In Vitro Antimicrobial Activity of Lavender, Mint, and Rosemary Essential Oils and the Effect of Their Vapours on Growth of Penicillium spp. in a Bread Model System

Phytocompounds from essential oil of Mentha aquatica L. cv. Lime prevent vemurafenib-promoted skin carcinogenesis via inhibiting HRASQ61L keratinocytes and reprogramming macrophage activities

BACKGROUND

Twenty to thirty percent of patients taking BRAF inhibitors such as vemurafenib (PLX4032) for melanoma develop cutaneous squamous cell carcinomas.

PURPOSE

This study aimed to elucidate the chemopreventive effect of essential oil from Mentha aquatica L. cv. Lime (EO) and its major constituents, limonene and carvone (L + C) that made up 45.68% of the EO, against PLX4032-induced cutaneous side effects.

METHODS

PLX4032 accelerated skin papilloma formation and keratinocyte HRAS mutation in 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced two-stage skin carcinogenesis mouse model was used to evaluate the in vivo bioefficacy of EO and L + C. The effects and molecular mechanisms of EO and L + C on deregulating mouse PDVHRASQ61L keratinocyte activities were demonstrated using a spectrum of bioactivity assays, western blotting, immunochemistry, and keratinocyte-macrophage co-culture assay.

RESULTS

Treatment with EO suppressed colony formation ability, cell migration, invasion, and induced G2/M cell-cycle arrest and apoptosis in PDVHRASQ61L keratinocytes, and L + C treatment inhibited colony formation, cell migration and invasion of PDV cells. In mouse skin irritated with DMBA/TPA (DT group) or DMBA/TPA with PLX4032 (DTP group), topical application of EO and L + C significantly delayed papilloma appearance and reduced papilloma incidence compared to DT or DTP controls. Histopathology results showed that EO and L + C treatment attenuated K14+ keratinocyte proliferation and paradoxical MAPK activation, and shifted the macrophage population from M2 (CD163+) to M1 (iNOS+) in the mouse skin microenvironment. The conditioned medium of EO or L + C pre-treated PDV keratinocytes promoted M0 macrophages to differentiate from THP-1 cells into M1-like macrophages.

CONCLUSION

This study demonstrates that EO and L + C in combination prevent PLX4032-induced cutaneous side-effects and skin carcinogenesis in mice through reprogramming the macrophage cell population and inhibiting keratinocyte activity. Both mint EO and the natural products L + C can be considered to be effective chemopreventive agents that might be useful in reducing cutaneous lesions in human patients administrated with BRAF inhibitors.

The efficient activity of plant essential oils for inhibiting Botrytis cinerea and Penicillium expansum: Mechanistic insights into antifungal activity

Botrytis cinerea and Penicillium expansum produce deterioration in fruit quality, causing losses to the food industry. Thus, plant essential oils (EOs) have been proposed as a sustainable alternative for minimizing the application of synthetic fungicides due to their broad-spectrum antifungal properties. This study investigated the efficacy of five EOs in suppressing the growth of B. cinerea and P. expansum and their potential antifungal mechanisms. EOs of Mentha × piperita L., Origanum vulgare L., Thymus vulgaris L., Eucalyptus globules Labill., and Lavandula angustifolia Mill., were screened for both fungi. The results showed that the EO of T. vulgaris and O. vulgare were the most efficient in inhibiting the growth of B. cinerea and P. expansum. The concentration increase of all EO tested increased fungi growth inhibition. Exposure of fungi to EOs of T. vulgaris and O. vulgare increased the pH and the release of constituents absorbing 260 nm and soluble proteins, reflecting membrane permeability alterations. Fluorescence microscopic examination revealed that tested EOs produce structural alteration in cell wall component deposition, decreasing the hypha width. Moreover, propidium iodide and Calcein-AM stains evidenced the loss of membrane integrity and reduced cell viability of fungi treated with EOs. Fungi treated with EOs decreased the mitochondria activity and the respiratory process. Therefore, these EOs are effective antifungal agents against B. cinerea and P. expansum, which is attributed to changes in the cell wall structure, the breakdown of the cell membrane, and the alteration of the mitochondrial activity.

Enhancement of agri-food by-products: green extractions of bioactive molecules with fungicidal action against mycotoxigenic fungi and their mycotoxins

Introduction

Today, alternative strategies based on the use of bioactive compounds have been proposed to reduce mycotoxin contamination and limit the use of chemical fungicides.

