrogen bonding between the hydroxyl groups of the film. The Fourier transform infrared spectroscopy analysis revealed the existence of COOH vibration and COC stretching groups of cellulose and eugenol. The antimicrobial studies showed high efficacy against Staphylococcus aureus followed by Salmonella typhmurium, Pseudomonas aeruginosa, and Klebsiella pneumoniae bacteria. Overall, eugenol-incorporated nanocellulose-based biodegradable packaging film could be an excellent candidate as an alternative to active packaging material and provide an opportunity for the efficient utilization of corn husk.

Antifungal Activity of 2-Allylphenol Derivatives on the Botrytis cinerea Strain: Assessment of Possible Action Mechanism

Botrytis cinerea is a phytopathogenic fungus that causes serious damage to the agricultural industry by infecting various important crops. 2-allylphenol has been used in China as a fungicide for more than a decade, and it has been shown that is a respiration inhibitor. A series of derivatives of 2-allylphenol were synthesized and their activity against B. cinerea was evaluated by measuring mycelial growth inhibition. Results indicate that small changes in the chemical structure or the addition of substituent groups in the aromatic ring induce important variations in activity. For example, changing the hydroxyl group by methoxy or acetyl groups produces dramatic increases in mycelial growth inhibition, i.e., the IC50 value of 2-allylphenol decreases from 68 to 2 and 1 μg mL−1. In addition, it was found that the most active derivatives induce the inhibition of Bcaox expression in the early stages of B. cinerea conidia germination. This gene is associated with the activation of the alternative oxidase enzyme (AOX), which allows fungus respiration to continue in the presence of respiratory inhibitors. Thus, it seems that 2-allylphenol derivatives can inhibit the normal and alternative respiratory pathway of B. cinerea. Therefore, we believe that these compounds are a very attractive platform for the development of antifungal agents against B. cinerea.

Biological Activity of Hybrid Molecules Based on Major Constituents of Cinnammomun verum and Thymus vulgaris Essential Oils

Plants have been used by humans since ancient times due their antimicrobial and medicinal properties. Essential oils (EOs) are complex mixtures of secondary plant metabolites, including terpenoids, phenylpropanoids, and other aromatic compounds. Cinnamomun verum and Thyme vulgaris EOs and their organic extracts exert numerous biological activities because of their major compounds, particularly thymol, carvacrol, eugenol, and benzoic and cinnamic acid. The structural motifs presented by these phytochemicals are responsible for their biological activities. Modification or hybridization of these structures could lead to new bio-based compounds with improved efficacy or multiple modes of action. In this work, we aimed to develop reliable methods of obtaining six hybrid molecules from the major constituents of C. verum and T. vulgaris EOs. For the first time, we tested their efficacy in the inhibition of the mycelium growth and spore germination of two of the most important phytopathogenic fungi, Fusarium oxysporum and Colletotrichum gloeosporioides, and one opportunistic human pathogen, Aspergillus niger. The cytotoxic activity of the obtained hybrids was assessed using the brine shrimp lethality assay. In addition, we report for the first time a biocatalytic process for the obtention of these bioactive hybrid molecules. The results of this work enable the possibility of using hybrid molecules based on the major constituents of EOs as active ingredients in strategic industries such as agriculture, aquaculture, and pharmaceuticals.

Antifungal and Immunomodulatory Ingredients from Traditional Chinese Medicine

Fungal infections have become a growing public health challenge due to the clinical transmission of pathogenic fungi. The currently available antifungal drugs leave very limited choices for clinical physicians to deal with such situation, not to mention the long-standing problems of emerging drug resistance, side effects and heavy economic burdens imposed to patients. Therefore, new antifungal drugs are urgently needed. Screening drugs from natural products and using synthetic biology strategies are very promising for antifungal drug development. Chinese medicine is a vast library of natural products of biologically active molecules. According to traditional Chinese medicine (TCM) theory, preparations used to treat fungal diseases usually have antifungal and immunomodulatory functions. This suggests that if antifungal drugs are used in combination with immunomodulatory drugs, better results may be achieved. Studies have shown that the active components of TCM have strong antifungal or immunomodulatory effects and have broad application prospects. In this paper, the latest research progress of antifungal and immunomodulatory components of TCM is reviewed and discussed, hoping to provide inspiration for the design of novel antifungal compounds and to open up new horizons for antifungal treatment strategies.

