Comparative efficacy of Zataria multiflora Boiss., Origanum compactum and Eugenia caryophyllus essential oils against E. coli O157:H7, feline calicivirus and endogenous microbiota in commercial baby-leaf salads

Application of essential oils as sanitizer alternatives on the postharvest washing of fresh produce

Growers commonly wash fresh produce with chemical sanitizers during postharvest handling. However, these sanitizers can be harsh to washing systems and pose a health risk to workers. Essential oils (EOs) can be used as alternatives to chemical sanitizers in produce washing. Previous studies reveal that the EOs from thyme, oregano, cinnamon, and clove are the main EOs evaluated in the studies as potential sanitizers for the washing of produce. The use of EOs and surfactants, such as tween80 and cetylpyridinium chloride, might be used to improve the antimicrobial activity of emulsions. However, studies are still required to evaluate the potential effect of different chemical components of EOs and preparations. Also, it is recommended that researchers focus on overcoming obstacles regarding EOs application in washing systems, including the high levels of EO required to reduce bacterial growth, undesired organoleptic impact on produce, and the poor solubility of EOs in aqueous solution.

Investigating the Antituberculosis Activity of Selected Commercial Essential Oils and Identification of Active Constituents Using a Biochemometrics Approach and In Silico Modeling

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis which has become prevalent due to the emergence of resistant M. tuberculosis strains. The use of essential oils (EOs) as potential anti-infective agents to treat microbial infections, including TB, offers promise due to their long historical use and low adverse effects. The current study aimed to investigate the in vitro anti-TB activity of 85 commercial EOs, and identify compounds responsible for the activity, using a biochemometrics approach. A microdilution assay was used to determine the antimycobacterial activity of the EOs towards some non-pathogenic Mycobacterium strains. In parallel, an Alamar blue assay was used to investigate antimycobacterial activity towards the pathogenic M. tuberculosis strain. Chemical profiling of the EOs was performed using gas chromatography-mass spectrometry (GC-MS) analysis. Biochemometrics filtered out putative biomarkers using orthogonal projections to latent structures discriminant analysis (OPLS-DA). In silico modeling was performed to identify potential therapeutic targets of the active biomarkers. Broad-spectrum antimycobacterial activity was observed for Cinnamomum zeylanicum (bark) (MICs = 1.00, 0.50, 0.25 and 0.008 mg/mL) and Levisticum officinale (MICs = 0.50, 0.5, 0.5 and 0.004 mg/mL) towards M. smegmatis, M. fortuitum, M. gordonae and M. tuberculosis, respectively. Biochemometrics predicted cinnamaldehyde, thymol and eugenol as putative biomarkers. Molecular docking demonstrated that cinnamaldehyde could serve as a scaffold for developing a novel class of antimicrobial compounds by targeting FtsZ and PknB from M. tuberculosis.

Essential oil for the control of fungi, bacteria, yeasts and viruses in food: an overview

This review begins with a general introduction to essential oils (EO) and their relation to food and microorganisms. Classification and characteristics of EO, addressing the major compounds with antimicrobial action. Subsequently, the main microorganisms followed by a collection of the main works published in recent years that approached the influence of the EO on the protection against microorganisms and food decontamination. At last, the major gaps and future perspectives on the subject. Using EO for fighting food contamination is a way of sustainably supplying the need for new antimicrobials to ensure microbial safety and is a viable source to solve the problem of current microbial resistance. Form of application, EO composition and microbiological load are reported as the responsible factors for the treatment's success. The EO's effects on fungi and bacteria are already well known, but its effect on viruses and yeasts is something to be explored.

