Thymus dacicus as a new source of antioxidant and antimicrobial metabolites

Computational studies on the interaction of Omicron subvariants (BA.1, BA.2, and BA.3) with ACE2 and polyphenols

INTRODUCTION

The SARS-CoV-2 Omicron variant BA.2 is spreading widely across the globe. The World Health Organization (WHO) designated BA.2 as a variant of concern due to its high transmission rate and pathogenicity. To elucidate the structural changes caused by mutations, we conducted a comparative analysis of BA.2 with variants BA.1 and BA.3.

OBJECTIVE

In the present study, we aimed to investigate the interactions of the spike glycoprotein receptor-binding domain (SGp RBD) of Omicron variants BA.1, BA.2, and BA.3 with the human receptor hACE2. Further, a library of 233 polyphenols was screened by molecular docking with the SGp RBDs of Omicron variants BA.1, BA.2, and BA.3.

METHODS

Protein-protein and protein-ligand molecular docking simulations were performed with AutoDock Vina and the ClusPro 2.0 server, respectively. The protein-ligand interactions were evaluated by BIOVIA Discovery Studio and ChimeraX 1.4. The molecular dynamics simulations for 100 ns were performed using GROMACS 2021.

RESULTS

Compared to other variants of concern, the structural changes in Omicron caused by mutations at key positions improved its ability to cause infection. Despite multiple mutations, many important polyphenols bind effectively at the RBDs of Omicron variants, with the required pharmacokinetic and ADME features and obeying the Lipinski rule.

CONCLUSION

Even though Omicron variants have multiple mutations and their transmission rate is relatively high, the computed binding affinities of lead polyphenols like epigallocatechin-3-O-gallate (EGCG) and luteolin-7-O-glucuronide (L7G) indicate that traditional medicines and proper immunity booster diets may be useful in the long-term fight against SARS-CoV-2.

Flowering phenophases influence the antibacterial and anti-biofilm effects of Thymus vulgaris L. essential oil

BACKGROUND

Essential oils are becoming increasingly popular in medicinal applications because of their antimicrobial effect. Thymus vulgaris L. (Lamiaceae) is a well-known and widely cultivated medicinal plant, which is used as a remedy for cold, cough and gastrointestinal symptoms. Essential oil content of thyme is responsible for its antimicrobial activity, however, it has been reported that the chemical composition of essential oils influences its biological activity. In order to explore flowering phenophases influence on the chemical composition of thyme essential oil and its antibacterial and anti-biofilm activity, plant materials were collected at the beginning of flowering, in full bloom and at the end of flowering periods in 2019.

METHODS

Essential oils from fresh and dried plant materials were distilled and analyzed with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The antibacterial activity was performed by broth microdilution and thin layer chromatography-direct bioautography (TLC-DB) assays and the anti-biofilm effect by crystal violet assay, respectively. Scanning electron microscopy was applied to illustrate the cellular changes of bacterial cells after essential oil treatment.

RESULTS

Thymol (52.33-62.46%) was the main component in the thyme essential oils. Thyme oil distilled from fresh plant material and collected at the beginning of flowering period exerted the highest antibacterial and anti-biofilm activity against Haemophilus influenzae, H. parainfluenzae and Pseudomonas aeruginosa.

CONCLUSION

The different flowering periods of Thymus vulgaris influence the antibacterial and anti-biofilm activity of its essential oils, therefore, the collection time has to be taken into consideration and not only the full bloom, but the beginning of flowering period may provide biological active thyme essential oil.

Nectar guides and floral nectary in Lamium album L. subsp. album: structure and histochemistry in light, fluorescence, and electron microscopy

