The chemical composition of the pharmacologically active Thymus species, its antibacterial activity against Streptococcus mutans and the antiadherent effects of T. vulgaris on the bacterial colonization of the in situ pellicle

Liquid chromatography-tandem mass spectrometry profile and antioxidant, antimicrobial, antiproliferative, and enzyme activities of Thymus pectinatus and Thymus convolutus: in vitro and in silico approach

BACKGROUND

The objective of this study is to investigate the antiproliferative, antioxidant, antimicrobial, and enzyme activity capacities and phytochemical compositions of Thymus pectinatus (TP), Thymus convolutus (TC), which are endemic to Türkiye. Quantitative analysis of phenolic compounds in the extracts was conducted using liquid chromatography-tandem mass spectrometry, targeting 53 phenolic compounds.

RESULTS

Rosmarinic acid, quinic acid, and cynaroside were identified as the major compounds, exhibiting quantitative variation in both extracts. The extracts had a high total phenolic content, with 113.57 ± 0.58 mg gallic acid equivalents (GAE)/g extract for TP and 130.52 ± 1.05 mg GAE/g extract for TC. Furthermore, although both extracts exhibited high total flavonoid content; the TP extract (75.12 ± 1.65 mg quercitin equivalents (QE)/g extract) displayed a higher flavonoid content than the TC extract (30.24 ± 0.74 mg QE/g extract) did. The extracts had a promising antiproliferative effect on C6, HeLa, and HT29 cancer cell lines with a less cytotoxic effect (10.5-14.2%) against normal cells. Both extracts exhibited very potent inhibitory activity against the xanthine oxidase enzyme, with half-maximal inhibitory concentration values of respectively 2.07 ± 0.03 μg mL-1 and 2.76 ± 0.06 μg mL-1 and moderate activity against tyrosinase and α-glucosidase. Docking simulations proved that rosmarinic acid and cynaroside, the major components of the extracts, were the most potent inhibitors of xanthine oxidase. According to antimicrobial activity results, the TC extract exhibited moderate activity against Staphylococcus aureus, and the TP extract had strong activity against both Enterococcus faecium and S. aureus.

CONCLUSION

These findings emphasize the beneficial effects of the two endemic Thymus species on human health and suggest their potential use as plant-derived bioactive agents. © 2024 Society of Chemical Industry.

Chemical Composition of Thyme (Thymus vulgaris) Extracts, Potential Inhibition of SARS-CoV-2 Spike Protein-ACE2 Binding and ACE2 Activity, and Radical Scavenging Capacity

Water and ethanol extracts of dried thyme (Thymus vulgaris) were analyzed for chemical composition, inhibition of the SARS-CoV-2 spike protein-ACE2 interaction, inhibition of ACE2 activity, and free radical scavenging capacity. Thirty-two compounds were identified in water extract (WE) and 27 were identified in ethanol extract (EE) of thyme through HPLC-MS. The WE (33.3 mg/mL) and EE (3.3 mg/mL) of thyme inhibited the spike protein-ACE2 interaction by 82.6 and 86.4%, respectively. The thyme WE at 5 mg/mL inhibited ACE2 activity by 99%, and the EE at 5 mg/mL inhibited ACE2 by 65.8%. Total phenolics were determined to be 38.9 and 8.8 mg of GAE/g in WE and EE, respectively. The HO• scavenging capacities were 1121.1 and 284.4 μmol of TE/g in WE and EE, respectively. The relative DPPH• scavenging capacities were 126.3 μmol TE/g in WE and 28.2 μmol TE/g in EE. The ABTS•+ scavenging capacities were 267.1 μmol TE/g in WE and 96.7 μmol TE/g in EE. The results suggested that the thyme extract could be potentially used to prevent SARS-CoV-2 infection and mitigate the complications from the infection.