Health beneficial and pharmacological properties of p-cymene

p-cymene also known as p-cymol or p-isopropyltoluene is an alkyl-substituted aromatic compound naturally occurring in essential oils (EOs) of various aromatic plants, including the genus of Artemisia, Protium, Origanum, and Thymus. It is related to the family of terpenes, especially monocyclic monoterpenes. p-cymene is also present in several food-based plants such as carrots, orange juice, grapefruit, tangerine, raspberries and several spices. Numerous studies have demonstrated the pharmacological properties of the monoterpenes p-cymene, including antioxidant, anti-inflammatory, antiparasitic, antidiabetic, antiviral, antitumor, antibacterial, and antifungal activities. The p-cymene has also been reported to act as an analgesic, antinociceptive, immunomodulatory, vasorelaxant and neuroprotective agent. Its anticancer effects are related to some mechanisms such as the inhibition of apoptosis and cell cycle arrest. In this review, we critically highlighted the in vitro and in vivo pharmacological properties of the p-cymene molecule, providing insight into its mechanisms of action and potential applications in drug discovery. In light of this finding, in-depth in vivo studies are strongly required to validate the safety and beneficial effects of the p-cymene molecule in human healthcare and industrial applications as a potential source of drug discovery.

Antimicrobial-Loaded Polymeric Micelles Inhibit Enteric Bacterial Pathogens on Spinach Leaf Surfaces During Multiple Simulated Pathogen Contamination Events

Protecting fresh-packed produce microbiological safety against pre- and post-harvest microbial pathogen contamination requires innovative antimicrobial strategies. Although largely ignored in the scientific literature, there exists the potential for gross failure in food safety protection of fresh fruits and vegetables leading to opportunity for multiple produce contamination events to occur during production and post-harvest handling of food crops. The primary objective of this research was to determine the efficacy of plant-derived antimicrobial-loaded nanoparticles to reduce Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium on spinach leaf surfaces whilst simulating multiple pathogen contamination events (pre-harvest and post-harvest). Spinach samples were inoculated with a blend of E. coli O157:H7 and S. Typhimurium, each diluted to ~8.0 log10 CFU/mL. The inoculated samples were then submerged in solutions containing nanoparticles loaded with geraniol (GPN; 0.5 wt.% geraniol), unencapsulated geraniol (UG; 0.5 wt.%), or 200 ppm chlorine (HOCl; pH 7.0), with untreated samples serving for controls. Following antimicrobial treatment application, samples were collected for surviving pathogen enumeration or were placed under refrigeration (5°C) for up to 10 days, with periodic enumeration of pathogen loads. After 3 days of refrigerated storage, all samples were removed, aseptically opened and subjected to a second inoculation with both pathogens. Treatment of spinach surfaces with encapsulated geraniol reduced both pathogens to non-detectable numbers within 7 days of refrigerated storage, even with a second contamination event occurring 3 days after experiment initiation. Similar results were observed with the UG treatment, except that upon recontamination at day 3, a higher pathogen load was detected on UG-treated spinach vs. GPN-treated spinach. These data fill a research gap by providing a novel tool to reduce enteric bacterial pathogens on spinach surfaces despite multiple contamination events, a potential food safety risk for minimally processed edible produce.

A systematic quantitative analysis of the published literature on the efficacy of essential oils as sanitizers in fresh leafy vegetables

This study carried out a systematic quantitative analysis of published literature on the efficacy of essential oils (EOs) as sanitizers in fresh leafy vegetables (FLVs). Efficacy of EO was measured by determining if their application could cause a reduction of microbial population in FLV, as well as by identifying experimental factors that might affect the achieved reduction levels. Data on efficacy of EO to reduce the microbial population and experimental conditions were collected from selected studies and compiled for a distribution and relational analysis. Reduction of an artificial inoculum and/or natural microbiota of FLV caused by 14 different EO were measured in 404 (73.8%) and 143 (26.2%) experiments, respectively. Results of quantitative analysis showed that EO are consistently effective to reduce microbial population in FLV either when the target microorganisms are forming an artificial inoculum or the natural microbiota, being overall similarly effective to or more effective than substances used ordinarily as sanitizers. EO were more effective to reduce the population of microorganisms forming an artificial inoculum than the natural microbiota. EO concentration and inoculum size had no significant effect on achieved reductions. Duration of sanitization treatment with EO had significant effect on achieved reductions and highest reductions were found when the sanitization time was >3 min. Although with the inherent variability in experimental designs found in available literature, the results of this quantitative analysis provide strong evidence that EO are promising candidates for use in strategies to sanitize FLV.