Lamium album is a native common plant growing in Eurasia. It is used in medicine and cosmetics and is highly valued in apiculture. The aim of the study was to investigate the structure of the floral nectary in three stages of flower development. Additionally, histochemical studies of the nectary and nectar guides present on the lower corolla lobe were carried out. No detailed analyses of nectary tissues in this species have been conducted to date. The present analyses were performed with the use of light, fluorescence, and scanning electron microscopy. The nectary gland in the flowers of Lamium album subsp. album formed an incomplete ring at the ovary base. The nectarostomata were arranged in clusters only in the adaxial epidermis of the anterior part of the nectary. During the secretory activity of the nectary (1st day of flowering), numerous small vacuoles and cells with large lobulate nuclei with surrounding plastid clusters were observed in the epidermis and glandular parenchyma cells. The vascular bundles contained xylem and phloem elements. Corolla wilting (3rd day of flowering) was accompanied by destructive changes in the nectary parenchyma, leading to the formation of empty spaces and appearance of cell remnants on the nectary surface. The histochemical analyses revealed the presence of starch and phenolic compounds as well as acidic and neutral lipids, which are characteristic of essential oils, in the nectary tissues. The nectar guides were composed of large yellow papillae containing phenolic compounds and acidic and neutral lipids, which were also present in glandular trichomes and abaxial parenchyma cells. The present study has demonstrated that the scent of Lamium album subsp. album flowers is produced with the involvement of essential oils contained in adaxial and abaxial epidermis cells, glandular trichomes, and nectary tissues.

Chemical Composition, Antioxidant and Antibacterial Activities of Essential Oil Obtained from Chincho (Tagetes elliptica Sm) Leaves Grown in the Peruvian Andes

The chemical composition, antioxidant, and antibacterial properties of the essential oil from the leaves of Tagetes elliptica Sm., grown in Peru, were studied. The EO was extracted using steam distillation, and its chemical composition was analyzed using GC-MS, while the antioxidant activity was evaluated using the radical, scavenging capacity (DPPH and ABTS assays), and ferric reducing antioxidant power (FRAP) assays, ferrous ion chelating (FIC) activity, and the Rancimat test. The antibacterial activity against Staphylococcus aureus, Escherichia coli, and Salmonella infantis was studied using the agar well diffusion method. Twenty-seven compounds were identified in the essential oil, and the major components were cis-tagetenone (37.27%), trans-tagetenone (18.84%), dihydrotagetone (14.38%), and trans-tagetone (5.15%). With regard to antioxidant properties, the IC₅₀ values obtained for the DPPH, ABTS, and FIC assays were 53.37, 46.38, and 22.65 mg/mL, respectively. These values were lower than those obtained for standard butylated hydroxytoluene and ascorbic acid. In the Rancimat test, antioxidant activity was achieved only at high concentration. T. elliptica essential oil showed a marked antibacterial activity against all bacterial strains at all concentrations assayed. This study demonstrated that T. elliptica essential oil could be considered as an alternative to synthetic antioxidants and antimicrobial agents in the food industry.

Chemical Composition of the Essential Oil of Thymus longicaulis C. Presl. subsp. longicaulis

In this study, the chemical composition of the essential oils obtained from the aerial parts of Thymus longicaulis subsp. longicaulis naturally grown in Turkey were analyzed by GC and GC-MS and chemical differences in terms of chemotaxonomy were discussed. The main compounds in the essential oils of T. longicaulis subsp. longicaulis essential oils were 1,8-cineole (30.1%), linalool (18.0%), β-pinene (17.3%) and (E)-β-ocimene (%12.6%) Hierarchical cluster analysis was performed by examining essential oil studies of 34 samples belonging to the genus Thymus, including the Sinop sample. The results of the study were discussed with other taxa belonging to the genus.

Luteolin-7-O-Glucuronide Improves Depression-like and Stress Coping Behaviors in Sleep Deprivation Stress Model by Activation of the BDNF Signaling

Stress exposure is a major risk factor for mental disorders such as depression. Because of the limitations of classical antidepressants such as side effects, low efficacy, and difficulty in long-term use, new natural medicines and bioactive molecules from plants with greater safety and efficacy have recently attracted attention. Luteolin-7-O-glucuronide (L7Gn), a bioactive molecule present in Perilla frutescens, is known to alleviate severe inflammatory responses and oxidative stress in macrophages. However, its antistress and antidepressant effects have not been elucidated. The present study aims to explore the antidepressant the effect of L7Gn on stress-induced behaviors and the underlying mechanism in a mouse sleep deprivation (SD) model. L7Gn treatment improved depression-like and stress coping behaviors induced by SD stress, as confirmed by the tail suspension test and forced swimming test. Furthermore, L7Gn treatment reduced the blood corticosterone and hippocampal proinflammatory cytokine levels which were increased by SD stress, and L7Gn also increased the mRNA and protein levels of hippocampal brain-derived neurotrophic factor (BDNF) which were reduced by SD stress. Additionally, treatment with L7Gn resulted in increases in the phosphorylation of tropomyosin-related kinase B (TrkB), extracellular signal-regulated kinase (ERK), and cAMP response element-binding protein (CREB), which are downstream molecules of BDNF signaling. These findings suggest that L7Gn have therapeutic potential for SD-induced stress, via activating the BDNF signaling.