Potential and Metabolic Pathways of Eugenol in the Management of Xanthomonas perforans, a Pathogen of Bacterial Spot of Tomato

Bacterial spot of tomato continues to pose a significant problem to tomato production worldwide. In Florida, bacterial spot of tomato caused by Xanthomonas perforans is one of the most important diseases responsible for tomato yield loss. This disease is difficult to control, and new strategies are continually being investigated to combat the devastating effect of this disease. Recent efforts focusing on essential oils based on small molecules have spurred interests in the utilization of this class of chemicals for disease management. In this study, we evaluated the efficacy of eugenol for the management of bacterial spot of tomato caused by X. perforans. In the greenhouse experiments, eugenol applied as a foliar spray significantly (p < 0.5) reduced bacterial spot disease compared to the untreated control. In the field experiments, the area under the disease progress curve (AUDPC) was significantly (p < 0.5) lower in the plots treated with eugenol or eugenol combined with the surfactant Cohere than in the untreated control plots, and it was comparable to the copper-based treatments. To provide additional insights into the possible pathways of eugenol activities, we applied a liquid chromatography mass spectrometry (LC-MS)-based metabolomic study using a thermo Q-Exactive orbitrap mass spectrometer with Dionex ultra high-performance liquid chromatography (UHPLC) on X. perforans strain 91−118 treated with eugenol. Our results showed that eugenol affected metabolite production in multiple pathways critical to bacterial survival. For example, treatment of cells with eugenol resulted in the downregulation of the glutathione metabolism pathway and associated metabolites, except for 5-oxoproline, which accumulation is known to be toxic to living cells. While the peaks corresponding to the putatively identified sarmentosin showed the most significant impact and reduced in response to eugenol treatment, branched-chain amino acids, such as L-isoleucine, increased in production, suggesting that eugenol may not negatively affect the protein biosynthesis pathways. The results from our study demonstrated the efficacy of eugenol in the management of bacterial spot of tomato under greenhouse and field conditions and identified multiple pathways that are targeted.

Impact of Geraniol and Geraniol Nanoemulsions on Botrytis cinerea and Effect of Geraniol on Cucumber Plants’ Metabolic Profile Analyzed by LC-QTOF-MS

In the present study, the bioactive substance geraniol was tested in vitro and in planta against B. cinerea on cucumber plants, and the changes in the metabolic profile of cucumber plants inoculated with the pathogen and/or treated with geraniol were monitored by a novel LC-QTOF-MS method employing target and suspect screening. The aforementioned treatments were also studied for their impact on membrane lipid peroxidation calculated as malondialdehyde (MDA) content. Additionally, geraniol-loaded nanoemulsions (GNEs) were synthesized and tested against B. cinerea as an integrated formulation mode of geraniol application. The EC₅₀ values calculated for geraniol and GNEs against B. cinerea were calculated at 235 μg/mL and 105 μg/mL, respectively. The in planta experiment on cucumber plants demonstrated the ability of geraniol and GNEs to significantly inhibit B. cinerea under greenhouse conditions. The LC-QTOF-MS analysis of the metabolic profile of the cucumber plants treated with geraniol demonstrated an increase in the concentration levels of myricetin, chlorogenic acid, and kaempferol rhamnoside, as compared to control plants and the presence of B. cinerea caused an increase in sinapic acid and genistein. These compounds are part of important biosynthetic pathways mostly related to responses against a pathogen attack.

