Antioxidant and antimicrobial activity of Satureja montana L. extracts

Effect of Satureja montana Essential Oil on Model Lipid Membranes

Satureja montana essential oil is a natural substance able to inhibit the growth of several pathogens. This antimicrobial effect is often attributed to its ability to penetrate cellular structures and disrupt them. Although these properties are recognized as playing a key role in the mechanism of action of this substance, many unresolved issues still exist, and fundamental studies focused on such aspects are scarce. In this framework, we investigated the interaction of SEO with lipid monolayers, which represent simplified models of cell membranes, using the Langmuir monolayer technique, complemented by fluorescence anisotropy and differential scanning calorimetry on lipid bilayers. By focusing on packing conditions that approximate those of biological membranes and using lipids with different polar heads and structures, such as the ones occurring in bacterial membranes, we aim to clarify the effect of this essential oil on the lipid membrane. Our results show that Satureja montana essential oil consistently manages to insert into the membrane and interfere with the lipid-lipid interactions, thereby altering the lipid packing and significantly increasing the membrane fluidity, depending on the oil concentration and the nature of the lipid.

Exploring the Antibacterial Potential of Lamiaceae Plant Extracts: Inhibition of Bacterial Growth, Adhesion, Invasion, and Biofilm Formation and Degradation in Pseudomonas aeruginosa PAO1

In response to the global rise in antibiotic resistance and the prevalence of bacterial biofilm-related infections, the antibacterial efficacy of methanolic, ethanolic, and aqueous extracts of 18 Lamiaceae plants from Serbia was evaluated. The total coumarins and triterpenes were detected spectrophotometrically, while a microdilution assay measured their effects on bacterial growth. Additionally, the impact of these extracts was assessed on Pseudomonas aeruginosa PAO1 adhesion and invasion in human fibroblasts and biofilm formation and degradation. The alcoholic extracts had the highest phytochemical content, with Teucrium montanum and Lavandula angustifolia being the richest in coumarins and triterpenes, respectively. Gram-positive bacteria, particularly Bacillus subtilis, were more susceptible to the extracts. Hyssopus officinalis ethanolic and Sideritis scardica methanolic extracts inhibited bacterial growth the most efficiently. Although the extracts did not inhibit bacterial adhesion, most ethanolic extracts significantly reduced bacterial invasion. Origanum vulgare and H. officinalis ethanolic extracts significantly inhibited biofilm formation, while Teucrium chamaedrys extract was the most active in biofilm degradation. This study significantly contributes to the literature by examining the antibacterial activity of Lamiaceae extracts, addressing major literature gaps, and underscoring their antibacterial potential, particularly Satureja montana and O. vulgare ethanolic extracts, linking their efficacy to coumarins and triterpenes.

Chemical Profile and Biological Activities of Brassica rapa and Brassica napus Ex Situ Collection from Portugal

This study aimed to analyse the chemical profile and biological activities of 29 accessions of Brassica rapa (turnips) and 9 of Brassica napus (turnips and seeds) collections, maintained ex situ in Portugal. HPLC-HRMS allowed the determination of glucosinolates (GLS) and polyphenolic compounds. The antioxidant and antimicrobial activities were determined by using relevant assays. The chemical profiles showed that glucosamine, gluconasturtiin, and neoglucobrassin were the most abundant GLS in the extracts from the turnip accessions. Minor forms of GLS include gluconapoleiferin, glucobrassicanapin, glucoerucin, glucobrassin, and 4-hydroxyglucobrassin. Both species exhibited strong antioxidant activity, attributed to glucosinolates and phenolic compounds. The methanol extracts of Brassica rapa accessions were assessed against a panel of five Gram-negative bacteria (Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serovar, and Yersinia enterocolitica) and three Gram-positive bacteria (Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus). The extracts exhibited activity against S. enterica and S. aureus, and two showed inhibitory activity against E. coli and Y. enterocolitica. This study provides valuable insights into the chemical composition and biological properties of Brassica rapa and Brassica napus collections in Portugal. The selected accessions can constitute potential sources of natural antioxidants and bioactive compounds, which can be used in breeding programs and improving human health and to promote healthy food systems.

Identification of essential oils with strong activity against stationary phase Mycobacterium abscessus

Purpose

To identify essential oils (EOs) active against non-growing stationary phase Mycobacterium abscessus and multidrug-resistant M. abscessus strains.

Methods

The activity of EOs against both stationary and log phase M. abscessus was evaluated by colony forming unit (CFU) assay and minimum inhibitory concentration (MIC) testing.

Results

We assessed the activity of 80 EOs against stationary phase M. abscessus and found 12 EOs (Cinnamon, Satureja montana, Palmarosa, Lemon eucalyptus, Honey myrtle, Combava, Health shield, Mandarin, Thyme, Rosewood, Valerian Root and Basil) at 0.5% concentration to be active against both growing and non-growing stationary phase M. abscessus. Among them, Satureja montana essential oil and Palmarosa essential oil could eliminate all stationary phase M. abscessus at 0.125% and Cinnamon essential oil could eliminate stationary phase bacteria at 0.063% after 1-day treatment. Interestingly, these EOs also exhibited promising activity against multidrug-resistant M. abscessus clinical strains.

Conclusions

Our study indicates that some EOs display outstanding effectiveness against both drug susceptible M. abscessus and multidrug-resistant M. abscessus isolates. These findings may be significant for the treatment of persistent M. abscessus infections.

Anti-inflammatory and in vitro antioxidant activities of Satureja montana dry extract

INTRODUCTION

Many chronic somatic and psychiatric diseases are associated with oxidative stress and inflammation, both of which have detrimental effects on human health.

