Sub-lethal concentrations of Perilla frutescens essential oils affect phytopathogenic fungal biofilms

Defense Mechanisms Induced by Celery Seed Essential Oil against Powdery Mildew Incited by Podosphaera fusca in Cucumber

This study aimed to evaluate the effectiveness of essential oil extracted from celery (Apium graveolens) seeds (CSEO) for the control of powdery mildew of cucumber (Cucumis sativus) incited by Podosphaera fusca and to investigate the metabolic and genetic defense mechanisms triggered by the treatment with this essential oil in cucumber seedlings. The main compounds in the CSEO as determined by gas chromatography-mass spectrometry (GC-MS) analysis were d-limonene, 3-butyl phthalide, β-selinene, and mandelic acid. The treatment with CSEO led to an increase in the content of both chlorophyll and phenolic/flavonoid compounds in cucumber leaves. In greenhouse tests, the application of CSEO reduced by 60% the disease severity on leaves of cucumber plants and stimulated the activity of defense-related enzymes such as β-1,3-glucanase, chitinase, phenylalanine ammonia-lyase, peroxidase, and polyphenol oxidase. Moreover, treatment with CSEO induced overexpression of β-1,3-glucanase, chitinase, and phenylalanine ammonia-lyase genes. A highly significant correlation was found between the β-1,3-glucanase, chitinase, and phenylalanine ammonia-lyase enzymatic activities and the relative expression of the corresponding encoding genes in both inoculated and non-inoculated cucumber seedlings treated with the essential oil. Overall, this study showed that CSEO is a promising eco-friendly candidate fungicide that can be exploited to control cucumber powdery mildew.

The significance of essential oils and their antifungal properties in the food industry: A systematic review

Essential oils (EOs) are natural products called volatile oils or aromatic and ethereal oils derived from various parts of plants. They possess antioxidant and antimicrobial properties, which offer natural protection against a variety of pathogens and spoilage microorganisms. Studies conducted in the last decade have demonstrated the unique applications of these compounds in the fields of the food industry, agriculture, and skin health. This systematic article provides a summary of recent data pertaining to the effectiveness of EOs and their constituents in combating fungal pathogens through diverse mechanisms. Antifungal investigations involving EOs were conducted on multiple academic platforms, including Google Scholar, Science Direct, Elsevier, Springer, Scopus, and PubMed, spanning from April 2000 to October 2023. Various combinations of keywords, such as "essential oil," "volatile oils," "antifungal," and "Aspergillus species," were used in the search. Numerous essential oils have demonstrated both in vitro and in vivo antifungal activity against different species of Aspergillus, including A. niger, A. flavus, A. parasiticus, A. fumigatus, and A. ochraceus. They have also exhibited efficacy against other fungal species, such as Penicillium species, Cladosporium, and Alternaria. The findings of this study offer novel insights into inhibitory pathways and suggest the potential of essential oils as promising agents with antifungal and anti-mycotoxigenic properties. These properties could make them viable alternatives to conventional preservatives, thereby enhancing the shelf life of various food products.

Development and Validation of a HTS Platform for the Discovery of New Antifungal Agents against Four Relevant Fungal Phytopathogens

Fungal phytopathogens are the major agents responsible for causing severe damage to and losses in agricultural crops worldwide. Botrytis cinerea, Colletotrichum acutatum, Fusarium proliferatum, and Magnaporthe grisea are included in the top ten fungal phytopathogens that impose important plant diseases on a broad range of crops. Microbial natural products can be an attractive alternative for the biological control of phytopathogens. The objective of this work was to develop and validate a High-throughput Screening (HTS) platform to evaluate the antifungal potential of chemicals and natural products against these four important plant pathogens. Several experiments were performed to establish the optimal assay conditions that provide the best reproducibility and robustness. For this purpose, we have evaluated two media formulations (SDB and RPMI-1640), several inoculum concentrations (1 × 106, 5 × 105 and 5 × 106 conidia/mL), the germination curves for each strain, each strain's tolerance to dimethyl sulfoxide (DMSO), and the Dose Response Curves (DRC) of the antifungal control (Amphotericin B). The assays were performed in 96-well plate format, where absorbance at 620 nm was measured before and after incubation to evaluate growth inhibition, and fluorescence intensity at 570 nm excitation and 615 nm emission was monitored after resazurin addition for cell viability evaluation. Quality control parameters (RZ' Factors and Signal to Background (S/B) ratios) were determined for each assay batch. The assay conditions were finally validated by titrating 40 known relevant antifungal agents and testing 2400 microbial natural product extracts from the MEDINA Library through both HTS agar-based and HTS microdilution-based set-ups on the four phytopathogens.

