Bio-efficacy of the essential oil of oregano (Origanum vulgare Lamiaceae. Ssp. Hirtum)

A Comprehensive Review of Essential Oils and Their Pharmacological Activities in Neurological Disorders: Exploring Neuroprotective Potential

Numerous studies have demonstrated essential oils' diverse chemical compositions and pharmacological properties encompassing antinociceptive, anxiolytic-like, and anticonvulsant activities, among other notable effects. The utilization of essential oils, whether inhaled, orally ingested, or applied topically, has commonly been employed as adjunctive therapy for individuals experiencing anxiety, insomnia, convulsions, pain, and cognitive impairment. The utilization of synthetic medications in the treatment of various disorders and symptoms is associated with a wide array of negative consequences. Consequently, numerous research groups across the globe have been prompted to explore the efficacy of natural alternatives such as essential oils. This review provides a comprehensive overview of the existing literature on the pharmacological properties of essential oils and their derived compounds and the underlying mechanisms responsible for these observed effects. The primary emphasis is on essential oils and their constituents, specifically targeting the nervous system and exhibiting significant potential in treating neurodegenerative disorders. The current state of research in this field is characterized by its preliminary nature, highlighting the necessity for a more comprehensive overlook of the therapeutic advantages of essential oils and their components. Integrating essential oils into conventional therapies can enhance the effectiveness of comprehensive treatment regimens for neurodegenerative diseases, offering a more holistic approach to addressing the multifaceted nature of these conditions.

Hypoglycemic effect of rosmarinic acid-rich infusion (RosCE) from Origanum vulgare in alloxan-induced diabetic rats

Origanum vulgare, known for its medicinal value, is officially accepted in many countries. The flowers and leaves are used globally in homeopathy. In Brazilian folk medicine, O. vulgare has been used to treat diabetes mellitus. This study evaluated the hypoglycemic activity of an infusion extract (RosCE) of commercially available O. vulgare leaves in alloxan-induced diabetic rats. Oral administration of RosCE resulted in the reduction of blood glucose levels after the first day of treatment, compared to the diabetic control group. These results showed that RosCE displays hypoglycemic activity, which may be due to the combined effect of rosmarinic acid, and other minor compounds. Reversed phase-high performance liquid chromatography-diode array detection was used to identify and quantify the major constituents of RosCE. This study presents evidence that supports the folkloric use of O. vulgare for the treatment of hyperglycemia, confirming the use of its infusion as an antidiabetic herbal medicine.

The Potential of Lamiaceae Herbs for Mitigation of Overweight, Obesity, and Fatty Liver: Studies and Perspectives

Numerous plants, plant extracts, and plant-derived compounds are being explored for their beneficial effects against overweight and liver diseases. Obesity is associated with the increased prevalence of non-alcoholic fatty liver disease (NAFLD), becoming the most common liver disease in Western countries. Obesity and NAFLD are closely associated with many other metabolic alternations such as insulin resistance, diabetes mellitus, and cardiovascular diseases. Many herbs of the Lamiaceae family are widely employed as food and spices in the Mediterranean area, but also in folk medicine, and their use for the management of metabolic disorders is well documented. Hereby, we summarized the scientific results of the medicinal and nutraceutical potential of plants from the Lamiaceae family for prevention and mitigation of overweight and fatty liver. The evidence indicates that Lamiaceae plants may be a cost-effective source of nutraceuticals and/or phytochemicals to be used in the management of metabolic-related conditions such as obesity and NAFLD. PubMed, Google Scholar, Scopus, and SciFinder were accessed to collect data on traditional medicinal plants, compounds derived from plants, their reported anti-obesity mechanisms, and therapeutic targets.

An Up-To-Date Review Regarding Cutaneous Benefits of Origanum vulgare L. Essential Oil

Due to the plethora of pharmacological activities reported in the literature, Origanum vulgare L. is a valuable aromatic plant for the medicine of the XXI century. Recent studies highlight that Origanum vulgare L. essential oil (OvEo) has gained attention in the dermatological field due to the cosmeceutical potential correlated with the presence of thymol and carvacrol. As a result of the fulminant expansion of bacterial resistance to antibiotics and the aggressiveness of skin infections, OvEo was extensively studied for its antimicrobial activity against Staphyloccocus spp. and Pseudomonas aeruginosa. Moreover, researchers have also assessed the anti-inflammatory activity of OvEo, suggesting its tissue remodeling and wound healing potential. Whereas OvEo comprises important biological activities that are used in a wide range of pathologies, recently, essential oils have shown great potential in the development of new therapeutic alternatives for skin disorders, such as acne, wounds or aging. Furthermore, substantial efforts have been committed to the development of modern formulations, such as microemulsions and nanoemulsions, in order to create the possibility for topical application. The review brings to the fore the most recent findings in the dermatological field regarding potential plant-based therapies involving OvEo, emphasizing the modern pharmaceutical formulation approaches and the cutaneous benefits in skin disorders.