Thymus quinquecostatus Celak. ameliorates cerebral ischemia-reperfusion injury via dual antioxidant actions: Activating Keap1/Nrf2/HO-1 signaling pathway and directly scavenging ROS

BACKGROUND

Thymus quinquecostatus Celak. has been widely used as a spice and a folk medicine for relieving exterior syndrome and alleviating pain in China.

PURPOSE

To explore the protective effects and the underlying mechanism against cerebral ischemia-reperfusion injury (CIRI) of the T. quinquecostatus combining with its chemical composition.

STUDY DESIGN AND METHODS

High-polar extract (HPE) was extracted from T. quinquecostatus and polyphenols in HPE were enriched to obtain polyphenol-rich fraction (PRF) using Macroporous resin. The free radicals and zebrafish embryos were used to compare the antioxidant activities of HPE and PRF in vitro and in vivo. Then, the transient middle cerebral artery occlusion (tMCAO) model was established in rats. Neurological deficit score, infarction rate, morphology and apoptosis of neurons were examined to investigate the protective effects of PRF on CIRI. The mRNA and protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) and the activities of downstream antioxidant enzymes in ischemia tissues were determined to clarify the underlying mechanisms. Also, reactive oxygen species (ROS) level in zebrafish embryos were detected after incubation with PRF for a short time (2 h) to investigate whether PRF could directly eliminate free radicals. Finally, chemical composition of PRF were analyzed to investigate the material basis for antioxidant activity and anti-CIRI effect.

RESULTS

Compared with HPE, PRF showed stronger antioxidant activities. PRF exhibited obvious protective effects including ameliorating neurological deficit, lowering infarction rate, and improving the cellular morphology in hippocampus CA1 and cortex after tMCAO. TUNEL staining suggested PRF dose-dependently improved the apoptosis of the neurons in ischemic cortex. RT-qPCR and Western Blot results suggested that PRF regulated oxidative stress (OS) via activating the Keap1/Nrf2/HO-1 signaling pathway. Also, PRF could directly scavenge excessive ROS in zebrafish embryos after a short-time PRF incubation. The anti-CIRI effect might be primarily attributed to the abundant polyphenols in PRF, including flavonoids, polymethoxylated flavonoids, flavonoid glycosides, and phenolic acids.

CONCLUSION

T. quinquecostatus contains abundant polyphenols and exhibited a good protective effect against CIRI via dual antioxidant mechanisms, providing a reference for further research and application for this plant.

Barks of Three Wild Pyrus Taxa: Phenolic Constituents, Antioxidant Activity, and in Vitro and in Silico Investigations of α-Amylase and α-Glucosidase Inhibition

Dry MeOH extracts of the twig barks of Pyrus communis subsp. pyraster, P. spinosa and their hybrid P.×jordanovii nothosubsp. velenovskyi, collected in wild in Serbia, were analyzed. By LC/MS, the contents of arbutin (99.9-131.0 mg/g), chlorogenic acid (2.2-6.3 mg/g), catechin (1.0-5.3 mg/g) and total dimeric and trimeric procyanidins (42.2-61.3 mg/g), including procyanidin B2 (8.9-17.2 mg/g), were determined. Colorimetrically, high contents of total phenolics (436.2-533.4 mg GAE/g) and tannins (339.4-425.7 mg GAE/g), as well as strong total antioxidant activities (FRAP values 4.5-5.9 mmol Fe²⁺ /g), and DPPH (SC₅₀ =6.6-7.1 μg/ml) and hydroxyl radical (SC₅₀ =447.1-727.7 μg/ml) scavenging abilities were revealed. In vitro, all extracts exhibited notable inhibition of α-amylase (IC₅₀ =310.8-617.7 μg/ml) and particularly strong inhibition of α-glucosidase (IC₅₀ =2.1-3.7 μg/ml). Molecular docking predicted that among identified compounds procyanidin B2 is the best inhibitor of these carbohydrate-digesting enzymes. Obtained results showed that the barks of investigated Pyrus hybrid and its parent taxa have similar composition and bioactivity.