Origanum compactum Benth., from traditional use to biotechnological applications

Origanum compactum Benth., is a Moroccan medicinal plant known by its local name as Zaatar. In Morocco, it has various traditional applications such as the use to treat diabetes, metabolic disorders, digestive, and respiratory problems. In this review, we critically highlighted current investigations on the ethnopharmacological studies, the phytochemistry, pharmacological investigations, biotechnological applications, and future perspective of O. compactum. A bibliometric electronic search in worldwide accepted scientific databases such as ScienceDirect, PubMed, SpringerLink, Web of Science, Scopus, Wiley Online, and Google Scholar was carried out to gather on O. compactum. Chemical analysis using GC-MS and/or HPLC allowed the identification of several bioactive compounds such as terpenoids and phenolic acids. Furthermore, O. compactum extracts and essential oils have been tested for various biological activities such as antibacterial, antioxidant, antiparasitic, antifungal, and anticancer effects. Moreover, an alignment between traditional use and biological effects was demonstrated, in particular for the antimicrobial activity. These properties are related to O. compactum bioactive components, especially the volatile compounds such as thymol and carvacrol. The pharmacological mechanisms involve several cellular and molecular targeted actions. Moreover, the biological potential of this species had led some laboratories to apply the biotechnological tools for its regeneration. PRACTICAL APPLICATIONS: Origanum compactum is applied as traditional drug against different illnesses and for food preservation. Scientific investigations proved the application of O. compactum essential oils in food industries as antioxidants and antimicrobials. These volatile compounds could be applied also in pharmaceutical industries, in particular as antibacterial, antifungal, and antileishmanial drugs. Moreover, further investigations concerning toxicological evidences and pharmacokinetic as well as pharmacodynamic mechanistic targets and clinical trials could develop anticancer, antimalaria and anti-inflammatory, and antidiabetic drugs. Finally, the results of the findings of these purposes encourage other research groups to carry out further investigations on the pharmacological properties of O. compactum.

Evaluation of Herbal Mouthwashes Containing Zataria Multiflora Boiss, Frankincense and Combination Therapy on Patients with Gingivitis: A Double-Blind, Randomized, Controlled, Clinical Trial

Background

Dental plaques as adhesive microbial aggregates on tooth surfaces are considered the first stage of tooth decay as well as gingivitis. Accordingly, the effect of different antimicrobial mouthwashes on removing dental plaques and preventing their formation has been evaluated in various studies. This study aimed to evaluate the efficacy of herbal mouthwashes containing hydro-alcoholic extract of Zataria multiflora (ZM), Frankincense (FR), and a combination of both (ZM+FR) and compare it with chlorhexidine (CHX) mouthwash in subjects with gingivitis.

Materials and Methods

In this randomized, controlled, clinical trial a total of 140 patients with gingivitis were divided into four groups including CHX (control group), ZM, FR, and ZM+FR groups. Plaque index (PI), gingival index (GI), and gingival bleeding index (GBI) were measured in days 1, 14, and 21.

Results

All three herbal types of mouthwash significantly improved plaque, gingivitis, and gingival bleeding throughout days 14 to 21 (P<0.001). There was no difference between herbal mouthwash with CHX groups. CHX mouthwash showed the most side effects (54.3%), while ZM mouthwash showed the least side effects and the highest consumer satisfaction (5.7% and 94%, respectively).

Conclusion

All of the herbal mouthwashes can be good candidates for controlling gingivitis. Comparing with CHX mouthwash, herbal mouthwashes have lower side effects and negligible alcohol content. Among the herbal mouthwashes, ZM outperforms FR and FR+ZM due to its lower side effects and higher levels of patients' satisfaction.

