The antioxidant and antimicrobial activity of essential oils against Pseudomonas spp. isolated from fish

Assessment of Anticancer Properties of Argemone mexicana L. and Berberine: A Comparative Study

Argemone mexicana L. has been used in traditional Mexican medicine. Among its bioactive constituents, berberine (BER) has garnered attention for its cytotoxic properties against different tumor cell lines. This study investigates the in vitro toxicity against HEP-G2 (human hepatocellular carcinoma) and murine lymphoma (L5178Y-R) cells using the MTT assay of the methanol extract (AmexM), sub-partitions of A. mexicana, and BER. Selectivity indices (SIs) were determined by comparing their cytotoxic effects on VERO (monkey kidney epithelial) and PBMC (human peripheral blood mononuclear) non-tumoral cells. Additionally, the anti-hemolytic effect of these treatments was assessed using the AAPH method. The treatment with the most promising activity against tumor cells and anti-hemolytic efficacy underwent further evaluation for toxicity in Artemia salina and antioxidant activities using DPPH, ABTS, and FRAP assays. BER demonstrated an IC50 = 56.86 µg/mL in HEP-G2 cells and IC50 < 5.0 µg/mL in L5178Y-R cells, with SI values of 15.97 and >5.40 in VERO and PBMC cells, respectively. No significant hemolytic effects were observed, although AmexM and BER exhibited the highest anti-hemolytic activity. BER also demonstrated superior antioxidant efficacy, with lower toxicity in A. salina nauplii compared to the control. Additionally, BER significantly attenuated nitric oxide production. This study highlights the antiproliferative effects of A. mexicana, particularly BER, against HEP-G2 and L5178Y-R tumor cell lines, along with its selectivity towards normal cells. Furthermore, its anti-hemolytic and antioxidant potentials were demonstrated, suggesting that BER is a promising candidate for potent chemotherapeutic agents.

Oil-in-water emulsion loaded with optimized antioxidant blend improved the shelf-life of trout (Oncorhynchus mykiss) fillets: a study with simplex-centroid design

This study aimed to obtain optimized mixture with three essential oils (EOs) for maximum antioxidant activity through the augmented simplex-centroid mixture design and evaluate the effect of this optimized blend on total aerobic psychrotrophic count (TAPC), lipid and protein oxidation, instrumental color parameters and texture profile in rainbow trout fillets at refrigerated storage for nine days. Considering the DPPH and FRAP assays, the ideal EO blend was 66% lemongrass and 34% oregano. During refrigerated storage, this blend at 2000 ppm was equally effective as BHT (100 ppm) (p > 0.05), mitigating the discoloration (a* and b*), lipid, and protein oxidation in 38.83%, 12.95%, 76.13%, and 35.13%, respectively, besides shows greater effectiveness for preserving texture changes (p < 0.05) and extending the shelf life in 13 h. The lemongrass + oregano EO blend reveals a promising natural alternative to enhance the quality of rainbow trout fillets under refrigerated storage. Furthermore, the multiresponse optimization showed to be a strong ally in enabling the use of these EOs by food industries.

Use of Essential Oils to Counteract the Phenomena of Antimicrobial Resistance in Livestock Species

Antimicrobial resistance is an increasingly widespread phenomenon that is of particular concern because of the possible consequences in the years to come. The dynamics leading to the resistance of microbial strains are diverse, but certainly include the incorrect use of veterinary drugs both in terms of dosage and timing of administration. Moreover, the drug is often administered in the absence of a diagnosis. Many active ingredients in pharmaceutical formulations are, therefore, losing their efficacy. In this situation, it is imperative to seek alternative treatment solutions. Essential oils are mixtures of compounds with different pharmacological properties. They have been shown to possess the antibacterial, anti-parasitic, antiviral, and regulatory properties of numerous metabolic processes. The abundance of molecules they contain makes it difficult for treated microbial species to develop pharmacological resistance. Given their natural origin, they are environmentally friendly and show little or no toxicity to higher animals. There are several published studies on the use of essential oils as antimicrobials, but the present literature has not been adequately summarized in a manuscript. This review aims to shed light on the results achieved by the scientific community regarding the use of essential oils to treat the main agents of bacterial infection of veterinary interest in livestock. The Google Scholar, PubMed, SciELO, and SCOPUS databases were used for the search and selection of studies. The manuscript aims to lay the foundations for a new strategy of veterinary drug use that is more environmentally friendly and less prone to the emergence of drug resistance phenomena.

An update about beneficial effects of medicinal plants in aquaculture: A review

Aquaculture is an essential and growing component of agricultural and global ecosystems worldwide. Aquaculture provides more than 25% of the total aquatic food consumption by humans. The development of the aquaculture industry should be followed in successive industrial years, and therefore it is necessary to pay attention to the management and type of farming system that is compatible with the environment. The use of antibiotics for disease control has been criticised for their negative effects, including the emergence of antibiotic-resistant bacteria, the suppression of the immune system and the environment, and the accumulation of residue in aquatic tissues. The use of these products reduces the need for treatments, enhances the effect of vaccines, and, in turn, improves production indicators. Medicinal plants have increasingly been used in recent years as a disease control strategy in aquaculture, boosting the immune system of aquatic animals and helping to develop strong resistance to a wide range of pathogens. Therefore, this review aims to provide an overview of the recent evidence on the beneficial use of medicinal plants to promote growth and strengthen the immune system in farmed aquatic animals.

