Antifungal mechanisms of α‐terpineol and terpene‐4‐alcohol as the critical components of Melaleuca alternifolia oil in the inhibition of rot disease caused by Aspergillus ochraceus in postharvest grapes

New Polymeric Hydrogels with Cannabidiol and α-Terpineol as Potential Materials for Skin Regeneration-Synthesis and Physicochemical and Biological Characterization

Dermatology and cosmetology currently prioritize healthy, youthful-looking skin. As a result, research is being conducted worldwide to uncover natural substances and carriers that allow for controlled release, which could aid in the battle against a variety of skin illnesses and slow the aging process. This study examined the biological and physicochemical features of novel hydrogels containing cannabidiol (CBD) and α-terpineol (TER). The hydrogels were obtained from ε-caprolactone (CL) and poly(ethylene glycol) (PEG) copolymers, diethylene glycol (DEG), poly(tetrahydrofuran) (PTHF), 1,6-diisocyanatohexane (HDI), and chitosan (CHT) components, whereas the biodegradable oligomers were synthesized using the enzyme ring-opening polymerization (e-ROP) method. The in vitro release rate of the active compounds from the hydrogels was characterized by mainly first-order kinetics, without a "burst release". The antimicrobial, anti-inflammatory, cytotoxic, antioxidant, and anti-aging qualities of the designed drug delivery systems (DDSs) were evaluated. The findings indicate that the hydrogel carriers that were developed have the ability to scavenge free radicals and impact the activity of antioxidant enzymes while avoiding any negative effects on keratinocytes and fibroblasts. Furthermore, they have anti-inflammatory qualities by impeding protein denaturation as well as the activity of proteinase and lipoxygenase. Additionally, their ability to reduce the multiplication of pathogenic bacteria and inhibit the activity of collagenase and elastase has been demonstrated. Thus, the developed hydrogel carriers may be effective systems for the controlled delivery of CBD, which may become a valuable tool for cosmetologists and dermatologists.

Antibacterial activity and mechanisms of α-terpineol against foodborne pathogenic bacteria

This study aimed to evaluate the antibacterial activities of α-terpineol against common foodborne pathogenic bacteria by agar well diffusion, broth microdilution, and colony counting assay. Propulsive research was conducted to reveal the antibacterial mechanisms, including morphology, infrared spectroscopy, membrane fluidity, membrane permeability, proton motive force, and oxidative phosphorylation. Results indicated that the antibacterial activity of α-terpineol decreased in the following order: Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes, and Staphylococcus aureus. With an initial cell count of 8 log CFU/mL, α-terpineol at 0.8% (v/v) reduced E. coli O157:H7 and S. aureus by approximately 5.6 and 3.9 log CFU/mL within 1 h, respectively. Remarkable destruction in cell envelopes and intracellular organizations was observed. The hydroxyl of α-terpineol might form glycosidic bonds with carbohydrates and hydrogen bonds with PO2- and COO- via infrared spectroscopy analysis. Generalized polarization of Laurdan revealed that the polar head groups of phospholipids transformed into close packed. The anisotropy variations of trimethyl amino-diphenylhexatriene (TMA-DPH) and DPH suggested membrane fluidity decreased. The N-phenyl-1-naphthylamine intake assay indicated that α-terpineol impaired the cell wall. Propidium iodide staining was indicative of damaged plasma membranes. Electron transport in the cytoplasmic membrane was impaired, inducing reactive oxygen species accumulation. Both membrane electrical potential and membrane pH gradient collapsed. The disruption of proton motive force and the leakage of ATP resulted in a deficit of intracellular ATP. Our research revealed the interaction between the hydroxyl group of α-terpineol and bacteria affects membrane function contributing to the bacteria's death. KEY POINTS: • α-Terpineol hydroxy formed glycosidic bonds and hydrogen bonds with bacteria • α-Terpineol increased the membrane gelation and reduced the membrane fluidity • Proton motive force and oxidative phosphorylation were impaired.