Methods

In the present work, several by-products collected from the agri-food chain (i.e., red and white grape marc, red grapevine leaves, grape seeds and stalks, pear, apple, green beans, tomato, and spent hops) were subjected to green extraction protocols (i.e., steam distillation, Ultrasound-Assisted, and Naviglio® extraction) to obtain extracts rich in polyphenols and terpenes. Each extract was assessed in vitro for its ability to inhibit the development of the main mycotoxigenic species and related mycotoxins.

Results and Discussion

Aspergillus flavus and A. carbonarius were significantly reduced by pear (from -45 to -47%) and grape marc (from -21 to -51%) extracts, while F. graminearum was shown to be highly influenced by grape stalk, pear, and grape marc extracts (-24% on average). On the contrary, F. verticillioides was inhibited only by pear (-18%) and to a very low and negligible extent by apple (-1%) and green beans (-3%). Regarding the reduction of mycotoxins, the extracts were able to inhibit OTA from 2 to 57%, AFB1 from 5 to 75%, and DON from 14 to 72%. The highest percentages of reduction were obtained against FBs (from 11 to 94%), ZEN (from 17 to 100%), and Alternaria toxins (from 7 to 96%). In conclusion, this work provided promising results for the production of bioactive extracts obtained from agri-food by-products, which could be exploited as potential biofungicides against the development of mycotoxigenic fungi and related mycotoxins.

Antifungal activity and aroma persistence of free and encapsulated Cinnamomum cassia essential oil in maize

The objective of this study was to evaluate the chemical composition and antifungal activity of free and encapsulated Cinnamomum cassia essential oil (EO) against Penicillium crustosum, Alternaria alternata, and Aspergillus flavus, and the aroma persistence in maize flour. Trans-cinnamaldehyde (TC) was identified as the major compound (86 %) in the C. cassia EO. The EO was encapsulated by spray-dryer with 45.26 % efficiency using gum arabic (GA) and maltodextrin (MD) in a ratio of 1:1 (m/m). C. cassia EO showed antifungal activity against A. alternata, A. flavus, and P. crustosum, with a minimum inhibitory concentration (MIC) of 0.5 % for both free and standard TC, and 5 % for the encapsulated EO. Fungal growth inhibition was evaluated under exposition to vapors at different concentrations of C. cassia EO and TC standard, with MIC of 6 % and 8 % against P. crustosum, 4 % and 1 % A. alternata, and 4 % A. flavus, respectively. The sensory analysis results of the free and encapsulated C. cassia EO in maize flour showed a significant difference between the treated samples in relation to the standard sample (p < 0.05). The sample with free EO has high aroma intensity persistence, while the samples treated with encapsulated EO were evaluated as being closer to the standard sample. The results suggest that the encapsulated C. cassia EOs can be used as natural alternatives to control fungi in maize flour.

Essential oils and their active components applied as: free, encapsulated and in hurdle technology to fight microbial contaminations. A review

Microbial contaminations are responsible for many chronic, healthcare, persistent microbial infections and illnesses in the food sector, therefore their control is an important public health challenge. Over the past few years, essential oils (EOs) have emerged as interesting alternatives to synthetic antimicrobials as they are biodegradable, extracted from natural sources and potent antimicrobials. Through their multiple mechanisms of actions and target sites, no microbial resistance has been developed against them till present. Although extensive documentation has been reported on the antimicrobial activity of EOs, comparisons between the use of whole EOs or their active components alone for an antimicrobial treatment are less abundant. It is also essential to have a good knowledge about EOs to be used as alternatives to the conventional antimicrobial products such as chemical disinfectants. Moreover, it is important to focus not only on planktonic vegetative microorganisms, but to study also the effect on more resistant forms like spores and biofilms. The present article reviews the current knowledge on the mechanisms of antimicrobial activities of EOs and their active components on microorganisms in different forms. Additionally, in this review, the ultimate advantages of encapsulating EOs or combining them with other hurdles for enhanced antimicrobial treatments are discussed.

Coacervation as a Novel Method of Microencapsulation of Essential Oils-A Review

These days, consumers are increasingly "nutritionally aware". The trend of "clean label" is gaining momentum. Synthetic additives and preservatives, as well as natural ones, bearing the E symbol are more often perceived negatively. For this reason, substances of natural origin are sought tfor replacing them. Essential oils can be such substances. However, the wider use of essential oils in the food industry is severely limited. This is because these substances are highly sensitive to light, oxygen, and temperature. This creates problems with their processing and storage. In addition, they have a strong smell and taste, which makes them unacceptable when added to the product. The solution to this situation seems to be microencapsulation through complex coacervation. To reduce the loss of essential oils and the undesirable chemical changes that may occur during their spray drying-the most commonly used method-complex coacervation seems to be an interesting alternative. This article collects information on the limitations of the use of essential oils in food and proposes a solution through complex coacervation with plant proteins and chia mucilage.

