Antioxidant and anticholinesterase activity of essential oils and ethanol extracts of Thymus algeriensis and Teucrium polium from Algeria

Phytochemical profile, in vitro antioxidant and antibacterial activities of different extracts of an Algerian endemic: Teucrium atratum

Teucrium atratum Pomel. is a species belonging to the Lamiaceae family used in Algerian folk medicine. The present work essentially aimed to assess the phenolic composition and to evaluate some of the biological effects of different extracts, never previously studied, of T. atratum growing in Algeria. High levels of total phenolic and flavonoids were recorded in the hydromethanolic extract. Chlorogenic acid, isoquercetin, coumarin, cinnamic acid, quercetin dihydrate, and catechin were identified in the methanolic extract by mean of HPLC. The antioxidant activity assessed showed that the methanolic extract was the most active, while, the hydromethanolic extract showed a great power to reduce iron. In addition, all extracts had a significant antibacterial effect against the four tested bacterial strains, with Staphylococcus aureus as the most sensitive one. These findings can be a starting point to evaluate the plant as a source of natural bioactive compounds with antioxidant and antibacterial effects.

Variation in Phenolic Content, Antioxidant Activity and Alpha-amylase and Acetylcholinesterase Inhibitory Capacities of Different Extracts from Tunisian Satureja barceloi (Willk) L

The antioxidant activity and the anti-α-amylase and anti-acetylcholinesterase capacities of secondary metabolites from different organs (roots, stems, leaves and flowers) of Tunisian Satureja barceloi were determined. The variation in the distribution of phenolic metabolites among roots, stems, leaves and flowers extracts of S. barceloi with various solvent systems (methanol, ethyl acetate, hexane and distilled water) has not been characterized before. Significant variation of phenolic compounds was observed according to organs rather than to extracting solvents. The analyzed organs show a high level of phenolic compounds although the stems contains the highest total polyphenols (132.53±0.48 mg AGE/g Ex), flavonoids (48.99±0.65 mg RE/g Ex) and flavonols (34.93±0.29 mg QE/g Ex) contents. The phenolic fraction was dominated by sagerinic acid, caffeic acid glucoside and epigallocatechin, detected using HPLC-PDA/ESI-MS. The antioxidant activity of all extracts, evaluated by four in vitro tests, was high and varied significantly according to the type of solvent used and the plant organ. The aqueous extracts of leaves exhibited the greatest inhibitory effect on alpha-amylase while the methanolic extract of leaves and stems revealed the most important acetylcholinesterase inhibitory effect. Hence, S. barceloi extracts could be used as a source of various bioactive molecules in pharmaceutical industry.

Towards a better understanding of commonly used medicinal plants from Turkiye: Detailed phytochemical screening and biological activity studies of two Teucrium L. species with in vitro and in silico approach

ETHNOPHARMACOLOGICAL RELEVANCE

Since ancient times, Teucrium L. species have been among the most commonly used traditional medicinal plants mainly in the Mediterranean region. From tackling gastrointestinal problems to maintaining the healthy functioning of endocrine glands, and from treating malaria to severe dermatological disorders, Teucrium species are known to have extensive therapeutic applications. Teucrium polium L. and Teucrium parviflorum Schreb. are the two members of the genus that have been used in Turkish folk medicine for various medicinal purposes.

AIM OF THE STUDY

To determine the phytochemical compositions of the essential oils and ethanol extracts of Teucrium polium and Teucrium parviflorum collected from different locations in Turkiye along with the investigation of in vitro antioxidant, anticancer, antimicrobial activities, and both in vitro and in silico enzyme inhibitory activities of the extracts.

MATERIALS AND METHODS

Ethanol extracts of Teucrium polium aerial parts and roots, and aerial parts of Teucrium parviflorum were prepared. Volatile profiling of the essential oils by GC-MS, phytochemical profiling of the ethanol extracts by LC-HRMS, antioxidant activity by DPPH radical scavenging, ABTS cation radical scavenging, CUPRAC, and metal chelating activity assays, anticholinesterase, antityrosinase, antiurease, activities by different enzyme inhibitory activity assays, anticancer activity by SRB cell viability assay, and antimicrobial activity against a standard panel of bacteria and fungi by the microbroth dilution technique. Molecular docking studies were performed by Autodock Vina (Ver. 1.1.2).