In Vitro and In Silico Activities of E. radiata and E. cinerea as an Enhancer of Antibacterial, Antioxidant, and Anti-Inflammatory Agents

Eucalyptus, a therapeutic plant mentioned in the ancient Algerian pharmacopeia, specifically two species belonging to the Myrtaceae family, E. radiata and E. cinerea, were investigated in this study for their antibacterial, antioxidant, and anti-inflammatory properties. The study used aqueous extracts (AE) obtained from these plants, and the extraction yields were found to be different. The in vitro antibacterial activity was evaluated using a disc diffusion assay against three typical bacterial strains. The results showed that the two extracts were effective against all three strains. Both extracts displayed significant antioxidant activity compared to BHT. The anti-inflammatory impact was evaluated using a protein (BSA) inhibition denaturation test. The E. radiata extract was found to inhibit inflammation by 85% at a concentration of 250 µg/mL, significantly higher than the Aspirin. All phytoconstituents present good pharmacokinetic characteristics without toxicity except very slight toxicity of terpineol and cineol and a maximum binding energy of -7.53 kcal/mol for its anti-TyrRS activity in silico. The study suggests that the extracts and their primary phytochemicals could enhance the efficacy of antibiotics, antioxidants, and non-steroidal anti-inflammatory drugs (NSAIDs). As pharmaceutical engineering experts, we believe this research contributes to developing natural-based drugs with potential therapeutic benefits.

Effects and mechanisms of plant bioactive compounds in preventing fungal spoilage and mycotoxin contamination in postharvest fruits: A review

Spoilage and mycotoxin contamination of fruits cause significant economic losses and food safety issues. Synthetic chemical fungicide treatment as primary postharvest management has attracted increasing public concern in recent years, because it may cause negative effects on the environment and human health. Numerous bioactive compounds from plants have demonstrated excellent control effects on fruit spoilage and mycotoxin contamination. Plant bioactive compounds have been considered one of the most promising alternatives, because they are generally regarded as safe and environmentally friendly. Here, we reviewed the most recent advances in plant bioactive compounds in the prevention of fungal spoilage and mycotoxin contamination in fruits. The control effects of these compounds and the mechanisms involved were summarized, and current limitations and future perspectives were discussed.

Resorcinol alleviates alpha-terpineol-induced cell death in Schizosaccharomyces pombe via increased activity of the antioxidant enzyme Sod2

Alpha-terpineol, popular monoterpenoid alcohol, is known to cause cytotoxicity in a few cancer cells or to have antioxidant activity, but underlying mechanisms or apoptotic processes in yeast cell death should be understood. We used the fission yeast (Schizosaccharomyces pombe) as a unicellular model to monitor cellular toxicology and physiological mechanisms for the involvement of alpha-terpineol in cell death. Alpha-terpineol caused Reactive oxygen species (ROS) overproduction and following cytotoxicity and apoptosis in a dose-dependent manner. The effect of oxidative stress was proved using sod1 and sod2 mutants (antioxidant-limited cells), and the results showed that apoptosis was caused by alpha-terpineol-driven oxidation. In addition, resorcinol, a herbal extract from medicinal plants, showed protective activity against alpha-terpineol cytotoxicity. Survival rates, apoptotic cell death ratios, oxidation levels, and antioxidant gene expressions were completely altered; surprisingly sod1 and sod2 levels dramatically increased. However, sod2 was highly upregulated in response to resorcinol treatment with alpha-terpineol. The potential role of the Sod2 enzyme was proved using sod2 mutant cells that do not have a mitochondrial radical-clearing activity. Consequently, the dose-dependent and ROS-mediated cytotoxic/apoptotic effects of alpha-terpineol and the Sod2-dependent protective and antioxidant effects of resorcinol were demonstrated in unicellular model organism S. pombe by this study.