Genetic and Flower Volatile Diversity in Natural Populations of Origanum vulgare subsp. hirtum (Link) Ietsw. in Bulgaria: Toward the Development of a Core Collection

We studied the genetic and flower volatile diversity in natural populations of Origanum vulgare subsp. hirtum (Link) Ietsw. in Bulgaria using simple sequence repeat (SSR) and sequence-related amplified polymorphism (SRAP) markers and gas chromatography/mass spectrometry (GC/MS) analysis of flower volatiles from individual plants. Two regions, including the Kresna Gorge and Eastern Rhodopes, typical for the species comprising eight populations and 239 individual plants were included in this study. An analysis with 11 SSR markers and eight SRAP primer combinations showed that SRAP markers were substantially more informative than the SSR markers and were further used for genetic diversity analysis. The results showed low-range to mid-range genetic differentiation between the populations with pairwise fixation index (Fst) values ranging between 0.0047 and 0.11. A total of 10 genetic clusters were identified. An analysis of the flower volatile diversity identified a total of 63 compounds with the vast majority of plants belonging to the carvacrol chemotype and just a single plant to the thymol chemotype. Large deviations were observed for individual compounds within each region as well as within the populations. Hierarchical clustering showed a clear sample grouping based on the two different regions. In addition, an in-depth analysis identified six major and 23 minor metabolite clusters. The overall data set and cluster analysis were further used for the development and testing of a simple and straightforward strategy for the selection of individual plants for the development of a core collection representing the sampled natural populations for this species in Bulgaria. The proposed strategy involves precise genetic clustering of the tested plants followed by the selection of a minimal set from each genetic cluster representing the different metabolite clusters. The selected core set was further compared with a core set extracted by the PowerCore software. A comparison of the genetic and metabolic affiliation of the members of both sets showed that the reported approach selected representatives from each genetic cluster and minor metabolic cluster, whereas some metabolic clusters were unrepresented in the PowerCore set. The feasibility and efficiency of applying the pointed strategy for the development of a core collection representing both the genetic and metabolite diversity of natural populations in aromatic and medicinal plants toward subsequent steps of selection and breeding are discussed.

Is the Antimicrobial Activity of Hydrolates Lower than That of Essential Oils?

Among the top five human infections requiring medical treatment is dermatitis. Treatment of bacterial and fungal skin infections is usually based on antibiotic therapy, which is often ineffective due to the involvement of antibiotic-resistant microbial strains. The aim of this study was to compare the antimicrobial activity of essential oils (EOs) and hydrolates (Hys) extracted from six aromatic plants grown in Italy (Lavandula angustifolia, Lavandula intermedia, Origanum hirtum, Satureja montana, Monarda didyma, and Monarda fistulosa) towards fungal (Candida albicans, Candida parapsilosis, Candida glabrata and Candida tropicalis; Trichophyton soudanense, Trichophyton tonsurans, Trichophyton rubrum, Trichophyton violaceum and Microsporum canis) and bacterial strains (Staphylococcus aureus MRSA, Staphylococcus aureus MSSA, Streptococcus pyogenes, E. faecalis, Enterococcus faecalis VRE, and Enterococcus faecium) potentially pathogenic for human skin. The composition and antimicrobial activity of EOs and Hys were evaluated using the Gas-chromatography mass spectrometry and micro dilution-broth test, respectively. The volatiles’ conversion factors (CFs) were calculated to compare the activity of Hys with that of the corresponding EOs. Data show that, although the minimum inhibitory concentration values of EOs are lower than the corresponding Hys, the volatiles contained in Hys are more effective at inhibiting microbial growth because they are active at lower concentrations.