Assessing Contact Time and Concentration of Thymus vulgaris Essential Oil on Antibacterial Efficacy In Vitro

The overuse and misuse of antibiotics can pose the risk of spreading mutant strains that show antimicrobial resistance (AMR), with negative impacts on the management of bacterial infections and economic implications for healthcare systems. The research and development of natural antibacterial agents could be a priority in the next years to improve a number of effective antibacterial molecules and to reduce the AMR phenomenon and its development. The present study identified the most effective concentration and contact time of Thymus vulgaris L. essential oil (TEO) to obtain bactericidal effects in vitro against different Gram-positive and Gram-negative bacterial strains. Six clinically isolated (wild types) bacterial strains, (Citrobacter freundii, Enterococcus feciorum, Proteus mirabilis, Acinetobacter cioffi, Pseudomonas putrefaciens and Klebsiella pneumoniae) and two ATCCs (Staphylococcus aureus and Streptococcus mutans) were tested after 1 min, 3 min and 5 min of contact with TEO. The preliminary results on S. aureus after 24 h of incubation revealed a TEO concentration of 9.28 mg/mL (w/v) that completely inhibited bacteria growth, keeping cell viability. The total suppression of bacterial growth at all tested contact times was observed for all tested bacterial strains, and the results were confirmed after 48 h of incubation. Bacterial growth suppression was confirmed even with the presence of organic components. These preliminary results showed the in vitro antimicrobial efficacy of TEO against different Gram-positive and Gram-negative bacterial strains. Future studies are necessary to confirm the reproducibility of these results even on other strains and to define the exact molecular mechanisms of EOs in order to consider TEO as a valid alternative to classic antibiotic therapies and subsequently to reduce the occurrence of AMR.

In Vitro and In Silico Evaluation of the Antimicrobial and Antioxidant Potential of Thymus pulegioides Essential Oil

The study was designed to analyze and evaluate the antioxidant and antibacterial properties of the essential oils of Thymus pulegioides L. grown in Western Romania. Thymus pulegioides L. essential oil (TPEO) was extracted by steam distillation (0.71% v/w) using a Craveiro-type apparatus. GC-MS investigation of the TPEO identified 39 different compounds, representing 98.46% of total oil. Findings revealed that thymol (22.89%) is the main compound of TPEO, followed by para-cymene (14.57%), thymol methyl ether (11.19%), isothymol methyl ether (10.45%), and beta-bisabolene (9.53%). The oil exhibits good antibacterial effects; C. parapsilosis, C. albicans, S. pyogenes, and S. aureus were the most sensitive strains. The antioxidant activity of TPEO was evaluated by peroxide and thiobarbituric acid value, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), [2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium] (ABTS) radical scavenging assay, and beta-carotene/linoleic acid bleaching testing. The antioxidative data recorded reveal, for the first time, that TPEO inhibits primary and secondary oxidation products, in some particular conditions, better than butylated hydroxyanisole (BHA) with significant statistical difference (p < 0.05). Moreover, TPEO antioxidant capabilities in DPPH and ABTS assays outperformed alpha-tocopherol (p < 0.001) and delta-tocopherol (p < 0.001). Molecular docking analysis revealed that one potential target correlated with the TPEO antimicrobial activity was d-alanine-d-alanine ligase (DDl). The best scoring ligand, linalyl anthranilate, shared highly similar binding patterns with the DDl native inhibitor. Furthermore, molecular docking analysis also showed that the main constituents of TPEO are good candidates for xanthine oxidase and lipoxygenase inhibition, making the essential oil a valuable source for protein-targeted antioxidant compounds. Consequently, TPEO may represent a new potential source of antioxidant and antibacterial agents with applicability in the food and pharmaceutic industries.

Comparative evaluation of various herbal extracts on biofilms of Streptococcus mutans and Scardovia wiggsiae: An in vitro study

BACKGROUND

Owing to their strong antimicrobial properties, Helichrysum arenarium (HA), Anzer thyme (AT), and Stevia rebaudiana (SR) have been commonly used in medicine.

AIM

This study aimed to evaluate antimicrobial activities of HA, AT, and SR against S. mutans and S. wiggsiae in biofilms formed on primary teeth.

DESIGN

Fifty enamel samples were divided into two groups: mono-species biofilm and two-species biofilm. Each biofilm group was divided into five subgroups (n = 5): group 1, HA; group 2, AT; group 3, SR; group 4, CHX (positive control); and group 5, distilled water (negative control). Minimum inhibitory concentration and minimum bactericidal concentration were determined. The number of viable microorganisms was counted. The presence of microorganisms was examined using a scanning electron microscope, and mineral analysis was performed using energy-dispersive X-ray analysis.