Comparing Crop Yield, Secondary Metabolite Contents, and Antifungal Activity of Extracts of Helichrysum odoratissimum Cultivated in Aquaponic, Hydroponic, and Field Systems

The overexploitation of wild plants for medicinal uses and conventional agricultural farming methods, which use high amounts of water, fertilizers, and pesticides, have had devastating environmental consequences. This study aimed to evaluate the prospects of using aquaponics and hydroponics as alternative approaches to soil cultivation by comparing the crop yields, secondary metabolite contents, and the antifungal activities of ethanol extracts of Helichrysum odoratissimum (L.) Sweet, a widely used medicinal plant species in Southern Africa. Six-week-old H. odoratissimum seedlings were grown in aquaponic and hydroponic systems. The growth parameters, secondary metabolite contents, and antifungal activity against Fusarium oxysporum were assessed. The results for crop yield (plant height, fresh and dry weights) and the tissue nutrient contents did not change substantially (p > 0.05) between aquaponic and hydroponic treatments. Gas chromatography−mass spectrometry (GC−MS) analysis showed that monoterpenes and sesquiterpenes were the most abundant compounds in H. odoratissimum; however, no statistical difference was observed among the field, hydroponic, and aquaponic plants (DF = 2; χ2 = 2.67; p > 0.05). While there was no significant difference in polyphenol contents among the three treatments, remarkably, the flavonol contents in the leaves varied significantly (DF = 2; χ2 = 6.23; p < 0.05) among the three treatments. A higher flavonol content occurred in leaves from the hydroponic system than in leaves from the aquaponic (p < 0.05) and field (p > 0.05) systems. The MIC results showed that the ethanolic extract of H. odoratissimum was fungistatic against F. oxysporum; however, this effect was more prominent in the ethanol extracts of plants grown in the aquaponic system, with a mean MIC value of 0.37 ± 0.00 mg/mL The key findings of this study are that aquaponically cultivated plants exhibited the best antifungal activity, while higher total flavonol contents occurred in the hydroponically cultivated plants. In conclusion, aquaponics and hydroponics performed better or similar to field cultivation and are viable alternative methods for cultivating H. odoratissimum plants.

Inhibitory effect and mechanism of action of juniper essential oil on gray mold in cherry tomatoes

Juniper essential oil (JEO), which is mostly known as an immune system booster and effective detoxifier, has substantial antimicrobial activity. A comparison of the inhibitory effects of three plant essential oils from juniper (Juniperus rigida), cedarwood (Juniperus virginiana), and cypress (Crupressus sempervirens) on four plant pathogenic fungi indicated that JEO was the most effective at inhibiting the growth of gray mold (Botrytis cinerea). Additional studies were subsequently conducted to explore the in vivo and in vitro antifungal activity and possible mechanism of JEO against B. cinerea. The results show that JEO inhibited the germination of spores and mycelial growth of B. cinerea in a concentration-dependent manner and exhibited strong inhibition when its concentration exceeded 10 μL/mL. JEO also significantly inhibited the incidence of disease and diameters of gray mold lesions on cherry tomato fruit (Solanum lycopersicum). After 12 h of treatment with JEO, the extracellular conductivity, and the contents of soluble protein, malondialdehyde, and hydrogen peroxide were 3.1, 1.2, 7.2, and 4.7 folds higher than those of the control group, respectively (P < 0.05), which indicated that JEO can damage membranes. Scanning electron microscopy observations revealed that JEO affected the morphology of mycelia, causing them to shrivel, twist and distort. Furthermore, JEO significantly improved the activities of the antioxidant-related enzymes superoxide dismutase and catalase but reduced the pathogenicity-related enzymes polygalacturonase (PG), pectin lyase and endoglucanase of B. cinerea (P < 0.05). In particular, PG was reduced by 93% after treatment with JEO for 12 h. Moreover, the 18 constituents of JEO were identified by gas chromatography/mass spectrometry (GC-MS) analysis, mainly limonene (15.17%), γ-terpinene (8.3%), β-myrcene (4.56%), terpinen-4-ol (24.26%), linalool (8.73%), α-terpineol (1.03%), o-cymene (8.35%) and other substances with antimicrobial activity. Therefore, JEO can be an effective alternative to prevent and control gray mold on cherry tomato fruit.