Probiotics mitigate kidney damage after exposure to Sri Lanka's local groundwater from chronic kidney disease with uncertain etiology (CKDu) prevalent area in zebrafish

Groundwater in Sri Lanka, contaminated with environmental toxins, is suspected to potentially induce chronic kidney disease of uncertain etiology (CKDu) in humans. This study aims to elucidate the potential mitigating effects of probiotics on kidney damage induced by exposure to this local groundwater (LW) in zebrafish. We used zebrafish as a model organism and exposed them to local groundwater to evaluate the risk of CKDu. Probiotics were then added at a concentration of 108 colony-forming units per milliliter (CFU/mL). Our findings revealed that exposure to local groundwater resulted in abnormalities, such as tail deletion and spinal curvature in zebrafish larvae. However, the addition of probiotics mitigated these effects, improving the hatching rate, heart rate, length, weight, deformity rate, survival rate, and abnormal behavior of zebrafish. It also positively influenced the differential expression levels of kidney development and immunity-related genes (dync2h1, foxj1, pkd2, gata3, slc20a1, il1β, and lyso). Furthermore, exposure to LW decreased both the diversity and abundance of microbiota in zebrafish larvae. However, treatment with probiotics, such as L. plantarum and L. rhamnosus partially restored the disrupted gut microbiota and significantly impacted the cellular process pathways of the microbial community, as determined by KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. In conclusion, this study highlights the risks associated with Sri Lanka's local groundwater from a CKDu prevalent area and confirms the beneficial effects of different probiotics. These findings may provide new insights into bacterial function in host kidney health.

Essential Oils: Useful Tools in Storage-Pest Management

This study aimed to verify the level of repellent and mortality effect of two chemical substances (DEET and 2-undecanone) and seven essential oils (EOs), Allium sativum, Artemisia annua, Ocimum basilicum, Lavandula angustifolia, Eucalyptus globulus, Pinus sylvestris, and Curcuma longa. The storage pests Tribolium confusum, Tenebrio molitor, and Acanthoscelides obtectus were exposed to various concentrations in an olfactometer-and-mortality test. The effects were recorded 24-48-72 h after the treatments were applied. A. sativum, E. globulus, and L. augustifolia were found to have significant repellence effects. A substantial lethal effect was observed for A. sativum, E. globulus, and O. basilicum. We also found that even if the most efficient EOs were diluted to low concentrations, they still produced repellent and mortality effects. The presented results indicate that A. sativum and O. basilicum were the most effective against T. confusum and T. molitor; simultaneously, L. angustifolia and C. longa showed high activity against A. obtectus. All of these efficient EOs could be applied as effective bio-control agents in various stored conditions.

Antimicrobial mechanisms of spice essential oils and application in food industry

Spice essential oils (SEOs) are commonly used in food flavoring and are considered an effective food preservative. It has a broad range of applications and promising development prospects. As a natural food additive, SEOs' antimicrobial effects have been widely studied and utilized towards food preservation. Many SEOs have exhibited significant antimicrobial activities against food-borne pathogenic and food spoilage microorganisms. We reviewed the antibacterial and antifungal properties of SEOs, the active components, their corresponding mechanisms of actions, as well as their application in the food industry, providing a theoretical basis for SEOs' further development and application as natural preservatives.

Protective Impact of Chitosan Film Loaded Oregano and Thyme Essential Oil on the Microbial Profile and Quality Attributes of Beef Meat

Edible films and essential oil (EO) systems have the potency to enhance the microbial quality and shelf life of food. This investigation aimed to evaluate the efficacy of chitosan films including essential oils against spoilage bacteria and foodborne pathogens associated with meat. Antimicrobial activity (in vitro and in vivo) of chitosan films (CH) incorporated with oregano oil (OO) and thyme oil (TO) at 0.5 and 1% was done against spoilage bacteria and foodborne pathogens, compared to the control sample and CH alone. Preliminary experiments (in vitro) showed that the 1% OO and TO were more active against Staphylococcus aureus compared to Escherichia coli O157:H7 and Salmonella Typhimurium. In in vivo studies, CH containing OO and TO effectively inhibited the three foodborne pathogens and spoilage bacteria linked with packed beef meat which was kept at 4 °C/30 days compared to the control. The total phenolic content of the EOs was 201.52 mg GAE L⁻¹ in thyme and 187.64 mg GAE L⁻¹ in oregano. The antioxidant activity of thyme oil was higher than oregano oil. The results demonstrated that the shelf life of meat including CH with EOs was prolonged ~10 days compared to CH alone. Additionally, CH-OO and CH-TO have improved the sensory acceptability until 25 days, compared to the control. Results revealed that edible films made of chitosan and containing EOs improved the quality parameters and safety attributes of refrigerated or fresh meat.