Hydroxypropyl-β-Cyclodextrin-Glycerol-Assisted Extraction of Phenolics from Satureja montana L.: Optimization, Anti-Elastase and Anti-Hyaluronidase Properties of the Extracts

A green method for hydroxypropyl-β-cyclodextrin-glycerol-assisted extraction (HCGAE) of bioactive phenolics from S. montana, Lamiaceae was optimized using Box-Behnken design and response surface methodology and compared conventional water/ethanol-based extraction. The procedure was aimed at obtaining extracts with the maximum content of total phenols (TP), flavonoids (TF), dihydroxycinnamic acids (TDCA), rosmarinic acid (RA), and luteolin 7-O-glucoside (LG). The impact of glycerol content (0–70%), 2-hydroxypropyl-β-cyclodextrin content (0–0.4 mmol), temperature (20–70 °C), herbal material weight (0.3–0.8 g), extraction duration (5–25 min), and ultrasound power (144–720 W) on the extraction efficiency was analyzed. Four extracts with maximum amounts of target phenols, OPT-TP (5.93 mg/mL), OPT-TDCA-RA (4.17 mg/mL and 1.16 mg/mL, respectively), OPT-TF (0.99 mg/mL), and OPT-LG (0.28 mg/mL) were prepared. Comparison of the content of TDCA, TF, RA, and LG with those obtained in water/ethanol-based extraction demonstrated the superiority of the HCGAE approach for the extraction of phenols from S. montana. The extracts displayed good anti-elastase and excellent anti-hyaluronidase activity. IC50 values of the anti-hyaluronidase activity (1.67 ± 0.06 μL extract/mL, 1.16 ± 0.08 μL extract/mL, 0.85 ± 0.03 μL extract/mL, and 0.79 ± 0.05 μL extract/mL for OPT-TP, OPT-TDCA-RA, OPT-TF, and OPT-LG, respectively) surpassed that of the applied positive control, tannic acid. The observed bioactivity of the optimized extracts makes them promising active ingredients for natural cosmetics. The results of this research indicate that HCGAE is an excellent alternative to conventional water/ethanol-based extraction of phenolics from Satureja montana L.-yielding extracts with potent anti-elastase and anti-hyaluronidase properties suitable for direct use in cosmetic products.

Bioactivity and phenolics profile of aqueous and ethyl acetate extracts of Satureja kitaibelii Wierzb. ex Heuff. obtained by ultrasound-assisted extraction

The aim of the study was to investigate the biological activity and chemical composition of Satureja kitaibelii Wierzb. ex Heuff. LC-PDA/MS analyses for the aqueous extracts (A1-stem, leaves and flowers, A2-leaves and flowers) and ethyl-acetate extracts (E1-stem, leaves and flowers, E2-leaves and flowers) obtained by ultrasound-assisted extraction enabled the identification of thirty-four compounds. Quantitative analysis revealed that the aqueous extract obtained from leaves and flowers was the richest in total phenolic acids (65.36 mg/g) and flavonoids (21.17 mg/g). The total polyphenol content was the highest in the aqueous extract obtained from leaves and flowers (274 ± 2.4 mg Gallic Acid equivalents/g). The best antioxidant activity was observed for the same extract using the DPPH (SC50 20 ± 10 µg/mL), ABTS (2.834 ± 0.02 mg Ascorbic Acid/g), FRAP (1.922 ± 0.03 mmol Fe²⁺/mg), and total reducing power tests (16.4 ± 1.0 mg Ascorbic Acid/g). Both ethyl acetate extracts were the most active against strains of Bacillus cereus and Micrococcus flavus (MIC 1.70-1.99 mg/mL and 1.99-3.41 mg/mL, respectively). They were more efficient against Aspergillus ochraceus (MFC 0.86 mg/mL) and towards HeLa cell lines. All the obtained results implied the good potential of the investigated extracts to be used as effective preservatives and functional ingredients in food products and dietary supplements.

Role of antioxidant activity of essential oils in their acaricidal activities against Rhipicephalus annulatus

Essential oils of Origanum majorana and Satureja thymbra as well as carvacrol are natural products that are known to have potent antioxidant activities. The current study was designed to investigate the role of the antioxidant properties of these natural products in their acaricidal activities against Rhipicephalus annulatus larvae. The synergistic and/or antagonistic effects of the addition of vitamins E and C and hydrogen peroxide (H2O2) to these natural products were also evaluated. Larval packet tests were used to evaluate the acaricidal activities against the larvae of R. annulatus. The antioxidant effectiveness of these products was determined by a DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging assay. The addition of vitamin E at 100 mg/mL to O. majorana and S. thymbra decreased the concentrations required to achieve the death of half of the larvae (LC50) to 0.44 and 0.47%, respectively. The combination of O. majorana and S. thymbra attained the LC50 at 1.54% which was decreased to 0.69% after addition of vitamin E. Also, the addition of vitamin E to carvacrol reduced the LC50 to 0.27%. The total antioxidant activity of these natural products increased significantly in presence of vitamin E. The addition of H2O2 inhibited the acaricidal activity of all tested materials, especially at low concentrations. All treatments induced an increase in lipid peroxidation, whereas carvacrol-treated larvae revealed the lowest values for the superoxide dismutase. Glutathione peroxidase and catalase activity decreased in larvae treated with S. thymbra combined with vitamin E. In conclusion, the addition of vitamins E and C increased the acaricidal activities of the tested compounds, whereas the addition of H2O2 decreased these activities. The antioxidant activities of essential oils and their active components may play an important role in mediating their acaricidal activities.

Variability in Biological Activities of Satureja montana Subsp. montana and Subsp. variegata Based on Different Extraction Methods

Winter savory (Satureja montana L.) is a well-known spice and medicinal plant with a wide range of activities and applications. Two subspecies of S. montana, subsp. montana and subsp. variegata, were used for the preparation of seven different extracts: steam distillation (essential oil (EO) and hydrolate (HY)), subcritical water (SWE), ultrasound-assisted (UAE-MeOH and UAE-H2O), and microwave-assisted (MAE-MeOH and MAE-H2O) extraction. The obtained EOs, HYs, and extracts were used for an in vitro evaluation of the antioxidant activity (DPPH, ABTS, reducing power, and superoxide anion methods) and in vitro antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Salmonella Typhimurium, Saccharomyces cerevisiae, and Candida albicans. The antimicrobial screening was conducted using disk-diffusion assessment, minimal inhibitory concentration, time-kill kinetics modeling, and pharmacodynamic study of the biocide effect. The total phenolic content (TPC) was highest in EO, followed by SWE, MAE, and UAE, and the lowest was in HY. The highest antimicrobial activity shows EO and SWE for both varieties, while different UAE and MAE extracts have not exhibited antimicrobial activity. The natural antimicrobials in the S. montana extract samples obtained by green extraction methods, indicated the possibility of ecologically and economically better solutions for future in vivo application of the selected plant subspecies.

