In vitro toxicological evaluation of essential oils and their main compounds used in active food packaging: A review

Comparative toxicological evaluation of carvacrol, acetylcarvacrol anda fipronil-based pesticide in human blood cells

Plant-derived chemicals are promising substances to control arthropod pests, although synthetic ones are still the most frequently used. Thus, comparative toxicological studies are needed to determine if natural substances are safe alternatives to replace the use of synthetic chemicals. This study aimed to compare the toxicity of carvacrol (natural origin), acetylcarvacrol (semi-synthetic) and a fipronil-based pesticide (synthetic). We assessed the effects of these chemicals on hemolytic activity, erythrocytes morphology and leucocyte viability using whole blood from human subjects. Additionally, DNA damage was evaluated through comet and DNA fragmentation assays. Fipronil and carvacrol caused hemolysis at concentrations ranging from 0.5 to 2.0%, whereas acetylcarvacrol did not cause hemolysis at 0.5 and 0.75%. Fipronil and carvacrol caused severe alterations in erythrocytes' morphology at 2%, such as ghost erythrocytes, elliptocyte-like shape and rouleau-like shape, presenting only 3.3 and 8.3% normal cells, respectively, at this concentration. However, 73.3% erythrocytes incubated with 2% acetylcarvacrol exhibited normal morphology. Fipronil considerably reduced leucocytes viability, decreasing it to 78% at 2%. Carvacrol and acetylcarvacrol showed no differences in leucocyte viability for 0.5 to 1.0%, but a decrease was observed for 2% carvacrol. The comet assay showed similar DNA damage for fipronil and carvacrol, but it was significantly lower for 1 and 2% acetylcarvacrol. Incubation with genomic DNA showed that only fipronil caused fragmentation of this molecule. Thus, we conclude that carvacrol and fipronil can present similar toxicity at higher concentrations. However, acetylation of carvacrol significantly reduced its toxicity to human blood cells compared with the other chemicals.

In Vitro Activity of Allium cepa Organosulfur Derivatives against Canine Multidrug-Resistant Strains of Staphylococcus spp. and Enterobacteriaceae

BACKGROUND

The increase of multi-resistant bacteria, especially Staphylococcus spp. and Enterobacteriaceae, constitutes a challenge in veterinary medicine. The rapid growth of resistance is outpacing antibiotic discovery. Innovative strategies are needed, including the use of natural products like Allium species (Allium sativum L. and Allium cepa L.), which have been used empirically for centuries to treat infectious diseases in humans and farm and aquaculture animals due to their antibacterial properties.

METHODS

This study aimed to evaluate the in vitro activity of two Allium-derived compounds, propyl propane thiosulfinate (PTS) and propyl propane thiosulfonate (PTSO), against multi-resistant Staphylococcus spp. (n = 30) and Enterobacteriaceae (n = 26) isolated from dogs referred to a veterinary teaching hospital in Madrid.

RESULTS AND DISCUSSION

The results indicated the in vitro efficacy of PTSO/PTS against the tested bacterial strains, and 56.7% of Staphylococcus pseudintermedius and 53.8% of Enterobacteriaceae showed sensitivity to PTS and PTSO compared with classic antibiotics. In addition, 50% of S. pseudintermedius strains resistant to erythromycin, ibofloxacin, difloxacin and orbifloxacin and 50% of Enterobacteriaceae strains resistant to tetracycline and doxycycline were sensitive to PTS and PTSO. Although studies are needed to verify their efficacy in vivo, the combined use of PTS and PTSO exhibits promise in enhancing bacterial sensitivity against S. pseudintermedius and Enterobacteriaceae infections, providing a first insight into the potential of both compounds in veterinary practice.

Risk assessment and environmental consequences of the use of the Allium-derived compound propyl-propane thiosulfonate (PTSO) in agrifood applications

The organosulfur compound propyl-propane thiosulfonate (PTSO), mainly found in Allium cepa, has a promising use in the agrifood industry. To confirm its safety for livestock, consumers, and environment, toxicological assessment is needed. In this regard, endocrine-disrupting chemicals (EDCs) are in the spotlight of research. Therefore, as part of the risk assessment of PTSO, in the present work, an in vivo study was performed in mice exposed to PTSO to investigate its potential reproductive toxicity considering fertility, genetic and endocrine endpoints. Five-weeks-old CD1 mice (80 males, 80 females) were exposed for 11 or 16 weeks (males or females, respectively) to different doses of PTSO (0, 14, 28 and 55 mg PTSO/kg b.w./day; 20 animals per group and sex) through the food pellets. No clinical observations or mortality and no changes in absolute organ weights and relative organ weights/body weight or brain ratios occurred during the study. The estrous cycle did not undergo any significant toxicologically relevant change. Most of the sex hormones displayed normal values. Some alterations in the expression of some genes related to reproduction is only observed in females, but they do not appear to have consequences in the development of sex organs. Docking results showed the impossibility of stable binding to estrogen and androgen receptors. Considering all the results obtained, the safe profile of PTSO can be confirmed for different agrifood applications at the conditions assayed.

Identification of in vitro metabolites of an Allium organosulfur compound and environmental toxicity prediction as part of its risk assessment

Propyl-propane-thiosulfonate (PTSO) is an organosulfur compound found inAllium spp. Due to its antioxidant and antimicrobial activities, PTSO has been proposed for applications in the agri-food sector, such as feed additive. However, its use with commercial purposes depends on its toxicity evaluation. The present work aimed to perform a pilot-study of toxicokinetic profile of PTSO combining in silico and in vitro techniques, important steps in the risk assessment process. In silico ecotoxicity studies were also performed considering the importance of the environmental impact of the compound before its commercial use. First, an analytical method has been developed and validated to determine the original compound and its metabolites by ultra-performance liquid chromatography-tandem mass spectrometry. The phase I and II metabolism of PTSO was predicted using Meta-Pred Web Server. For the phase I metabolism, rat (male and female) and human liver microsomes were incubated with PTSO and NADPH regeneration system. Furthermore, in the phase II, microsomes were incubated with PTSO and glutathione or uridine 5'- diphosphoglucuronic acid. The analysis revealed the presence of propylpropane thiosulfinate (PTS) originated by redox reaction in phase I, and two conjugates from the phase II: S-propylmercaptoglutathione (GSSP) and S-propylmercaptocysteine (CSSP). Additionally, considering the environmental fate of PTSO and its metabolites, the ADME parameters and the potential ecotoxicity were also predicted using in silico softwares. The results of the ecotoxicity in silico study evidenced that the metabolism induced the formation of detoxified metabolites from the parent compound, except for dimercaprol and 3-mercaptopropane1,2-diol. Further in vivo assays are needed to confirm this prediction.

