Plants belonging to the genus Thymus as antibacterial agents: from farm to pharmacy

Virucidal and antiviral effects of Thymus vulgaris essential oil on feline coronavirus

Feline infectious peritonitis (FIP) is a fatal systemic disease of felids caused by a Coronavirus (CoV) (FIPV). In spite of its clinical relevance and impact on feline health, currently the therapeutic possibilities for treatment of FIP in cats are limited. The emergence of the pandemic Severe Respiratory Syndrome (SARS) coronavirus (CoV) type 2 (SARS-CoV-2), etiological agent of the 2019 Coronavirus Disease (COVID-19), able to infect a broad spectrum of animal species including cats, triggered the interest for the development of novel molecules with antiviral activity for treatment of CoV infections in humans and animals. Essential oils (EOs) have raised significant attention for their antiviral properties integrating and, in some cases, replacing conventional drugs. Thymus vulgaris EO (TEO) has been previously shown to be effective against several RNA viruses including CoVs. In the present study the antiviral efficacy of TEO against FIPV was evaluated in vitro. TEO at 27 μg/ml was able to inhibit virus replication with a significant reduction of 2 log10 TCID50/50 μl. Moreover, virucidal activity was tested using TEO at 27 and 270 μg/ml, over the cytotoxic threshold, determining a reduction of viral titre as high as 3.25 log10 TCID50/50 μl up to 1 h of time contact. These results open several perspectives in terms of future applications and therapeutic possibilities for coronaviruses considering that FIPV infection in cats could be a potential model for the study of antivirals against CoVs.

P-cymene prevent high-fat diet-associated colorectal cancer by improving the structure of intestinal flora

Objective: To investigate the preventing effect of P-cymene on high fat diet-related colorectal cancer and its mechanism.

Methods: Forty Wistar rats were randomly divided into G1 group (high-fat diet), G2 group (high-fat diet + DMH), G3 group (high-fat diet + P-cymene), and G4 group (high-fat diet + DMH + P-cymene).G2 and G4 groups were subcutaneously injected with dimethylhydrazine (DMH), and G3 and G4 groups were intragastrically administered with P-cymene to investigate the effects of P-cymene on tumor formation, inflammatory factors, glucose, lipid metabolism and gut microbes.

Results: No tumors were formed in the high-fat diet group (G1) or the high-fat diet + P-cymone group (G3). 7 rats (70%) of the high-fat diet + DMH group (G2) developed 8 cancerous nodules, including 6 adenocarcinomas and 2 signet ring cell carcinomas; 4 rats (40%) in the high-fat diet + DMH + P-cymene group (G4) group formed 4 cancerous nodules, all of which were adenocarcinoma. There was no significant difference in the changes of glucose and lipid metabolism in each group. After the use of P-cymene, IL-1 decreased, IL-6 increased, and LEP decreased in the G4 group.The difference was statistically significant.The contents of Candida and Unclassified Bacteria in the G3 group rats were significantly lower than those in the G1 group.At the species level comparison, compared with the G2 group, the content of Clostridium XlVa in the intestinal tract of the G2 group rats was significantly increased compared to the G1 group.

Conclusion: In this study, it was found that p-cymenen can prevent the occurrence of colorectal cancer related to high-fat and high-calorie diet. The mechanism may be is reducing the expression of inflammatory factors such as IL-1 and LEP, increasing the expression of inflammatory factors of IL-6, and promoting the growth of probiotics such as bifidobacteria, isobacteria and clostridium IV in the intestinal tract.

Antibacterial Activities of Homemade Matrices Miming Essential Oils Compared to Commercial Ones

The increasing bacterial resistance to antibiotics is a worldwide concern. Essential oils are known to possess remarkable antibacterial properties, but their high chemical variability complicates their development into new antibacterial agents. Therefore, the main purpose of this study was to standardize their chemical composition. Several commercial essential oils of ajowan (Trachyspermum ammi L.) and thyme (chemotype thymol) (Thymus vulgaris L.) were bought on the market. GC-MS analysis revealed that thyme essential oils have a chemical composition far more consistent than ajowan essential oils. Sometimes thymol was not even the major compound. The most abundant compounds and the homemade mixtures were tested against two Staphylococcus aureus strains. The antibacterial property of β-caryophyllene presented no direct activity against S. aureus LMG 15975, but in association with thymol or carvacrol at equal percentages an MIC of 125 μg/mL was observed. The mixture of those three compounds at equivalent percentages also decreased by 16-fold the MIC of the penicillin V. Against S. aureus LMG 21674, β-caryophyllene presented an MIC of 31.3 μg/mL and decreased by 267-fold the MIC of the penicillin V. These observations led us to question the benefits of using a complex chemical mixture instead of one active compound to fight bacterial resistance.

Evaluation of the in vitro antibacterial activity of some essential oils and their blends against Staphylococcus spp. isolated from episodes of sheep mastitis

Staphylococcus aureus and coagulase-negative staphylococci are among the major causes of mastitis in sheep. The main goal of this research was to determine the in vitro antibacterial activity of several essential oils (EOs, n 30), then five of them were chosen and tested alone and in blends against staphylococci isolates. Five bacteria were isolated from episodes of ovine mastitis (two S. aureus and three S. xylosus). Biochemical and molecular methods were employed to identify the isolates and disk diffusion method was performed to determine their antimicrobial-resistance profile. The relative percentage of the main constituents in the tested essential oils and their blends was detected by GC-EIMS analysis. Antibacterial and bactericidal effectiveness of essential oils and blends were evaluated through minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). All of them showed sensitivity to the used antimicrobials. The EOs with the highest antibacterial activity were those belonging to the Lamiaceae family characterized by high concentrations of thymol, carvacrol and its precursor p-cymene, together with cinnamon EO, rich in cinnamaldehyde. In terms of both MIC and MBC values, the blend composed by Thymus capitatus EO 40%, Cinnamomum zeylanicum EO 20%, Thymus serpyllum EO 20% and Satureja montana EO 20% was found to be the most effective against all the isolates. Some essential oils appear to represent, at least in vitro, a valid tool against ovine mastitis pathogens. Some blends showed a remarkable effectiveness than the single oils, highlighting a synergistic effect in relation to the phytocomplex.