Assessment of Chitosan Coating Enriched with Free and Nanoencapsulated Satureja montana L. Essential Oil as a Novel Tool for Beef Preservation

The effect of chitosan coating enriched with free and nanoencapsulated Satureja montana L. essential oil (EO) on microbial, antioxidant and sensory characteristics of beef was analyzed. Different concentrations of free Satureja montana L. EO (SMEO) and nanoparticles (CNPs) were added to chitosan coatings, namely 0.25%, 0.5% and 1%. The beef samples were immersed in the chitosan coatings and stored at +4 °C for 20 days. In this period, the changes in pH value, total viable count (TVC), lactic acid bacteria, psychrophilic bacteria and Pseudomonas spp. were analyzed. The lipid oxidation of beef was determined by the TBAR assay, while sensory analysis was performed by means of the descriptive evaluation method. Generally, the influence of chitosan coating with CNPs on the growth of the tested microorganisms was more pronounced compared to SMEO. Treatment with coating enriched with 1% CNPs resulted in the reduction in TVC and Pseudomonas spp. by 2.4 and 3 log CFU/g, compared to the control, respectively. Additionally, all applied coatings with SMEO and CNPs resulted in the prolonged oxidative stability of the meat The addition of free SMEO created an unnatural aroma for the evaluators, while this odor was neutralized by nanoencapsulation. The durability of color, smell and general acceptability of beef was significantly increased by application of chitosane coatings with the addition of SMEO or SMEO-CNPs, compared to the control. This research indicates the potential application of enriched chitosan coatings in beef preservation in order to improve meat safety and prolong shelf-life.

Walking around the Autonomous Province of Trento (Italy): An Ethnobotanical Investigation

The Trentino-South Tyrol region is a special statute region of northeastern Italy. This territory is of particular interest for its morphology, flourishing vegetation, and history, having been a meeting area among different civilizations. Hence, Trentino is characterized by an ethnic plurality and a rich ethnobotanical knowledge, even if the available information is fragmentary, widely dispersed, and often guarded in oral popular culture. To fill this gap, in the present work 200 subjects were interviewed using an ethnobotanical survey. The resulting 817 citations referred to 64 native species, used either for human or animal health or for domestic purposes. As a second step, for each plant exploited for medicinal purposes, local importance was evaluated by calculating their relative frequency of citation. Moreover, the main traditional preparations were discussed. Among them, the most cited and exploited ones are Achillea millefolium, Arnica montana, Hypericum perforatum, Malva sylvestris, Pinus mugo, and Satureja montana, for which a deeper analysis has been performed. Lastly, the ethnobotanical knowledge of the plants growing in this territory will add a piece to the mosaic of traditional medicine in Italy and may lay the foundation for a nature-aided drug discovery process.

Enzymatic and Microwave Pretreatments and Supercritical CO2 Extraction for Improving Extraction Efficiency and Quality of Origanum vulgare L. spp. hirtum Extracts

The goal of the study was to establish a procedure for improving the efficiency of supercritical carbon dioxide (scCO2) extraction of Origanum vulgare L. spp. hirtum (Greek oregano) and enhancing the quality of obtained extracts. Microwave and enzymatic pretreatments of the plant material were applied prior to the scCO2 extraction. It was determined that the microwave pretreatment with irradiation power 360 W during 2 min accelerated the extraction of lipophilic compounds and provided a twofold higher extraction yield compared to the control. Moreover, this pretreatment also led to an increase in oxygenated monoterpenes content and the most dominant component carvacrol, as well as the extracts' antioxidant activity. The enzymatic pretreatment caused a significant increase in the extraction yield and the attainment of the extract with the most potent antioxidant properties. Coupling the pretreatments with scCO2 extraction improves the process of obtaining high value lipophilic products of oregano in terms of utilization of the plant material, acceleration of the extraction with the possibility to adjust its selectivity and quality of extracts, and enhancement of biological activity.

New Perspective of Origanum vulgare L. and Satureja montana L. Essential Oils as Bovine Mastitis Treatment Alternatives

Mastitis represents a heavy burden for the dairy sector worldwide with high economic and animal welfare impact. Antibiotic treatment is an important component of mastitis control programs. However, emergence and transfer of antimicrobial-resistant (AMR) bacteria is becoming a growing concern. Therefore, the development of novel agents is required for prevention and treatment of mastitis. Hence, our aim was to assess the antibacterial properties of two essential oils (EOs) obtained from oregano (Origanum vulgare L., Lamiaceae) and mountain savory (Satureja montana L., Lamiaceae) against mastitis-associated bacteria in Serbia. The chemical composition and antioxidant potential of these EOs were also evaluated. The present study was conducted on strains derived from aseptic milk samples collected from Holstein-Friesian cows with clinical or subclinical mastitis, during the morning milking. Clinical mastitis was assessed by clinical examination, while subclinical mastitis was confirmed using somatic cell count in the milk samples. The microdilution method was used to determine the antibacterial activity, while antioxidant potential of the EOs was evaluated in several in vitro assays. The values of minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were used to quantitatively measure the antibacterial activity of each EO. MIC/MBC ranged from 0.78/6.25 and 0.39/0.78 mg/mL for oregano and mountain savory, respectively. A total of 25 compounds were identified in the oregano EO, while 47 were identified in winter savory EO, among which aromatic oxygenated monoterpenes were the most abundant compounds. The tested EOs have shown promising antimicrobial activity and could be considered as one of the treatment approaches in mastitis-affected cows.

Nanoemulsions of Satureja montana Essential Oil: Antimicrobial and Antibiofilm Activity against Avian Escherichia coli Strains

Satureja montana essential oil (SEO) presents a wide range of biological activities due to its high content of active phytochemicals. In order to improve the essential oil’s (EO) properties, oil in water nanoemulsions (NEs) composed of SEO and Tween-80 were prepared, characterized, and their antimicrobial and antibiofilm properties assayed against Escherichia coli strains isolated from healthy chicken. Since surfactant and oil composition can strongly influence NE features and their application field, a ternary phase diagram was constructed and evaluated to select a suitable surfactant/oil/water ratio. Minimal inhibitory concentration and minimal bactericidal concentration of NEs, evaluated by the microdilution method, showed that the SEO NE formulation exhibited higher inhibitory effects against planktonic E. coli than SEO alone. The quantification of biofilm production in the presence of NEs, assessed by crystal violet staining and scanning electron microscopy, evidenced that sub-MIC concentrations of SEO NEs enable an efficient reduction of biofilm production by the strong producer strains. The optimized nanoemulsion formulation could ensure food safety quality, and counteract the antibiotic resistance of poultry associated E. coli, if applied/aerosolized in poultry farms.