RESULTS

In the mono-species biofilm, CHX was significantly more effective against S. mutans than other groups (p < .001). Furthermore, HA, AT, and SR groups showed significantly lower colony counts of S. mutans than distilled water (p < .05). In the two-species biofilm group, AT, SR, and CHX were significantly more effective against S. wiggsiae than distilled water (p < .05).

CONCLUSIONS

HA, AT, and SR have been suggested as effective natural alternatives to CHX against cariogenic bacteria.

Biological properties of Thymus zygis essential oil with emphasis on antimicrobial activity and food application

The Thymus plants have been used for centuries in traditional medicine and as a food spice, among this genus, Thymus zygis (red thyme) is a widespread plant, vastly used as a culinary flavouring agent. Its essential oil has demonstrated diverse bioactive properties, such as antimicrobial, insecticidal, larvicidal and antiparasitic activities. Numerous studies have characterized this essential oil showing that it possesses a broad antimicrobial spectrum and may even enhance the effect of certain antimicrobial agents. Its potential application as a food preservative has been analysed on different matrixes pointing to its antimicrobial activity against spoilage and pathogenic microorganisms in food. This review provides an insight in the chemical composition, antimicrobial, insecticidal, larvicidal and antiparasitic activities and toxicity of T. zygis essential oil, as well as its potential application in food as a preservative.

Antibacterial Activity of Essential Oils against Oral Pathogens

This updated review article covers the literature between 2011 and 2021 on the antibacterial activity of EOs against the main bacteria that cause caries and periodontal diseases. The criteria to classify the in vitro antibacterial activity of EOs is updated and the most promising results are addressed.

Phenolic compounds, antioxidant and antibacterial activities of extracts from aerial parts of Thymus zygis subsp. gracilis, Mentha suaveolens and Sideritis incana from Morocco

Thymus zygis subsp. gracilis , Mentha suaveolens and Sideritis incana (Lamiaceae family) are well recognized for their medicinal, pharmaceutical and aromatic properties. The present study aimed to investigate for the first time the polyphenolic composition, the antioxidant and antibacterial properties of the extracts obtained from the aerial parts of these species collected from the Ifrane region of Morocco. The polyphenolic compounds were determined using high-performance liquid chromatography coupled to photodiode array and electrospray ionization mass spectrometry (HPLC-PDA-ESI/MS). The antioxidant activity was investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power and ferrous ion chelating assays. The antibacterial activity was evaluated against three Gram-negative bacteria ( Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium ) and three Gram-positive bacteria ( Staphylococcus aureus, Enterococcus faecalis and Listeria monocytogenes ). A total of thirty-three, sixteen and thirteen polyphenolic compounds were positively identified and characterized in T. zygis subsp. gracilis , M. suaveolens and S. incana extracts, respectively. Among the extracts, M. suaveolens exhibited the highest antioxidant activity, followed by S. incana and T. zygis subsp. gracilis in both DPPH and reducing power assays; all extracts showed the lowest activity in the chelating assay. In addition, all extracts demonstrated a bactericidal effect against Gram-positive bacteria and bacteriostatic effect against Gram-negative bacteria. Therefore, the aerial parts of Moroccan T. zygis subsp. gracilis , M. suaveolens and S. incana might be considered as a valuable source of natural antioxidant and antibacterial agents with potential application in food and pharmaceutical industries.

Lamiaceae Essential Oils, Phytochemical Profile, Antioxidant, and Biological Activities

Medicinal and aromatic plants present important active compounds that have potential for use in food, pharmaceutical, and agriculture industries. In this sense, the present work aimed to conduct a literature review on the potential applications of essential oils from Lamiaceae species. Antioxidant, anti-inflammatory, and antimicrobial activities were evaluated. The importance of this study is demonstrated as a way to theoretically provide information on the use of different plants belonging to the Lamiaceae family, especially with regard to the physical, chemical, and biological properties of its essential oils.

Enamel remineralization and surface roughness after treatment with herbal-containing toothpastes

Background

Oral care products containing bioactive agents obtained from extracts of plant drugs were launched. This in vitro study investigated the effects of herbal-containing toothpastes associated or not with fluoride to remineralize the enamel after cariogenic challenge with pH cycling. The chemical and physical factors of toothpastes and the enamel surface roughness after brushing were also analyzed.