RESULTS

The studied extracts were found to be quite rich in various biologically important volatile and phenolic compounds. (-)-Epigallocatechin gallate, which is a molecule renowned for having great therapeutic potential, was the major compound of all extracts. Teucrium polium aerial parts extract was revealed as a great source for naringenin with 16327 ± 685.23 μg/g extract. All extracts exerted significant antioxidant activity by different methods. All extracts demonstrated antibutrylcholinesterase, antityrosinase, and antiurease activities by in vitro and in silico assays. Teucrium polium roots extract stood out with remarkable tyrosinase and urease inhibitory and cytotoxic activities.

CONCLUSION

The obtained results from this multi-disciplinary study proves that the traditional use of these two Teucrium species is justified, and the mechanisms behind are enlightened.

Trace Element Quantification in Two Algerian Thymes (Thymus algeriensis Boiss & Reut. and Thymus capitatus (L.) Hoffm. & Link) Using EDXRF Spectrometry

In an attempt to know the elemental composition of two endemic Algerian thyme species, we analyzed eleven mineral and trace elements (Br, Ca, Cr, Cu, Fe, K, Mn, Rb, Sr, V, and Zn) in Thymus algeriensis Boiss & Reut. and Thymus capitatus (L.) Hoffm. & Link. These species are commonly used in Algeria as aromatic and medicinal shrubs. The total concentrations of chemical elements were determined by EDXRF spectrometry. The instrument calibration was assessed through the analysis of certified reference material CRM-336 (Lichen) from the IAEA, Vienna, Austria. The results show that the highest concentrations of the micronutrients (Br, Cr, Cu, Mn, Sr, V, and Zn) were registered in T. algeriensis, while the maximum concentrations of Ca, Fe, and the non-essential element, Rb, were found in T. capitatus. Potassium contents were similar in the two species. The concentrations of essential chemical elements in T. algeriensis leaves were found in the following order: K > Ca > Mn > Fe > Zn > Cu > Cr. However, the order of these elements in T. capitatus was Ca > K > Fe > Zn > Mn > Cu > Cr. Principal component analysis (PCA) showed that T. algeriensis was highly associated with Br, Cr, Cu, Mn, Sr, V, and Zn, while T. capitatus was correlated with Ca, Fe, K, and Rb. Dietary element intakes through ingestion of 1 teaspoon of dry powder (~ 10 g) were estimated and compared to recommended daily intakes and permissible limits under FAO/WHO guidelines. In all cases, these estimates were below those levels. These findings can enhance the dissemination of these medicinal plants, which have medicinal and organoleptic properties, and provide an experiment-based guidance to the pharmaceutical and food industries.

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.

The Therapeutic Potential of Ethnomedicinally Important Anatolian Thyme Species: A Phytochemical and Biological Assessment