Essential Oils as a Good Weapon against Drug-Resistant Candida auris

Candida auris is a recently found Candida species, mainly associated with nosocomial outbreaks in intensive care hospital settings, and unlike other Candida species, it can be transmitted through person-to-person or by contact with surfaces. C. auris is described as resistant to first-line antifungals and, consequently, associated with high mortality. Nowadays, essential oils (EOs) are known to be effective against fungal and bacterial infections. This work aimed to evaluate the effect of four EOs (tea tree, niaouli, white thyme and cajeput) against C. auris. The EO’s effect on C. auris planktonic growth was evaluated by the minimum inhibitory concentration determination and by the agar disc diffusion method. Then, the same effect was evaluated on biofilm by colony-forming units’ enumeration. The results showed that EOs were able to inhibit the C. auris planktonic growth, with an MIC50 between 0.78 and 1.56% and halos of 20–21 mm for white thyme and tea tree and 13–14 mm for cajeput and niaouli. In addition, the EOs were also able to completely inhibit biofilm formation. Moreover, white thyme and cajeput completely eradicate pre-formed biofilms, while tea tree and niaouli significantly reduce it. Thus, this work demonstrates that EOs are a possible therapeutic alternative and a future perspective for the hard fight against C. auris.

Development and In Vitro Validation of Antibacterial Paints Containing Chloroxylenol and Terpineol

The establishment of self-disinfecting surfaces is an important method to avoid surface contamination. Recently, paints with antimicrobial properties have been developed to be applied on different surfaces, avoiding contamination with pathogens. In this work, self-disinfecting paints containing Chloroxylenol (CLX), Terpineol (TRP), and a mixture of both substances were developed. The goal was to evaluate and validate these paints using international standards for eventual commercialization and application in scenarios where surface contamination represents a problem. The paints were challenged with five different bacteria, Gram-positive and Gram-negative, before and after a scrub resistance test, where the long-term efficacy of the paints was evaluated. The antibacterial activity assessment was performed following ISO 22196 and JIS Z2801. In general, the paints showed very promising results, demonstrating their antibacterial activity, before and after scrub resistance test. The paint incorporating the mixture of CLX and TRP (CLX+TRP) stood out by revealing consistent results of antibacterial activity both before and after the scrub resistance test for most of the tested bacteria. The cytotoxicity of the developed paints was assessed in vitro by performing tests by direct contact with a human skin cell line, HaCaT, and testes on extracts with HaCaT and a pulmonary cell line, A549. The methodologies for cytotoxicity assessment were developed based in ISO 10993. For genotoxicity assessment, alkaline comet assay was conducted on both cell lines. The cytotoxicity assessment revealed promising results with the paints, demonstrating values of cellular viability above 70% and values of lactate dehydrogenase (LDH) leakage below 30%. The genotoxic assessment also revealed acceptable values of primary DNA damage for the developed antibacterial paints. In general, the selected methodologies presented good potential to be applied in the validation of both efficacy and safety of the antimicrobial paints, aiming to be applied in real scenarios.