Material and Methods

Sixty bovine enamel blocks were obtained and divided into 3 thirds: intact (untreated), demineralized (artificial caries lesion), and treated (caries lesion, pH cycling, and brushing with toothpastes). Toothpastes containing herbal compounds contained no fluoride [Galla chinensis (GCH)], low-F concentration [D’Or (DOR); Herbal Bliss (HBL)], or a different fluoride type [Elmex Anticaries (EAC)]. The results were compared to NaF-containing toothpastes: 1450 and 5000 ppm. Enamel blocks were brushed with the toothpastes using a pH-cycling model (7 days). The Knoop hardness (25g/10s) of the surface and the longitudinal sections were then evaluated. The percentage of surface hardness recovery (%SHR) was calculated. The enamel surface roughness, pH, particle size, zeta potential, and polydispersity index of toothpaste slurries were also evaluated. Data were statistically analyzed (α=5%).

Results

No significance was observed when %SHR was compared (p>0.05). DOR, GCH, and HBL were more effective in remineralizing the enamel subsurface. Significantly higher surface roughness was observed when treated with EAC and GCH (p<0.05).

Conclusions

All toothpastes were able to remineralize the enamel, especially the subsurface, with results equal or better than that of standard toothpastes.

Key words:Enamel, hardness, roughness, toothpaste, tooth remineralization.

Impact of Thymus vulgaris extract on sodium nitrite-induced alteration of renal redox and oxidative stress: Biochemical, molecular, and immunohistochemical study

Thyme (Thymus vulgaris) is an herbal plant with pleiotropic medicinal properties. In this study, we examined the possible protective effect of an ethanolic extract of thyme leaves against the renal oxidative stress induced by sodium nitrite (NaNO₂ ). Male Swiss mice received either saline or thyme extract for 15 days (0.5 g/kg body weight, orally). NaNO₂ (60 mg/kg) was injected intraperitoneally at Day 14. The protective group received the thyme extract for 15 days and NaNO₂ on Day 14. Blood and kidney samples were taken from all groups to measure serum urea, blood urea nitrogen (BUN), creatinine, serum, tissue antioxidant activity, and the inflammatory cytokines IL-1β and IL-6. Quantitative real-time PCR (qRT-PCR) was used to examine the expression of kidney injury marker-1 (Kim-1), TNF-α, nuclear factor erythroid-2 related factor 2 (Nrf2), and hemoxygenase-1 (HO-1), all of which are associated with kidney redox and oxidative stress. Pretreatment with thyme extract reduced the effects of NaNO₂ on urea, BUN, and creatinine, and reversed its effect on tissue and serum antioxidants. NaNO₂ -induced nephritis as demonstrated by the upregulation in mRNA expression of Kim-1 and TNF-α, which was, however, recovered and protected by pretreatment with thyme extract. Expression of Nrf2 and HO-1 was upregulated by treatment with thyme extract and downregulated by NaNO₂ intoxication. NaNO₂ -induced congestion in glomeruli and dilatation of the renal tubules, conditions that were restored in the group pretreated with thyme extract. NaNO₂ upregulated Bax immunoreactivity and caused apoptosis in renal structures. Thus, thyme extract is effective in managing the renal toxicity associated with oxidative stress and renal redox. PRACTICAL APPLICATIONS: The results from this study have shown that use of thyme extract may promote better health due to its high antioxidant activity. For instance, it could be ingested to alleviate the symptoms of renal inflammation and oxidative stress associated with nitrite toxicity. Thyme extract regulated renal redox, oxidative stress, antioxidant levels, and inflammation-associated genes at the molecular, biochemical, and cellular immunohistochemical levels.