Natural Compounds With Antimicrobial and Antiviral Effect and Nanocarriers Used for Their Transportation

Due to the increasing prevalence of life-threatening bacterial, fungal and viral infections and the ability of these human pathogens to develop resistance to current treatment strategies, there is a great need to find and develop new compunds to combat them. These molecules must have low toxicity, specific activity and high bioavailability. The most suitable compounds for this task are usually derived from natural sources (animal, plant or even microbial). In this review article, the latest and most promising natural compounds used to combat bacteria, filamentous fungi and viruses are presented and evaluated. These include plant extracts, essential oils, small antimicrobial peptides of animal origin, bacteriocins and various groups of plant compounds (triterpenoids; alkaloids; phenols; flavonoids) with antimicrobial and antiviral activity. Data are presented on the inhibitory activity of each natural antimicrobial substance and on the putative mechanism of action against bacterial and fungal strains. The results show that among the bioactive compounds studied, triterpenoids have significant inhibitory activity against coronaviruses, but flavonoids have also been shown to inhibit SARS-COV-2. The last chapter is devoted to nanocarriers used to improve stability, bioavailability, cellular uptake/internalization, pharmacokinetic profile and reduce toxicity of natural compunds. There are a number of nanocarriers such as liposomes, drug delivery microemulsion systems, nanocapsules, solid lipid nanoparticles, polymeric micelles, dendrimers, etc. However, some of the recent studies have focused on the incorporation of natural substances with antimicrobial/antiviral activity into polymeric nanoparticles, niosomes and silver nanoparticles (which have been shown to have intrinsic antimicrobial activity). The natural antimicrobials isolated from animals and microorganisms have been shown to have good inhibitory effect on a range of pathogens, however the plants remain the most prolific source. Even if the majority of the studies for the biological activity evaluation are in silico or in vitro, their internalization in the optimum nanocarriers represents the future of “green therapeutics” as shown by some of the recent work in the field.

Antimicrobial Activity and Chemical Composition of Essential Oils against Pathogenic Microorganisms of Freshwater Fish

Antimicrobials are widely applied in aquaculture for treatment of infectious diseases in fish. The increased antimicrobial resistance of fish pathogens to conventional antimicrobial treatment highlights the need for research on the antibacterial properties of natural products—in this case, essential oils (EOs). The aim of the present study was to detect the antimicrobial activity of the essential oils on pathogenic microorganisms found in freshwater fish. Freshwater fish isolates of Aerococcus spp., Aeromonas spp., Enterococcus spp., Escherichia spp., Pseudomonas spp., Shewanella spp., Yersinia spp., and Vagococcus spp. were tested for antimicrobial resistance and antimicrobial activity against 14 commercially available essential oils. Antimicrobial resistance was identified in Pseudomonas spp. isolates against cefepime and ciprofloxacin; while all Aeromonas, Enterococcus, and Yersinia isolates were fully susceptible. All tested EOs revealed antimicrobial activity against the tested freshwater fish isolates at different extents. Cinnamomum camphora exhibited strong antimicrobial activity against Aeromonas spp. (3.12 μL/mL), Enterococcus spp. (0.78–1.56 μL/mL), and Pseudomonas spp. with the MIC method. EOs of Gaultheria procumbens and Litsea cubeba showed strong antibacterial activity against Yersinia spp. and Vacococcus spp. (6.25 μL/mL). The study shows the antimicrobial activity of EOs against the most relevant freshwater fish pathogens and indicates the application opportunities in aquaculture.

Use of Essential Oils in Veterinary Medicine to Combat Bacterial and Fungal Infections

Essential oils (EOs) are secondary metabolites of plants employed in folk medicine for a long time thanks to their multiple properties. In the last years, their use has been introduced in veterinary medicine, too. The study of the antibacterial properties of EOs is of increasing interest, because therapies with alternative drugs are welcome to combat infections caused by antibiotic-resistant strains. Other issues could be resolved by EOs employment, such as the presence of antibiotic residues in food of animal origin and in environment. Although the in vitro antimicrobial activity of EOs has been frequently demonstrated in studies carried out on bacterial and fungal strains of different origins, there is a lack of information about their effectiveness in treating infections in animals. The scientific literature reports some studies about in vitro EOs' activity against animal clinical bacterial and fungal isolates, but in vivo studies are very scanty. The use of EOs in therapy of companion and farm animals should follow careful studies on the toxicity of these natural products in relation to animal species and route of administration. Moreover, considering the different behavior of EOs in relation to both species and strain pathogen, before starting a therapy, an aromatogram should be executed to choose the oil with the best antimicrobial activity.

Antifungal Effects of Drimane Sesquiterpenoids Isolated from Drimys winteri against Gaeumannomyces graminis var. tritici