PEGylated Lecithin-Chitosan Nanoparticle-Encapsulated Alphα-Terpineol for In Vitro Anticancer Effects

The aim of this study was to fabrication PEGylated lecithin-chitosan nanoparticles (PLC-NPs) as alphα-Terpineol's (αT-PLC-NPs) delivery system and examine its anti-cancer effects. αT-PLC-NPs were synthesized by self-assembling method; after characterization, entrapment efficiency of α-T was measured by HPLC procedure. MTT test was conducted for cytotoxicity evaluation. Chick chorioallantoic membrane (CAM) and quantitative polymerase chain reaction (qPCR) analysis were used to determine the angiogenesis properties, and qPCR, flow cytometry, and acridine orange and propidium iodide (AO/PI) staining were used to evaluate the pro-apoptotic effects of αT-PLC-NPs. Finally, the anti-inflammatory and antibacterial activity of the αT-PLC-NPs was also evaluated. αT-PLC-NPs with a size of 220.8 nm, polydispersity index (PDI) of 0.3, zeta potential of +29.03 mV, and encapsulation efficiency of 82% showed higher inhibitory effect on MCF7 cells (IC₅₀: 750 μg/mL) compared to HFF cells (above 1000 μg/mL). Decreased angiogenesis indices and embryonic growth factors in CAM assay, decreased expression of VEGF and VEGF-R genes, and decreased cell migration showed the inhibitory effect of αT-PLC-NPs on angiogenesis. Increased expression of P53, P21, and caspase9 genes, as well as the results of AO/PI staining along with increasing the number of SubG1 phase cells in flow cytometry, confirmed the pro-apoptotic effects of αT-PLC-NPs. Also, its anti-inflammatory effects were demonstrated by inhibiting the expression of pro-inflammatory cytokines (TNF-α and IL-6). The inhibitory power of αT-PLC-NPs in suppressing gram-positive and negative bacterial strains was demonstrated by disk diffusion (DD), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. PLC-NPs are a promising carrier for α-T transfer for preclinical studies.

Increasing the Storability of Fresh-Cut Green Beans by Using Chitosan as a Carrier for Tea Tree and Peppermint Essential Oils and Ascorbic Acid

The quality of fresh-cut green beans deteriorates rapidly in storage, which contributes to increased food waste and lower perceived customer value. However, chitosan (Cs) and certain plant essential oils show promise in reducing postharvest quality loss during storage. Here, the effect of Cs and the combinations of Cs + tea tree oil (TTO), Cs +x peppermint oil (PMO), and Cs + ascorbic acid (AsA) on the quality of fresh-cut green bean pods (FC-GB) is studied over a 15-d storage period at 5 °C. All four FC-GB treatments reduced weight loss and maintained firmness during storage when compared to uncoated FC-GB. Furthermore, all treatments showed higher total chlorophyll content, AsA, total phenolic compounds, and total sugars compared to the control. The best treatment for reducing microbial growth was a combination of Cs + AsA. Additionally, the combination of Cs with TTO, PMO, or AsA showed a significant reduction in the browning index and increased the antioxidant capacity of FC-GB up to 15 d postharvest.

Melaleuca alternifolia formulations in the treatment of experimental pythiosis

Essential oils (EO) are aromatic compounds from the plant secondary metabolism. Melaleuca alternifolia EO is well known for its medicinal properties and promising use as an antimicrobial agent. Pythiosis is a difficult-to-treat and emerging disease caused by the oomycete Pythium insidiosum. This study evaluated a nanoemulsion formulation of M. alternifolia (NEMA) in topical and intralesional application to treat experimental pythiosis. Dermal toxicity tests were performed on M. alternifolia EO in Wistar rats. Pythiosis was reproduced in rabbits (n = 9) that were divided into groups: group 1 (control), cutaneous lesions with daily topical application of a non-ionizable gel-based formulation and intralesional application of sterile distilled water every 48 h; group 2 (topical formulation), lesions treated daily with topical application of a non-ionizable gel-based formulation containing 5 mg/ml of NEMA; and group 3 (intralesional formulation), lesions treated with NEMA at 5 mg/ml in aqueous solution applied intralesionally/48 h. The animals were treated for 45 days, and the subcutaneous lesion areas were measured every 5 days. M. alternifolia EO showed no dermal toxicity. The lesion areas treated with intralesional NEMA reduced at the end of treatment, differing from groups 1 and 2 (P < 0.05). In the topically treated group, the lesion areas did not differ from the control group, although the number of hyphae significantly reduced (P < 0.05). Under the experimental conditions of this study, the NEMA formulations presented a favorable safety profile. However, further studies are required to evaluate if this safety applies to higher concentrations of NEMA and to validate its use in clinical pythiosis.