A systematic review on ethnopharmacology, phytochemistry and pharmacological aspects of Thymus vulgaris Linn

Thymus vulgaris Linn. is a medicinal and culinary herb from the Southern European region known for its anti-infective, cardioprotective, gastroprotective, anti-inflammatory, and immunomodulatory activities since the Egyptian era. The reported pharmacological activities of T. vulgaris L. include antibacterial, antioxidant, anti-inflammatory, antiviral, and anti-cancerous activities. In this review, a comprehensive approach is put forth to scrutinize and report the available data on phytochemistry, ethnopharmacology, pharmacology, and toxicology of the plant. The different extracts and essential oil obtained from the plant have been assessed and reported to treat ailments like microbial infections, inflammation, non-communicable diseases like cancer, and sexually transmitted diseases like HIV-1 and Herpes. The literature review has also indicated the use of volatile oils, phenolic acids, terpenoids, flavonoids, saponins, steroids, tannins, alkaloids, and polysaccharides in pharmacotherapy. Applications of these compounds including antidiabetic, anti-Alzheimer's, cardio, neuro and hepatoprotective, anti-osteoporosis, sedative, immunomodulatory, antioxidant, anti-tyrosinase, antispasmodic, antinociceptive, gastroprotective, anticonvulsant, antihypertensive, antidepressant, anti-amnesia, and anti-helminthic activities have been mentioned. Further, based on research gaps, recommendations have been provided to evaluate T. vulgaris L. systematically to develop plant-based drugs, nutraceuticals, and to evaluate their clinical efficiency and safety.

The Effects of Pre-Treatment and Post-Treatment of Thymol against tert-Butyl Hydroperoxide (t-BHP) Cytotoxicity in MCF-7 Cell Line and Fibroblast Derived Foreskin

Background

Some recent studies have reported anti-tumor activity for Thymol, but the findings are inconsistent. This study aimed to investigate and compare Thymol's effects on MCF-7 cancer cells and fibroblasts while treated with tert-Butyl hydroperoxide (t-BHP).

Methods

In the pre-treatment, MCF-7 and fibroblast cells were treated with various Thymol concentrations and incubated for 24 h. Then, t-BHP was added to a final concentration of 50 μM, and the cells were incubated for one h. In the post-treatment, cells were incubated first with 50 μM t-BHP for one h and then treated with Thymol. Cell viability was tested by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Thymol's antioxidant capacity was measured by DPPH and FRAP assays, and lipid peroxidation levels were determined by the TBARS method.

Results

The thymol effects were dose-dependent, and despite their antioxidant properties, at concentrations of 100 µg/ml or more, increased t-BHP toxicity and reduced cancer cell viability. MTT assay result showed that pre-treatment and post-treatment with Thymol for 24 hours effectively reduced MCF-7 and fibroblast cell viability compared with the untreated control group. Both pre- and post-treatment of Thymol, normal fibroblast cell viability was significantly greater than that of the MCF-7 cells.

Conclusion

Our finding showed that Thymol appears to be toxic to MCF-7 cells at lower concentrations than fibroblasts after 24 hours of incubation. Pre-treatment with Thymol neutralized the oxidative effect of t-BHP in fibroblasts but was toxic for MCF-7 cells.

Topical Antibacterials in Dermatology

Topical antibacterials are commonly used for superficial pyodermas such as impetigo and treatment or prevention of infections following minor cuts, abrasions, burns, and surgical wounds. Several antibiotics and antiseptics are available for use in different indications. One of the major uses of topical antibacterials is acne in which benzoyl peroxide is the drug of the first choice either singly or in combination with antibiotics or retinoids. Mupirocin and fusidic acid are the two most commonly used antibiotics for the treatment of superficial pyodermas and eradication of staphylococcal carrier state. Bacterial resistance to topical antibiotics is a growing concern and topical antiseptics such as gentian violet are getting renewed interest as alternatives. Incidence of contact dermatitis is a limiting factor for the use of several topical antibacterials. Although many botanical products have demonstrated in vitro activities against skin pathogens, their clinical utilities remain to be established by good-quality clinical trials.

Ecotypic Variations Affected the Biological Effectiveness of Thymus daenensis Celak Essential Oil

Thymus (Lamiaceae) is famous for its pharmacological properties. Thymus daenensis Celak (Avishan-e-denaee in Persian) is an endemic Thymus species in Iran and is traditionally used for its digestive, carminative, antitussive, antispasmodic, and expectorant attributes in folk medicine. Ecotypic oils were extracted and analyzed with the GC-MS. Their biological properties in terms of antimicrobial, antioxidant, and antigenotoxic activities were evaluated using the minimal inhibitory concentration, minimal bactericidal concentration, and DPPH, β-carotene, and comet assays. The GC-MS results for Thymus daenensis Celak oils revealed thymol (73.86%) and carvacrol (51.89%) as the most abundant components. Due to the results, reasonable bactericidal activity values range from 0.14 to 5.00 mg/ml, and fungicidal activity ranges from 0.17 to 0.58 mg/ml. The necessary oil free radical scavenging capacity (0.41-1.79 mg/ml), bleaching inhibitory activity (0.01-1.06 mg/ml), and genoprotective potential (1.04-7.78 mg/ml) indicated the dose-dependent activity. The results suggest that Thymus daenensis is an important antibacterial and antifungal bioresource. Additionally, the antioxidant and radical scavenging capacity suggests this species has a role as a natural preservative in oxidative diseases and in the prevention of food spoilage.