Histochemical and Phytochemical Analysis of Lamium album subsp. album L. Corolla: Essential Oil, Triterpenes, and Iridoids

The aim of this study was to conduct a histochemical analysis to localize lipids, terpenes, essential oil, and iridoids in the trichomes of the L. album subsp. album corolla. Morphometric examinations of individual trichome types were performed. Light and scanning electron microscopy techniques were used to show the micromorphology and localization of lipophilic compounds and iridoids in secretory trichomes with the use of histochemical tests. Additionally, the content of essential oil and its components were determined using gas chromatography-mass spectrometry (GC-MS). Qualitative analyses of triterpenes carried out using high-performance thin-layer chromatography (HPTLC) coupled with densitometric detection, and the iridoid content expressed as aucubin was examined with spectrophotometric techniques. We showed the presence of iridoids and different lipophilic compounds in papillae and glandular and non-glandular trichomes. On average, the flowers of L. album subsp. album yielded 0.04 mL/kg of essential oil, which was dominated by aldehydes, sesquiterpenes, and alkanes. The extract of the L. album subsp. album corolla contained 1.5 × 10^-3 ± 4.3 × 10^-4 mg/mL of iridoid aucubin and three triterpenes: oleanolic acid, β-amyrin, and β-amyrin acetate. Aucubin and β-amyrin acetate were detected for the first time. We suggest the use of L. album subsp. album flowers as supplements in human nutrition.

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.

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.

Thymus zygis subsp. zygis an Endemic Portuguese Plant: Phytochemical Profiling, Antioxidant, Anti-Proliferative and Anti-Inflammatory Activities

Thymus zygis subsp. zygis is an endemic Portuguese plant belonging to the Thymus zygis species. Although T. zygis is commonly used as a condiment and as a medicinal herb, a detailed description of the polyphenol composition of hydroethanolic (HE) and aqueous decoction (AD) extracts is not available. In this work, we describe for the first time a detailed phenolic composition of Thymus zygis subsp. zygis HE and AD extracts, together with their antioxidant, anti-proliferative and anti-inflammatory activities. Unlike other Thymus species, T. zygis subsp. zygis extracts contain higher amounts of luteolin-(?)-O-hexoside. However, the major phenolic compound is rosmarinic acid, and high amounts of salvianolic acids K and I were also detected. T. zygis subsp. zygis extracts exhibited significant scavenging activity of ABTS⁺, hydroxyl (^•OH), and nitric oxide (NO) radicals. Regarding the anti-proliferative/cytotoxic effect, tested against Caco-2 and HepG2 cells, the AD extract only slightly reduced cell viability at higher concentrations (IC₅₀ > 600 µg/mL, 48 h exposure), denoting very low toxicity, while the HE extract showed a high anti-proliferative effect, especially at 48 h exposure (IC₅₀ of 85.01 ± 15.10 μg/mL and 82.19 ± 2.46 μg/mL, for Caco-2 and HepG2, respectively). At non-cytotoxic concentrations, both extracts reduced the nitric oxide (NO) release by lipopolysaccharide (LPS)-stimulated RAW 264.7 cells (at 50 μg/mL, HE and AD extracts inhibited NO release in ~89% and 48%, respectively). In conclusion, the results highlight the non-toxic effect of aqueous extracts, both resembling the consumption of antioxidants in foodstuff or in functional food. Furthermore, the HE extract of T. zygis subsp. zygis is a source of promising molecules with antioxidant, anti-inflammatory and anticancer activities, highlighting its potential as a source of bioactive ingredients for nutraceutical and pharmaceutical industries.