Gaeumannomyces graminis var. tritici is a soilborne pathogen that causes "take-all" disease, affecting cereal roots. In wheat, G. graminis var. tritici is the most important biotic factor, causing around 30 to 50% losses of yield. Chemical control of this fungal disease is difficult because G. graminis var. tritici is able to reside for a long time in soils. Therefore, the development of environmentally friendly biotechnological strategies to diminish the incidence of soilborne diseases is highly desirable. Natural products are a promising strategy for biocontrol of plant pathogens. A special emphasis is on medicinal plants due to their reported fungitoxic effects. Drimys winteri (canelo) is a medicinal plant that is widely used by the Mapuche ethnic group from Chile due to its anti-inflammatory activity. In addition, inhibitory effects of canelo against phytopathogenic fungi and pest insects have been reported. In this study, we isolated, purified, and identified six drimane sesquiterpenoid compounds from canelo (drimenin, drimenol, polygodial, isodrimeninol, valdiviolide, and drimendiol). Then, we evaluated their antimicrobial effects against G. graminis var. tritici. Compounds were identified by comparing Fourier-transform infrared spectroscopy (FTIR) data and the retention time in thin-layer chromatography (TLC) with those of pure standards. The putative antagonistic effects were confirmed by assessing hyphal cell wall damage using confocal microscopy and lipid peroxidation. Here, we reported the high potential of drimane sesquiterpenoids as natural antifungals against G. graminis var. tritici. Polygodial and isodrimeninol were the most effective, with 50% lethal concentrations (LC₅₀s) between 7 and 10 μg ml^-1 and higher levels of fungal lipid peroxidation seen. Accordingly, natural sesquiterpenoids purified from canelo are biologically active against G. graminis var. tritici and could be used as natural biofungicides for sustainable agriculture.IMPORTANCE More than two billion tons of pesticides are used every year worldwide. An interesting sustainable alternative to control plant pathogens is the use of natural products obtained from plants, mainly medicinal plants that offer secondary metabolites important to human/animal health. In this study, we isolated and identified six pure drimane sesquiterpenoids obtained from the bark of Drimys winteri Additionally, we evaluated their antifungal activities against Gaeumannomyces graminis (the main biotic factor affecting cereal production, especially wheat) by assessing fungal cell wall damage and lipid peroxidation. The compounds obtained showed important antifungal properties against G. graminis var. tritici, mainly isodrimenol, which was the second-most-active compound after polygodial, with an LC₅₀ against G. graminis var. tritici of around 9.5 μg ml^-1 This information could be useful for the development of new natural or hemisynthetic antifungal agents against soilborne phytopathogens that could be used in green agriculture.

Toxicity of the essential oil from Thymus serpyllum and thymol to larvae and pupae of the housefly Musca domestica L. (Diptera: Muscidae)

The essential oil (EO) of Thymus serpyllum and thymol were evaluated for their insecticidal activity against the housefly (Musca domestica) larvae and pupae. Contact toxicity and fumigation bioassays were used. Chemical composition analysis of T. serpyllum EO by gas chromatographic mass spectrometry (GC-MS) revealed that thymol (41.6%), p-cymene (21.9%), and γ-terpinene (19.2%) were the major components. For larval assays, the LC₅₀ value of T. serpyllum EO was 0.4 μl/cm² for contact toxicity and 20.9 μl/l for fumigation toxicity. For thymol, the contact toxicity LC₅₀ value was 0.035 μl/cm² and the fumigation LC₅₀ value was 2.0 μl/l. For the pupal assay, T. serpyllum EO had a percentage inhibition rate (PIR) value of 100% for both contact toxicity (1.0 μl/cm²) and fumigation toxicity assay (25 μl/l), whereas thymol had a PIR of 100% for contact toxicity (0.1 μl/cm²) and fumigation assay (5 μl/l). This study shows that T. serpyllum EO and thymol are toxic to housefly larvae and pupae and have the potential for use in the population control of this species.

Targeting fish spoilers Pseudomonas and Shewanella with oregano and nettle extracts

To control Pseudomonas and Shewanella as important psychrotrophic spoilage bacteria in fish meat, we used ethanolic extracts of oregano (Origanum vulgare subsp. vulgare) and nettle (Urtica dioica), with phytochemical characterisation of the extracts and their bioactive compounds. Liquid chromatography coupled with photodiode array detection and electrospray ionisation-mass spectrometry was used for qualitative compositional determination of the extracts. Four main compounds were identified in the oregano extract, with rosmarinic acid the most abundant, followed by three glycosylated phenolics, one of which is reported for the first time in O. vulgare: 4'-O-β-d-glucopyranosyl-3',4'-dihydroxybenzyl-4-hydroxybenzoate. Six main compounds were identified in the nettle extract, as caffeoylmalic acid and five flavonoid glycosides. These oregano and nettle ethanolic extracts showed in-vitro antimicrobial activities against selected Pseudomonas and Shewanella strains in broth and fish meat homogenate when evaluated at two inoculum concentrations. The antimicrobial activities were more pronounced for the nettle extract at the lower inoculum concentration, and for both the Shewanella strains. Growth inhibition in the fish meat homogenate was evaluated at 3.13 mg/mL and 1.56 mg/mL at 5 °C. Again, the nettle extract showed greater antimicrobial activity, which was seen as the lowest maximum growth rate, followed by the oregano extract, which was inhibitory only at 3.13 mg/mL. Finally, the extracts were applied to fish meat that was then stored at 5 °C for 9 days. Evaluation here was for the counts of the mesophilic, psychrotrophic, Pseudomonas and H2S producers. These confirmed the better antimicrobial effects of the nettle extract, especially against the H2S-producing bacteria, which included Shewanella. Both of the extracts were rich in glycosides of flavonoids and phenolic acids. The enzymatic activities of the Pseudomonas and Shewanella spoilage bacteria and their actions on the phenolic glycosides from natural sources will be further investigated.