Dissecting dietary and semisynthetic volatile phenylpropenes: A compile of their distribution, food properties, health effects, metabolism and toxicities

Phenylpropenes represent a major subclass of plant volatiles, including eugenol, and (E)-anethole. They contribute to the flavor and aroma of many chief herbs and spices, to exert distinct notes in food, i.e., spicy anise- and clove-like to fruit. Asides from their culinary use, they appear to exert general health effects, whereas some effects are specific, e.g., eugenol being a natural local anesthetic. This review represents the most comprehensive overview of phenylpropenes with respect to their chemical structures, different health effects, and their food applications as flavor and food preservatives. Side effects and toxicities of these compounds represent the second main part of this review, as some were reported for certain metabolites generated inside the body. Several metabolic reactions mediating for phenylpropenes metabolism in rodents via cytochrome P450 (CYP450) and sulfotransferase (SULT) enzymes are presented being involved in their toxicities. Such effects can be lessened by influencing their pharmacokinetics through a matrix-derived combination effect via administration of herbal extracts containing SULT inhibitors, i.e., nevadensin in sweet basil. Moreover, structural modification of phenylpropanes appears to improve their effects and broaden their applications. Hence, such review capitalizing on phenylpropenes can help optimize their applications in nutraceuticals, cosmeceuticals, and food applications.

Eco-friendly 'ochratoxin A' control in stored licorice roots - quality assurance perspective

According to toxicity data, ochratoxin A (OTA) is the second most important mycotoxin and is produced by Aspergillus and Penicillium. As a natural antifungal agent, clove essential oil (CEO) is a substance generally recognised as safe (GRAS) and shows strong activity against fungal pathogens. Here, we aimed to investigate the control efficacy of CEO in nano-emulsions (CEN) against OTA production in licorice roots and rhizomes during storage. The experiments were performed under simulated conditions of all four seasons (i.e. Spring, Summer, Autumn and Winter). Relative humidity (RH) and temperature were simulated in desiccators along with various salt solutions in incubators. Fresh licorice roots were immersed in CEN at various concentrations (150, 300, 600, 1200 and 2400 µl/l). Before utilising the nano-emulsions, we measured their polydispersity index and mean droplet size by the dynamic light scattering (DLS) technique. Also, the chemical composition of the CEO was determined using GC and GC-MS analyses. Sampling was carried out to monitor OTA once every five days. The samples were dried immediately and analysed by high-performance liquid chromatography (HPLC). Results showed that various concentrations of CEN inhibited the growth of fungi and OTA production. The most effective CEN concentrations were 1200 and 2400 µl/l, which reduced OTA production to 19 and 20 ppb under Winter and Autumn conditions, respectively. These results suggest an effective eco-friendly method for the storage of licorice to reduce postharvest fungal decay.

A Lesion Microenvironment-Responsive Fungicide Nanoplatform for Crop Disease Prevention and Control

Controlled fungicide delivery in response to the specific microenvironment produced by fungal pathogens is an advisable strategy to improve the efficacy of fungicides. Herein, the authors construct a smart fungicide nanoplatform, using mesoporous silica nanoparticles (MSNs) as nanocarriers loaded with eugenol (EU) and Ag⁺ coordinated polydopamine (Ag⁺ -PDA) as a coating to form Ag⁺ -PDA@MSNs-EU NPs for Botrytis cinerea (B. cinerea) control. As a botanical fungicide, EU offers an eco-friendly alternative to synthetic fungicides and can upregulate several defense-related genes in the tomato plant. The Ag⁺ -PDA coating can lock the EU inside the nanocarriers and respond to the oxalic acid produced by B. cinerea to corelease the loaded EU and Ag⁺ . The results demonstrate that Ag⁺ -PDA@MSNs-EU NPs can effectively inhibit the mycelial growth of B. cinerea on detached and potted tomato leaves. The construction of such a smart fungicide nanoplatform provides new guidance to design controlled fungicides release systems, which can respond to the microenvironment associated with plant pathogen to realize fungus control.