Essential oil from Lavandula angustifolia elicits expression of three SbWRKY transcription factors and defense-related genes against sorghum damping-off

Sorghum damping-off, caused by Fusarium solani (Mart.) Sacc., is a serious disease which causes economic loss in sorghum production. In this study, antagonistic activity of lavender essential oil (EO) at 0.5, 0.75, 1.0, 1.25, 1.5, and 1.6% against F. solani was studied in vitro. Their effects on regulation of three SbWRKY transcription factors, the response factor JERF3 and eight defense-related genes, which mediate different signaling pathways, in sorghum were investigated. Effects of application under greenhouse conditions were also evaluated. The results showed that lavender EO possesses potent antifungal activity against F. solani. A complete inhibition in the fungal growth was recorded for lavender EO at 1.6%. Gas chromatography-mass spectrometric analysis revealed that EO antifungal activity is most likely attributed to linalyl anthranilate, α-terpineol, eucalyptol, α-Pinene, and limonene. Observations using transmission electron microscopy revealed many abnormalities in the ultrastructures of the fungal mycelium as a response to treating with lavender EO, indicating that multi-mechanisms contributed to their antagonistic behavior. Results obtained from Real-time PCR investigations demonstrated that the genes studied were overexpressed, to varying extents in response to lavender EO. However, SbWRKY1 was the highest differentially expressed gene followed by JERF3, which suggest they play primary role(s) in synchronously organizing the transcription-regulatory-networks enhancing the plant resistance. Under greenhouse conditions, treating of sorghum grains with lavender EO at 1.5% prior to infection significantly reduced disease severity. Moreover, the growth parameters evaluated, the activities of antioxidant enzymes, and total phenolic and flavonoid contents were all enhanced. In contrast, lipid peroxidation was highly reduced. Results obtained from this study support the possibility of using lavender EO for control of sorghum damping-off. However, field evaluation is highly needed prior to any usage recommendation.

Peppermint Essential Oil Suppresses Geotrichum citri-aurantii Growth by Destructing the Cell Structure, Internal Homeostasis, and Cell Cycle

Peppermint essential oil (Peo) is an efficient antifungal agent, and 2.0 μL of Peo per milliliter culture medium can completely inhibit the mycelium growth and spore germination of Geotrichum citri-aurantii. In vitro experiments showed that the main functional component in Peo was l-menthol, which could lead to changes in sugar and protein contents, reduce the content of alkaline phosphatase (AKP), and destroy the spore membrane structure, with a significant increase in electrical conductivity. Meanwhile, the content of reactive oxygen (ROS) accumulated sharply, and the enzyme activity changed significantly with the change in the gene expression level. In addition, l-menthol could cause degradation in spore genetic material differently. Furthermore, a total of 1704 differentially expressed genes (DEGs) in G. citri-aurantii after 1.6 μL/mL l-menthol exposure for 2 h were obtained by the transcriptome sequencing. These DEGs were involved in transmembrane transport, carbohydrate transmembrane transport protein activity, and mitogen-activated protein kinase (MAPK) signaling pathway. The protein-protein interaction (PPI) analysis of DEGs yielded 10 highly cross-linked nodes, and these genes were associated with DNA replication and cell cycle. The expression level of the hub gene was confirmed by real-time quantitative PCR (RT-qPCR), with the most significant changes in POL 30 (5.9-fold). Molecular simulation was performed and it was found that the binding site between l-menthol and POL 30 was the 44th ARG residue in POL 30, and it was speculated that l-menthol and POL 30 may be combined by hydrogen bonding interaction. The results of flow cytometry assay showed that l-menthol blocked the replication process in the S-phase of G. citri-aurantii. This study provides new insights into the development and application of Peo in food safety.