Chemical Characterization and Bioactivity of Extracts from Thymus mastichina: A Thymus with a Distinct Salvianolic Acid Composition

Thymus mastichina, also called mastic thyme or Spanish marjoram, is endemic to the Iberian Peninsula, where it is widely used in folk medicine especially for treating digestive and respiratory systems disorders, and as a condiment to season olives. This work describes for the first time the detailed phenolic composition of exhaustive hydroethanolic extracts and aqueous decoctions of Thymus mastichina. Unlike other species of the Thymus genera, Thymus mastichina extracts contain high amounts of salvianolic acid derivatives, with salvianolic acid A isomer being the main derivative. This isomer was identified in extracts from Thymus mastichina for the first time. Also, an undescribed salvianolic acid derivative in Thymus mastichina was identified and its structure was tentatively described. Extracts from Thymus mastichina showed significant scavenging activity of 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical cation, hydroxyl, and nitric oxide radicals. The anti-proliferative effect of both T. mastichina extracts were tested against Caco-2 and HepG2 cells; the hydroethanolic extract showed a high anti-proliferative activity against Caco-2 cells compared to HepG2 cells (at 24 h exposure, the concentration that inhibits 50% of proliferation, IC₅₀, was 71.18 ± 1.05 µg/mL and 264.60 ± 11.78 µg/mL for Caco-2 and HepG2, respectively). Thus, these results make this species a promising candidate for further investigation of its anti-tumoral potential. Therefore, Thymus mastichina can be potentially used as a functional food (used as a decoction or herbal tea) or as a source of bioactive ingredients with antioxidant and anti-proliferative properties.

Chemical Analysis of Selected Seaweeds and Seagrass from the Adriatic Coast of Montenegro

Three seaweeds (Halimeda tuna, Codium bursa and Cystoseira barbata) and one seagrass (Cymodocea nodosa) were collected from the Coast of Montenegro, Gulf of Boka Kotorska and their chemical analysis was performed. In seagrass C. nodosa, three phenolic compounds were identified (diosmetin 7-sulfate, caftaric and coutaric acid). The content of β-glucan, fatty acids, sterols and micro- and macro-elements were investigated among all samples. The highest content of β-glucan was detected in C. nodosa seagrass (13.04±0.42 g/100 g). The highest polyunsaturated fatty acids (PUFAs) level was reported in C. barbata, the brown alga (7.157 mg/g), which also had the significant sterol content (fucosterol, 21.76±0.1 μg/g). Green algae, C. bursa and H. tuna, showed the highest level of sterols (β-sitosterol, 95.21±0.16 μg/g and 73.90±0.08 μg/g, respectively). H. tuna had the highest content of calcium (Ca) in amount of 55125 μg/g. In C. bursa, C. barbata and C. nodosa, the Na/K ratio was low (0.43, 0.46 and 0.69, respectively).

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.

The Antialgal Mechanism of Luteolin-7-O-Glucuronide on Phaeocystis globosa by Metabolomics Analysis

Antialgal compounds from plants have been identified as promising candidates for controlling harmful algal blooms (HABs). In our previous study, luteolin-7-O-glucuronide was used as a promising algistatic agent to control Phaeocystis globosa (P. globose) blooms; however, its antialgal mechanism on P. globosa have not yet been elaborated in detail. In this study, a liquid chromatography linked to tandem mass spectrometry (LC-MS/MS)-based untargeted metabolomic approach was used to investigate changes in intracellular and extracellular metabolites of P. globosa after exposure to luteolin-7-O-glucuronide. Significant differences in intracellular metabolites profiles were observed between treated and untreated groups; nevertheless, metabolic statuses for extracellular metabolites were similar among these two groups. For intracellular metabolites, 20 identified metabolites showed significant difference. The contents of luteolin, gallic acid, betaine and three fatty acids were increased, while the contents of α-Ketoglutarate and acetyl-CoA involved in tricarboxylic acid cycle, glutamate, and 11 organic acids were decreased. Changes in those metabolites may be induced by the antialgal compound in response to stress. The results revealed that luteolin played a vital role in the antialgal mechanism of luteolin-7-O-glucuronide on P. globosa, because luteolin increased the most in the treatment groups and had strong antialgal activity on P. globosa. α-Ketoglutarate and acetyl-CoA were the most inhibited metabolites, indicating that the antialgal compound inhibited the growth through disturbed the tricarboxylic acid (TCA) cycle of algal cells. To summarize, our data provides insights into the antialgal mechanism of luteolin-7-O-glucuronide on P. globosa, which can be used to further control P. globosa blooms.

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.

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.