Selected Aspects Related to Medicinal and Aromatic Plants as Alternative Sources of Bioactive Compounds

Natural compounds obtained from different medicinal and aromatic plants have gained respect as alternative treatments to synthetic drugs, as well as raw materials for different applications (cosmetic, food and feed industries, environment protection, and many others). Based on a literature survey on dedicated databases, the aim of the present work is to be a critical discussion of aspects regarding classical extraction versus modern extraction techniques; possibilities to scale up (advantages and disadvantages of different extraction methods usually applied and the influence of extraction parameters); and different medicinal and aromatic plants' different applications (medical and industrial applications, as well as the potential use in nanotechnology). As nowadays, research studies are directed toward the development of modern, innovative applications of the medicinal and aromatic plants, aspects regarding future perspectives are also discussed.

Effect of Active-Edible Coating and Essential Oils on Lamb Patties Oxidation during Display

The use of natural products to reduce the use of synthetic additives in meat products, reducing the oxidation and improving the shelf life is a current challenge. Meat quality from lamb patties during 10 days of display on modified atmosphere packaging (MAP) and active-edible coating were tested under six treatments: uncoated patties without coating (CON); patties with alginate coating (EC) and patties with coating and 0.1 or 0.05% of essential oils (EOs) from either thyme (TH 0.1; TH 0.05) or oregano (OR 0.1; OR 0.05). Display and treatment significantly modified (P < 0.001) all the studied meat quality variables (pH, color, water holding capacity, weight losses, thiobarbituric acid reactive substances (TBARS), antioxidant activity). Display produced discoloration and lipid oxidation, however, the samples with essential oils presented lower (P < 0.001) lipid oxidation than the CON or EC groups. Coated samples with or without EOs showed better color (lower lightness but higher redness and yellowness) and lower water losses (P < 0.001) than the CON. The addition of thyme EO caused a decrease (P < 0.001) in the consumer’s overall acceptability, whereas no statistical differences appeared between CON, EC and oregano EO addition. Thus, using EOs as natural antioxidants, especially those from oregano at low dosages (0.05%), could be considered a viable strategy to enhance the shelf life and the product quality of lamb meat patties without damaging the sensory acceptability.

A comprehensive review on the antiviral activities of chalcones

Some viral outbreaks have plagued the world since antiquity, including the most recent COVID-19 pandemic. The continuous spread and emergence of new viral diseases have urged the discovery of novel treatment options that can overcome the limitations of currently marketed antiviral drugs. Chalcones are natural open chain flavonoids that are found in various plants and can be synthesised in labs. Several studies have shown that these small organic molecules exert a number of pharmacological activities, including antiviral, anti-inflammatory, antimicrobial and anticancer. The purpose of this review is to provide a summary of the antiviral activities of chalcones and their derivatives on a set of human viral infections and their potential for targeting the most recent COVID-19 disease. Accordingly, we herein review chalcones activities on the following human viruses: Middle East respiratory syndrome coronavirus, severe acute respiratory syndrome coronavirus, human immunodeficiency, influenza, human rhinovirus, herpes simplex, dengue, human cytomegalovirus, hepatitis B and C, Rift Valley fever and Venezuelan equine encephalitis. We hope that this review will pave the way for the design and development of potentially potent and broad-spectrum chalcone based antiviral drugs.

Polyphenol composition and biological activity of Thymus citriodorus and Thymus vulgaris: Comparison with endemic Iberian Thymus species

The polyphenol compositions of Thymus × citriodorus and Thymus vulgaris extracts as obtained by exhaustive hydroethanolic (HE) extraction and aqueous decoction (AD) were compared. In addition, their compositions and bioactivities were compared to those of Thymus pulegioides and Thymus mastichina, grown under the same edaphoclimatic conditions, and Thymus carnosus. Rosmarinic acid was the most abundant polyphenol followed by luteolin-hexuronide, salvianolic acids I and K. Cluster analysis suggests a similarity of the polyphenol composition of T. citriodorus and T. vulgaris. A significant antioxidant activity was observed and correlated with their polyphenol levels. The same being observed for the higher anti-proliferative activity/cytotoxicity of HE extracts on Caco-2 and HepG2 cells as compared to AD extracts. Significant association between the total phenolic compounds with the anti-proliferative activity, for both cell lines, was observed. These results support the importance of salvianolic acids levels in Thymus extracts and their in vitro anti-proliferative/cytotoxic activities.

Carvacrol: An In Silico Approach of a Candidate Drug on HER2, PI3Kα, mTOR, hER-α, PR, and EGFR Receptors in the Breast Cancer

Carvacrol is a phenol monoterpene found in aromatic plants specially in Lamiaceae family, which has been evaluated in an experimental model of breast cancer. However, any proposed mechanism based on its antitumor effect has not been reported. In our previous study, carvacrol showed a protective effect on 7,12-dimethylbenz[α]anthracene- (DMBA-) induced breast cancer in female rats. The main objective in this research was to evaluate by using in silico study the carvacrol on HER2, PI3Kα, mTOR, hER-α, PR, and EGFR receptors involved in breast cancer progression by docking analysis, molecular dynamic, and drug-likeness evaluation. A multilevel computational study to evaluate the antitumor potential of carvacrol focusing on the main targets involved in the breast cancer was carried out. The in silico study starts with protein-ligand docking of carvacrol followed by ligand pathway calculations, molecular dynamic simulations, and molecular mechanics energies combined with the Poisson-Boltzmann (MM/PBSA) calculation of the free energy of binding for carvacrol. As result, the in silico study led to the identification of carvacrol with strong binding affinity on mTOR receptor. Additionally, in silico drug-likeness index for carvacrol showed a good predicted therapeutic profile of druggability. Our findings suggest that mTOR signaling pathway could be responsible for its preventive effect in the breast cancer.