Thyme has been used for various therapeutic purposes in many different cultures, which makes it one of the most riveting medicinal plants throughout history. From its beneficial effects on the respiratory tract or the gastrointestinal system, to its unique skin-related activities, the investigation of the medicinal properties of thyme has always been an alluring topic for researchers aiming to develop conventional medications from this traditional herb. With an incentive to contribute to the extensive thyme research, three Thymus L. species namely Thymus cariensis Hub-Mor. & Jalas (endemic), Thymus praceox subsp. grossheimii (Ronniger) Jalas, and Thymus pubescens Boiss. et Kotschy ex Celak from Turkey were deeply investigated within this study. The analysis of the phytochemical constituents of the extracts was conducted by LC-MS/MS. 12 biologically important secondary metabolites (p-coumaric acid, caffeic acid, salicylic acid, quinic acid, fumaric acid, vanillin, malic acid, rutin, apigenin, naringenin, and nicotiflorin) were detected in all extracts. Their total phenolic and flavonoid contents were calculated (11.15 ± 0.17-61.12 ± 2.59 μg PEs/mg extract, 2.53 ± 0.04-40.28 ± 0.92 μg QEs/mg extract, respectively), and the antioxidant potential of the extracts was evaluated by DPPH and ABTS radical scavenging and CUPRAC activity methods, accordingly, the extracts were shown to possess significant antioxidant activity. Among them, Thymus cariensis Hub-Mor. & Jalas was the most active with IC50 values of 34.97 ± 1.00 μg/ml and 9.98 ± 0.04 μg/ml regarding the DPPH and ABTS radical scavenging assays, respectively, and an A0.5 value of 5.80 ± 0.02 μg/ml according to CUPRAC activity method. Their anticholinesterase, antityrosinase, and antiurease activities were also tested, Thymus cariensis Hub-Mor. & Jalas (35.61 ± 1.20%) and Thymus pubescens Boiss. et Kotschy ex Celak aerial part extract (33.49 ± 1.39%) exhibited moderate antibutyrylcholinesterase activity at 200 μg/ml concentration. The results of the cell viability assay indicated that the extracts demonstrated moderate-to-low cytotoxicity on A498 human renal cell lines. Furthermore, all studied extracts exerted noteworthy antimicrobial activity, especially against Candida tropicalis (MIC values: 19.53-78.12 μg/ml). The presented data substantiates the use of thyme extracts as therapeutic agents in both ethnomedicine and conventional therapies.

Unraveling the Phytochemistry, Traditional Uses, and Biological and Pharmacological Activities of Thymus algeriensis Boiss. & Reut

Growing concern for public health has increased the need to change the paradigm towards a healthcare system that advocates holistic practices while reducing adverse effects. Herbal therapy is becoming an integral part of the therapeutic arsenal, and several successful plant-derived compounds/molecules are being introduced into the market. The medicinal plants belonging to the genus Thymus are among the most important species within the Lamiaceae family. One of them is Thymus algeriensis which is mainly distributed in the Mediterranean region. For a long time, this species has been used in traditional medicine to treat several disorders and diseases including inflammation, diabetes, rheumatism, digestive, and respiratory affections. This review describes the traditional uses, phytochemical composition, and biological and pharmacological activities of T. algeriensis extracts. Data were obtained using electronic databases such as SciFindern, ScienceDirect, Scopus, and Web of Science. Several plant-based extracts and a broad spectrum of identified secondary metabolites were highlighted and discussed with respective activities and modes of action. T. algeriensis represents a promising natural resource for the pharmaceutical industry mainly for antioxidant, anti-inflammatory, antimicrobial, and anticancer activities. Considering these findings, more research is needed to transmute the conventional uses of T. algeriensis into scientifically sound information. Moreover, extensive preclinical, clinical, toxicological, and pharmacokinetic trials on this species and its derivatives compounds are required to underpin the mechanisms of action and ensure its biosafety and efficiency. This comprehensive review provides a scientific basis for future investigations on the use of T. algeriensis and derived compounds in health maintenance and promotion and disease prevention.

Determination of Anti-Alzheimer's Disease Activity of Selected Plant Ingredients

Neurodegenerative diseases, among which one of the more common is Alzheimer’s disease, are the one of the biggest global public health challenges facing our generation because of the increasing elderly population in most countries. With the growing burden of these diseases, it is essential to discover and develop new treatment options capable of preventing and treating them. Neurodegenerative diseases, among which one of the most common is Alzheimer’s disease, are a multifactorial disease and therefore demand multiple therapeutic approaches. One of the most important therapeutic strategies is controlling the level of acetylcholine—a neurotransmitter in cholinergic synapses—by blocking the degradation of acetylcholine using acetylcholinesterase inhibitors such as tacrine, galantamine, donepezil and rivastigmine. However, these drugs can cause some adverse side effects, such as hepatotoxicity and gastrointestinal disorder. Thus, the search for new, more effective drugs is very important. In the last few years, different active constituents from plants have been tested as potential drugs in neurodegenerative disease therapy. The availability, lower price and less toxic effects of herbal medicines compared with synthetic agents make them a simple and excellent choice in the treatment of neurodegenerative diseases. The empirical approach to discovering new drugs from the systematic screening of plant extracts or plant-derived compounds is still an important strategy when it comes to finding new biologically active substances. The aim of this review is to identify new, safe and effective compounds that are potential candidates for further in vivo and clinical tests from which more effective drugs for the treatment of Alzheimer’s disease could be selected. We reviewed the methods used to determine anti-Alzheimer’s disease activity. Here, we have discussed the relevance of plant-derived compounds with in vitro activity. Various plants and phytochemical compounds have shown different activity that could be beneficial in the treatment of Alzheimer’s disorders. Most often, medicinal plants and their active components have been investigated as acetylcholinesterase and/or butyrylcholinesterase activity inhibitors, modifiers of β-amyloid processing and antioxidant agents. This study also aims to highlight species with assessed efficacy, usable plant parts and the most active plant components in order to identify species and compounds of interest for further study. Future research directions are suggested and recommendations made to expand the use of medicinal plants, their formulations and plant-derived active compounds to prevent, mitigate and treat Alzheimer’s disease.