Cytotoxic effects of Satureja montana L. essential oil on oocytes of engorged Rhipicephalus microplus female ticks (Acari: Ixodidae)

In addition to pesticidal activity, the capacity of natural compounds to inhibit the reproduction of parasites emerge as an important alternative tick control method. In this context, Satureja spp. stand out due to their recognized pesticidal properties. Among parasites of veterinary importance, the cattle tick, Rhipicephalus microplus, is responsible for great economic losses in livestock and transmission of relevant pathogens. Thus, the aim of this study was to evaluate the effects of different concentrations of the essential oil of Satureja montana L. on the ovary morphology of R. microplus engorged females through histological and histochemical techniques. The most remarkable morphological changes found were: cytoplasmic vacuolation of germ cells, irregular and thicker chorion, irregular oocyte shape, ring-shaped nucleolus, decrease in protein and carbohydrate content in oocytes, in addition to cellular changes in the oviduct and pedicel. All morphological changes were assessed using a semiquantitative method already established in the literature. Ticks exposed to 5.0 μl/ml of essential oil showed the most significant changes when compared to control groups. Thus, the essential oil of S. montana L. damaged the reproductive system of R. microplus, which may impair ticks' offspring production and promote a long-term control of this species. HIGHLIGHTS: The essential oil of Satureja montana L. affects the ovary morphology of the cattle tick. The main morphological alterations found were cytoplasmic vacuolation, irregular and thicker chorion and irregular oocyte shape. These alterations may impair the development of eggs.

Evaluation of Anticancer Activity of Satureja montana Supercritical and Spray-Dried Extracts on Ehrlich's Ascites Carcinoma Bearing Mice

Satureja montana herbal species belongs to aromatic medicinal plants with a significant place in traditional medicine. However, products produced with conventional procedures do not meet the requirements of the modern market which include environmentally-safe processes that provide quality, safe, and standardized products. In this study, the antiproliferative activity of S. montana extracts obtained by supercritical carbon dioxide and solid-liquid extraction followed by spray drying was investigated using the in vivo model of Ehrlich ascites carcinoma (EAC) in mice. The impact of two concentrations of extracts on the growth of tumor and the redox status of malignant cells was monitored. It was determined that the extracts induced oxidative stress in the malignant cells which was confirmed by the changes in activity of biochemical indicators of oxidative stress. The posttreatment was not an efficient approach, while the extracts applied as pretreatment and treatment resulted in an increase in the xanthine oxidase (XOD) activity, a decrease in catalase (CAT) activity, and an increase in the intensity of lipid peroxidation (LPx). Furthermore, a decrease in the values of reduced glutathione (GSH) and an increase in glutathione reductase (GR) and glutathione peroxidase (GSHPx) in EAC cells were recorded.

Phytochemical Evaluation of Tinctures and Essential Oil Obtained from Satureja montana Herb

Winter Savory (Satureja montana L.) has been used in traditional medicine and as a spice or natural food preservative in the Mediterranean region for centuries. In this paper, some technological and analytical aspects of the S. montana tinctures development and an evaluation of the essential oil composition are provided. The total phenolic and flavonoid contents and phenolic compounds profile analyzed spectrophotometrically and by high-performance thin-layer chromatography (HPTLC), respectively, were evaluated in the developed tinctures. The results showed that the tinctures prepared from the S. montana herb by maceration or remaceration are rich in polyphenols, and there is an influence of the technological factors (particle size and extraction mode) on the total phenolic and flavonoid contents. Caffeic, rosmarinic, and chlorogenic acids, (–)-catechin and rutin were identified in the tinctures using the HPTLC method. p-Thymol (81.79%) revealed by gas chromatography-mass spectrometry (GC-MS) was the predominant compound of the essential oil of this plant. Thus, the high contents of polyphenols and flavonoids in the developed tinctures and p-thymol among the volatile components of the S. montana essential oil could indicate the promising antioxidant and antimicrobial properties of these herbal preparations. The obtained results are a ground for the organization of the manufacture of the S. montana tincture and essential oil with the purpose of performing preclinical studies.

Effect of High Hydrostatic Pressure Extraction on Biological Activities and Phenolics Composition of Winter Savory Leaf Extracts

Satureja montana L. has several biological properties related to its diverse composition of secondary metabolites. Nevertheless, it has been mainly studied for its essential oil, with only a few studies on the profile and bioactivities of the bioactive compounds from its leaf extracts being reported. This work aimed to study the antioxidant activity (by oxygen radical absorbance capacity (ORAC) assay), antimicrobial minimum inhibitory and bactericidal concentrations (MIC and MBC) determination, antibiofilm (by colorimetry), impact upon DNA (anti- and pro-oxidant assay), and cytotoxicity (by cell metabolism viability assays) of S. montana extracts obtained by high-pressure-assisted extraction (HPE). The extract obtained at 348 MPa, 35% (v/v) ethanol presented the highest concentration of individual phenolic compounds, and a minimum bactericidal concentration of 20 mg/mL against Listeria monocytogenes. HPE extracts showed antioxidant activity not only in ORAC but they were also able to prevent/attenuate peroxide-induced damage upon DNA. Moreover, on its own, HPE extract induced less oxidative damage than the control extract. Concerning the cytotoxicity, HPE extracts (at 0.5 and 1.0 mg/mL) were not harmful to HT29 cell lines, while control extracts (obtained at atmospheric pressure) at higher concentrations (>1.0 mg/mL) slightly reduced the metabolism of the cells. Finally, all extracts showed inhibition of the viability of 3 cancerous cell lines (>2.0 mg/mL for Caco-2, HeLa, and TR146) to below 15%.