Chemical Composition and Bioactivity of Essential Oil of Ten Labiatae Species

Using antibiotics as feed additives have been successively banned worldwide from 1986; therefore, it is an urgent task to finding safe and effective alternatives. As natural products of plant origin, essential oils (EOs) are an outstanding option due to their reported bioactivity. In this research, ten EOs of Labiatae species were extracted by steam distillation and its chemical constituents were identified by gas chromatography-mass spectrometry (GC-MS). A total of 123 chemical compounds, including alkenes, phenols, aldehydes and ketones, were identified. The results of antioxidant activity carried out through DPPH free radical scavenging (DPPH) and ferric reducing antioxidant power (FRAP), showing that EOs of Ocimum basilicum Linn. (ObEO), Thymus mongolicus Ronn. (TmEO), Origanum vulgare Linn. (OvEO) and Mosla chinensis Maxim. (McEO) have strong antioxidant activities. Their 50%-inhibitory concentration (IC₅₀) value was <1.00, 1.42, 1.47 and 1.92 μg/mL, respectively; and their FRAP value was 1536.67 ± 24.22, 271.84 ± 4.93, 633.71 ± 13.14 and 480.66 ± 29.90, respectively. The results of filter paper diffusion showing that McEO, OvEO and TmEO inhibition zone diameter (IZD) are all over 30 mm. The results of two-fold dilution method showed that McEO, OvEO and TmEO have strong antibacterial activities against Staphylococcus aureus (S. aureus) and their minimal inhibitory concentrations (MIC) value was 1 μL/mL, 2 μL/mL, and 2 μL/mL, respectively. In conclusion, the results in this work demonstrate the possibility for development and application of EOs as potential feed additives.

Suppression of lncRNA MALAT1 by betulinic acid inhibits hepatocellular carcinoma progression by targeting IAPs via miR-22-3p

Betulinic acid (BA) is a natural product extracted from a broad range of medicinal and edible herbal plants. Previous studies showed that BA induces cell death in tumors derived from multiple tissues; however, the underlying mechanism remains obscure. The present study aimed to study the effects of BA on autophagy and apoptosis of hepatocellular carcinoma (HCC). Human HCC cell lines and orthotopic HCC implanted mice were employed to examine the BA-induced tumor suppression; RT2 long noncoding RNA (lncRNA) PCR array and database analysis were used to explore the possible mechanisms; validation of pathways was performed using siRNA and miRNA inhibitors. The results indicated that BA regulated autophagy and induced apoptosis in HCC. The degradation of inhibitor of apoptosis proteins (IAPs), the conversion of LC3-I to LC3-II, and p62 accumulation were enhanced by BA, thereby suggesting that the downregulation of IAPs and autophagic cell death are induced by BA. The addition of autophagy and lysosomal inhibitors indicated that BA induced autophagy-independent apoptosis via degradation of IAPs. Moreover, RT2 lncRNA PCR array and database analysis suggested that BA downregulated the levels of lncRNA MALAT1, which is considered to be an oncogene. Further investigations demonstrated that lncRNA MALAT1 functioned as a ceRNA (competing endogenous RNA) to contribute to BA-mediated degradation of IAPs by sponging miR-22-3p. Therefore, BA could be developed as a potential anticancer agent for HCC.

Targeting Oxidative Stress Reduction and Inhibition of HDAC1, MECP2, and NF-kB Pathways in Rats With Experimentally Induced Hyperglycemia by Administration of Thymus marshallianus Willd. Extracts

The effects of two lyophilized extracts obtained from the aerial parts of Thymus marschallianus Willd. and harvested from wild flora (TMW) and obtained from culture (TMC) were evaluated in Wistar rats with experimentally induced hyperglycemia. The hyperglycemia was induced by streptozotocin (STZ) administration and the obtained results were evaluated in comparison for TMW and TMC. The polyphenolic composition of extracts was evaluated by spectrophotometrical and LC-MS methods. In vitro antioxidant capacity assays (DPPH, FRAP, EPR) were performed in order to preliminary establish the ability of tested samples to protect against free radical induced damage. Afterwards, the effects of these extracts were assessed in vivo on rats with experimental-induced hyperglycemia. Oxidative stress biomarkers (e.g. malondialdehyde-MDA), phosphorylated transcription factor subunit of nuclear kappaB (NF-kB) p65, methyl CpG binding protein (MECP) 2 and histone deacetylase 1 (HDAC1) expressions in hippocampus and frontal lobe were assessed. Open Field Test (OFT) and Elevated Plus Maze (EPM) were conducted on tested animals. Malondialdehyde (MDA) levels and HDAC1and MeCP2 expressions increased significantly in hippocampus (p<0.05) and frontal lobe (p<0.001) of diabetes group compared to the control group in parallel with decreasing of GSH/GSSG ratio. TMW and TMC administration reduced blood glucose levels and diminished lipid peroxidation, HDAC1 expression and enhanced antioxidant capacity in frontal lobe. TMW improved central locomotion of rats, increased phospho-NFkB p65 and diminished MECP2 expressions in hippocampus. Both tested samples exerted a beneficial effect by increasing the antioxidant defense. Our findings indicate that the administration of these extracts might represent a good option in the treatment of diabetes and its complications.