Antibacterial and antioxidant activities of a novel enol ether nor-sesquiterpene isolated from Myrtus nivellei Batt. & Trab

Myrtus nivellei is a plant traditionally used to treat diseases including infection of microbial origin. Several M. nivellei Batt. & Trab. extracts (dichloromethane, methanol and ethanol/water) were screened for their activity against 36 microorganisms, including strains resistant to antibiotics. These extracts inhibited on average 15 bacteria strains with minimum inhibition concentrations (MICs) ranging from 0.07 to 1.20 mg/mL. Bioassay guided fractionation was carried out with bioautography on TLC plates using four pathogenic bacteria strains, and following chromatographies (CPC and HPLC) led to the isolation of two novel enol ether nor-cadinane sesquiterpenes from the dichloromethane extract. The major compound (1) showed a strong antibacterial activity. Minimal inhibition concentration and minimal bactericidal concentration (MBC) values were determined against four bacteria: Acinetobacter baumanii, Stenotrophomonas maltophilia, Yersinia pseudotuberculosis and Staphylococcus lugdunensis. The best activity was observed against Acinetobacter baumanii with a MIC value of 9.7 μg/mL. This novel compound was also very active against a Staphylococcus aureus strain resistant to amoxicillin (MIC 19.5 μg/mL). In addition, compound 1 showed a very high antioxidant activity with both DPPH and metal chelate methods.

A Review of the Phytochemistry, Traditional Uses and Biological Activities of the Essential Oils of Genus Teucrium

The genus Teucrium is a large and polymorphic genus of the Lamiaceae family distributed in mild climate zones, particularly in the Mediterranean basin and Central Asia. Studies of nonvolatile constituents of Teucrium species showed that they are a rich source of neo-clerodane diterpenoids, considered as chemotaxonomic markers of the genus. In addition to the nonvolatile metabolites, there has been a large interest in the essential oils of this genus. In this review, a complete survey of the chemical composition and biological properties of the essential oils isolated from Teucrium taxa is provided. In traditional medicine, since ancient times, species of this genus have been widely implemented for their biological properties, including antimicrobial, anti-inflammatory, antispasmodic, insecticidal, anti-malaria, etc. Therefore, a complete review of all of the traditional uses of Teucrium taxa are also reported.

Distillation time effecting on the composition of Origanum floribundum essential oils and their antioxidant and antimicrobial activities

The essential oils (EOs) of Origanum floribundum Munby, an aromatic and medicinal plant endemic in Algeria, were extracted by different hydrodistillation times (30 min, 1, 2 and 3 h) and analyzed by GC and GC-MS. The chromatographic analysis showed that thymol (32.7-45.0%), p-cymene (16.8-23.1%) and γ-terpinene (21.6-28.7%) were the most prominent components of the oils. The antioxidant ability was measured using the reductive potential, thiobarbituric acid reactive substances (TBARS) assay and the inhibition of free radicals DPPH^● and ABTS^●+. Antibacterial activity was assessed by the disc diffusion method against three bacteria (Escherichia coli, Staphylococcus aureus and Bacillus subtilis) and one fungus (Candida albicans). Minimal inhibitory concentrations (MICs) were determined using a microdilution method. Thymol is one of the compounds of EOs, which are widely reported as very biologically active. Although the oil isolated for 30 min was the less-thymol rich, it was the most active with all the antioxidant tests. In the most cases, the antimicrobial activity showed the best results with oils isolated for 30 min and 3 h (MIC = 0.25-1.75 μL/mL). These results suggest that it might be possible to isolate the EO from this plant for a minimum distillation time to obtain oil that can give maximum biological activities.