Satureja montana L. and Origanum majorana L. Decoctions: Antimicrobial Activity, Mode of Action and Phenolic Characterization

Medicinal and aromatic plants are known to have a wide range of uses and health benefits, and should be exploited for their bioactivity. Here we evaluated the antimicrobial activity of decoctions of Satureja montana L. and Origanum majorana L. against Gram-positive and Gram-negative bacteria and Candida spp. as well as their mechanism of action and phenolic characterization. The Satureja montana and Origanum majorana extracts were effective against a broad set of species, including the Gram-positive Staphylococcus aureus, Enterococcus faecalis, and Streptococcus dysgalactiae and the Gram-negative Klebsiella pneumoniae and Pseudomonas aeruginosa. Both extracts were found to have rosmarinic acid as the main phenolic compound and to exert their antimicrobial activity at the level of the cell membrane. Membrane perturbations by the extracts impaired cell membrane integrity only a few hours after exposure. This study confirms the bioactive potential of Satureja montana and Origanum majorana decoctions, and supports the development of novel formulations with wide antimicrobial properties based on these medicinal and aromatic herbs.

In Vitro Effect of the Common Culinary Herb Winter Savory (Satureja montana) against the Infamous Food Pathogen Campylobacter jejuni

The culinary herb Satureja montana, known as winter savory, is an ingredient of traditional dishes known in different parts of the world. As an ingredient of foods it has the potential to improve their safety. In this study, the herb's activity was investigated against Campylobacter jejuni, the leading cause of the most prevalent bacterial gastroenteritis worldwide. The ethanolic extract and essential oil of the herb were chemically characterized and six pure compounds-carvacrol, thymol, thymoquinone, p-cymene, γ-terpinene, and rosmarinic acid-were chosen for further analysis. The antimicrobial activity of the ethanolic extract (MIC 250 mg/L) was 4-fold higher compared to the essential oil. Carvacrol, thymol and thymoquinone had the strongest antimicrobial effect (MIC 31.25 mg/L) and a strong synergistic activity between carvacrol and thymol was determined (FICi 0.2). Strong inhibitory effect on C. jejuni efflux pumps (2-fold inhibition) and disruption of membrane integrity (> 80% disruption) of the herb were determined as modes of action. For resistance against the herb, C. jejuni need efflux pumps, although increased resistance against this herb does not co-occur with increased efflux pump activity, as for antibiotics. This study shows the potential of a common culinary herb for the reduction of the food pathogen C. jejuni without increasing resistance.

Chemical Composition, Antibacterial and Radical Scavenging Activity of Essential Oils from Satureja macrantha C.A.Mey. at Different Growth Stages

Essential oils (EOs) from medicinal and aromatic plants are interesting products to be used as natural food preservatives. The EOs from the genus Satureja are reported to inhibit foodborne pathogens being worthy of use as food preservatives. Satureja macrantha is found in Western and Northwest Iran and commonly used as a food flavoring agent and for the treatment of urinary diseases. The objective of the present study was to identify the chemical composition of S. macrantha EOs at different growth stages (vegetative, flowering and fruiting stages) and to evaluate their biological activities. Chemical compositions were analyzed using GC-FID and GC-MS. The antibacterial activity was evaluated using the broth microdilution method against the foodborne pathogenic bacteria Staphylococcus aureus (ATCC23922), Enterococcus faecalis (ATCC29212) (Gram-positive), Enterobacter aerogenes (ATCC13046) and Escherichia coli. The antioxidant activity was estimated using the DPPH, ABTS and reducing power assays. The yields of S. macrantha EOs were in the range of 1.4–1.8%, thus scalable for the manufacture of food preservatives on an industrial level. The main compounds of EOs were carvacrol (42.7–48.2%), thymol (0.2–16.5%), p-cymene (10.1–14.7%) and γ-terpinene (7.9–9.1%) in all phenological stages examined. The strongest antibacterial activity (MICs = 5–20 µg/mL) of the EOs was recorded in samples obtained during the flowering stage where carvacrol (42.7%) and thymol (16.5) were present both at high percentages. On the other hand, the antioxidant activity was found to be slightly higher in the other stages. As the EO obtained at flowering showed the best inhibitory properties against foodborne pathogenic bacteria, it is suggested that plants at this stage can be selected as main sources of food preservative agents.

Scent of a Killer: Microbial Volatilome and Its Role in the Biological Control of Plant Pathogens

The use of synthetic fungicides represents the most common strategy to control plant pathogens. Excessive and/or long-term distribution of chemicals is responsible for increased levels of environmental pollution, as well as adverse health consequence to humans and animals. These issues are deeply influencing public perception, as reflected by the increasing demand for safer and eco-friendly agricultural commodities and their by-products. A steadily increasing number of research efforts is now devoted to explore the use of safer and innovative approaches to control plant pathogens. The use of microorganisms as biological control agents (BCAs) represents one of the most durable and promising strategies. Among the panoply of microbial mechanisms exerted by BCAs, the production of volatile organic compounds (VOCs) represents an intriguing issue, mostly exploitable in circumstances where a direct contact between the pathogen and its antagonist is not practicable. VOCs are potentially produced by all living microorganisms, and may be active in the biocontrol of phytopathogenic oomycetes, fungi, and bacteria by means of antimicrobial activity and/or other cross-talk interactions. Their biological effects, the reduced residuals in the environment and on agricultural commodities, and the ease of application in different agricultural systems make the use of VOCs a promising and sustainable approach to replace synthetic fungicides in the control of plant pathogens. In this review, we focus on VOCs produced by bacteria and fungi and on their role in the cross-talk existing between the plant pathogens and their host. Biologic systemic effect of the microbial volatile blends on both pathogen and host plant cells is also briefly reviewed.

Application of Deep Eutectic Solvents for the Extraction of Rutin and Rosmarinic Acid from Satureja montana L. and Evaluation of the Extracts Antiradical Activity

Satureja montana L. was used in the current research as the plant exhibits numerous health-promoting benefits due to its specific chemical composition. The extraction method based on deep eutectic solvents (DESs) was used for the extraction of rutin and rosmarinic acid from this plant. Five different choline chloride-based DESs with different volumes of water (10%, 30%, and 50% (v/v)) were used for the extraction at different temperatures (30, 50, and 70 °C) to investigate the influence on rosmarinic acid and rutin content obtained by high-performance liquid chromatography with diode-array detector (HPLC-DAD) in the obtained extracts. A principal component analysis was employed to explore and visualize the influence of applied parameters on the efficiency of the extraction procedure of rutin and rosmarinic acid. Among the tested DESs, choline chloride:lactic acid (mole ratio 1:2) and choline chloride:levulinic acid (mole ratio 1:2) were the most suitable for the extraction of rutin, while for rosmarinic acid choline chloride:urea (mole ratio 1:2) was the most effective solvent. The extract showing the best antiradical activity was obtained with choline chloride:urea (mole ratio 1:1) at 30 °C and 50% H₂O (v/v).