Microwave-Assisted Hydrodistillation of Essential Oil from Plectranthus amboinicus: Evaluation of Its Antifungal Effect and Chemical Composition

Fusarium wilt, a vascular syndrome in a wide range of plants, is caused by the pathogen Fusarium Oxysporum. The objective of this investigation was to evaluate the antifungal effect of four essential oils (EOs) (Plectranthus amboinicus, Syzygium aromaticum, Lippia alba, and Rosmarinus officinalis), which were obtained by using microwave-assisted hydrodistillation (MAH), against F. oxysporum. The yield obtained from P. amboinicus with the use of MAH was 0.2%, which was higher than that of a conventional extraction; its extraction time was also shorter. For concentrations of 100 and 300 μL/L, P. amboinicus caused an inhibition rate of 27.2 and 55.7%, respectively, while S. aromaticum caused an inhibition rate of 23.1 and 87.3%, respectively. It was observed that increasing the concentration also increased the % inhibition rate. The extracts of L. alba and R. officinalis caused an inhibition rate of 14.5 and 14.7% at 500 µL/L, respectively, at 10 days of incubation, while at this concentration, P. amboinicus and S. aromaticum achieved 100%. The major chemical compounds of P. amboinicus were carvacrol (41.20%), o-cymene (11.61%), caryophyllene (11.45%), α-bergamotene (7.71%), and caryophyllene oxide (4.62%), and these monoterpene hydrocarbons were responsible for the biological activity. The essential oil of P. amboinicus in appropriate concentrations is a potent antifungal agent that could be used for the control of F. oxysporum.

Natural essential oils: A promising strategy for treating cardio-cerebrovascular diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Essential oils (EO) are volatile compounds obtained from different parts of natural plants, and have been used in national, traditional and folk medicine to treat various health problems all over the world. Records indicate that in history, herbal medicines rich in EO have been widely used for the treatment of CVDs in many countries, such as China.

AIM OF THE STUDY

This review focused on the traditional application and modern pharmacological mechanisms of herbal medicine EO against CVDs in preclinical and clinical trials through multi-targets synergy. Besides, the EO and anti-CVDs drugs were compared, and the broad application of EO was explained from the properties of drugs and aromatic administration routes.

MATERIALS AND METHODS

Information about EO and CVDs was collected from electronic databases such as Web of Science, ScienceDirect, PubMed, and China National Knowledge Infrastructure (CNKI). The obtained data sets were sequentially arranged for better understanding of EO' potential.

RESULTS

The study showed that EO had significant application in CVDs at different countries or regions since ancient times. Aiming at the complex pathological mechanisms of CVDs, including intracellular calcium overload, oxidative stress, inflammation, vascular endothelial cell injury and dysfunction and dyslipidemia, we summarized the roles of EO on CVDs in preclinical and clinical through multi-targets intervention. Besides, EO had the dual properties of drug and excipients. And aromatherapy was one of the complementary therapies to improve CVDs.

CONCLUSIONS

This paper reviewed the EO on traditional treatment, preclinical mechanism and clinical application of CVDs. As important sources of traditional medicines, EO' remarkable efficacy had been confirmed in comprehensive literature reports, which showed that EO had great medicinal potential.

Uncovering the Industrial Potentials of Lemongrass Essential Oil as a Food Preservative: A Review

The food industry is growing vastly, with an increasing number of food products and the demand of consumers to have safe and pathogen-free food with an extended shelf life for consumption. It is critical to have food safe from pathogenic bacteria, fungi, and unpleasant odors or tastes so that the food may not cause any health risks to consumers. Currently, the direction of food industry has been shifting from synthetically produced preservatives to natural preservatives to lower the unnecessary chemical burden on health. Many new technologies are working on natural prevention tools against food degradation. Lemongrass is one such natural preservative that possesses significant antimicrobial and antioxidant activity. The essential oil of lemongrass contains a series of terpenes that are responsible for these activities. These properties make lemongrass acceptable in the food industry and may fulfill consumer demands. This article provides detailed information about the role of lemongrass and its essential oil in food preservation. The outcomes of the research on lemongrass offer room for its new technological applications in food preservation.

Acute and subchronic 90-days toxicity assessment of propyl-propane-thiosulfinate (PTS) in rats

The organosulfur compounds (OSC) extracted from Allium spp. exhibit antibacterial, antifungal, and antioxidant properties. The agri-food industry is taking advantage of these properties by using them as natural feed and food additives. In the present work, an acute and a subchronic 90-days toxicity studies have been conducted for the first time to assess the safety of the OSC propyl-propane-thiosulfinate (PTS). Both studies were carried out following the Organization for Economic Co-operation and Development test guidelines (425 and 408, respectively). The acute study provided a maximum tolerated dose (MTD) of 175 mg/kg and the subchronic study established the Non Observed Adverse Effect Level (NOAEL) ≥ 55 mg/kg body weight (b.w.)/day in both sexes. In addition, the subchronic study performed on rats exposed to 14, 28 and 55 mg/kg b.w./day PTS, revealed no changes in any of the hematological parameters measured as well as no differences in body weight and water/food consumption. However, biochemical parameters were altered in some groups, although they were not biologically significant (Ca2+ in female rats, and the thyroids hormones T3 and T4 in rat males). Furthermore, the histopathological assessment evidenced no abnormality on the gastrointestinal, respiratory, lymphoid, urinary, circulatory, nervous, musculoskeletal, and reproductive systems.