Antifungal activity of selected volatile essential oils against Penicillium sp

Phytopathogenic fungi have been responsible for considerable economic losses in vineyards, and therefore, more attention should be paid to the development and implementation of preventative treatment that is environmentally friendly. The aim of this study was to evaluate the antifungal activity of ten essential oils (EOs) (viz. Lavandula angustifolia Mill., Carum carvi L., Pinus mugo var. pumilio, Mentha piperita L., Foeniculum vulgare L., Pinus sylvestris L., Satureja hortensis L., Origanum vulgare L., Pimpinella anisum L. and Rosmarinus officinalis L.). For the antifungal activity evaluation against Penicillium brevicompactum, P. citrinum, P. crustosum, P. expansum, P. funiculosum, P. glabrum, P. chrysogenum, P. oxalicum, P. polonicum and Talaromyces purpurogenus a disc diffusion method was used. The ten EOs exhibited different antifungal properties. Three tested EOs (Carum carvi L., Satureja hortensis L. and Pimpinella anisum L.) at concentrations of 0.75, 0.50, 0.25 and 0.125 µL/mL showed antifungal activity, inhibiting the mycelial growth. The Origanum vulgare L. EOs exhibited a lower level of inhibition. Overall, Lavandula angustifolia Mill., Pinus mugo var. pumilio, Mentha piperita L., Foeniculum vulgare L., Pinus sylvestris L., Satureja hortensis L., Pimpinella anisum L. and Rosmarinus officinalis L. were effective as fungicidal agents but their efficiency varied between the strains of fungi. Carum carvi L. showed strong antifungal activity against all tested strains at both full strength and reduced concentrations. These EOs could be considered as potential sources of antifungal compounds for treating plant fungal diseases.

Zein Nanoparticles Impregnated with Eugenol and Garlic Essential Oils for Treating Fish Pathogens

The supply of food derived from aquaculture has increased significantly in recent years. The aim of this industrial sector is to produce sustainable products to meet the needs of consumers, providing food security and nutritional benefits. The development of aquaculture has faced challenges including disease outbreaks that can cause substantial economic losses. These diseases can be controlled using chemicals such as antibiotics. However, the indiscriminate use of these substances can have major negative impacts on human health and the environment with the additional risk of the emergence of resistant organisms. The present manuscript describes the use of phytotherapy in association with nanotechnology in order to obtain a more effective and less harmful system for the control of bacterial diseases in fish. Zein nanoparticles associated with eugenol and garlic essential oil were prepared through antisolvent precipitation and characterized. Zein nanoparticles are promising carrier systems as zein proteins are biodegradable and biocompatible and, in this way, good candidates for encapsulation of active ingredients. The system presented good physicochemical properties with an average particle diameter of approximately 150 nm, a polydispersity index lower than 0.2, and a zeta potential of approximately 30 mV. High encapsulation efficiency was obtained for the active compounds with values higher than 90%, and the compounds were protected against degradation during storage (90 days). The nanoparticle formulations containing the botanical compounds also showed less toxicity in the tests performed with a biomarker (Artemia salina). In addition, the systems showed bactericidal activity against the important fish pathogenic bacteria Aeromonas hydrophila, Edwardsiella tarda, and Streptococcus iniae in vitro. The present study opens new perspectives for the use of botanical compounds in combination with nanotechnology to treat fish diseases caused by bacteria, contributing to a more sustainable fish chain production.

Antioxidant and antimicrobial applications of biopolymers: A review

Biopolymers have generated mounting interest among researchers and industrialists over the recent past. Rising consciousness on the use of eco-friendly materials as green alternatives for fossil-based biopolymers has shifted the research focus towards biopolymers. Advances in technologies have opened up new windows of opportunities to explore the potential of biopolymers. In this context, this review presents a critique on applications of biopolymers in relation to antioxidant and antimicrobial activities. Some biopolymers are reported to contain inherent antioxidant and antimicrobial properties, whereas, some biopolymers, which do not possess such inherent properties, are used as carriers for other biopolymers or additives having these properties. Modifications are often performed in order to improve the properties of biopolymers to suit them for different applications. This review aims at presenting an overview on recent advances in the use of biopolymers with special reference to their antioxidant and antimicrobial applications in various fields.

Chemical composition, antioxidant, anti-inflammatory and antiproliferative activities of the essential oil of Cymbopogon nardus, a plant used in traditional medicine

Objectives Natural products commonly used in traditional medicine, such as essential oils (EOs), are attractive sources for the development of molecules with anti-proliferative activities for future treatment of human cancers, e.g., prostate and cervical cancer. In this study, the chemical composition of the EO from Cymbopogon nardus was characterized, as well as its antioxidativeproperties and anti-inflammatory and antiproliferative activities on LNCaP cells derived from prostate cancer. Methods The chemical composition of the EO was determined by GC/FID and GC/MS analyses. The antioxidative properties were assessed using DPPH radical scavenging assay and ABTS+• radical cation decolorization assay, and the anti-inflammatory capacity was determined by the inhibition of the lipoxygenase activity. Antiproliferative activity was evaluated by MTT assay. Results Collectively, our data show that the major constituents of C. nardus EO are citronellal (33.06 %), geraniol (28.40 %), nerol (10.94 %), elemol (5.25 %) and delta-elemene (4.09 %). C. nardus EO shows modest antioxidant and anti-inflammatory activity compared to the standard galic acid. C. nardus EO exhibits the best antiproliferative activity on the prostate cancer cell line LNCaP with an IC50 of 58.0 ± 7.9 μg/mL, acting through the induction of the cell cycle arrest. Conclusions This study has determined that C. nardus EO efficiently triggers cytotoxicity and pens a new field of investigation regarding the putative use of this EO in vivo.