Novel Galactosyl Moiety-Conjugated Furylchalcones Synthesized Facilely Display Significant Regulatory Effect on Plant Growth

The expansion of weed infestation has increased the demand on new herbicides. A series of novel galactosyl moiety-conjugated furylchalcones was facilely synthesized in which the furyl group (A ring) was combined with the substituted benzene group (B ring), and a galactosyl moiety was introduced. All these galactosyl furylchalcones were predicted to be phloem-mobile. Most of the galactosyl furylchalcones significantly promoted early seedling growth of sorghum and barnyardgrass under dark conditions, but all of them revealed considerable anti-growth ability on illuminated pot plants; especially, 1-(3'-(4″-O-β-d-galactopyranosyl)furyl)-3-(4″-nitrophenyl)-2-en-1-one (B₁₁) had a better herbicidal activity against rapeseed and Chinese amaranth than haloxyfop-R-methyl. The median efficient concentrations (EC₅₀) of compound B₁₁ against cucumber and wheat were 9.55 and 26.97 mg/L, respectively, also showing a stronger suppressing capacity than 2,4-D. Molecular docking with phosphoenolpyruvate carboxylase protein showed a stable binding conformation in which the galactosyl group interacted with LYS363 and GLU369, the furan ring and carbonyl bound with ARG184, and the crosslink of the nitro group with GLU240 formed a salt bridge. The results demonstrate that galactosyl furylchalcones possess the great potential as new herbicides for weed management, and further evaluations on more weeds are required for practical application.

Structure activity evaluation and computational analysis identify potent, novel 3-benzylidene chroman-4-one analogs with anti-fungal, anti-oxidant, and anti-cancer activities

SIGNIFICANCE

3-Benzylidene chroman-4-ones share close homology with naturally occurring bioactive compounds.

OBJECTIVES

This study evaluated the antifungal, antioxidant, and anticancer activities of novel 3-benzylidene chromanone analogs with respect to their structure-activity relationships.

METHODS

Compounds 45e-64e were synthesized inhouse. Aspergillus niger (MTCC 1344) Aspergillus flavus and Botrytis cinerea were the fungal strains tested. Computational docking analysis was carried out for vanin-1, estrogen receptor (ER), and Akt proteins using Auto-dock vina. Free radical scavenging and total antioxidant capacity was analyzed using spectrophotometric methods. MCF-7 (breast cancer) cell line was used for anticancer assays. Flow cytometry was used to detect cell cycle and apoptosis.

RESULTS

Out of the twenty compounds screened, compounds 47e, 50e, 52e, 57e, and 61e that possessed either methoxy and ethoxy/methyl/isopropyl group exhibited very good activity against all fungi. Compounds possessing methoxy group alone showed moderate activity and compounds devoid of methoxy, and ethoxy groups did not show any activity. When computationally analyzed against target proteins for antioxidant properties, the compounds exhibited excellent binging efficacy to vanin-1 and ERs. These predictions were translated in the in vitro free-radical scavenging and antioxidant assays. The compounds exhibited anti-proliferative efficacy in breast cancer cell line, increased the sub-G₀/G₁ cell cycle populations and total apoptosis in MCF-7 cells. Additionally, the compounds also depicted excelling binging energy when computationally analyzed for Akt enzyme binding.

CONCLUSION

In summary, our study identified potential analogs of 3-benzylidene chroman-4-one molecules with excellent anti-fungal, anti-oxidant, and anticancer activities which demand further research for drug developments.

The role of antifungal activity of ethyl acetate extract from Artemisia argyi on Verticillium dahliae

AIMS

This study investigated the antifungal activity and mechanisms of ethyl acetate extract of Artemisia argyi (EAAA) against Verticillium dahliae.

METHODS AND RESULTS

Optical and scanning electron microscopy observation showed that 2.0 mg ml^-1 EAAA treatment reduced spore germination rate to 4.56%. Histochemical staining showed that 2.0 mg ml^-1 EAAA treatment increased reactive oxygen species (ROS) by more than two times. Physiological test showed that EAAA treatment decreased the contents of soluble proteins and sugars, and reduced the activities of malate dehydrogenase and succinate dehydrogenase by nearly half. Transcriptome analysis showed that EAAA treatment down-regulated the expression of genes involved in primary metabolic pathways of V. dahliae.