Boosted Antioxidant Effect Using a Combinatory Approach with Essential Oils from Origanum compactum, Origanum majorana, Thymus serpyllum, Mentha spicata, Myrtus communis, and Artemisia herba-alba: Mixture Design Optimization

Several studies have demonstrated the possible synergistic effect as an effective strategy to boost the bioactivity of essential oils. Using this framework, this study was conducted to effectively establish the ideal combination of six essential oils from different plants (Origanum compactum, Origanum majorana, Thymus serpyllum, Mentha spicata, Myrtus communis, and Artemisia herba-alba) that would express the best antioxidant activity. Each mixture was optimized using a mixture design approach to generate the most effective blend. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging method was used as a reference method to assess the antioxidant activity. Each essential oil's composition was identified using the GC/MS method. The single essential oil activities demonstrated variable antioxidant effects, and following the mixture design approach, the optimal antioxidant blend was revealed, as two mixtures demonstrated the best antiradical activity with 79.46% obtained with the mixture of O. majorana (28%) and M. spicata (71%) and 78.8% obtained with the mixture O. compactum (64%), O. majorana (13%), and T. serpyllum (21%). This study proposes a practical way to elaborate mixtures in the search for a boosting effect that can be oriented for the food or pharmaceutical industry.

Anti-Inflammatory and Antioxidant Properties of Carvacrol and Magnolol, in Periodontal Disease and Diabetes Mellitus

Periodontal disease and diabetes mellitus are two pathologies that are extremely widespread worldwide and share the feature of chronic inflammation. Carvacrol is a phenolic monoterpenoid, produced by a variety of herbs, the most well-known of which is Origanum vulgare. Magnolol is a traditional polyphenolic compound isolated from the stem bark of Magnolia officinalis, mainly used in Chinese medicine. The purpose of this paper is to review the therapeutic properties of these bioactive compounds, in the treatment of periodontitis and diabetes. Based on our search strategy we conducted a literature search in the PubMed and Google Scholar databases to identify studies. A total of one hundred eighty-four papers were included in the current review. The results show that carvacrol and magnolol have anti-inflammatory, antioxidant, antimicrobial, anti-osteoclastic, and anti-diabetic properties that benefit both pathologies. Knowledge of the multiple activities of carvacrol and magnolol can assist with the development of new treatment strategies, and the design of clinical animal and human trials will maximize the potential benefits of these extracts in subjects suffering from periodontitis or diabetes.

Carrageenan/agar-based functional film integrated with zinc sulfide nanoparticles and Pickering emulsion of tea tree essential oil for active packaging applications

A functional carrageenan/agar-based film was prepared by combining tea tree oil Pickering emulsion (PET) and zinc sulfide nanoparticles (ZnSNP). PET was formulated using tea tree essential oil stabilized with nanocellulose fibers. PET and ZnSNPs were uniformly dispersed in the binary polymer matrix and formed compatible films. The incorporation of ZnSNPs improved the mechanical strength, whereas PET slightly decreased the strength, but the combined addition of ZnSNP and PET maintained the mechanical strength with slightly improved flexibility. The addition of ZnSNP and PET, alone or in combination, slightly improved the water vapor barrier, water resistance, and thermal stability of the film. In addition, the carrageenan/agar-based composite membrane showed distinct antioxidant and antibacterial activity. The ZnSNP and PET incorporated binary composite films with enhanced physical and functional properties are likely to be used in active food packaging applications.

Simultaneous determination of Allium compounds (Propyl propane thiosulfonate and thiosulfinate) in animal feed using UPLC-MS/MS

Propyl-propane-thiosulfonate (PTSO) and Propyl-propane-thiosulfinate (PTS) are organosulfur compounds used to supplement the diet of livestock because of their beneficial effects on feed palatability, their antibacterial, anti-inflammatory, and antimethanogenic activities. Besides, antibiotic residues in the environment can be reduced by using these natural bioactive compounds. The objective of this study was to optimize the extraction parameters for the analysis of PTSO and PTS in feed matrices by performing a solid-liquid extraction and quantification by Ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). Optimization was performed using the Response Surface Methodology on a Box-Behnken experimental design, optimizing the following parameters: solvent:sample ratios and evaporation temperature set for the rotary evaporator. The method was validated for 3 concentration levels for both PTSO (100, 500, 1000 ng g^-1) and PTS (500, 1150, 2300 ng g^-1). The highest recoveries of PTSO and PTS were obtained using 12.5 mL of 100% acetonitrile, stirring for 15 min, and an evaporation temperature of 20 °C. The validated method was further applied to detect and quantify these compounds in different feed matrices. In conclusion, this is the first study to simultaneously analyze PTSO and PTS at low concentrations, employing a sensitive technique such as UPLC-MS/MS.

Principal Metabolites in Extracts of Different Plants Responsible for Antibacterial Effects

The increase in bacterial resistance and decreased effectiveness of antibacterial agents has forced researchers to look for new antibacterial agents from environmentally friendly sources such as essential oils and oil extracts. The functional group of the metabolites present in the essential oils or plant extract and the synergy effects between them play an important role in the biological activity and can be the principal factor affecting the antibacterial effect. All of these bioactive oils showed the same action mechanism, and the best way to implement them is by extracting them without changing their original properties, whereby the characterization and evaluation of the compounds are important steps. All of these themes are extensively reviewed, analyzed, and discussed in this work.