Foodborne viruses: Detection, risk assessment, and control options in food processing

In a recent report by risk assessment experts on the identification of food safety priorities using the Delphi technique, foodborne viruses were recognized among the top rated food safety priorities and have become a greater concern to the food industry over the past few years. Food safety experts agreed that control measures for viruses throughout the food chain are required. However, much still needs to be understood with regard to the effectiveness of these controls and how to properly validate their performance, whether it is personal hygiene of food handlers or the effects of processing of at risk foods or the interpretation and action required on positive virus test result. This manuscript provides a description of foodborne viruses and their characteristics, their responses to stress and technologies developed for viral detection and control. In addition, the gaps in knowledge and understanding, and future perspectives on the application of viral detection and control strategies for the food industry, along with suggestions on how the food industry could implement effective control strategies for viruses in foods. The current state of the science on epidemiology, public health burden, risk assessment and management options for viruses in food processing environments will be highlighted in this review.

Effect of nanoliposomes containing Zataria multiflora Boiss. essential oil on gene expression of Shiga toxin 2 in Escherichia coli O157:H7

AIMS

Enterohaemorrhagic Escherichia coli serotype O157:H7 as a major human pathogen is responsible for food borne outbreaks, bloody diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome and even death. In this study, the antibacterial activity of the Zataria multiflora essential oil (ZMEO) and nanoliposome-encapsulated ZMEO was evaluated on the pathogenicity of E. coli O157:H7.

METHODS AND RESULTS

The minimum inhibitory concentrations (MIC) of essential oil (EO) were determined against the bacterium before and after encapsulation into nanoliposome. Then, the effect of subinhibitory concentrations was evaluated on Shiga toxin 2 (Stx2) production. The effect of free and nanoliposomal EO was also studied on the gene expression of Stx2 by real-time PCR. It was found that inhibitory activity of EO was improved after incorporation into nanoliposomes (P < 0·05). The MIC of free EO against E. coli O157:H7 was 0·03% (v/v), while this value decreased to 0·015%, after encapsulation of EO into nanoliposomes. Furthermore, subinhibitory concentrations of liposomal EO (50 and 75% MIC) had significantly higher inhibitory effect on Stx2 titre than its free form (P < 0·05). Sub-MICs of nanoencapsulated EO also showed a better activity in reduction of Stx2A gene expression than free EO. Using 75% MIC of nanoliposomal EO, the relative transcriptional level of Stx2A gene was decreased from 0·721 to 0·646.

CONCLUSIONS

The findings of present study suggest that application of nanoliposomes can improve the antibacterial effect of EOs like ZMEO.

SIGNIFICANCE AND IMPACT OF THE STUDY

Due to the enhancement of antimicrobial activity, nanoencapsulation of plant EOs and extracts may increase their commercial application not only in food area but also in the pharmaceutics, cosmetics and health products.

Antiviral activities of Artemisia princeps var. orientalis essential oil and its α-thujone against norovirus surrogates

Artemisia princeps var. orientalis is a well-known medicinal food, which has been used for the treatment of several diseases including bacterial infection. We examined the antiviral effects of the essential oil from A. princeps var. orientalis and its compounds, borneol, α-thujone and camphor, against murine norovirus-1 (MNV-1) and feline calicivirus-F9 (FCV-F9). The time-of-addition plaque assays were used to determine the ability of essential oil to interfere with viral infection. The maximum activities, following the pretreatment of FCV-F9 and MNV-1, reached 48% inhibition on FCV-F9 and 64% inhibition on MNV-1 at 0.1 and 0.01% of the essential oil, respectively. Neither borneol nor camphor exhibited an antiviral activity, whereas α-thujone, a major compound of the essential oil, showed strong inhibition on FCV-F9 and MNV-1.