The anti-corrosion behaviour of Satureja montana L. extract on iron in NaCl solution

The effect of Satureja montana L. extract (SM) and phenolic fraction of Satureja montana L. (PF) on the corrosion behaviour of iron in 0.1 mol L-1 sodium chloride solution was studied by electrochemical techniques, UV/Vis spectrophotometry and atomic absorption spectrometry. The results of all techniques showed that SM and PF contributed to iron corrosion inhibition. The calculated inhibition efficiency values were about 45% for SM and 55% for PF. Results indicate that the inhibitive action occurs via a precipitation of the Fe-complex onto the iron surface which resulting in a decrease of the passive current density. The atomic absorption spectrometry (AAS) method was applied to the quantitative determination of iron in solution. The obtained results demonstrated good agreement with results obtained by electrochemical techniques.

Phytochemical Properties of Satureja kitaibelii, Potential Natural Antioxidants: a New Insight

Satureja kitaibelii Wierzb. ex Heuff. has a great importance in Serbian ethnopharmacology/herbal traditional medicine, as well as a flavoring food additive. Ethanol extract of aerial parts of Satureja kitaibelii analyzed by liquid chromatography-mass spectrometry revealed the presence of 18 compounds among which the most abundant were phenolic acids, flavonoids, jasmonic acid derivatives and rosmanol. The extracts were rich in total phenolics and flavonoid contents, while rosmarinic acid was the dominant compound (18.30-29.52 mg/g). As assessments of antioxidant properties of natural extracts are important because of their growing use in medicine and food industry, antioxidant activity of ethanol extracts of Satureja kitaibelii was analyzed by several assays. The half maximal scavenging capacity (SC₅₀) of 2,2'-diphenyl-1-picrylhydrazyl ranging from 71.20 to 125.65 μg/mL, the total antioxidant capacity from 272.37 to 714.12 mg ascorbic acid/g, and ferric ion reducing antioxidant power ranging from 0.74 to 1.94 μmol Fe/mg, clearly imply a significant antioxidant potential of Satureja kitaibelii. The extracts inhibit growth of Micrococcus luteus and Pseudomonas aeruginosa with inhibition zones 20-30 and 16-26 mm, respectively. Antioxidant and antibacterial activity of compounds identified in extracts suggest a great potential for Satureja kitaibelii application as valuable food ingredient.

Satureja montana L. essential oil and its antimicrobial activity alone or in combination with gentamicin

Many essential oils (EOs) are screened as potential sources of antimicrobial compounds. EOs from the genus Satureja have recognized biological properties, including analgesic, anti-inflammatory, immunomodulatory, anticancer, and antimicrobial activity. This study aimed to obtain a metabolite profile of commercial essential oil of S. montana L. (SEO) and to evaluate its antimicrobial properties, both alone and combined with gentamicin towards Gram-negative and Gram-positive bacterial strains. Untargeted analyses based on direct infusion Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and on GC-MS have provided a high metabolome coverage, allowing to identify carvacrol, cymene and thymol as the major components of commercial SEO. SEO exerted an antimicrobial activity and induced a synergistic interaction with gentamicin against both reference and clinical bacterial strains. A significant reduction of Escherichia coli, Staphylococcus aureus and Listeria monocytogenes biofilm formation was induced by SEO. As a result of SEO treatment, clear morphological bacterial alterations were visualized by scanning electron microscopy: L. monocytogenes and S. aureus showed malformed cell surface or broken cells with pores formation, whereas E. coli displayed collapsed cell surface. These results encourage further studies about bactericidal and antibiotic synergistic effect of SEO for combined therapy in clinical setting as well as in agricultural systems.

Satureja subspicata and S. horvatii Extracts Induce Overexpression of the BCl-2 Family of Anti-apoptotic Genes and Reduce Micronuclei Frequency in Mice

Satureja subspicata and S. horvatii are endemic species of the Balkan Peninsula and often used in traditional medicine in Bosnia and Herzegovina to treat different health conditions. We aimed to analyze the unevaluated apoptotic, genotoxic and cytotoxic effects of two Satureja species, as well as their content of phenolics that are mainly responsible for the plant's biological activity. Apoptotic and geno/cytotoxic activities of S. subspicata and S. horvatii were investigated in vitro in human lymphocyte culture and in vivo in mice. The content of the main phenolics in plant extracts was determined by ultra-high pressure liquid chromatography-MS-MS (UHPLC–MS/MS). Genotoxic and cytotoxic activities of Satureja extracts were evaluated in vitro by applying a cytokinesis-block micronucleus cytome assay in human lymphocyte culture and in vivo applying a mice reticulocytes micronucleus assay. SALSA RT-MLPA R011-C1 apoptosis assay was used for measuring the relative expression of 44 genes associated with the regulation of the apoptotic pathways in human lymphocyte cultures treated with different concentrations of two Satureja extracts. The first analysis of phenolic compounds in S. horvatii and S. subspicata determined by an UHPLC-MS/MS method revealed high levels of rosmarinic and caffeic acids. Minor genotoxic potential was determined in relation to the tested concentrations while no cytostatic and cytotoxic effects were revealed in vitro. However, when applied in concentrations of 200 mg/kg per os, aqueous extracts of two Satureja species significantly decreased frequency of reticulocytes micronuclei in treated mice against controls. Extracts of S. subspicata and S. horvatii in concentrations of 0.2 mg/mL, regardless of solvent used, downregulated pro-apoptotic and upregulated anti-apoptotic genes, showing anti-apoptotic activity. Our results indicate that the registered anti-genotoxic and anti-apoptotic activity is most likely related to the high level of phenolic acids (particularly rosmarinic and caffeic) in the tested extracts.