Exploiting the chemical composition of essential oils from Psidium cattleianum and Psidium guajava and its antimicrobial and antioxidant properties

The genus Psidium comprises several native Brazilian plants, such as the araçá and guava trees. They are interesting sources of essential oils (EOs) that can be used as natural preservatives in foods due to their bioactive properties. This work aimed to evaluate and correlate the biological properties of the EOs from araçá and guava leaves with their chemical compounds. The gas chromatography-mass spectrometry (GC/MS) was used to determine the chemical composition of EOs. The antimicrobial activity was tested against 16 foodborne pathogens and the antioxidant capacity was determined by ABTS, DPPH, and FRAP assays. The major compounds identified in the essential oil of araçá (EOA) were β-caryophyllene and β-elemene, representing 38.69% and 7.47%, respectively, whereas β-selinene (13.83%), α-humulene (10.90%), and β-caryophyllene (7.61%) were the major compounds identified in the essential oil of guava (EOG). Both EOs showed activity against Salmonella Enteritidis, with MIC being 1.41 µg/ml for the EOA and 1.37 µg/ml for the EOG. The EOA was more effective than the EOG against strains of Listeria monocytogenes and Pseudomonas aeruginosa, with the MIC being 1.41 µg/ml. The EOA showed 10.43, 12.35, and 3.92 µmol TE/ml at 90 µg/ml whereas the EOG showed 4.54, 8.94, and 3.43 µmol TE/ml at 88 µg/ml for ABTS, DPPH, and FRAP, respectively. Thus, the EOs demonstrated an effective action against foodborne pathogens and free radicals, indicative of their potential use as natural preservatives for foods. PRACTICAL APPLICATION: Guava and araçá are native Brazilian plants producers of essential oils, natural compounds with antimicrobial and antioxidant potential. The chemical composition of essential oils is responsible for its beneficial properties. The results demonstrated that the essential oils studied are rich in β-caryophyllene and has excellent activity against malefic microorganisms and free radicals, and can also be used as natural preservatives in foods.

Antilisterial Effect of a Natural Formulation Based on Citrus Extract in Ready-To-Eat Foods

Controlling Listeria in food is a major challenge, especially because it can persist for years in food processing plants. The best option to control this pathogen is the implementation of effective cleaning and disinfection procedures that guarantee the safety and quality of the final products. In addition, consumer trends are changing, being more aware of the importance of food safety and demanding natural foods, minimally processed and free of chemical additives. For this reason, the current consumption model is focusing on the development of preservatives of natural origin, from plants or microorganisms. In sum, this study aimed to evaluate the antimicrobial effectiveness of a citrus extract formulation rich in flavonoids against several L. monocytogenes and L. innocua strains, using in vitro test (agar diffusion test, minimum bactericidal concentration (MBC), and time-kill curves) and challenge test in food trials (carne mechada, salami, fresh salmon, lettuce, brine, and mozzarella cheese). The results presented in this work show that citrus extract, at doses of 5 and 10%, had a relevant antimicrobial activity in vitro against the target strains tested. Besides this, citrus extract applied on the surface of food had a significant antilisterial activity, mainly in carne mechada and mozzarella cheese, with reductions of up to eight logarithmic units with respect to the control. These results suggest that citrus extract can be considered a promising tool to improve the hygienic quality of ready-to-eat foods.

Application of Interactive and Intelligent Packaging for Fresh Fish Shelf-Life Monitoring

Smart packaging, also known as intelligent packaging, is responsive to external stimuli, moisture, light, oxygen, heat, pH, and bacterial growth. It has evolved from extensive applications in food safety, bacterial response, and medical packaging. Interactive packaging has a scientific basis for additional information about food products because these codes give all required data. This work deals with a combination of frontline food sciences, smart and interactive packaging that are applicable for future production of nutrition packages through smart detection of food spooling. Additionally, it verifies the best degree of food safety and population demands as the third generation of packaging technology. High qualified duplex laminated package with a nano-encapsulated pH monitoring label for fresh fish was printed. The interactive Quick Response code icon was combined in a designed package with important information about cooking, smart packaging, and fish quality. Therefore, particle size, zeta potential, and surface area are measured for a nanoencapsulated indicator which exhibits 74.4 nm, 23.6 mV, and 88.9 m²/g, respectively: overall migration, water vapor, and oxygen permeability. The properties of printing for 11 color spots are evaluated by x-rite before and after the cold storage period without any detectable changes in the rate of color change (ΔE). The bacterial count of the tested sample is examined by counting the microbial colonies in the agar plate media. There is good agreement between microbial count and smart indicator color change as an effective direct detection tool for sustainable food quality and safety.

A Regioselective Synthesis of Novel Functionalized Organochalcogen Compounds by Chalcogenocyclofunctionalization Reactions Based on Chalcogen Halides and Natural Products

The regioselective synthesis of novel functionalized condensed organochalcogen compounds by chalcogenocyclofunctionalization reactions based on chalcogen halides and the natural products thymol and carvacrol has been developed. The reactions of selenium dibromide with allyl thymol and allyl carvacrol proceeded in methylene chloride at room temperature in the presence of NaHCO₃ affording bis[(7-isopropyl-4-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] and bis[(4-isopropyl-7-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] selenides in 90–92% yield. Similar sulfides were obtained in 70–72% yields by the reaction of sulfur dichloride in chloroform under reflux. Trihalotellanes containing the same organic moieties were synthesized from allyl thymol, allyl carvacrol and tellurium tetrachloride or tetrabromide in quantitative yields. Corresponding functionalized ditellurides were prepared in 91–92% yields by the reduction of the trichlorotellanes with sodium metabisulfite in two-phase solvent system. The comparison of reactivity of sulfur, selenium and tellurium halides in chalcogenocyclofunctionalization and distinguishing features of each reaction were discussed.

Combination of Natural Compounds With Novel Non-thermal Technologies for Poultry Products: A Review

Ensuring safe, fresh, and healthy food across the shelf life of a commodity is an ongoing challenge, with the driver to minimize chemical additives and their residues in the food processing chain. High-value fresh protein products such as poultry meat are very susceptible to spoilage due to oxidation and bacterial contamination. The combination of non-thermal processing interventions with nature-based alternatives is emerging as a useful tool for potential adoption for safe poultry meat products. Natural compounds are produced by living organisms that are extracted from nature and can be used as antioxidant, antimicrobial, and bioactive agents and are often employed for other existing purposes in food systems. Non-thermal technology interventions such as high-pressure processing, pulsed electric field, ultrasound, irradiation, and cold plasma technology are gaining increasing importance due to the advantages of retaining low temperatures, nutrition profiles, and short treatment times. The non-thermal unit process can act as an initial obstacle promoting the reduction of microflora, while natural compounds can provide an active obstacle either in addition to processing or during storage time to maintain quality and inhibit and control growth of residual contaminants. This review presents the application of natural compounds along with emerging non-thermal technologies to address risks in fresh poultry meat.