CONCLUSIONS

Our results revealed that EAAA inhibited the growth and development of V. dahliae from multiple levels and multiple targets, including inhibiting the germination and development of V. dahliae spores, destroying the structure of cell membranes, inducing ROS burst, reducing the activities of respiratory-related enzymes and down-regulating the expression of genes in primary metabolic pathways.

SIGNIFICANCE AND IMPACT OF THE STUDY

The mechanism of the multitarget effects of EAAA against V. dahliae may limit the potential of fungus developing resistance and provide the efficient methods to control verticillium wilt disease in the future.

Tailored Functionalization of Natural Phenols to Improve Biological Activity

Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols' anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

Assessing the Control of Postharvest Gray Mold Disease on Tomato Fruit Using Mixtures of Essential Oils and Their Respective Hydrolates

Gray mold disease, which is caused by Botrytis cinerea Pers ex. Fr., results in serious economic losses to Lycopersicum esculentum (tomato) crop productivity. In this study, we explored the possibility that mixtures of essential oils (EOs) and their respective hydrolates (HYSs) could be used to control this disease. Thus, EOs and HYSs were obtained from Origanum vulgare, Thymus vulgaris, Citrus limon, and Citrus sinensis by hydrodistillation. In vitro antifungal activities were evaluated, and EC50 values of 15.9 and 19.8 µg/mL were obtained for EOs of thyme and oregano, respectively. These activities are due mainly to volatile compounds, thymol and carvacrol. Results from in vivo assays show that although most tomatoes were infested five days after inoculation, the damage was considerably reduced by the application of an EO/HYS mixture of thyme. The disease incidence indexes of B. cinerea tomato rot, percentage and severity, measured four days after inoculation, were reduced by 70% and 76%, respectively, as compared with the inoculum control. These results suggest that a combination of HYSs and EOs enhances antifungal activity, and that optimization of relative concentrations, volumes, and the nature of the compounds, could design a formulation able to control B. cinerea inoculum on tomato fruits.

Anti-oomycetes and immunostimulatory activity of natural plant extract compounds against Saprolegnia spp.: Molecular docking and in-vitro studies

This study aimed to investigate the effectiveness of five natural plant extract compounds Curcumin (CUR); Eugenol (EUG), Cinnamaldehyde (CIN), Stigmasterol (ST) and Morin (MOR), on two species of Saprolegnia; Saprolegnia parasitica and S. australis. Selective compounds were screened for the minimum inhibitory concentration, first for anti-oomycetes activity and then mycelium growth inhibition, spore germination inhibition and colonisation test. Nitric oxide production and myeloperoxidase activity of the compounds were tested in head kidney leukocytes of rainbow trout, Oncorhynchus mykiss to assess the immunostimulatory potential. Molecular docking of effective compounds was carried out with effector proteins of S. parasitica to investigate the target binding sites. Among all, CUR could completely inhibit zoospore production and significantly (p ≤ .05) inhibit hyphal growth at 16 mg l^-1 against S. parasitica and S. australis. CIN at the concentration of 50 mg l^-1 completely inhibited hyphal growth of both Saprolegnia spp., although the zoospore production of S. parasitica and S. australis was reduced at 25 mg l^-1 and 10 mg l^-1. In the case of EUG, significant inhibition of the hyphal growth and germination of S. parasitica zoospores was observed at 50 mg l^-1. ST and MOR did not show antioomycetes activity. The molecular docking results were consistent with in vitro studies, possibly due to the binding with the vital proteins (Plasma membrane ATPase, V-type proton ATPase, TKL protein kinase, Host targeting protein 1) of S. parasitica and ultimately inhibiting their activity. CUR and CIN showed increased nitric oxide production at the highest concentration of 250 and 256 mg l^-1 but the value was not significant (p ≤ .05) with control. CUR showed significantly higher peroxidase activity (p ≤ .05) at a concentration of 256 mg l^-1 though values were significantly similar with concentration from 16 to 128 mg l^-1. The nitric oxide and total peroxidase activity of rainbow trout leukocytes in the case of CIN showed a significant difference only at 250 mg l^-1 against the control. The results conclude that CUR, CIN showed the better anti-Saprolegnia activity and could be used as phyto-additives in aquaculture. Among all, the inclusion of CUR as phyto-additives will provide additional immunostimulatory activity.