Fate of Foodborne Viruses in the "Farm to Fork" Chain of Fresh Produce

Norovirus (NoV) and hepatitis A virus (HAV) are the most important foodborne viruses. Fresh produce has been identified as an important vehicle for their transmission. In order to supply a basis to identify possible prevention and control strategies, this review intends to demonstrate the fate of foodborne viruses in the farm to fork chain of fresh produce, which include the introduction routes (contamination sources), the viral survival abilities at different stages, and the reactions of foodborne viruses towards the treatments used in food processing of fresh produce. In general, the preharvest contamination comes mainly from soli fertilizer or irrigation water, while the harvest and postharvest contaminations come mainly from food handlers, which can be both symptomatic and asymptomatic. Foodborne viruses show high stabilities in all the stages of fresh produce production and processing. Low-temperature storage and other currently used preservation techniques, as well as washing by water have shown limited added value for reducing the virus load on fresh produce. Chemical sanitizers, although with limitations, are strongly recommended to be applied in the wash water in order to minimize cross-contamination. Alternatively, radiation strategies have shown promising inactivating effects on foodborne viruses. For high-pressure processing and thermal treatment, efforts have to be made on setting up treatment parameters to induce sufficient viral inactivation within a food matrix and to protect the sensory and nutritional qualities of fresh produce to the largest extent.

The effect of carvacrol on enteric viruses

Carvacrol, a monoterpenic phenol, is said to have extensive antimicrobial activity in a wide range of food spoilage or pathogenic fungi, yeast and bacteria. The aim of this study was to assess its antiviral activity on norovirus surrogates, feline calicivirus (FCV), murine norovirus (MNV), and hepatitis A virus (HAV), as well as its potential in food applications. Initially, different concentrations of carvacrol (0.25, 0.5, 1%) were individually mixed with each virus at titers of ca. 6-7 log TCID50/ml and incubated 2h at 37°C. Carvacrol at 0.5% completely inactivated the two norovirus surrogates, whereas 1% concentration was required to achieve ca. 1 log reduction of HAV. In lettuce wash water, carvacrol efficacy on MNV was dependent on the chemical oxygen demand (COD), with no effect over 300 ppm. A 4 log reduction in FCV infectivity was observed when 0.5% carvacrol was used to sanitize lettuce wash water, regardless of COD. Carvacrol was also evaluated as a natural disinfectant of produce, showing 1% carvacrol reduced inoculated NoV surrogates titers in lettuce by 1 log after 30 min contact. These results represent a step forward in improving food safety by using carvacrol as an alternative natural additive to reduce viral contamination in the fresh vegetable industry.

Effects of Oils and Essential Oils from Seeds of Zanthoxylum schinifolium against Foodborne Viral Surrogates

Human noroviruses are the most frequent cause of foodborne viral disease and are responsible for the vast majority of nonbacterial gastroenteritis. However, no specific therapies are available for the efficient control or prevention of foodborne viral disease. Here, we determined the antiviral activities of oils from seeds of Zanthoxylum schinifolium (ZSO) against foodborne viral surrogates, feline calicivirus-F9 (FCV-F9), and murine norovirus-1 (MNV-1), using plaque assay. Time-of-addition experiments were designed to determine the antiviral mechanism of action of ZSO against the surrogates. Maximal antiviral effect was observed upon pretreatment of FCV-F9 or MNV-1 with ZSO, which comprised oleic acid, linoleic acid, palmitic acid, and linolenic acid as the major fatty acids. FCV-F9 was more sensitive to ZSO than MNV-1, and the 50% effective concentration of ZSO against pretreatment of FCV-F9 was 0.0007%. However, essential oils from Z. schinifolium (ZSE), which comprised 42% estragole, showed no inhibitory effects against FCV-F9 and MNV-1. These results suggest that the inhibitory activities of ZSO were exerted by direct interaction of FCV-F9 or MNV-1 virion with ZSO, which may be a food material candidate for control of foodborne viral disease.