Antibacterial activity of jalapeño pepper (Capsicum annuum var. annuum) extract fractions against select foodborne pathogens

Capsicum annuum fruits have been investigated for antimicrobial activity in a number of studies. Capsaicin or other cinnamic acid pathway intermediates are often suggested to be the antimicrobial component, however there are conflicting results. No research has specifically fractionated jalapeño pepper (Capsicum annuum var. annuum) extract to isolate and identify compound(s) responsible for inhibition. In this study, fractions were collected from jalapeño pepper extracts using reverse‐phase HPLC and tested for antibacterial activity using the disk diffusion method. Following initial fractionation, two fractions (E and F) displayed antibacterial activity against all three pathogens (p > .05). Commercial standards were screened to determine when they elude and it was found that capsaicin elutes at the same time as fraction E. Fractions E and F were subject to further HPLC fractionation and antibacterial analysis using two methods. The only fraction to display clear inhibition using both was fraction E1, inhibiting the growth of L. monocytogenes. Fraction E1 was analyzed using HPLC‐MS. The resulting mass spectra revealed fraction E1 contained compounds belonging to a group of C. annuum‐specific compounds known as capsianosides. Limited research is available on antibacterial activity of capsianosides, and a pure commercial standard is not available. In order to confirm the potential antimicrobial activity of the compound(s) isolated, methods need to be developed to isolate and purify capsianosides specifically from jalapeño peppers.

Inhibition of methicillin-resistant Staphylococcus aureus (MRSA) by antimicrobial peptides (AMPs) and plant essential oils

CONTEXT

Drug-resistant bacterial infections cause considerable patient mortality and morbidity. The annual frequency of deaths from methicillin-resistant Staphylococcus aureus (MRSA) has surpassed those caused by human immunodeficiency virus/acquired immune deficiency syndrome. The antimicrobial peptides (AMPs), plant essential oils (EOs) and their combinations have proven to be quite effective in killing a wide selection of bacterial pathogens including MRSA.

OBJECTIVES

This review summarizes the studies in the use of AMPs, plant EOs and their combinations for coping with MRSA bacteria, and to formulate new prospects for future studies on this topic.

METHODS

The sources of scientific literature such as PubMed, library search, Google Scholar, Science Direct and electronic databases such as 'The Antimicrobial Peptide Database', 'Collection of Anti-Microbial Peptides' and 'YADAMP'. Physicochemical data of anti-MRSA peptides were determined by Scientific DataBase Maker software.

RESULTS

Of the 118 peptides, 88 exhibited an activity against MRSA with the highest activity of minimum inhibitory concentration values. Various plant EOs have been effective against MRSA. Remarkably, lemongrass EOs completely inhibited all MRSA growth on the plate. Lemon myrtle, Mountain savory, Cinnamon bark and Melissa EOs showed a significant inhibition.

CONCLUSION

Several of these AMPs, EOs and their combinations were effective against MRSA. Their activities have implications for the development of new drugs for medical use.

Inhibitory effect of essential oils on growth and on aflatoxins production by Aspergillus parasiticus

The aim of this work was to assess the inhibitory effect of essential oils on the growth and aflatoxin production of Aspergillus parasiticus, as well as to correlate it with the chemical composition of the essential oils. Essential oils from six aromatic species (Cymbopogon citratus, Eucalyptus globulus, Origanum vulgare, Ruta graveolens, Salvia officinalis, Satureja montana) were characterised by gas chromatography and tested for their inhibitory effect against A. parasiticus strain MUM 92.02. Furthermore, the in vitro inhibitory effects of these essential oils on the production of aflatoxins were evaluated by HPLC. Results showed that all essential oils retarded the time for visible growth. Growth rate was affected differently depending on the essential oil. S. montana essential oil prevented growth in all cases. The essential oil of R. graveolens inhibited most of the aflatoxin production even though growth inhibition was low, while with C. citratus essential oil trace levels of aflatoxins were detected. Essential oils containing carvacrol and/or thymol (S. montana and O. vulgare) have the highest activity against fungal growth, while an essential oil (R. graveolens) containing 2-undecanone and 8-phenyl-2-octanone inhibited the synthesis of aflatoxins. Although the main component of this essential oil was 2-undecanone (91%), when pure 2-undecanone was tested, it did not inhibit aflatoxin production. Inhibition activity is probably due to the recently identified minor compound or to a synergistic effect. Essential oils seem to be a good alternative to fungicides not only because of environmental issues but also because they do not seem to enhance mycotoxin production as it has been reported for some fungicides.

Antimicrobial Effects of Nisin, Essential Oil, and γ-Irradiation Treatments against High Load of Salmonella typhimurium on Mini-carrots

This study aimed at using essential oil (EO) alone or combined EO with nisin and γ-irradiation to control Salmonella Typhimurium during the refrigerated storage of mini-carrots. Peeled mini-carrots were inoculated with S. Typhimurium at a final concentration of approximately 7 log CFU/g. Inoculated samples were coated by 5 different coating solutions: (i) nisin solution at final concentration of 10(3) IU/mL; (ii) mountain savory EO solution at 0.35%; (iii) carvacrol solution at 0.35%; (iv) mountain savory EO at 0.35% plus nisin solution of 10(3) IU/mL; or (v) carvacrol at 0.35% plus nisin solution of 10(3) IU/mL. Coated mini-carrots were then irradiated at 0.5 or 1.0 kGy and compared to an unirradiated control sample. Samples were kept at 4 °C and microbial analyses were conducted at days 1, 3, 6, and 9. The results showed that mini-carrots coated by carvacrol plus nisin solution or mountain savory EO plus nisin solution in combination with irradiation at 1.0 kGy completely eliminated S. Typhimurium to under the detection limit during the storage. Thus, the combined treatments using carvacrol plus nisin or mountain savory EO plus nisin coating solution and irradiation at 1.0 kGy could be used as an effective method for controlling S. Typhimurium in mini-carrots.

PRACTICAL APPLICATION

This study shows the effect of using γ irradiation at low dose (1 kGy) to reduce significantly the growth of Salmonella typhimurium in mini-carrots. It also shows that combination of nisin, essential oils with γ irradiation have the best antibacterial effects against S. Typhimurium during the storage of mini-carrots. The results can be used for practical application in food industry in terms of food safety.

A pharmacological and phytochemical overview on Satureja

CONTEXT

Satureja (Lamiaceae) species are used as flavoring compounds in food, pharmaceutical, and cosmetic industries because of its sweetness and simple cultivation characteristics. They have traditionally been used as muscle pain relievers, tonic, and carminative agents to treat stomach and intestinal disorders such as cramps, nausea, indigestion, and diarrhea, due to their considerable phytochemical characteristics.

OBJECTIVE

This review evaluates some information published since 1989 on Satureja genus from a systematic perspective in terms of its pharmacological and phytochemical characteristics.