Genotoxicity Evaluation of Propyl-Propane-Thiosulfinate (PTS) from Allium genus Essential Oils by a Combination of Micronucleus and Comet Assays in Rats

Propyl-propanethiosulfinate (PTS) is a component of Allium essential oils. This organosulfur molecule can be used as a feed additive to decrease the appearance of bacterial resistances caused by the residues of antibiotics. In previous in vitro genotoxicity studies, contradictory results were reported for PTS. In this work, the in vivo genotoxicity of PTS in male and female rats was assessed for the first time, following OECD (Organisation for Economic Co-operation and Development) guidelines. After oral administration (doses: 5.5, 17.4, and 55.0 mg/kg PTS body weight), a combination of the micronucleus (MN) assay (OECD 474) in bone marrow and the standard and enzyme-modified comet assay (OECD 489) was performed. After necropsy, histopathological studies were also carried out. The results did not show the in vivo genotoxicity of PTS at any doses assayed, revealed by the absence of increased MN, and DNA strand breaks or oxidative DNA damage in the standard and enzyme-modified comet assays. The histopathological study revealed that only the highest dose tested (55.0 mg/kg) in the liver and all dose groups in the stomach presented minimal pathological lesions in the organs studied. Consequently, the present work confirms that PTS is not genotoxic at the doses assayed, and it is a promising natural alternative to synthetic preservatives and antibiotics in animal feed.

Inhibition of growth and virulence of Vibrio cholerae by carvacrol, an essential oil component of Origanum spp

AIMS

In the age where bacterial resistance to conventional antibiotics is increasing at an alarming rate, the use of the traditional plant, herb extracts or other bioactive constituents is gradually becoming popular as an anti-virulence agent to treat pathogenic diseases. Carvacrol, a major essential oil fraction of Oregano, possesses a wide range of bioactivities. Therefore, we aimed to study the effect of sub-inhibitory concentrations of carvacrol on major virulence traits of Vibrio cholerae.

METHODS AND RESULTS

We have used in vitro as well as ex vivo models to access the anti-pathogenic role of carvacrol. We found that the sub-inhibitory concentration of carvacrol significantly repressed bacterial mucin penetrating ability. Carvacrol also reduced the adherence and fluid accumulation in the rabbit ileal loop model. Reduction in virulence is associated with the downregulated expression of tcpA, ctxB, hlyA and toxT. Furthermore, carvacrol inhibits flagellar synthesis by downregulating the expression of flrC and most of the class III genes.

CONCLUSIONS

Carvacrol exhibited anti-virulence activity against V. cholerae, which involved many events including the inhibition of mucin penetration, adhesion, reduced expression of virulence-associated genes culminating in reduced fluid accumulation.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings indicate that carvacrol possesses inhibitory activity against V. cholerae pathogenesis and might be considered as a potential bio-active therapeutic alternative to combat cholera.

Phytochemical composition and in vitro safety evaluation of Ziziphora clinopodioides Lam. ethanolic extract: Cytotoxicity, genotoxicity and mutagenicity assessment

ETHNOPHARMACOLOGICAL RELEVANCE

The application of the herb Ziziphora clinopodioides Lam. in folk medicine and as a food additive has been recommended due to its many claimed bioactivities. Regardless of the plant benefits, its safety considerations are largely unknown.

AIM OF THE STUDY

The aim of the present research was to determine the chemical compositions and cytotoxicity, genotoxicity, and mutagenicity potentials of the ethanolic extract of Ziziphora clinopdioides Lam. (EEZC).

MATERIALS AND METHODS

GC-MS and LC-MS analysis were used for chemical composition determination. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and trypan blue exclusion dye assays were used for cytotoxicity and the Comet assay was employed for genotoxicity assessment on human blood lymphocytes. Also, the Ames Salmonella/microsome test was carried out for the evaluation of mutagenicity.

RESULTS

Pulegone was the main component of the n-hexane fraction. Different phenolic acids and flavonoids were detected by LC-MS. The cytotoxicity study indicated a conspicuous decline in human lymphocyte viability ranging from 52% to 100% as showed by the MTT assay and 67% up to 100% by the trypan blue assay, at 1 and 10 mg/mL, respectively. The Comet assay results revealed a dose dependent genotoxicity, in so much as 90% and 98% of the cells were screened as damaged at concentrations of 5 and 10 mg/mL, respectively. An incidence rate of 8% and 13% of grade 4 damage was observed at 5 and 10 mg/mL, respectively. Additionally, the DNA damage index (DI) was elevated dose-dependently by a rising concentration of the extract, wherein the DI at 10 mg/mL concentration was 2.22, which was 22 times greater than that of negative control, and even more than positive control. The Ames test exhibited no signs of mutagenicity for neither Salmonella typhimurium TA98 nor TA100 strains, accompanied or unaccompanied by S9 metabolic activation.

CONCLUSION

Results indicated a dose-dependent cytotoxicity and genotoxicity potential of the EEZC on human lymphocytes, suggesting that this plant should be used with caution by consumers, even in the food and pharmaceutical industries. Since the plant usage in daily life continues to increase due to its ever growing phytotherapical and phytonutritional properties, it may pose a health risk by its high concentration's uptake. Although no mutagenicity of this extract was observed in this study, further research is recommended to clarify the mutagenic risks of this herb.