Extending the Shelf-Life of Fresh-Cut Green Bean Pods by Ethanol, Ascorbic Acid, and Essential Oils

Green beans are a perishable crop, which deteriorate rapidly after harvest, particularly when minimally processed into ready-to-eat fresh-cut green beans. This study investigated the effectiveness of ethanol, ascorbic acid (AsA), tea tree essential oil (TTO), and peppermint essential oil (PMO) on the quality and storability of fresh-cut green bean pods samples stored at 5 °C for 15 days. Our results indicated that samples treated with ethanol, AsA, TTO, and PMO preserved appearance, firmness (except ethanol), chlorophyll content, and moisture compared with the samples without any treatment (control). Additionally, higher vitamin C, total soluble solids (TSS), total sugars, and total phenolic compounds (TPC) were observed in samples treated with ethanol, AsA, TTO, and PMO compared with the control. The most effective treatments for controlling microbial growth were ethanol followed by either TTO or PMO. All the treatments had positive effects on shelf life, maintained quality, and reducing microbial growth during 15 days of cold storage. A particular treatment can be selected based on the economic feasibility and critical control point in the value chain.

Sesamol-based terpenoids as promising bio-sourced crop protection compounds against the wheat pathogen Zymoseptoria tritici

BACKGROUND

Research into environmentally friendly alternatives to conventional plant protection products, to promote sustainable agriculture and healthy food, is strongly encouraged.

RESULTS

In this context, 20 naturally occurring terpenoids and phenolic compounds were selected and evaluated in vitro as crop protection compounds against Zymoseptoria tritici, the causal agent of Septoria tritici blotch of wheat. After selection of the most active compounds, some hemisynthetic modifications were conducted to modify their lipophilicity. These modifications led to the discovery of sesamol esters as promising antifungal agents, with IC₅₀ around 10 μg/mL and a total absence of cytotoxicity against human cells.

CONCLUSION

These sesamol-based derivatives should be selected for further evaluations in planta to validate their use as wheat crop protection agents. Moreover, the importance of a balanced hydrophily/lipophilicity ratio should be further studied. © 2021 Society of Chemical Industry.

Novel Prosopis juliflora leaf ethanolic extract as natural antimicrobial agent against food spoiling microorganisms

Fresh produces spoilage is a worldwide concern that accompany the global increase in food demand. Adverse human health and environmental effects of commercial spoilage control agents are major public concern. In this study, Prosopis juliflora leaves and fruit extracts had their antimicrobial activities evaluated against the growth of selected bacteria and yeast, and against mycelial growth and conidial germination of selected mycotoxins-producing fungi. P. juliflora water-soluble leaf ethanolic (PJ-WS-LE) extract with its novel extraction method showed the strongest antibacterial activity. Antimicrobial tests showed total inhibition of Botrytis cinerea, Alternaria alternata, Bacillus subtilis, Staphylococcus aureus and Candida albicans with MICs ranging between 0.125 and 1 mg/ml. Percent inhibition of mycelial growth (PIMG) of the extract was also determined against seven other fungal strains with highest value against Geotrichum candidum (66.2%). Even the least affected fungal strain showed alterations in their hyphae and spores exposed to PJ-WS-LE extract when observed using scanning electron microscope (SEM), alterations include exfoliated flakes, pores, vacuolation and applanation. Small-scale fruit bioassays controlled experiment showed high efficacy of the extract in protecting inoculated cherry tomato samples from B. cinerea and A. alternata infections. In conclusion, PJ-WS-LE extract is a feasible, natural antifungal agent that can replace common anti-spoiling chemicals.