MATERIALS AND METHODS

Web of Science, PubMed, Scopus, and Google Scholar databases were searched up to March 2014. "Satureja" was used as a research term without narrowing or limiting research elements. After obtaining all reports from database (a total number is about 637), the papers were carefully analyzed in order to find data related to the topic of this review.

RESULTS

In this review, 453 reports were used which were published between 1989 and 2014. The study was compiled into two sections (Pharmacology and Phytochemistry). In the pharmacology section, more than 50 different activities were studied. In the second section, in addition to other compounds and inorganic substances, volatiles, phenolic acids, and flavonoids were discussed.

DISCUSSION AND CONCLUSION

According to our contemporary information, Satureja species have been evaluated for their wide range of biological activities. However, a small part of these studies have been carried out on the active principles. Therefore, in the future, more studies should be carried out to identify responsible phytochemicals for the various activities.

Plant essential oils and their constituents in coping with multidrug-resistant bacteria

Antibiotic resistance is documented to be a serious problem that affects the choice of appropriate antibiotic therapy and increases the probability of unfavorable infection outcome. One of the proposed methods to cope with multidrug-resistant (MDR) bacteria is the use of alternative antibacterial treatments, which include natural antimicrobial substances such as plant essential oils (EOs). The aim of the present article is to review published studies on the activity of EOs and their constituents against MDR bacteria and to formulate perspectives for the future. In general, published studies indicate that EOs can be used as effective antiseptics against many species, including MDR bacteria, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, resistant isolates of Pseudomonas aeruginosa, Klebsiella pneumoniae and others; certain EOs may potentiate the effectiveness of antibiotics against MDR bacteria; EOs can be synergistic with bacteriophages; and polymeric nanoparticles can be used for delivery of EOs and enhancement of their activity at the site of infection.

In Vitro Study to Evaluate Antibacterial and Non-haemolytic Activities of Four Iranian Medicinal Plants

OBJECTIVE

Aqueous extracts of four medicinal plants including Ferula gummosa, Echinophora orientalis, Nasturtium microphyllum and Verbascum thapsus were used to determine their antibacterial activities and minimum inhibitory concentration (MIC). The aim of this study was to assess antibacterial activity of extracts of four medicinal plants against a Gram-positive and a Gram-negative bacteria (Staphylococcus aureus PTCC1431, and Escherichia coli HP101BA 7601c).

METHODS

Radial diffusion assay was used to assess the antibacterial activity of extracted samples. Haemolysis assay was also used to examine their nontoxic effects on human red blood cells (RBCs).

RESULTS

This study showed that all the mentioned plants have satisfactory antibacterial effects against both Gram-positive and Gram-negative bacteria. Minimum inhibitory concentration values of these samples were less than 750 µg/mL. In addition, no significant haemolytic activity was observed at their MIC values.

CONCLUSION

The results of this study showed that all these studied plants have good potential for further studies for drug discovery.

Fatty acid composition, physicochemical properties, antioxidant and cytotoxic activity of apple seed oil obtained from apple pomace

BACKGROUND

Apple pomace is generated in huge quantities in juice-processing industries the world over and continuous efforts are being made for its inclusive utilization. In this study, apple seeds separated from industrial pomace were used for extraction of oil. The fatty acid composition, physicochemical and antioxidant as well as in vitro anticancer properties of extracted oil were studied to assess its suitability in food and therapeutic applications.

RESULTS

The fatty acid composition of seed oil revealed the dominance of oleic (46.50%) and linoleic acid (43.81%). It had high iodine (121.8 g I 100 g⁻¹) and saponification value (184.91 mg KOH g⁻¹ oil). The acid value, refractive index and relative density were 4.28 mg KOH g⁻¹, 1.47 and 0.97 mg mL⁻¹, respectively. The antioxidant potential (IC₅₀) of apple seed oil was 40.06 µg mL⁻¹. Cytotoxicity of apple seed oil against CHOK1, SiHa and A549 cancer cell lines ranged between 0.5 ± 0.06% and 88.6 ± 0.3%.

CONCLUSION

The physicochemical properties of apple seed oil were comparable with edible food oil, indicating its better stability and broad application in the food and pharmaceutical industries. Apple seed oil could be a good source of natural antioxidants. Also, the in vitro cytotoxic activity against specific cell lines exhibited its potential as an anticancer agent.

In Vitro Study to Evaluate Antibacterial and Non-haemolytic Activities of Four Iranian Medicinal Plants

OBJECTIVE

Aqueous extracts of four medicinal plants including Ferula gummosa, Echinophora orientalis, Nasturtium microphyllum and Verbascum thapsus were used to determine their antibacterial activities and minimum inhibitory concentration (MIC). The aim of this study was to assess antibacterial activity of extracts of four medicinal plants against a Gram-positive and a Gram-negative bacteria (Staphylococcus aureus PTCC1431, and Escherichia coli HP101BA 7601c).

METHODS

Radial diffusion assay was used to assess the antibacterial activity of extracted samples. Haemolysis assay was also used to examine their nontoxic effects on human red blood cells (RBCs).

RESULTS

This study showed that all the mentioned plants have satisfactory antibacterial effects against both Gram-positive and Gram-negative bacteria. Minimum inhibitory concentration values of these samples were less than 750 µg/mL. In addition, no significant haemolytic activity was observed at their MIC values.

CONCLUSION

The results of this study showed that all these studied plants have good potential for further studies for drug discovery.

In vitro evaluation of antimicrobial activities of various commercial essential oils, oleoresin and pure compounds against food pathogens and application in ham

The purpose of this research was to evaluate the application of commercially available essential oils (EOs) and oleoresins to control bacterial pathogens for ready to eat food. In this study, sixty seven commercial EOs, oleoresins (ORs) and pure compounds were used to evaluate in vitro their antimicrobial activity against six food pathogens. These products were first screened for their antimicrobial activity using disk diffusion assay. Forty one products were then chosen for further analysis to determine their minimum inhibitory concentration against 6 different bacteria. There were 5 different products (allyl isothiocyanate, cinnamon Chinese cassia, cinnamon OR, oregano and red thyme) that showed high antimicrobial activity against all tested bacteria. Further analysis examined the effect of four selected EOs on controlling the growth rate of mixed cultures of Listeria monocytogenes in ham. A reduction of the growth rate by 19 and 10% was observed when oregano and cinnamon cassia EOs were respectively added in ham at a concentration of 500 ppm.