Zerumbone Disturbs the Extracellular Matrix of Fluconazole-Resistant Candida albicans Biofilms

This study assessed the effect of zerumbone (ZER) against fluconazole-resistant (CaR) and -susceptible Candida albicans (CaS) biofilms and verified the influence of ZER on extracellular matrix components. Initially, to determine the treatment conditions, the minimum inhibitory concentration (MIC), the minimum fungicidal concentration (MFC) and the survival curve were evaluated. Biofilms were formed for 48 h and exposed to ZER at concentrations of 128 and 256 µg/mL for 5, 10 and 20 min (n = 12). One group of biofilms did not receive the treatment in order to monitor the effects. The biofilms were evaluated to determine the microbial population (CFU/mL), and the extracellular matrix components (water-soluble polysaccharides (WSP), alkali-soluble polysaccharides (ASPs), proteins and extracellular DNA (eDNA), as well as the biomass (total and insoluble) were quantified. The MIC value of ZER for CaS was 256 μg/mL, and for CaR, it was 64 μg/mL. The survival curve and the MFC value coincided for CaS (256 μg/mL) and CaR (128 μg/mL). ZER reduced the cellular viability by 38.51% for CaS and by 36.99% for CaR. ZER at 256 µg/mL also reduced the total biomass (57%), insoluble biomass (45%), WSP (65%), proteins (18%) and eDNA (78%) of CaS biofilms. In addition, a reduction in insoluble biomass (13%), proteins (18%), WSP (65%), ASP (10%) and eDNA (23%) was also observed in the CaR biofilms. ZER was effective against fluconazole-resistant and -susceptible C. albicans biofilms and disturbed the extracellular matrix.

A comprehensive review of the botany, ethnopharmacology, phytochemistry, pharmacology, toxicity and quality control of Perillae Fructus

ETHNOPHARMACOLOGICAL RELEVANCE

Perilla frutescens (Linnaeus) Britton, Mem. Torrey Bot. Club 5: 277. 1894., is famous as a worldwide plant with multiple medical parts, including leaves, stems, fruits, etc. Perillae Fructus, the desiccative ripe fruit of P. frutescens, is locally called Zisuzi in Chinese Pharmacopoeia. It is a popularly used herb for relieving cough and asthma, dissipating phlegm and treating constipation in some Asian countries, such as China, Japan, India, South Korea, etc. Various chemical compounds were isolated and identified from Perillae Fructus.

THE AIM OF THE REVIEW

This review aims to summarize the botany, ethnopharmacological applications, phytochemistry, pharmacology, toxicity and quality control of Perillae Fructus to provide scientific evidence for development and utilization Perillae Fructus.

MATERIALS AND METHODS

Relevant information about Perillae Fructus was collected from ScienceDirect, PubMed, Web of science, CNKI, WanFang data, ancient classics and clinical reports. Some electronic databases were also retrieved.

RESULTS

Perillae Fructus was exerted to treat cough and asthma in traditional application. It also had the effect on moistening intestine to relieve constipation for tremendous lipid substances. Up to now, 193 compounds have been isolated and identified from Perillae Fructus, mainly including fatty acids, flavonoids, phenolic acids, phytosterols, triterpenoids and volatile oils. As for its pharmacological activities, prevalent traditional applications of Perillae Fructus have been supported by modern pharmacological experiments in vivo or in vitro, such as anti-inflammatory and anti-oxidant effects. Besides, Perillae Fructus also has hypolipidemic, anti-tumor, antibacterial effects, etc. This review will provide a scientific basis for further studies and rational applications of Perillae Fructus in the future.

CONCLUSIONS

According to its traditional applications, phytochemicals and pharmacological activities, Perillae Fructus was regarded as a valuable herb for application in medicine and food fields. Although some ingredients have been confirmed to have multiple pharmacological activities, their mechanisms of action are still unclear. Further studies on the material basis and mechanism of action are clearly warranted.

Correlation between Perturbation of Redox Homeostasis and Antibiofilm Capacity of Phytochemicals at Non-Lethal Concentrations

Biofilms are the multicellular lifestyle of microorganisms and are present on potentially every type of biotic or abiotic surface. Detrimental biofilms are generally targeted with antimicrobial compounds. Phytochemicals at sub-lethal concentrations seem to be an exciting alternative strategy to control biofilms, as they are less likely to impose selective pressure leading to resistance. This overview gathers the literature on individual phytocompounds rather than on extracts of which the use is difficult to reproduce. To the best of our knowledge, this is the first review to target only individual phytochemicals below inhibitory concentrations against biofilm formation. We explored whether there is an overall mechanism that can explain the effects of individual phytochemicals at sub-lethal concentrations. Interestingly, in all experiments reported here in which oxidative stress was investigated, a modest increase in intracellular reactive oxygen species was reported in treated cells compared to untreated specimens. At sub-lethal concentrations, polyphenolic substances likely act as pro-oxidants by disturbing the healthy redox cycle and causing an accumulation of reactive oxygen species.