Determination of selected terpenic substances in grapes and wine of the cultivar Pálava

The presented study is focused on the determination of the content of terpenic substances in grapes and subsequently produced a wine of Czech variety Pálava (the Czech Republic, wine region Morava), which is a protected landscape with long-term tradition and culture. The aim of this study was the analysis of the aromatic profile of the cultivar Pálava, which was fermented by the original yeast strains from the Moravian wine region. Larger amounts of flavoring substances occur in grapes as bound flavoring substances, most often in the form of glycosides. One of the basic groups of aromatic substances is monoterpenes. The content of twelve free and bound terpenic substances was measured by the GC-MS method, namely linalool, ho-trineol, α-terpeniol, β-citronellol, nerol, geraniol, furan linalool oxide 1, furan linalool oxide 2, nerol oxide, epoxylinalol 1, epoxylinalol 2 and 2,6-dimethyl-3,7-octadiene-2,6-diol. The results were statistically compared by using a simple descriptive statistical method and ANOVA method. We noted a difference between the content of free and bound terpenes was very significant (p ≤0.05). We found that using uncommercial yeasts could have an effect on the content of the volatile and terpenic compounds in wines. An important finding was that in fresh berry extracts there was a higher proportion of bound terpenes than free terpenes. The results have shown that the production technology of wine and the fermentation process has a clear impact on the content of the substances.

Mānuka Oil-A Review of Antimicrobial and Other Medicinal Properties

Mānuka oil is an essential oil derived from Leptospermum scoparium, a plant that has been used by the indigenous populations of New Zealand and Australia for centuries. Both the extracted oil and its individual components have been associated with various medicinal properties. Given the rise in resistance to conventional antibiotics, natural products have been targeted for the development of antimicrobials with novel mechanism of action. This review aimed to collate available evidence on the antimicrobial, anti-parasitic and anti-inflammatory activities of mānuka oil and its components. A comprehensive literature search of was conducted using PubMed and Embase (via Scopus) targeting articles from database inception until June 2020. Chemical structures and IUPAC names were sourced from PubChem. Unpublished information from grey literature databases, Google search, targeted websites and Google Patents were also included. The present review found extensive in vitro data supporting the antimicrobial effects of mānuka oil warrants further clinical studies to establish its therapeutic potential. Clinical evidence on its efficacy, safety and dosing guidelines are necessary for its implementation for medical purposes. Further work on regulation, standardization and characterization of the medicinal properties of mānuka oil is required for establishing consistent efficacy of the product.

An Endophytic Diaporthe apiculatum Produces Monoterpenes with Inhibitory Activity against Phytopathogenic Fungi

Volatile organic compounds (VOCs) from endophytic fungi are becoming a potential antibiotic resource. The inhibitive effects of VOCs produced by an endophytic fungus in Leucaena leucocephala were investigated on plant pathogens in this study. Using standard morphological methods and multigene phylogeny, the fungus was identified as Diaporthe apiculatum strain FPYF 3052. Utilizing a two- compartment Petri plate bioassay method, the VOCs from this fungus showed bioactivity ranging from 23.8% to 66.7% inhibition on eight plant pathogens within 24 hours. The SPME-GC/MS technique identified fifteen volatile compounds with dominant terpenoids γ-terpinene (39.8%), α-terpinene (17.2%), and (-)-4-terpineol (8.4%) from the VOCs. Commercial α-terpinene, γ-terpinene, and (-)-4-terpineol demonstrated inhibition on the tested pathogens at concentrations from 0.2 to 1.0 µl/ml within 72 h in the bioassay system. The inhibition rates were from 28% to 100% percent using 1.0 µl/ml within 48 h. (-)-4-Terpineol was the most active of the terpenoids causing up to 100% inhibition. The data illustrate that these monoterpenes play an important role in the inhibitive bioactivity of the VOCs of D. apiculatum FPYF 3052. Most importantly, (-)-4-terpineol is now for the first time, reported to have capability of strong antifungal activity and could be developed as an antibiotic substance.