Using Rosemary Essential Oil as a Potential Natural Preservative during Stirred-like Yogurt Making

The popularity of rosemary has grown as a natural alternative over the synthetic supplements due to its potential health benefits. The rosemary plant has been utilized to preserve food due to its ability to prevent oxidation and microbial contamination. The reason for this study was to determine the phytochemical components and antimicrobial activity of rosemary essential oil (REO) and the effect of REO addition (0.5 and 0.7%) on the chemical, microbiological, and sensory properties of stirred-like yogurt (SLY) during 16 days of storage at 4 °C. The obtained data observed that REO exhibited antimicrobial action against Escherichia coli, Staphylococcus aureus, and Salmonella marcescens, as well as fungi (Aspergillus flavus) and yeasts (Candida albicans). Increased REO to 0.7% accelerated (p < 0.05) the development of lactic acid bacteria (LAB) in SLY (8.3 log cfu/g) and delayed yeast growth up to 12 days. Molds and coliforms were also not found in the SLY samples with REO. In comparison to control samples, sensory results showed that the addition of REO improves the overall acceptance of SLY (p < 0.05). In conclusion, the current study found that REO could be used as a natural preservative during the production of SLY to extend shelf-life and promote LAB development.

Assessment of Chemical Composition and Anti-Penicillium Activity of Vapours of Essential Oils from Abies Alba and Two Melaleuca Species in Food Model Systems

The possibilities of the practical utilization of essential oils (EOs) from various plant species in the food industry have attracted the attention of the scientific community. Following our previous studies, the antifungal activities of three further commercial EOs, Melaleuca armillaris subsp. armillaris (rosalina; REO), Melaleuca quinquenervia (niaouli; NEO), and Abies alba (fir; FEO), were evaluated in the present research in respect to their chemical profiles, over four different concentrations, 62.5 μL/L, 125 μL/L, 250 μL/L, and 500 μL/L. The findings revealed that the major compounds of REO, NEO, and FEO were linalool (47.5%), 1,8-cineole (40.8%), and α-pinene (25.2%), respectively. In vitro antifungal determinations showed that the inhibition zones of a Penicillium spp. mycelial growth ranged from no inhibitory effectiveness (00.00 ± 00.00 mm) to 16.00 ± 1.00 mm, indicating a very strong antifungal activity which was detected against P. citrinum after the highest REO concentration exposure. Furthermore, the in situ antifungal efficacy of all EOs investigated was shown to be dose-dependent. In this sense, we have found that the highest concentration (500 µL/L) of REO, NEO, and FEO significantly reduced (p < 0.05) the growth of all Penicillium strains inoculated on the bread, carrot, and potato models. These results indicate that the investigated EOs may be promising innovative agents in order to extend the shelf life of different types of food products, such as bread, carrot and potato.

Seasonal variability in essential oil composition and biological activity of Rosmarinus officinalis L. accessions in the western Himalaya

Rosmarinus officinalis L. is an imperative herb used in pharmaceutical yet knowledge on chemical and activity profile of essential oil (EO) to harvest seasons and accessions from the Himalayan region is limited. Thus, accessions were evaluated to determine the EO content, compositional, antimicrobial, and cytotoxic potential of rosemary in different harvest seasons during 2018‒2019. EO content was 30.5% higher in IHBT/RMAc-1 compared with IHBT/RMAc-2 accession while 27.9% and 41.6% higher in the autumn as compared with summer and rainy season, respectively. Major EO compound was 1,8-cineole; ranged from 32.50‒51.79% during harvest seasons and 38.70‒42.20% in accessions. EO was active against both the tested Gram-positive bacteria (Micrococcus luteus MTCC 2470 and Staphylococcus aureus MTCC 96). EOs showed inhibition of Gram-negative bacteria (Salmonella typhi MTCC 733), while Klebsiella pneumoniae MTCC 109 was found to be resistant. The rosemary EO of T1 (Rainy season IHBT/RMAc-1) was most effective against S. aureus MTCC 96 with the minimum inhibitory concentration (MIC) of 4% (v/v). In vitro cytotoxicity evaluation showed no potential anti-proliferative activity of EO. The rosemary EO profile in the western Himalayan region was influenced by harvesting seasons and genetic variability within the accessions; furthermore, a promising antibacterial agent in pharmaceutical and flavour industries.