Hepatoprotective effect of Thymus vulgaris extract on sodium nitrite-induced changes in oxidative stress, antioxidant and inflammatory marker expression

The herb thyme (Thymus vulgaris) has multiple therapeutic uses. In this study, we explored how T. vulgaris leaf extract protects liver cells against sodium nitrite-(NaNO₂) induced oxidative stress. Mice were divided into four groups; each group received one of the following treatments orally: saline; T. vulgaris extract alone; NaNO₂ alone; or T. vulgaris extract + NaNO₂. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), reduced glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), IL-1β, IL-6, TNF-α, and total proteins were measured in serum using standard methods. TNF-α, hemooxygenase-1 (HO-1), thioredoxin, SOD, and GSH synthase, all of which are linked to oxidative stress, were measured using quantitative real-time PCR (qRT-PCR). In mice treated with T. vulgaris extract, the effect of NaNO₂ on ALT and AST levels and total proteins was reduced, and its effect on antioxidant levels was reversed. Normally, NaNO₂ causes hepatocyte congestion and severe hepatic central vein congestion. Tissues in the mice treated with T. vulgaris were restored to normal conditions. Our results demonstrate that NaNO₂-induced hepatic injury is significantly reduced by pretreatment with T. vulgaris extract, which protects against hepatic oxidative stress and its associated genes at the biochemical, molecular, and cellular levels.

Antibiofilm effects of Thymus vulgaris and Hyptis spicigera essential oils on cariogenic bacteria

Aim: The inhibitory and antibiofilm effects of Thymus vulgaris (EOTv) and Hyptis spicigera essential oils (EOHs) on cariogenic microorganisms were evaluated. Materials & methods: The chemical characterization of EOTv was performed by gas chromatography/mass spectrometry. Streptococcus mutans, Streptococcus gordonii, Streptococcus sanguinis, Streptococcus mitis, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces naeslundii were used for agar diffusion assays and determination of minimal inhibitory and minimal bactericide concentrations. In addition, 20 streptococci and lactobacilli clinical isolates were also tested. The effects of essential oil on microbial initial biofilm formation and on preformed microcosm biofilm formed from human saliva were studied. Results & conclusion: Both essential oils had inhibitory effects on the cariogenic species and reduced the bacterial adherence to dental enamel. Essential oils were able to disrupt preformed microcosm biofilms. Thymus vulgaris and Hyptis spicigera essential oils have potential to be used in the development of formulations to the control of cariogenic biofilms.

Effects of Experimental Agents Containing Tannic Acid or Chitosan on the Bacterial Biofilm Formation in Situ

Chitosan and tannic acid are known for their antibacterial properties. In the present in-situ study, their antibacterial and anti-adherent effects on biofilm formation on enamel were investigated. Six subjects carried upper jaw splints with bovine enamel specimens, allowing in-situ biofilm formation. During the two-day trial, subjects rinsed with experimental solutions that contained either chitosan, tannic acid (pH = 2.5), tannic acid (pH = 7) or hydrochloric acid. Water served as the negative and chlorhexidine as the positive control. Rinsing occurred four or five times following two different rinsing protocols to investigate both the immediate and long-lasting effects. After 48 h of intraoral exposure, the dental plaque was stained with LIVE/DEAD^® BacLight, and fluorescence micrographs were evaluated by using the software ImageJ. The results were verified by scanning electron microscopy. Rinsing with chitosan resulted in little immediate antibacterial and anti-adherent effects but failed to show any long-lasting effect, while rinsing with tannic acid resulted in strong immediate and long-lasting effects. Except for a slightly lower antibacterial effect, the neutral solution of tannic acid was as good as the acidic solution. Hydrochloric acid showed neither an antibacterial nor an anti-adherent effect on dental biofilm formation. Experimental solutions containing tannic acid are promising anti-biofilm agents, irrespective of the pH values of the solutions. Chitosan, on the other hand, was not able to prevent biofilm formation.

Effect of fragaria vesca, hamamelis and tormentil on the initial bacterial colonization in situ

OBJECTIVE

The presentin situ study aims to examine the influence of the polyphenolic tea drugs fragaria vesca, hamamelis and tormentil on the initial oral bioadhesion.

DESIGN

Initial biofilm formation was performed on bovine enamel slabs which were carried intraorally by 12 subjects. After 1 min of intraoral pellicle formation, the subjects rinsed with fragaria vesca, tormentil (0.8 mg/8 mL) and hamamelis (0.2 mg/8 mL) for 10 min. Tap water served as negative control, 0.2 % CHX as positive control. The investigations took place on different days (wash-out: 2 days). Afterwards, fluorescence microscopy has been performed per test solution (n = 5) and per subject (n = 12) to visualize bacterial adhesion and glucan formation (8 h oral exposition) with DAPI, ConA and BacLight. Additionally, TEM was used to visualize the pellicle ultrastructure and expectorate samples. Statistical evaluation was carried out using the Kruskal-Wallis- (p < 0.5), Mann-Whitney U test (p < 0.5) and Bonferroni-Holm-correction (p < 0.1).