Biological Properties and Prospects for the Application of Eugenol-A Review

Eugenol is a phenolic aromatic compound obtained mainly from clove oil. Due to its known antibacterial, antiviral, antifungal, anticancer, anti-inflammatory and antioxidant properties, it has long been used in various areas, such as cosmetology, medicine, and pharmacology. However, high concentrations can be toxic. A dose of 2.5 mg/kg body weight is regarded as safe. This paper reviews the current state of knowledge regarding the activities and application of eugenol and its derivatives and recent research of these compounds. This review is based on information concerning eugenol characteristics and recent research from articles in PubMed. Eugenol remains of great interest to researchers, since its multidirectional action allows it to be a potential component of drugs and other products with therapeutic potential against a range of diseases.

Essential oils and their components in combating fungal pathogens of animal and human skin

OBJECTIVE

The most common problems of modern medicine include fungal infections of the skin and its appendages caused by dermatomycetes, yeast-like fungi and moulds. Due to toxicity of pharmacological fungicides and promotion of ecology, natural substances with high antifungal properties are sought. Essential oils and their components show potential in this regard.

MATERIAL AND METHOD

Fourteen commercial essential oils were tested for antifungal activity. The study were carried out by agar dilution method against the following fungal species: Microsporum gypseum, Microsporum canis, Trichophyton mentagrophytes, Trichophyton violaceum, Aspergillus niger, Scopulariopsis brevicaulis and (IZ 1) dog skin isolate. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) values were determined for all tested oils and individual components of oils with the highest activity against the tested fungi. GC-MS analysis was performed for the most active oils.

RESULTS

Cinnamon, thyme, clove, geranium and manuka oils were most active against the test fungi. The MIC values in the tested oils were in the range of 0.5->10μg/μl and the MFC amounted to 1.25->10μg/μl. Activity of individual components against the tested fungi strains was selective and clearly higher against dermatomycetes fungi and IZ 1 isolate. The strongest effect on dermatomycetes fungi was of cinnamaldehyde, thymol and carvacrol-with the values of 0.039-1.25μg/μl (MIC) and 0.078-1.25μg/μl (MFC). In turn, the highest activity against IZ 1 isolate was of cinnamaldehyde, eugenol, carvacrol, geraniol and thymol. Their MIC and MFC was 0.313-1.25μg/μl.

CONCLUSION

The results prove the applicability of selected oils and their components as alternatives to synthetic agents in combating fungal dermatoses in animals and humans.

Application of Plant Extracts to Control Postharvest Gray Mold and Susceptibility of Apple Fruits to B. cinerea from Different Plant Hosts

Sustainable plant protection can be applied on apples against fungal pathogens such as Botrytis cinerea (which is responsible for gray mold)-a significant global postharvest disease. This pathogen can affect a wide range of hosts; and fruits may have variable susceptibilities to B. cinerea from different plant hosts. New possibilities to control gray mold in food production are under demand due to the emergence of resistance against antifungal agents in fungal pathogens. Cinnamon, pimento, and laurel extracts were previously assessed for antifungal activities under in vitro conditions and were found to have the potential to be effective against postharvest gray mold. Therefore, this study aimed to investigate the antifungal activity of cinnamon, pimento, and laurel extracts in vitro and against postharvest gray mold on apples to determine the susceptibility of apple fruits to B. cinerea from different plant hosts, and to analyze the chemical composition of the extracts. Apples (cv. "Connell Red") were treated with different concentrations of extracts and inoculated with B. cinerea isolates from apple and strawberry followed by evaluation of in vitro antifungal activity. The results reveal that most of the concentrations of the extracts that were investigated were not efficient enough when assessed in the postharvest assay, despite having demonstrated a high in vitro antifungal effect. Apples were less susceptible to B. cinerea isolated from strawberry. To conclude, cinnamon extract was found to be the most effective against apple gray mold; however, higher concentrations of the extracts are required for the efficient inhibition of B. cinerea in fruits during storage.