Control of Panama disease of banana by intercropping with Chinese chive (Allium tuberosum Rottler): cultivar differences

Panama disease (Fusarium wilt disease) caused by Fusarium oxysporum f. sp. cubense race 4 (FOC) severely threatens banana (Musa spp.) production worldwide. Intercropping of banana with Allium plants has shown a potential to reduce Panama disease. In this study, six cultivars of Chinese chive (Allium tuberosum Rottler) were selected to compare their differences in antifungal activity and active compounds. Three cultivars Duokang Fujiu 11, Fujiuhuang 2, and Duokang Sijiqing with higher levels of antifungal compounds were further used for intercropping with banana in the pots and field to compare their effects on growth and disease incidence of banana.The six cultivars showed significant differences in antifungal activity against FOC mycelia growth in both leaf volatiles and aqueous leachates. The aqueous leachates displayed stronger antifungal activity than the volatiles. FJH cultivar showed the best inhibitory effect among all six cultivars. Contents of three main antifungal compounds dipropyl trisulfide (DPT), dimethyl trisulfide (DMT), and 2-methyl-2-pentenal (MP) in volatiles and aqueous leachates varied considerably among cultivars. Pot and field experiments showed that intercropping with three selected Chinese chive cultivars significantly improved banana vegetative growth, increased photosynthetic characteristics and yield but decreased disease incidence of Panama disease.Our results indicate that intercropping with Chinese chive shows potential to reduce banana Panama disease and selection of appropriate cultivars is vital for effective disease control.

In vitro Synergy of Polyphenolic Extracts From Honey, Myrtle and Pomegranate Against Oral Pathogens, S. mutans and R. dentocariosa

The increasing incidence rate of oral diseases, the wide spread of antimicrobial resistance, and the adverse effects of conventional antibiotics mean alternative prevention and treatment options are needed to counteract oral pathogens. In this regard, our study aims to evaluate the antibacterial activity of polyphenolic extracts prepared from acacia honey, myrtle leaves, and pomegranate peel against cariogenic bacteria, such as Streptococcus mutans and Rothia dentocariosa. The chemical-physical parameters of acacia honey and the RP-HPLC polyphenolic profile of pomegranate peel extract have been previously described in our studies, while the characterization of myrtle extract, performed by HPLC analysis, is reported here. All the extracts were used singly and in binary combinations to highlight any synergistic effects. Moreover, the extracts were tested in association with amoxicillin to evaluate their ability to reduce the effective dose of this drug in vitro. The values of minimal inhibitory concentrations and minimal bactericidal concentrations have been used to quantitatively measure the antibacterial activity of the single extracts, while the fractional inhibitory concentration index has been considered as predictor of in vitro anticariogenic synergistic effects. Finally, a time-kill curve method allowed for the evaluation of the bactericidal efficacy of the combined extracts. The microbiological tests suggest that acacia honey, myrtle, and pomegranate extracts are able to inhibit the cariogenic bacteria, also with synergistic effects. This study provides useful and encouraging results for the use of natural extract combinations alone or in association with antibiotics (adjuvant therapy) as a valid alternative for the prevention and treatment of oral infectious diseases.

An In-Vivo Study on Anticonvulsant, Anxiolytic, and Sedative-Hypnotic Effects of the Polyphenol-Rich Thymus Kotschyanus Extract; Evidence for the Involvement of GABAA Receptors

Antidepressant-like activity of T. kotschyanus has been recently reported by scientists but insufficient attention has been so far devoted to T. kotschyanus, and there is a lack of information on the other neurobehavioral effects and side effects of this species. In the current study, the anticonvulsant, anxiolytic, and sedative-hypnotic, effects of Thymus kotschyanus extract on male NMRI mice were evaluated using pentylenetetrazole, maximal electroshock, elevated plus maze, and pentobarbital-induced sleeping tests. Since phenolic compounds and flavonoids have main roles in pharmacological effects of most plant extracts, the phenolic and flavonoid contents of the extract were measured with Folin-Ciocalteu and AlCl₃ reagents. Acute toxicity, passive avoidance, and open field tests were carried out to assess the toxicity of the extract. To find out the possible mechanism of action, flumazenil as the specific GABA_A receptor antagonist was used. Anticonvulsant and hypnotic effects of the extract were observed at 400 and 600 mg/kg. The extract at the dose of 200 mg/kg revealed significant anxiolytic effects, but it did not show any adverse effects on learning and memory at all the tested doses. Results of this study indicate that Thymus kotschyanus extract has anticonvulsant‎, anxiolytic, and hypnotic effects, which are likely related to the ability of some phenolic compounds to activate α1-containing GABA_A receptors but more experiments still need to be carried out in order to find the exact mechanism, active component, and the toxicity of the Thymus kotschyanus extract.

Thymus vulgaris L. Essential Oil Solid Formulation: Chemical Profile and Spasmolytic and Antimicrobial Effects

A new Thymus vulgaris L. solid essential oil (SEO) formulation composed of liquid EO linked to solid excipients has been chemically analysed and evaluated for its intestinal spasmolytic and antispastic effects in ex vivo ileum and colon of guinea pig and compared with liquid EO and excipients. Liquid EO and solid linked EO were analysed by original capillary electrochromatography coupled to diode array detection (CEC-DAD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodologies. The main bioactive constituents are thymol and carvacrol, with minor constituents for a total of 12 selected analysed compounds. Liquid EO was the most effective in decreasing basal contractility in ileum and colon; excipients addiction permitted normal contractility pattern in solid linked EO SEO. In ileum and colon, the Thymus vulgaris L. solid formulation exerted the relaxant activity on K⁺-depolarized intestinal smooth muscle as well as liquid EO. The solid essential oil exhibits antimicrobial activity against different strains (Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Salmonella Thyphimurium, Candida albicans) similarly to liquid oil, with activity against pathogen, but not commensal strains (Bifidobacterium Breve, Lactobacillus Fermentum) in intestinal homeostasis. Therefore, Thymus vulgaris L. solid essential oil formulation can be proposed as a possible spasmolytic and antispastic tool in medicine.