RESULTS

Rinsing with the polyphenolic tea extracts reduced significantly initial bacterial colonization (DAPI) compared to the negative control. There was no significant difference betweenfragaria vesca, hamamelis and tormentil. All solutions showed a reducing effect on the glucan formation. No significant difference was observed between fragaria vesca and CHX. Considerable alterations of the pellicle's ultrastructure manifested by an increase in thickness and electron density resulted from rinsing with the three polyphenolic aqueous extracts.

CONCLUSIONS

Fragaria vesca, hamamelis and tormentil significantly reduce initial bioadhesion and glucan formation in situ and are therefore recommended as adjuvant antibacterial oral therapeutics.

Polyphenols in Dental Applications

(1) Background: polyphenols are a broad class of molecules extracted from plants and have a large repertoire of biological activities. Biomimetic inspiration from the effects of tea or red wine on the surface of cups or glass lead to the emergence of versatile surface chemistry with polyphenols. Owing to their hydrogen bonding abilities, coordination chemistry with metallic cations and redox properties, polyphenols are able to interact, covalently or not, with a large repertoire of chemical moieties, and can hence be used to modify the surface chemistry of almost all classes of materials. (2) Methods: the use of polyphenols to modify the surface properties of dental materials, mostly enamel and dentin, to afford them with better adhesion to resins and improved biological properties, such as antimicrobial activity, started more than 20 years ago, but no general overview has been written to our knowledge. (3) Results: the present review is aimed to show that molecules from all the major classes of polyphenolics allow for low coast improvements of dental materials and engineering of dental tissues.

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

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

Differentiation of Phenolic Composition Among Tunisian Thymus algeriensis Boiss. et Reut. (Lamiaceae) Populations: Correlation to Bioactive Activities

: Twelve Tunisian Thymus algeriensis populations growing wild in different bioclimatic zones, extending from the subhumid to the upper-arid bioclimates, were compared regarding their phenolic composition and their ability to serve as antioxidant, anti-acetylcholinesterase, and antibacterial agents. A significant variation of phenol profile was observed between the analyzed populations, as assessed by ultra-high-performance liquid chromatography coupled with a diode array detector and an electrospray mass spectrometer (UHPLC-DAD-ESI/MSⁿ) technique. Rosmarinic acid was the main phenolic compound in most populations (383.8-1157.8 µg/mL extract), but still, those from the upper-arid bioclimatic zone were distinguished by the presence of carvacrol (1374.7 and 2221.6 µg/mL extract), which was absent in the remaining ones. T. algeriensis methanolic extracts were found to possess a substantial antioxidant and anti-acetylcholinesterase activities, with significant variation observed between populations, which were correlated to their phenolic contents. The antibacterial activity of the extracts tested against seven bacteria was revealed only by populations collected from upper-arid bioclimate and mainly associated with the presence of carvacrol. Extracts revealed a bacteriostatic effect against all bacteria (MIC = 1.4 mg/mL). Yet, the bactericidal activity (MBC = 1.4mg/mL) was restricted to the gram-negative bacteria Escherchia coli.

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.

Essential Oils as Antimicrobial Agents-Myth or Real Alternative?

Herbs and the essential oils derived from them have been used from the beginning of human history for different purposes. Their beneficial properties have been applied to mask unpleasant odors, attract the attention of other people, add flavor and aroma properties to prepared dishes, perfumes, and cosmetics, etc. Herbs and essential oils (EOs) have also been used in medicine because of their biological properties, such as larvicidal action, analgesic and anti-inflammatory properties, antioxidant, fungicide, and antitumor activities, and many more. Many EOs exhibit antimicrobial properties, which is extremely important in fields of science and industry, such as medicine, agriculture, or cosmetology. Among the 250 EOs which are commercially available, about a dozen possess high antimicrobial potential. According to available papers and patents, EOs seem to be a potential alternative to synthetic compounds, especially because of the resistance that has been increasingly developed by pathogenic microorganisms. In this review we summarize the latest research studies about the most-active EOs that are known and used because of their antimicrobial properties. Finally, it is noteworthy that the antimicrobial activities of EOs are not preeminent for all strains. Further investigations should, thus, focus on targeting EOs and microorganisms.