Discovering microbiota and volatile compounds of surströmming, the traditional Swedish sour herring

In this study, the microbiota of ready-to-eat surströmming from three Swedish producers were studied using a combined approach. The pH values of the samples ranged between 6.67 ± 0.01 and 6.98 ± 0.01, whereas their a_w values were between 0.911 ± 0.001 and 0.940 ± 0.001. The acetic acid concentration was between 0.289 ± 0.009 g/100 g and 0.556 ± 0.036 g/100 g. Very low concentrations of lactic acid were measured. Viable counting revealed the presence of mesophilic aerobes, mesophilic lactobacilli and lactococci as well as halophilic lactobacilli and lactococci, coagulase-negative staphylococci, halophilic aerobes and anaerobes. Negligible counts for Enterobacteriaceae, Pseudomonadaceae and total eumycetes were observed, whereas no sulfite-reducing anaerobes were detected. Listeria monocytogenes and Salmonella spp. were absent in all samples. Multiplex real-time PCR revealed the absence of the bont/A, bont/B, bont/E, bont/F, and 4gyrB (CP) genes, which encode botulinic toxins, in all the samples analyzed. Metagenomic sequencing revealed the presence of a core microbiota dominated by Halanaerobium praevalens, Alkalibacterium gilvum, Carnobacterium spp., Tetragenococcus halophilus, Clostridiisalibacter spp. and Porphyromonadaceae. Psychrobacter celer, Ruminococcaceae, Marinilactibacillus psychrotolerans, Streptococcus infantis and Salinivibrio costicola were detected as minor OTUs. GC-MS analysis of volatile components revealed the massive presence of trimethylamine and sulphur compounds. Moreover, 1,2,4-trithiolane, phenols, ketones, aldehydes, alcohols, esters and long chain aliphatic hydrocarbons were also detected. The data obtained allowed pro-technological bacteria, which are well-adapted to saline environments, to be discovered for the first time. Further analyses are needed to better clarify the extent of the contribution of either the microbiota or autolytic enzymes of the fish flesh in the aroma definition.

New Tricks for Old Guys: Recent Developments in the Chemistry, Biochemistry, Applications and Exploitation of Selected Species from the Lamiaceae Family

Lamiaceae is one of the largest families of flowering plants comprising about 250 genera and over 7,000 species. Most of the plants of this family are aromatic and therefore important source of essential oils. Lamiaceae are widely used as culinary herbs and reported as medicinal plants in several folk traditions. In the Mediterranean area oregano, sage, rosemary, thyme and lavender stand out for geographical diffusion and variety of uses. The aim of this review is to provide recent data dealing with the phytochemical and pharmacological studies, and the more recent applications of the essential oils and the non-volatile phytocomplexes. This literature survey suggests how the deeper understanding of biomolecular processes in the health and food sectors as per as pest control bioremediation of cultural heritage, or interaction with human microbiome, fields, leads to the rediscovery and new potential applications of well-known plants.

Rapid bactericidal effect of cinnamon bark essential oil against Pseudomonas aeruginosa

AIMS

This study aimed to identify the most effective antimicrobial agent from a selection of essential oils (EO) and investigate its bactericidal properties against Pseudomonas aeruginosa.

METHODS AND RESULTS

The disc diffusion assay and minimal inhibitory/bactericidal concentration tests were used to identify antimicrobial potential. Several oils exhibited antimicrobial effects at concentrations as low as 0·03% (v/v). Significantly, cinnamon (Cinnamomum zeylanicum) bark EO exhibited a broad-spectrum activity against Gram-negative and Gram-positive bacteria and showed bacteriostatic and bactericidal effects against P. aeruginosa PAO1 at 0·125% (v/v) and all other tested organisms, including known multidrug resistant species. Time-kill assays and metabolic activity tests showed cinnamon oil to exhibit rapid killing, with bactericidal activity observed in ≤6 min at ≥0·5% (v/v). Furthermore, scanning electron microscopy and a membrane permeability assay indicated damage to membrane integrity, loss of turgor and cell collapse.

CONCLUSION

Cinnamon bark EO is a broad-spectrum antimicrobial agent capable of rapid killing at low concentrations.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides a sound basis for further investigation of the potential of cinnamon bark EO as an alternative to conventional antimicrobial products due to its fast-acting bactericidal properties at low concentrations.

Antioxidant active packaging systems to extend the shelf life of sliced cooked ham

The effectiveness of active packaging systems with green tea extract and oregano essential oil was checked for their use in sliced cooked ham. Three packaging systems were evaluated: i) control group without active film, ii) ATGT packed with active film of green tea extract (1%) and iii) ATRX with a mixture of green tea extract and oregano essential oil (1%). The evolution of microbiological, physicochemical (pH, aw, colour and lipid oxidation) and sensory attributes were analysed after 0, 7, 14 and 21 days of refrigerated storage. Microbial populations were below the limits established by the European Regulations (10⁶ UFC/g). The samples packed with ATGT showed the better antimicrobial activity against total viable counts (TVC) and lactic acid bacteria (BAL), while lower counts of Brochothrix thermosphacta was observed in ATRX film (1.48 vs. 1.78 and 2.59 UFC/g for ATRX vs. ATGT and CON, respectively). Regarding colour, low differences were found between the samples packaged with active and control films. Unlike L*, a* and b* parameters showed a progressive diminution throughout the storage in all batches, being the films that contained green tea (ATGT) were the ones that showed the less discolouration at the end of storage (8.86 vs. 8.63 and 7.50 for ATGT vs. CON and ATRX, respectively). The low fat content of this type of product and the use of anaerobic atmosphere for the packaging of cooked ham did not allow to show an antioxidant effect on lipid oxidation (values below 0.15 mg MDA/kg). Finally, the use of ATGT and ATRX did not suppose a modification of the sensorial attributes of the product, being acceptance scores under the acceptance limit during the whole display.