Essential Oils as Natural Sources of Fragrance Compounds for Cosmetics and Cosmeceuticals

Fragrance is an integral part of cosmetic products and is often regarded as an overriding factor in the selection of cosmetics among consumers. Fragrances also play a considerable role in masking undesirable smells arising from fatty acids, oils and surfactants that are commonly used in cosmetic formulations. Essential oils are vital assets in the cosmetic industry, as along with imparting pleasant aromas in different products, they are able to act as preservatives and active agents and, simultaneously, offer various benefits to the skin. Moreover, the stimulating demand for natural ingredients has contributed massively to a renewed interest in cosmetic and wellness industries in plant derivatives, especially essential oils. This has led popular cosmetic companies to endorse natural fragrances and opt for minimally processed natural ingredients, given the potentially adverse health risks associated with artificial fragrance chemicals, which are major elements of cosmetics. Among the high-valued essential oils used as fragrances are citrus, lavender, eucalyptus, tea tree and other floral oils, among others, while linalool, geraniol, limonene, citronellol, and citral are much-appreciated fragrance components used in different cosmetics. Thus, this review aimed to highlight the enormous versatility of essential oils as significant sources of natural fragrances in cosmetics and cosmeceuticals. Moreover, a special focus will be laid on the different aspects related to essential oils such as their sources, market demand, chemistry, fragrance classification, aroma profile, authenticity and safety.

In Vivo and In Vitro Toxicity Testing of Cyanobacterial Toxins: A Mini-Review

Harmful cyanobacterial blooms are increasing and becoming a worldwide concern as many bloom-forming cyanobacterial species can produce toxic metabolites named cyanotoxins. These include microcystins, saxitoxins, anatoxins, nodularins, and cylindrospermopsins, which can adversely affect humans, animals, and the environment. Different methods to assess these classes of compounds in vitro and in vivo include biological, biochemical, molecular, and physicochemical techniques. Furthermore, toxic effects not attributable to known cyanotoxins can be observed when assessing bloom material. In order to determine exposures to cyanotoxins and to monitor compliance with drinking and bathing water guidelines, it is necessary to have reliable and effective methods for the analysis of these compounds. Many relatively simple low-cost methods can be employed to rapidly evaluate the potential hazard. The main objective of this mini-review is to describe the assessment of toxic cyanobacterial samples using in vitro and in vivo bioassays. Newly emerging cyanotoxins, the toxicity of analogs, or the interaction of cyanobacteria and cyanotoxins with other toxicants, among others, still requires bioassay assessment. This review focuses on some biological and biochemical assays (MTT assay, Immunohistochemistry, Micronucleus Assay, Artemia salina assay, Daphnia magna test, Radionuclide recovery, Neutral red cytotoxicity and Comet assay, Enzyme-Linked Immunosorbent Assay (ELISA), Annexin V-FITC assay and Protein Phosphatase Inhibition Assay (PPIA)) for the detection and measurement of cyanotoxins including microcystins, cylindrospermopsins, anatoxin-a, saxitoxins, and nodularins. Although most bioassay analyses often confirm the presence of cyanotoxins at low concentrations, such bioassays can be used to determine whether some strains or blooms of cyanobacteria may produce other, as yet unknown toxic metabolites. This review also aims to identify research needs and data gaps concerning the toxicity assessment of cyanobacteria.

Safety assessment of propyl-propane-thiosulfonate (PTSO): 90-days oral subchronic toxicity study in rats

Propyl-propane-thiosulfonate (PTSO) is one of the main organosulfur compounds present in Allium essentials oil. Different applications in the food sector have been proposed for PTSO, such as food and feed additive and as active packaging. However, the authorization of its use depends on its toxicity profile. Thus, as a part of its safety assessment, in this work a repeated dose 90-day oral toxicity study has been conducted for the first time in rats following the OECD guideline 408. PTSO was administered to groups of 10 male and 10 female rats at dose levels of 0, 14, 28, and 55 mg/kg/day. No clinical signs or mortality and no changes in body weight, food consumption and feed conversion efficiency were detected through the study. Moreover, no treatment-related changes in hematological and biochemical parameters were observed, for either sex or dose groups. The histopathology study performed revealed no differences in organ weights, and no morphological and histopathological changes were observed. Based on these results, the no-observed-adverse-effect level (NOAEL) of PTSO was judged to be ≥ 55 mg/kg/day for both sexes.

Antitumor Activity of Ethanolic Extract from Thymbra Spicata L. aerial Parts: Effects on Cell Viability and Proliferation, Apoptosis Induction, STAT3, and NF-kB Signaling

Thyme-like plants including Thymbra spicata L. are widely used as food and folk medicinal remedies in the Mediterranean area. This study aimed to explore the in vitro antitumor potential of polyphenol-enriched extracts from aerial parts of T. spicata. The ethanolic extract significantly inhibited proliferation of different human tumor cell lines, without significant effects on non-neoplastic cells. A deeper investigation of the molecular mechanism sustaining the in vitro antitumor activity of the extract was carried on the human breast cancer cells MCF-7 in comparison with the normal breast cells MCF-10A. The effects on MCF-7 cells were associated with the following: (i) production of reactive oxygen species (ROS) and release of nitric oxide; (ii) apoptosis induction; and (iii) reduction in STAT3 and NF-kB phosphorylation. The ethanolic extract from T. spicata leaves might represent a novel therapeutic tool in combination with conventional chemotherapy to reduce the adverse side effects and drug resistance.

The Enigma of Bioactivity and Toxicity of Botanical Oils for Skin Care

Botanical oils have a long history of traditional use and are routinely applied to skin care. The focus of this review is to contrast the functionality of skin oils versus the differential biological and toxicological effects of major plant oils, and to correlate them to their compositional changes. In total, over 70 vegetable oils were clustered according to their lipid composition to promote awareness of health practitioners and botanical product manufacturers for the safety and efficacy of oil-based interventions based on their fatty acid profiles. Since multiple skin disorders result in depletion or disturbance of skin lipids, a tailored mixture of multiple botanical oils to simultaneously maintain natural skin-barrier function, promote repair and regeneration of wounded tissues, and achieve corrective modulation of immune disorders may be required. As bioactive constituents of botanical oils enter the human body by oral or topical application and often accumulate in measurable blood concentrations, there is also a critical need for monitoring their hazardous effects to reduce the possible over-added toxicity and promote maximal normal tissue sparing. The review also provides a useful tool to improve efficacy and functionality of fatty acid profiles in cosmetic applications.