The Extracts of Cinnamon and Clove as Potential Biofungicides against Strawberry Grey Mould

Biofungicides from plants are a possibility for the biocontrol of fungal diseases, as chemical products may be harmful to the environment and humans. Strawberry is one of the many plants infected by grey mould (Botrytis cinerea), and innovative methods of biocontrol against B. cinerea are under investigation. Clove (Syzygium aromaticum L.) and cinnamon (Cinnamomum cassia L.) accumulate natural compounds, such as eugenol and cinnamaldehyde, which provide antimicrobial and antifungal properties; thus, extracts of these plants could be possibly used as biofungicides. During this study, the inhibition of B. cinerea by clove and cinnamon extracts was evaluated in vitro on Petri plates and detached strawberry leaves; additionally, the chemical composition of volatiles was identified. Clove extract consisted of 52.88% eugenol, and cinnamon consisted of 74.67% cinnamaldehyde. The efficacy of the extracts on detached strawberry leaves showed that 12 mL L⁻¹ concentration of clove extract was effective in suppressing the grey mould infection. Clove and cinnamon extracts showed an equal ability to inhibit B. cinerea on Petri plates. However, the results of the detached strawberry leaves assay showed that clove extract was more effective as a biocontrol product. Overall, clove extract expressed a high potential for application in biofungicides formulations.

Cellular apoptosis and necrosis as therapeutic targets for novel Eugenol Tosylate Congeners against Candida albicans

Despite the rise of new Candida species, Candida albicans tops the list with high morbidity and mortality rates. To tackle this problem there is a need to explore new antifungals that could replace or augment the current treatment options. We previously reported that tosylation of eugenol on hydroxyl group resulted in molecules with enhanced antifungal potency. In line with that work, we synthesized new eugenol tosylate congeners (ETC-1–ETC-7) with different substituents on pendent sulfonyl group and tested their susceptibility against different fluconazole susceptible and resistant C. albicans strains. We evaluated physiology and mode of cell death in response to the most active derivatives by analyzing major apoptotic markers in yeast such as phosphatidylserine externalization, DNA fragmentation, mitochondrial depolarization and decrease in cytochrome c oxidase activity. The results demonstrated that all C. albicans strains were variably susceptible to the test compounds with MIC ranging from 0.125–512 µg/ml, and the most active compounds (ETC-5, ETC-6 and ETC-7) actuate apoptosis and necrosis in Candida cells in a dose-dependent manner via metacaspase-dependent pathway. Furthermore haemolytic assay showed low cytotoxicity effect of these ETCs. Overall the results indicated that ETCs exhibit potential antifungal activity against C. albicans by activating apoptotic and necrotic pathways.

Synthesis and In Vitro Growth Inhibition of 2-Allylphenol Derivatives Against Phythopthora cinnamomi Rands

Phytophthora cinnamomi is a phytopathogen that causes extensive damage in different crops, and therefore, produces important economic losses all around the world. Chemical fungicides are a key factor for the control of this disease. However, ecological and environmental considerations, as well as the appearance of strains that are resistant to commercial fungicides, have prompted the quest for new antifungal agents which are of low ecological impact. In this work, a series of new 2-allylphenol derivatives was synthesized, and their structures were confirmed by FT-IR, NMR, and MS. Some of the synthesized compounds, more specifically nitro derivatives, exhibit strong growth inhibition of P. cinnamomi with EC₅₀ as low as 10.0 µg/mL. This level of activity is similar to that exhibited by METALAXYL MZ 58 WP, a commonly-used commercial fungicide; therefore, these compounds might be of agricultural interest due to their potential use as fungicides against P. cinnamomi. The results indicate that this activity depends on the chemical structures of the 2-allylphenol derivatives, and that it is strongly enhanced in molecules where nitro and hydroxyl groups adopt a -para configuration. These effects are discussed in terms of the electronic distribution of the aromatic ring induced by substituent groups.