Thymus pulegioides L. as a rich source of antioxidant, anti-proliferative and neuroprotective phenolic compounds

The potential of Thymus pulegioides L. as an alternative and valuable source of functional ingredients has been assessed. For this purpose, the phenolic constituent profiles and the antioxidant, anti-proliferative, neuroprotective, anti-aging and anti-diabetic activities of both T. pulegioides aqueous decoctions (AD) and hydro-ethanolic extracts (HE) were studied and compared for the first time. Rosmarinic acid was the main phenolic compound, accounting for 35.2% or 47.8% of total identified phenols in AD or HE, respectively (58.5 and 151.9 mg g-1 extract). Furthermore, large amounts of luteolin-O-hexuronide (AD: 39.9 ± 2.5 mg g-1, HE: 60.8 ± 7.0 mg g-1), eriodictyol-O-hexuronide (AD: 19.9 ± 2.5 mg g-1, HE: 26.8 ± 7.0 mg g-1) and chrysoeriol hexoside (AD: 23.5 ± 0.7 mg g-1, HE: 16.0 ± 0.7 mg g-1) were found. Both extracts showed significant in vitro antioxidant activity and anti-proliferative activity against Caco-2 cells (IC50 82.25 μg mL-1 and 105.44 μg mL-1, AD and HE, respectively), and reduced hepatotoxicity (HepG2 cells). In general, both T. pulegioides extracts showed poor anti-diabetic activity, moderate anti-aging effects and high neuroprotective activity with both AD and HE extracts, at 0.5 mg mL-1, showing 80% inhibition of the acetylcholinesterase activity and 94% inhibition of the tyrosinase activity. The present study highlights the important potential of this herb as a functional food ingredient.

Investigation on the Antibacterial and Anti-T3SS Activity of Traditional Myanmar Medicinal Plants

Myanmar has a rich pool of, but less known, medicinal plants with traditional knowledge. In this study, we aimed to investigate the inhibitory activity of traditional Myanmar medicinal plants against the type III secretion system (T3SS) of Salmonella enterica serovar Typhimurium UK-1 χ8956 and the intestinal disease-caused by microbes including S. enterica serovar Typhimurium UK-1 χ8956, Proteusbacillus vulgaris CPCC 160013, Escherichia coli CICC 10003, and Staphylococcus aureus ATCC 25923. The EtOH extracts of 93 samples were used to screen the inhibitory activities against the secretion of T3SS effector proteins SipA/B/C/D of S. enterica and the antibacterial activity against S. enterica, P. vulgaris, E. coli, and S. aureus. Out of 71 crude drugs traditionally used, 18 were proofed to be effective either on the growth inhibition of tested bacteria and/or as inhibitors for the T3SS. The EtOH extracts of five plants, Luvunga scandens (Roxb.) Buch.-Ham. ex Wight & Arn. (My7), Myrica nagi Thunb. (My11), Terminalia citrina Roxb. ex Fleming (My21), Thymus vulgaris L. (My49), and Cinnamomum bejolghota (Buch.-Ham.) Sweet (My104), showed potent inhibitory activities against the secretion of T3SS proteins SipA/B/C/D of S. enterica serovar Typhimurium UK-1 χ 8956. Mansonia gagei J.R.Drumm (My3) and Mesua ferrea (Roxb.) L. (My10) showed strong antibacterial activities against P. vulgaris and S. aureus. This study provided the first scientific evidence of T3SS prohibiting and antibacterial properties for the traditional knowledge in Myanmar of using plants as medicines for treating infections and gastrointestinal disease. Further researches are proposed to discover the active chemical compounds and mechanism of L. scandens (Roxb.) Buch.-Ham. ex Wight & Arn, M. nagi Thunb., T. citrina Roxb. ex Fleming, T. vulgaris L., and C. bejolghota (Buch.-Ham.) Sweet as antivirulence drugs and the potential of M. gagei J.R.Drumm and M. ferrea L. as new broad spectrum plant antibiotics.