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ATGT and ATRX could extend shelf life of sliced cured ham.

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ATGT packaging system showed a preservative effect against bacterial spoilage.

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ATGT was the best effective against discoloration.

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Low oxidation values were observed during the whole display.

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Oregano essential oil and green tea extract improved the quality of sliced cooked ham.

The Influence of Selected Plant Essential Oils on Morphological and Physiological Characteristics in Pseudomonas Orientalis

The aim of this work was to estimate the antibacterial activity of selected essential oils on Pseudomonas orientalis strains isolated from foods. An attempt was also made to identify the mechanisms of the action of the plant oils. Classical methods of assessment of the effectiveness of antimicrobial activity of oils were linked with flow cytometry. It was observed that bergamot, lemongrass, bitter orange, juniper, and black pepper oils have bacteriostatic effect against P. orientalis P49. P. orientalis P110 is sensitive to lime, lemongrass, juniper, rosemary, and black pepper oils. Additionally, plant oils with biostatic effect on P. orientalis limited the intracellular metabolic activity of cells; this was closely linked with the ability of plant oils' bioactive components to interact with bacteria cell membrane, causing the release of membrane proteins. As a result, the selective permeability of the cell membranes were damaged and the bacterial shape was transformed to coccoid in form.

Terpene Derivatives as a Potential Agent against Antimicrobial Resistance (AMR) Pathogens

The evolution of antimicrobial resistance (AMR) in pathogens has prompted extensive research to find alternative therapeutics. Plants rich with natural secondary metabolites are one of the go-to reservoirs for discovery of potential resources to alleviate this problem. Terpenes and their derivatives comprising of hydrocarbons, are usually found in essential oils (EOs). They have been reported to have potent antimicrobial activity, exhibiting bacteriostatic and bactericidal effects against tested pathogens. This brief review discusses the activity of terpenes and derivatives against pathogenic bacteria, describing the potential of the activity against AMR followed by the possible mechanism exerted by each terpene class. Finally, ongoing research and possible improvisation to the usage of terpenes and terpenoids in therapeutic practice against AMR are discussed.

Identification and antibiotic susceptibility of bacterial microbiota of freshwater fish

The fish meat is an essential part of human diet. However, fish may be contaminated with different microorganisms, including pathogens. Antimicrobial resistance of fish microbiota may facilitate the spread of resistant microorganisms causing serious consequences for human health. The aim of the present study was to detect bacterial contamination in fish gill, gut and skin and to determine antimicrobial susceptibility of the bacterial isolates. Rainbow trout (Oncorhynchus mykiss) and bream (Abramis bram) were obtained from the market in Jelgava city. Chub (Leuciscus cephalus), crucian carp (Carassius carassius) and tench (Tinca tinca) were collected from fishermen. Fish samples were examined for the total bacterial count (TBC), coliforms, Enterobacteriaceae, Pseudomonas spp. and Aeromonas spp. Testing was done in accordance with International Organization for Standardization (ISO) standards. Identification of all bacteria was accomplished with the Matrix Assisted Laser Desorption Ionization – Time of Flight Mass Spectrometry (MALDI-TOF MS) method. The disc diffusion method was used for the detection of antibiotic susceptibility of isolated bacterial species. TBC ranged from 2.70 to 7.00 log CFU.g-1, coliforms from 0 to 2.67 log CFU.g-1, Enterobacteriaceae from 0 to 2.85 log CFU.g-1. The highest contamination with Pseudomonas spp. and Aeromonas spp. was observed in chub gut samples with 1.60 log CFU.g-1 and 2.23 log CFU.g-1, respectively. Altogether, 16 microbial genera and 31 bacterial species were identified. The dominant bacterial species belonged to Pseudomonas spp. (54%) and Enterobacteriaceae. Pseudomonas spp. were resistant to ticarcillin, susceptibility to ciprofloxacin showed 88% of isolates. All Enterobacteriaceae isolates were susceptible to imipenem. The microbial quality of the fish was acceptable, but the presence of antibiotic resistant bacteria may further cause a negative impact on public health.