Electrospinning of Essential Oils

The extensive and sometimes unregulated use of synthetic chemicals, such as drugs, preservatives, and pesticides, is posing big threats to global health, the environment, and food security. This has stimulated the research of new strategies to deal with bacterial infections in animals and humans and to eradicate pests. Plant extracts, particularly essential oils, have recently emerged as valid alternatives to synthetic drugs, due to their properties which include antibacterial, antifungal, anti-inflammatory, antioxidant, and insecticidal activity. This review discusses the current research on the use of electrospinning to encapsulate essential oils into polymeric nanofibres and achieve controlled release of these bioactive compounds, while protecting them from degradation. The works here analysed demonstrate that the electrospinning process is an effective strategy to preserve the properties of essential oils and create bioactive membranes for biomedical, pharmaceutical, and food packaging applications.

Evaluation of antimicrobial activity of the hydrolate of Coridothymus capitatus (L.) Reichenb. fil. (Lamiaceae) alone and in combination with antimicrobial agents

Background

Hydrolates, complex mixtures containing traces of essential oils (EOs), are inexpensive, easy to make and less toxic than their corresponding EOs. The antibacterial and antifungal activity of the hydrolate of Coridothymus capitatus (L.) Reichenb. fil. (Lamiaceae) alone and in combination with antimicrobial drugs, such as tetracycline and itraconazole, were evaluated.

Methods

The chemical composition was analysed by gas-chromatography-mass spectrometry (GC-MS). Standard methods were performed to evaluate the susceptibility of some Gram-positive and Gram-negative bacteria, and Candida spp. to the hydrolate, in comparison with its EO. The hydrolate mechanism of action was assayed by propidium iodide and MitoTracker staining. Checkerboard tests were carried out for combinations studies.

Results

GC-MS identified 0.14% (v/v) of total EO content into hydrolate and carvacrol as a dominant component. The hydrolate showed a good antimicrobial activity against bacteria and yeasts. It exhibited a synergistic effect with itraconazole against Candida krusei, and an additive effect with tetracycline against methicillin-resistant Staphylococcus aureus strains. Hydrolate changed the membranes permeability of bacteria and yeasts and altered mitochondrial function of yeasts.

Conclusions

Our study extends the knowledge by exploiting non-conventional antimicrobial agents to fight the emergence of antibiotic resistance.

Composition, Antifungal, Phytotoxic, and Insecticidal Activities of Thymus kotschyanus Essential Oil

Essential oils (EOs) are some of the outstanding compounds found in Thymus that can exert antifungal, phytotoxic, and insecticidal activities, which encourage their exploration and potential use for agricultural and food purposes. The essential oils (EO) obtained from Thymus kotschyanus collected in the East Azerbaijan Province (Iran) were characterized using a gas chromatography-mass spectrometry (GC-MS) analysis. Thymol was the most important compound (60.48%), although 35 other active compounds were identified in the EO. Significant amounts of carvacrol (3.08%), p-cymene (5.56%), and γ-terpinene (6.67%) were found in the EO. The T. kotschyanus EO was tested against important phytopathogenic fungi (Botrytis cinerea, Aspergillus niger, and Penicillium expansum). The antifungal assay showed that the use of ≥500 ppm of EO resulted in a fungicidal effect against all funguses tested. In a similar way, the use of ≥500 ppm of EO inhibited the germination of all crop weed seeds (Amaranthus retroflexus L. and Panicum miliaceum L.) and their subsequent growth, which demonstrated its herbicidal effect. Finally, the insecticidal capacity of T. kotschyanus EO was also observed against selected insects (Oryzaephilus surinamensis and Sitophilus oryzae). O. surinamensis was more susceptible to the effect of EO (LC50 = 4.78 µL/L air) than S. oryzae (LC50 = 13.20 µL/L air). The obtained results of the present study can provide new safe resources to the development of new products for the food, agriculture, and pharmaceutical industries.

Effects of active edible coating based on thyme and garlic essential oils on lamb meat shelf life after long-term frozen storage

BACKGROUND

The frozen preservation of lamb meat could be crucial for successful international trade. The shelf life of thawed meat is shorter than that of fresh meat, so techniques or procedures are required to improve post-thawing meat quality attributes. This study investigated the effect of alginate-based edible coatings after the incorporation of essential oils of thyme (Thymus vulgaris L.) and garlic (Allium sativum L.) on thawed lamb meat (longissimus thoracis et lumborum muscle) quality after long-term frozen storage. Meat samples came from ten light lambs and the evolution of attributes related to shelf life, such as water-holding capacity, color stability, and lipid oxidation, was monitored during display (1, 4 and 7 days). Four meat treatments were evaluated: control (CON, uncoated meat), edible coat of alginate meat (ECA), and ECA with thyme or garlic essential oils (0.05%) (THY and GAR).

RESULTS

The alginate-based edible coatings decreased exudative losses (P < 0.001) and modified color characteristics, especially increasing yellowness (P < 0.001) and chrome (P < 0.001). GAR decreased redness (P < 0.001) and the oxy/met ratio [R (630/580) wavelength light reflectance] or discoloration [R (630-580)]. THY was the treatment that best retained color during display and also showed a significantly lower lipid oxidation (P < 0.05) than CON and ECA, whereas GAR presented intermediate values.

CONCLUSION

The addition of bioactive essential oils to alginate-based edible coatings improved preservation and shelf life of lamb meat after thawing. © 2019 Society of Chemical Industry.

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.