Genotoxicity assessment of saline extract from Pilosocereus gounellei (Cactaceae) and its chemopreventive effect against cyclophosphamide-induced DNA damage

Pilosocereus gounellei (Cactaceae) is used to treat wounds and inflammation. In this study, we evaluated whether the saline extract from its stem would have genotoxic or anti-genotoxic effects. In the genotoxicity evaluation, mice received the extract (500, 1,000, or 2,000 mg/kg) orally while negative and positive controls were treated with saline solution (0.9% NaCl) per os and cyclophosphamide (CPA, 80 mg/kg i.p.), respectively. In the anti-genotoxicity assay, using other animals, treatments were carried out by administering the extract (500, 1,000 or 2,000 mg/kg) or saline solution (negative control) per os and then CPA (80 mg/kg i.p.) 1 h later. Genotoxic effects were evaluated by micronucleus test and comet assay using peripheral blood and bone marrow cells. Oral administration of only the extract at 500 and 1,000 mg/kg did not result in genotoxicity. A slight increase in the incidence of micronucleus was observed at the highest dose (2,000 mg/kg). Administration of the extract before CPA reduced the micronucleated polychromatic erythrocytes (MNPCE) number by 49.07–71.43%, and DNA fragmentation in peripheral blood (85.04–94.44%) and bone marrow (87.43–92.70%) cells also decreased. In conclusion, when administered orally at the tested doses, the extract is genotoxically safe, being cautious in doses above 1,000 mg/kg, and has a protective effect against CPA-induced DNA damage.

Lignosulfonate Microcapsules for Delivery and Controlled Release of Thymol and Derivatives

Thymol and the corresponding brominated derivatives constitute important biological active molecules as antibacterial, antioxidant, antifungal, and antiparasitic agents. However, their application is often limited, because their pronounced fragrance, their poor solubility in water, and their high volatility. The encapsulation of different thymol derivatives into biocompatible lignin-microcapsules is presented as a synergy-delivering remedy. The adoption of lignosulfonate as an encapsulating material possessing relevant antioxidant activity, as well as general biocompatibility allows for the development of new materials that are suitable for the application in various fields, especially cosmesis. To this purpose, lignin microcapsules containing thymol, 4-bromothymol, 2,4-dibromothymol, and the corresponding O-methylated derivatives have been efficiently prepared through a sustainable ultrasonication procedure. Actives could be efficiently encapsulated with efficiencies of up to 50%. To evaluate the applicability of such systems for topical purposes, controlled release experiments have been performed in acetate buffer at pH 5.4, to simulate skin pH: all of the capsules show a slow release of actives, which is strongly determined by their inherent lipophilicity.

In Vitro and In Vivo Toxicity Studies on Cymbopogon giganteus Chiov. Leaves Essential Oil from Benin

Cymbopogon giganteus Chiov. (Poaceae) is a medicinal plant used to treat various diseases in traditional medicine in several African countries. The present study aims to evaluate the oral and inhalation toxicity as well as the mutagenic effects of the essential oil of Cymbopogon giganteus leaves (EOCG) from a sample collected in Benin. Mutagenic potential was assessed by the Ames test using Salmonella typhimurium strains TA98 and TA100. Oral acute toxicity was carried out by administration of a single dose of 2000 mg/kg b.w. to Wistar rats while oral subacute toxicity was assessed by daily administration of 50 and 500 mg/kg of EOCG for 28 days. Finally, inhalation toxicity was assessed by administration of a single dose of 0.125%, 0.5%, 2% or 5% v/v of EOCG emulsions in 0.05% v/v lecithin solution in sterile water for the first experiment, and in a second one by administration of single dose of 0.125% or 0.5% v/v. A broncho-alveolar lavage was performed after 3 h or 24 h, respectively. The results show that EOCG is not mutagenic on Salmonella typhimurium strains at the highest concentration tested (200 μg/plate). In the acute oral toxicity study, EOCG induce neither mortality nor toxicity, showing that the LD₅₀ is greater than 2000 mg/kg. The subacute oral toxicity study at both doses did not show any significant difference in body weight, relative organ weight, hematological and/or biochemical parameters or histopathology as compared to the control group. EOCG induced mortality and inflammation in lungs 3 h after administration of a single dose of 5% or 2% v/v. Single doses of 0.125% or 0.5% v/v did not induce inflammation, cell recruitment nor cytotoxicity in lungs 3 h or 24 h after administration, suggesting safety at these concentrations. This first report on the in vivo toxicity will be useful to guide safe uses of EOCG.

Chitosan-starch film containing pomegranate peel extract and Thymus kotschyanus essential oil can prolong the shelf life of beef

The aim of the current study was to investigate the effects of pomegranate peel extract (PPE) and chitosan-starch (CH-S) composite film incorporated with Thymus kotschyanus essential oil (TEO) on the shelf-life of beef during storage period of 21 days at 4 °C. The physico-mechanical parameters, the color and Fourier Transform Infrared spectra values of the films were determined. Changes in odor, color, pH, thiobarbituric value for lipid oxidation levels and Pseudomonas spp. total viable counts, lactic acid and Listeria monocytogenes were determined during the storage time. All treated films showed lower elongation, strength and transparency values compared with chitosan - starch (CH-S) group. Results showed that CH-S-PPE 1%-TEO 2% treatment had the highest inhibition effect against L. monocytogenes. The bacterial counts and lipid oxidation were successfully inhibited using PPE and TEO. CH-S-PPE 1% group containing up to 2% TEO had the best acceptable sensory characteristic. Beef samples wrapped with CH-S film containing PPE and TEO also had longer shelf life.