Gluten-Free Bread and Bakery Products Technology

Gluten, a protein fraction from wheat, rye, barley, oats, their hybrids and derivatives, is very important in baking technology. The number of people suffering from gluten intolerance is growing worldwide, and at the same time, the need for foods suitable for a gluten-free diet is increasing. Bread and bakery products are an essential part of the daily diet. Therefore, new naturally gluten-free baking ingredients and new methods of processing traditional ingredients are sought. The study discusses the use of additives to replace gluten and ensure the stability and elasticity of the dough, to improve the nutritional quality and sensory properties of gluten-free bread. The current task is to extend the shelf life of gluten-free bread and bakery products and thus extend the possibility of its distribution in a fresh state. This work is also focused on various technological possibilities of gluten-free bread and the preparation of bakery products.

Comparative Study on Microencapsulation of Lavender (Lavandula angustifolia Mill.) and Peppermint (Mentha piperita L.) Essential Oils via Spray-Drying Technique

Essential oils have been studied for various applications, including for therapeutic purposes. There is extensive literature regarding their properties; however, their low stability limits their application. Generally, the microencapsulation of essential oils allows enhanced stability and enables the potential incorporation in solid dosage forms. Lavender and peppermint oils were encapsulated in microparticles using a spray-drying technique under optimized conditions: 170 °C temperature, 35 m³/h aspiration volume flow, and 7.5 mL/min feed flow. Arabic gum and maltodextrin were used as coating polymers individually in varying concentrations from 5 to 20% (w/v) and in combination. The microparticles were studied for morphology, particle size, oil content, and flowability. The formulated powder particles showed a high yield of 71 to 84%, mean diameter 2.41 to 5.99 µm, and total oil content of up to 10.80%. The results showed that both the wall material type and concentration, as well as the type of essential oil, significantly affected the encapsulation process and the final particle characteristics. Our study has demonstrated that the encapsulation of lavender and peppermint oils in Arabic gum/maltodextrin microparticles by spray-drying represents a feasible approach for the conversion of liquids into solids regarding their further use in powder technology.

The Citrus reticulata essential oil: evaluation of antifungal activity against penicillium species related to bakery products spoilage

Fungal food spoilage plays a key role in the deterioration of food products, and finding a suitable natural preservative can solve this problem. Therefore, antifungal activity of green mandarin (Citrus reticulata) essential oil (GMEO) in the vapor phase against the growth of Penicillium (P.) expansum and P. chrysogenum inoculated on wheat bread (in situ experiment) was investigated in the current research. The volatile compounds of the GMEO were analyzed by a gas chromatograph coupled to a mass spectrometer (GC–MS), and its antioxidant activity was determined by testing free radical-scavenging capacity (DPPH assay). Moreover, the disc diffusion method was used to analyze the antifungal activity of GMEO in in vitro conditions. The results demonstrate that the Citrus reticulata EO consisted of α-limonene as the most abundant component (71.5%), followed by γ-terpinene (13.9%), and β-pinene (3.5%), and it displayed the weak antioxidant activity with the value of inhibition 5.6 ±0.7%, which corresponds to 103.0 ±6.4 µg TEAC.mL-1. The findings from the GMEO antifungal activity determination revealed that values for the inhibition zone with disc diffusion method ranged from 0.00 ±0.00 (no antifungal effectiveness) to 5.67 ±0.58 mm (moderate antifungal activity). Finally, exposure of Penicillium strains growing on bread to GMEO in vapor phase led to the finding that 250 μL.L-1 of GMEO exhibited the lowest value for mycelial growth inhibition (MGI) of P. expansum (-51.37 ±3.01%) whose negative value reflects even supportive effect of the EO on the microscopic fungus growth. On the other hand, GMEO at this concentration (250 μL.L-1) resulted in the strongest inhibitory action (MGI: 54.15 ±1.15%) against growth of P. chrysogenum. Based on the findings it can be concluded that GMEO in the vapor phase is not an effective antifungal agent against the growth of P. expansum inoculated on bread; however, its antifungal potential manifested against P. chrysogenum suggests GMEO to be an appropriate alternative to the use of chemical inhibitors for bread preservation.