Sequencing and variation of terpene synthase gene (TPS2) as the major gene in biosynthesis of thymol in different Thymus species

Thyme (Thymus spp.) is a valuable genus of Lamiaceae family with different pharmaceutical and food properties. Thymol has also been considered as the major essential oil compound in most of the studied Thymus species. In this research, the gene encoding γ-terpinene synthase (Ttps2) was sequenced in T. vulgaris and in eight Iranian thymes including T. carmanicus, T. daenensis, T. fedtschenkoi, T. kotschyanus, T. migricus, T. pubescens, T. serpyllum, and T. trautvetteri. Genetic relationships based on terpene synthase genes were also determined among the studied species. Rapid Amplification of cDNA Ends (RACE) PCR was done to complete the sequence of all species. The cDNA of the studied species possessed an open reading frame ranging from 1788 to 1794 bp that encode for a protein of 596-598 amino acids, presenting all the conserved motifs characteristics of monoterpene synthases. The taxonomic status of Thymus species was determined based on eight reported sections. The species were classified in three major groups. The first and second group comprised species of Micantes and Mastichina sections. The third cluster included the species belonging to Serpyllum and Pseudothymbra sections. Overall, phylogenetic analysis according to whole sequence of Ttps2 gene can help providing insights in respect to its evolutionary process. Finally, clustering based on the amount of main essential oils components (thymol and carvacrol) was compared with that based on Ttps2 gene classification in the studied Thymus species, showing that clustering is not always in accordance.

Traditional Uses, Chemical Constituents and Biological Activities of Plants from the Genus Thymus

The genus Thymus (Lamiaceae) comprises about 214 species throughout the world, mainly found in North Africa, Europe, and temperate Asia zone. They are traditionally used as food additives and folk medicines. This review comprehensively summarizes information about traditional uses, chemical constituents, and biological activities of this genus and provides recommendations for future investigations. All information was gathered from scientific databases including Google Scholar, Sci-Finder, Web of Science, ScienceDirect, and CNKI. Volatile oils are the most concerned constituents of this genus. Flavonoids, phenylpropanoids, tannins, organic acids, terpenoids, and phytosterols were also summarized. This genus plants possessed a variety of activities including antimicrobial, antioxidant, anti-inflammatory, cytotoxic, analgesic, and antidiabetic. In brief, this review will be helpful to provide valuable data for explorations and create more interests towards Thymus genus in the future.

In vitro and in vivo evaluation of thyme (Thymus vulgaris) essential oil as an alternative for antibiotic in quail diet1

The thyme (Thymus vulgaris) essential oil was assessed as antibiotic growth promoter replacement in quail chick diet and in vitro test. In total, 250-d-old Japanese quail chicks (mixed sex) were allocated into 5 dietary treatments of 5 replications (6 females and 4 males in each cage with the size of 40× 90× 25 cm) under a completely randomized design. The dietary treatments were included the control diet, control diet without any additive, control diet plus 100 ppm flavophospholipol as an antibiotic growth promoter, control diet plus 200 ppm TVE, control diet plus 300 ppm TVE, and control diet plus 400 ppm T. vulgaris essential (TVE) oil. Feed intake, BW gain, feed conversion ratio (FCR), organs weight, morphology of intestine, serum lipids, and microbial population were measured on day 35. Lipid oxidation of stored muscle tissue was measured by TBARS test. GC-MS assay, DPPH method, and well diffusion method were evaluated for determination of components, antioxidant, and antimicrobial properties, respectively. FCR improved significantly in 400 ppm TVE compared with 200 and 300 ppm TVE (P < 0.05). The serum triglyceride decreased significantly in both sexes receiving 400 ppm TVE compared with control. Villi height increased significantly in duodenum accompanied by decreasing crypt dept at all TVE levels compared with control and antibiotic. The breast muscle tissue of quail fed on 300 and 400 ppm TVE reduced the rate of oxidation during refrigerated storage compared with control. Thymol was the main component (35.40%) of the thymus oil. The considerable antioxidant activity of TVE was identified by IC50 of 58.48 µg/mL. Moreover, zones of growth inhibition of Gram-positive bacteria and Escherichia coli were numerically greater in different doses of TVE than antibiotics. Therefore, The TVE is suitable alternative component for antibiotic growth promoters by dosing consideration. However, it is possible that antibiotic resistance would increase for these natural compounds along the time.

Phytochemical Profile and Antimicrobial Potential of Extracts Obtained from Thymus marschallianus Willd

Thymus marschallianus Willd. is a Lamiaceae species spread in a large variety of habitats worldwide. The aim of the present research was to analyse two different samples belonging to this species, one obtained from the spontaneous flora and one from culture. The total polyphenols, flavonoids, and phenolic acid contents were spectrophotometrically determined. Qualitative and quantitative analysis of polyphenols was performed by an HPLC-DAD-ESI (+)-MS method. For the antibacterial assay, the well-diffusion and the broth microdilution methods were used. Analysis of polyphenols revealed for both samples the presence of flavonoids like luteolin, quercetin, apigenin and their derivatives, but also of rosmarinic acid and methyl-rosmarinate. Differences regarding the amount of these compounds were emphasized. Significantly larger amounts of flavonoids were found for the sample harvested in the spontaneous flora, while for the rosmarinic acid, larger amounts were found for the cultured sample. Both samples displayed promising antibacterial activity, particularly towards Gram positive organisms. T. marschallianus represents, therefore, a rich source of polyphenolic compounds that prove its promising potential as a medicinal species.