Chemical profiling, biostatic and biocidal dynamics of Origanum vulgare L. essential oil

Origanum vulgare L. (Lamiaceae) is a widespread flavoring culinary and medicinal herb. The present study aimed at investigating the antimicrobial activity of Origanum vulgare (OV) essential oil (EO) through illustrating its biostatic, biocidal and the dynamics of the biocidal activity against 11 different microorganisms. GC/MS of OV EO allowed the identification of 32 compounds representing 99.94% of the oil. The two major identified compounds were terpinen-4-ol (38.35%) and trans-sabinene hydrate (10.06%). Different methods were employed to illustrate the biostatic activity of OV EO. Results of the biostatic studies on OV EO using agar and broth dilution methods showed that Staphylococcus aureus (S. aureus) was the most sensitive organism; with a Minimum inhibitor concentration (MIC) 1.18 mg/ml. Agar diffusion method showed that the highest activity was observed against Bordetella bronchiseptica (Br. bronchiseptica), Saccharomyces cerevisiae (S. cerevisiae), Bacillus subtilis (B. subtilus) and Staphylococcus epidermidis (S. epidermidis) with inhibition zones 38 ± 1.5, 29.5 ± 0.8, 26.9 ± 0.9 and 26.9 ± 1.1 mm, respectively. Studying the dynamics of 1% v/v OV essential oil emulsion over a period of 6 h revealed that Escherichia coli (E. coli), B. subtilis, S. epidermidis and S. cerevisiae had the fastest response. Also increasing concentrations of OV oil emulsion increased the rate of cell killing and the duration of growth lag phase increased correspondingly. These data indicated that OV EO produces a concentration and time-dependent antimicrobial activity.

Affordable Production of Antioxidant Aqueous Solutions by Hydrodynamic Cavitation Processing of Silver Fir (Abies alba Mill.) Needles

Extracts from parts of coniferous trees have received increased interest due to their valuable bioactive compounds and properties, useful for plenty of experimental and consolidated applications, in fields comprising nutraceutics, cosmetics, pharmacology, food preservation, and stimulation of plant growth. However, the variability of the bioactive properties, the complexity of the extraction methods, and the use of potentially harmful synthetic chemicals, still represent an obstacle to the spreading of such valuable natural compounds. Hydrodynamic cavitation is emerging as a promising innovative technique for the extraction of precious food components and by-products from waste raw material of the agro-food production chain, which can improve processing efficiency, reduce resource consumption, and produce healthy, high-quality products. In this study, a process based on controlled hydrodynamic cavitation was applied for the first time to the production of aqueous solutions of silver fir (Abies alba Mill.) needles with enhanced antioxidant activity. The observed levels of the in vitro antioxidant activity, comparable or higher than those found for reference substances, pure extracts, and other water extracts and beverages, highlight the very good potential of the hydrodynamic cavitation (HC) process for the creation of solvent-free, aqueous solutions endowed with bioactive compounds extracted from silver fir needles.

Cinnamomum zeylanicum, Origanum vulgare, and Curcuma longa Essential Oils: Chemical Composition, Antimicrobial and Antileishmanial Activity

The resistance mechanisms of bacteria and protozoans have evidenced the need of discover new compounds with potential pharmaceutical activity against pathogenic microorganisms. Medicinal plants have been for centuries a promising alternative as sources of new drugs. The objective of this work was to evaluate the chemical composition, antimicrobial and antileishmanial activities of Cinnamomum zeylanicum, Origanum vulgare, and Curcuma longa essential oils. Chemical analysis was performed by gas chromatography-mass spectrometry. Antimicrobial activity was performed by disk diffusion and minimum inhibitory concentration (MIC) test. Antileishmanial activity was performed against antipromastigote and intracellular amastigote of Leishmania amazonensis. Cytotoxic and nitrite production were realized in BALB/c peritoneal macrophages. The major compounds of the essential oils were cinnamic aldehyde (46.30%) in C. zeylanicum, cis-p-menth-2-en-1-ol (33.88%) and linalyl acetate (13.90%) in O. vulgare, and turmerone (55.43%) in C. longa. The MIC showed significant antimicrobial activity of C. longa essential oil against S. aureus (83.3 ± 14.43 µg/mL). Antipromastigote activity showed IC₅₀ values >500 µg/mL to C. zeylanicum, 308.4 ± 1.402 µg/mL to O. vulgare, and 405.5 ± 1.119 µg/mL to C. longa essential oil. Activity against intracellular amastigote of L. amazonensis showed IC₅₀ of 63.3 ± 1.369 µg/mL and cytotoxic was not observed, resulting in selectivity index higher than 15.79 to parasite. C. longa essential oil decreased nitrite production in peritoneal macrophages, but not in Leishmania-infected cells. The chemical composition of the three essential oils is directly associated to its potential biological action, as the antimicrobial activity. C. longa presented a potent antileishmanial activity against promastigote and intracellular amastigote of L. amazonensis, although this activity is not linked to nitric oxide, since C. longa essential oil inhibits its production.

Phytochemical Profile and Biological Activities of Satureja hortensis L.: A Review of the Last Decade

Satureja hortensis L. (summer savory) is an annual herbaceous crop, native to Europe and in our days spread and used all over the world. Although its use as spice and medicinal plant is known since ancient times, peer-reviewed studies presenting the scientific data are scarce. The natural products obtained from summer savory (extracts and essential oil) are dominated by polyphenols and flavonoids, responsible for their antioxidant, antimicrobial, antiparasitic, pesticidal, anti-inflammatory, analgesic, hepatoprotective and anticancer properties, among others. The current study presents the progress made in the last decade regarding the potential applications of summer savory, being the first review study focused on S. hortensis, in the same time suggesting future research opportunities, as they appear from the properties of other Satureja species. The available data presenting the properties of summer savory represents a scientific support for application in industry, for developing “clean label” food products.