Physicochemical and bioactive properties of edible methylcellulose films containing Rheum ribes L. extract

Methylcellulose (MC) polymer was used to prepare the edible films. Then, the Rheum ribes L. ethanol extract (RE) was added to the films in order to act as a natural antimicrobial agent. All the methylcellulose films were characterized for bioactivity and the physicochemical analysis were carried out to define functional group interactions between the polymer and RE. The strongest antimicrobial effect was obtained with MC films enriched with 2% (w/w) RE against to Listeria monocytogenes with 20.3 ± 2.5 mm zone diameter. In the presence of RE, the tensile strength of film decreased, whereas the extract concentration significantly increased. The elongation at break and the water vapor permeability (WVP) values of the films were found to have decreased significantly in parallel with the increase in RE content. Moreover, the increase in the concentration of RE caused an increment in the hydrophilic properties, especially contact angle values of the films.

Encapsulation of cinnamon oil in cyclodextrin nanosponges and their potential use for antimicrobial food packaging

The main goal of this work is the encapsulation of cinnamon essential oil in cyclodextrin nanosponges and the assessment of their antimicrobial activity against foodborne pathogens. After nanosponge synthesis, a headspace-solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) method was validated to quantify essential oil major compounds. Results showed that essential oil was successfully encapsulated in cyclodextrin nanosponges with α-NS and β-NS being able to encapsulate higher essential oil amounts. Cinnamon essential oil, alone and encapsulated in nanosponges, proved to have antimicrobial activity against foodborne bacteria. Time-kill assays proved that the essential oil, alone or encapsulated, had a bacteriostatic effect against all bacteria tested, with the exception of Y. enterocolitica where a bactericidal action was observed. Furthermore, the controlled release achieved by its encapsulation, allowed cinnamon essential oil to be effective at a much lower concentration in culture medium than when solely dissolved in culture medium. Thus, the results described herein encourage the use of cyclodextrin nanosponges as encapsulating agents for active food packaging applications.

Virucidal activity of ginger essential oil against caprine alphaherpesvirus-1

The emergence of alphaherpesvirus strains resistant to commonly used antiviral drugs has prompted the research for alternative, biologically active anti-herpetic agents. Essential oils (EOs) have shown anti-infective properties against human herpes simplex viruses (HSV-1 and -2). Caprine alphaherpesvirus 1 (CpHV-1) induces genital lesions in its natural host and it is regarded as a useful homologous animal model for the study of HSV-2 infection, chiefly for the assessment of antiviral drugs in in vivo studies. In the present study we evaluated the activity in vitro of ginger EO (GEO) against CpHV-1. GEO was found to be effective as virucide on cell-free virus, inactivating CpHV-1 up to 100%. The virucidal activity of GEO is likely accounted for by disruption of herpesvirus envelope and its associated structures which are necessary for virus adsorption and entry into host cells. On the opposite, GEO was not able to inhibit virus adsorption and/or replication, as treatment of cells before and after infection did not abolish virus infectivity. GEO could be suggested for topical applications in in vivo experiments using CpHV-1/goat model, since the lipophilic nature of EOs favours their adsorption through the cutaneous/mucosal barrier, either alone or in conjunction with other molecules. These findings open several perspectives in terms of therapeutic possibilities for a number of human and animal alphaherpesviruses.

Cinnamaldehyde and related phenylpropanoids, natural repellents, and insecticides against Sitophilus zeamais (Motsch.). A chemical structure-bioactivity relationship

BACKGROUND

The insecticidal and repellent effects on adult Sitophilus zeamais of 12 cinnamaldehyde-related compounds was evaluated by contact toxicity bioassays and a two-choice olfactometer. To determine non-toxicity in mammals, body weight, serum biochemical profiles, liver weight, physiological parameters, sperm motility, and histopathological data were obtained as complementary information in C57BL/6 mice treated with the best natural compound.

RESULTS

Based on 24 h LC₉₅ and LC₅₀ values, α-methyl-cinnamaldehyde and cinnamaldehyde exhibited better insecticidal action than the other compounds. The best repellent effect was observed with α-bromo-cinnamaldehyde, which even repelled at the lowest concentration studied (0.28 µmol L^-1 ). The evaluation of a quantitative structure-activity relationship found a linear relationship between the LC₅₀ values for adult weevil toxicity and dipolo with Q values (giving the difference between orbital electronegativity carbon 1 and orbital electronegativity carbon 3 of the molecule) in cinnamaldehyde-related compounds. The polar surface and Log P descriptors also revealed a linear relationship with the S. zeamais repellent effect for cinnamaldehyde analogues. Cinnamaldehyde did not show toxicity in the parameters evaluated in mice.

CONCLUSION

From the phenylpropanoid components studied, the natural compound that had the best insecticidal and repellent action against S. zeamais was cinnamaldehyde. It presented no mammalian toxicity. © 2018 Society of Chemical Industry.

The anticonvulsant and anti-plasmid conjugation potential of Thymus vulgaris chemistry: An in vivo murine and in vitro study

The high-performance counter-current chromatography was used for the efficient purification of single constituents from Thymus vulgaris essential oil. Mixtures of n-heptane, ethyl acetate, methanol, and water (5:2:5:2 and 4:1:4:1 v/v), allowed purification of eugenol, 1-octen-3- ol, borneol, thymol, terpinen-4-ol, and camphor, while n-hexane, acetonitrile, and tert-butyl methyl ether (1:1:0.1 v/v) yielded carvacrol, borneol, linalyl acetate, caryophyllene oxide, p-cymene, and eucalyptol. The anticonvulsant activities were evaluated in the maximal electroshock-induced seizure test in mice model (systemic i. p. administration). The oil exerted protection against MES-induced seizures when administered 15 and 30 min before the tests (50 and 62.5%, respectively). Among the isolates, borneol, thymol, and eugenol exerted the strongest protection against seizures. Moreover, linalool had the ability to reduce the transfer of the pKM101 plasmid by 84%, what has the potential to reduce virulence and resistance spread in E. coli. No acute toxic effects towards the CNS were noticed either for the essential oil or for single compounds, in the chimney and grip-strength tests. The preclinical screening of Thymus vulgaris EO, as well as isolated terpenoids, provides evidence that the EO has partial protective activity against seizures and HPCCC technique is suitable for its large scale isolation.