Antioxidative Activity of Thyme (Thymus vulgaris) and Oregano (Origanum vulgare) Essential Oils and Their Effect on Oxidative Stability of Minced Pork Packaged Under Vacuum and Modified Atmosphere

The antioxidant stability of minced pork treated with thyme and oregano essential oils (EOs) was determined. Minced pork containing different concentrations (0%, 0.3%, 0.6%, or 0.9%) of thyme (TEO) or oregano essential oil (OEO) and packaged under vacuum or modified atmosphere (MAP) (30%O₂ /50%CO₂ /20%N₂ ) was evaluated within 15 days of refrigeration (3 ± 1 °C) storage. EOs were examined for scavenging capacity toward 2,2-diphenyl-1-picrylhydrazyl, nitric oxide radicals, and hydroxyl, and inhibition of lipid peroxidation and ferric ion reducing antioxidant power (butylated hydroxytoluene was used as positive controls). The order of antioxidative effectiveness was as follows: butylated hydroxytoluene > OEO > TEO, with significant differences between agents (P < 0.05). Lipid oxidation in meat was determined by monitoring malondialdehyde (MDA) formation and lipolysis was assessed by measuring the acidity index immediately and after 3, 6, 9, 12, and 15 days of storage. EOs significantly (P < 0.05) increased the stability of minced pork with respect to lipid oxidation compared with the control, and the antioxidative effect was dose-dependent. Moreover, vacuum packaging resulted in mince with significantly lower oxidation and lipolysis levels than modified atmosphere packaged mince (P < 0.05). The results demonstrate that both EOs examined effectively reduced lipid oxidation in raw pork mince after 2 weeks' storage. PRACTICAL APPLICATION: The natural food preservatives market is growing rapidly, as is high demand for organic foods. These results are likely to be of interest to the scientists, researchers, and persons who work in the meat industry. Results and discussion can contribute to a better understanding of antioxidative properties of essential oils in food model. Furthermore, no study has reported the effect of these MAP on pork oxidative stability.

Natural Berberine-Based Chinese Herb Medicine Assembled Nanostructures with Modified Antibacterial Application

The abuse of traditional antibiotics has caused a series of health problems including antimicrobial resistance, which threatens human health. Therefore, searching for broad sources of antimicrobial agents and developing multidimensional strategies to combat bacterial infections are urgent. Here, we reported two natural self-assembling modes between berberine (BBR) and flavonoid glycosides: nanoparticles (NPs) and nanofibers (NFs), which were both mainly governed by electrostatic and hydrophobic interactions. These two nanostructures exhibited different antibacterial properties from BBR. NPs showed significantly enhanced bacteriostatic activity, whereas NFs displayed a much weaker effect than BBR. The distinguishing properties can be attributed to the different spatial configurations and self-assembly processes of NPs and NFs. Flavonoid glycosides and BBR first formed a one-dimensional complex unit and subsequently self-assembled into three-dimensional nanostructures. With the hydrophilic glucuronic acid toward the outside, NPs exhibited stronger affinity to bacteria, thereby inducing the collapse of the bacteria population and the decrease in biofilm. In addition, in vitro hemolysis tests, cytotoxicity tests, and in vivo zebrafish toxicity evaluation showed that the obtained self-assemblies had good biocompatibility. This supramolecular self-assembly strategy can be applied to construct other nanoscale antibacterial drugs and thus provides weapons for the development of self-delivering drugs in bacterial infection treatment.

Antimicrobial activity of cellulosic pads amended with emulsions of essential oils of oregano, thyme and cinnamon against microorganisms in minced beef meat

Cellulosic pads, amended with emulsions containing essential oils of thyme and oregano, exhibited antimicrobial activity against the psychrophilic microbiota of minced beef. In addition, the pads were active against specific meat bacterial species (Pseudomonas putida, Pseudomonas fragi, Pseudomonas fluorescens, Enterococcus faecalis and Lactococcus lactis) and some common foodborne pathogens (Salmonella enterica, Campylobacter jejuni and Staphylococcus aureus). Three emulsions, IT131017, Mediterranean and Etnic, containing different percentages of carvacrol, thymol, linalool, and ɑ and β-pinene, significantly reduced the growth of S. enterica and P. putida. Pads derived from emulsions Mediterranean and Etnic induced slight (0.3-0.8 Log₁₀ CFUs/g) but reproducible reduction of the psychrophilic microbiota in minced meat and hamburger stored for 12 and 15 days at 4 °C.

Essential oils inhibit the bovine respiratory pathogens Mannheimia haemolytica, Pasteurella multocida and Histophilus somni and have limited effects on commensal bacteria and turbinate cells in vitro

AIMS

The objective of this study was to determine antimicrobial activities of essential oils (EOs) against bovine respiratory disease (BRD) pathogens and nasopharyngeal commensal bacteria, as well as cytotoxicity in bovine turbinate (BT) cells in vitro.

METHODS AND RESULTS

The chemical composition of 16 EOs was determined using gas chromatography-mass spectrometry. All EOs were first evaluated for growth inhibition of a single BRD pathogen Mannheimia haemolytica serotype 1 strain (L024A). The most inhibitory EOs (n = 6) were then tested for antimicrobial activity against multidrug-resistant strains of M. haemolytica (serotypes 1, 2 and 6); the BRD pathogens Pasteurella multocida and Histophilus somni, as well as commensal bacteria that were isolated from the nasopharynx of feedlot cattle. The cytotoxicity of 10 EOs was also evaluated using a BT cell line. The EOs ajowan, thyme and fennel most effectively inhibited all BRD pathogens tested including multidrug-resistant strains with minimum inhibitory concentrations (MIC) of ≤0·025% (volume/volume, v/v). For these EOs, the MIC was 2-32 fold greater against commensal bacteria, compared to BRD-associated pathogens. No cytotoxic effects of EOs against BT cells were observed within the tested range of concentrations (0·0125-0·4%, v/v).

CONCLUSIONS

The EOs ajowan, thyme and fennel inhibited M. haemolytica, P. multocida and H. somni at a concentration of 0·025% and had minimal antimicrobial activity against nasopharyngeal commensal bacteria and cytotoxicity against BT cells.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated that EOs may have potential for intra-nasal administration to mitigate bovine respiratory pathogens in feedlot cattle.