Advances in the Pharmacological Activities and Effects of Perilla Ketone and Isoegomaketone

As components of a traditional Chinese herbal medicine with many physiological activities, perilla ketone and isoegomaketone isolated from perilla essential oil are important active components of Perilla frutescens. Recent studies have shown that these two compounds have promising antitumor, antifungal, antirheumatoid arthritis, antiobesity, anti-inflammatory, healing-promoting, and other activities and can be used to combat toxicity from immunotherapy. Therefore, the multitude of pharmacological activities and effects demonstrate the broad research potential of perilla ketone and isoegomaketone. However, no reviews have been published related to the pharmacological activities or effects of perilla ketone and isoegomaketone. The purpose of this review is as follows: (1) outline the recent advances made in understanding the pharmacological activities of perilla ketone and isoegomaketone; (2) summarize their effects; and (3) discuss future research perspectives.

Preparation and characterization of gelatin/zein nanofiber films loaded with perillaldehyde, thymol, or ɛ-polylysine and evaluation of their effects on the preservation of chilled chicken breast

Three edible food packaging films loaded with perillaldehyde (P), thymol (T), or ɛ-polylysine (ɛ-PL) in gelatin/zein (G/Z) nanofibers were prepared and characterized. Their effects on the preservation of chilled chicken breast were evaluated. Results showed that the addition of perillaldehyde, thymol, and ɛ-polylysine improved the morphology and diameter of the G/Z. Loading with perillaldehyde improved the elongation and tensile strength of the G/Z/P by 18% and 55%, respectively. The water vapor permeability and oxygen permeability of the G/Z/P were lower than those of the G/Z/T and G/Z/ɛ-PL. X-ray diffraction, differential scanning calorimetry suggested that perillaldehyde enhanced the thermal stability of the G/Z/P. Measurements of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), total volatile basic nitrogen, and total viable bacterial counts demonstrated that the G/Z/P had good bio-compatibility and effectively prolonged the shelf life of chilled chicken breasts by over 6 days. Therefore, the G/Z/P developed herein has potential application in chilled meat packaging.

Recent advances and future perspective of essential oils in control Colletotrichum spp.: A sustainable alternative in postharvest treatment of fruits

The world population growth has raised concerns about food security. Agricultural systems are asked to satisfy a growing demand for food with increasingly limited resources, and simultaneously still must reduce the impacts on the environment. This scenario encourages the search for safe and sustainable production strategies. Reducing losses in the production process can be one of the main ways to guarantee food safety. In fruticulture, it is estimated that more than 50% of the production can be lost between harvest and the final consumer due to postharvest diseases caused by phytopathogenic fungi. The fungi of the genus Colletotrichum are opportunistic and are associated with several diseases, being the anthracnose the most relevant in terms of the quality and yield losses in fruit species around worldwide. To control these diseases, the use of synthetic fungicides has been the main instrument utilized, however, because of their phytotoxicity to human health, the environment, and strong selection pressure imposed by continuous applications, the fungicides have caused resistance in the pathogen populations. So reducing the excessive application of these products is indispensable for human health and for sustainable Agriculture. Towards this purpose, research has been carried out to identify the phytopathological potentiality of essential oils (EOs) extracted from plants. Therefore, this review aims to contribute to the formation of knowledge bases, about the discoveries, recent advances, and the use of EOs as a strategy to alternatively control fungal disease caused by Colletotrichum spp. in postharvest fruits. Here, we provide valuable information exploring the application potential of essential oils as commercially useful biorational pesticides for food preservation, contributing to sustainable production and global food security.

Fabrication and Characterization of Gelatin/Zein Nanofiber Films Loading Perillaldehyde for the Preservation of Chilled Chicken

Perillaldehyde is a natural antibacterial agent extracted from perilla essential oil. In our methodology, five antibacterial nanofiber packaging films are prepared by loading different concentrations of perillaldehyde (P) into gelatin/zein (G/Z) polymers. Morphology observations show that the G/Z/P film had a good uniform microstructure and nano-diameter as the weight ratio of 5:1:0.02 (G/Z/P). Fourier transform infrared spectroscopy, and X-ray indicate that these three ingredients had good compatibility and strong interaction via hydrogen bonding. Water contact angle results show that the G/Z/P films gradually change from hydrophilic to hydrophobic with the increase of perillaldehyde. Thermal analysis indicates that the G/Z/P (5:1:0.02) film has good thermal stability. Antibacterial and storage analysis indicates that G/Z/P (5:1:0.02) film is effective to inactivate Staphylococcus aureus and Salmonella enteritidis, and obviously reduces the increasing rate of total bacteria counts and volatile basic nitrogen of chicken breasts. This study indicates that the G/Z/P (5:1:0.02) is a kind of potential antibacterial food packaging film.