The Essential Oil Compositions of Three Teucrium Taxa Growing Wild in Sicily: HCA and PCA Analyses

The chemical composition and the qualitative and quantitative variability of the essential oils of three taxa belonging to the Teucrium genus were studied. The investigated taxa, that grow wild in Sicily, were Teucrium flavum L. (section Chamaedrys (Mill.) Scheb.), Teucrium montanum and Teucrium capitatum L. of section Polium (Mill.) Scheb. Essential oils were extracted by hydrodistillation and analyzed by GC-MS. In total, 74 compounds were identified. Sesquiterpene hydrocarbons were found to be the main group for T. flavum (48.3%). T. capitatum consisted essentially of monoterpene hydrocarbons (72.7%), with α-pinene (19.9%), β-pinene (27.6%) and sylvestrene (16.6%) as the most abundant compounds whereas ledene oxide (12.1%), epiglobulol (13.5%) and longifolenaldehyde (14.5%) were identified as the main constituents among the oxygenated sesquiterpenes (63.5%) of T. montanum. Furthermore, a complete literature review on the composition of the essential oils of all the other accessions of these Teucrium taxa, studied so far, was performed. Hierarchical Cluster Analysis (HCA) and Principal Component Analyses (PCA) were used in order to demonstrate geographical variations in the composition of the essential oils.

LC-MS Analysis and Antioxidant Activity of the Hydro-alcoholic Extract of Melissa Officinalis L. From Algeria

The present work focuses on evaluation of the chemical composition and antioxidant activity of the hydro-methanolic extract of Melissa officinalis from Algeria. The liquid chromatography-mass spectrometry analysis allowed the identification of six compounds: caffeic acid, caftaric acid, hydroxyjasmonic acid glucoside, caftaric acid glucoside, rosmarinic acid and sagerinic acid. The in-vitro antioxidant activity of the hydro-methanolic extract was evaluated by using four different methods including: radical scavenging assay (DPPH), scavenging activity (ABTS), cupric reducing antioxidant capacity, and ferric reducing power assay. The extract exhibited a relatively strong antioxidant activity compared to the synthetic antioxidants. The highest radical scavenging activity was registered using DPPH and ABTS methods, IC50= 20.53±2.64 μg/mL and 22.50±0.67 μg/mL, respectively. These results suggest that Melissa officinalis L. could be considered a potential source of natural antioxidants with potential interest in the agrochemical and pharmaceutical industries.

Enhancement of Antioxidant Activity in O/W Emulsion and Cholesterol-Reducing Capacity of Epigallocatechin by Derivatization with Representative Phytosterols

In this study, derivatization of epigallocatechin (EGC) by representative phytosterols (stigmasterol and β-sitosterol) was performed employing Steglich esterification. The structural identity and purity of epigallocatechin β-sitosterol (ESi) and epigallocatechin stigmasterol (ESt) were confirmed by NMR, FT-IR, and HPLC-MS. Further evaluation of ESi and ESt revealed their extraordinary antioxidant activities in O/W emulsion. Two different radical sources in oil or aqueous phase were applied to explore the antioxidant behavior in O/W emulsion. The mechanism was further investigated by fluorescent microscopy and transmission electron microscopy (TEM). Furthermore, incorporation of EGC with stigmasterol and β-sitosterol notably enhanced the cholesterol-reducing activity. TEM studies suggested the hydrogen bonding of EGC strengthened the aggregation network of ESi and ESt in the bile salt micelle. The exceptional properties of ESi and ESt signified their intriguing utilization in the food industry.