A Review of the Phytochemistry and Antimicrobial Properties of Origanum vulgare L. and Subspecies

Origanum vulgare L. (O. vulgare) is an important medicinal herb of the family Lamiaceae. In the current study, we explained the critical evaluation of traditional uses, the phytochemistry and the antimicrobial properties of O. vulgare and its subspecies, with a focus on the mechanisms of actions of the most important phytochemicals from O. vulgare subspecies. The most important phytochemicals of O. vulgare are volatile (essential oil) and non-volatile phenolic compounds (phenolic acids & flavonoids). The constituents of the O. vulgare essential oil (EO) include high percentages of thymol and carvacrol with excellent antimicrobial activity alone or in combination with other antibiotics. Interesting results have been reported the remarkable antimicrobial activities of infusion or tea products of O. vulgare with a high amount of EO against multidrug-resistant bacterial and fungal microorganism (such as Escherichia coli, Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa). The most important antibacterial mechanisms of O. vulgare are enzyme inhibition, efflux pump inhibition, ATP depletion, biofilm formation inhibition and cytoplasmic membrane damage. The antimicrobial activity of the hirtum subspecies has been confirmed in different in-vitro and in-vivo studies. The present review confirms the clinical and preclinical research showing the O. vulgare and its subspecies antimicrobial effects.

Phytochemical constituents, biological activities, and health-promoting effects of the genus Origanum

Origanum species are mostly distributed around the Mediterranean, Euro-Siberian, and Iran-Siberian regions. Since time immemorial, the genus has popularly been used in Southern Europe, as well as on the American continent as a spice now known all over the world under the name "oregano" or "pizza-spice." Origanum plants are also employed to prepare bitter tinctures, wines, vermouths, beer, and kvass. The major components of Origanum essential oil are various terpenes, phenols, phenolic acids, and flavonoids with predominant occurrence of carvacrol and thymol (with reasonable amounts of p-cymen and -terpinene) or of terpinene-4-ol, linalool, and sabinene hydrate. Many species of Origanum genus are used to treat kidney, digestive, nervous, and respiratory disorders, spasms, sore throat, diabetes, lean menstruation, hypertension, cold, insomnia, toothache, headache, epilepsy, urinary tract infections, etc. Origanum essential oil showed potent bioactivities owing to its major constituents' carvacrol, thymol, and monoterpenes. Several preclinical studies evidenced its pharmacological potential as antiproliferative or anticancer, antidiabetic, antihyperlipidemic, anti-obesity, renoprotective, antiinflammatory, vasoprotective, cardioprotective, antinociceptive, insecticidal, and hepatoprotective properties. Its nanotechnological applications as a promising pharmaceutical in order to enhance the solubility, physicochemical stability, and the accumulation rate of its essential oils have been investigated. However, Origanum has been reported causing angioedema, perioral dermatitis, allergic reaction, inhibition of platelet aggregation, hypoglycemia, and abortion. Conclusive evidences are still required for its clinical applications against human medical conditions. Toxicity analyses and risk assessment will aid to its safe and efficacious application. In addition, elaborate structure-activity studies are needed to explore the potential use of Origanum-derived phytochemicals as promising drug candidates.

Date of harvesting affects yields and quality of Origanum vulgare ssp. hirtum (Link) Ietswaart

BACKGROUND

The aim of this experiment was to determine the essential oil, flavonoid and phenolic acid contents as well as yields of raw material collected from different morphological parts of Greek oregano in five consecutive developmental stages. Antibacterial and antifungal properties of methanol and hexane extracts from the aerial parts of Greek oregano were assessed as well.

RESULTS

The findings showed that Greek oregano grown in the cool climate of central Europe had a considerable variation in the essential oil yield and chemical composition related to the harvesting stage. Forty volatile compounds were detected in essential oils, with the highest amount of carvacrol, thymol, p-cymene and γ-terpinene, constituting in total from 90.72 to 92.9%.

CONCLUSION

Different morphological parts of the plants contained different amounts of essential oils, with dominant amounts in the flowers. The essential oil content systematically increased, reaching its maximum in the full blooming period. In that phase, the plants produced the highest yields of aboveground parts and provided approximately 190 L ha^-1 of essential oils. Mainly owing to its content of phenolic compounds, the Greek oregano raw material exhibited relatively high antioxidant activity. The data obtained clearly showed the inhibitory activity of methanol and hexane extracts against pathogenic bacteria and fungi. © 2019 Society of Chemical Industry.

Physico-Chemical and Biological Evaluation of PLCL/SF Nanofibers Loaded with Oregano Essential Oil

Essential oils are complex volatile compounds, extracted from specific plant species, with promising therapeutic potentials. However, their volatile nature presents a major hindrance in using them as therapeutic agents. In the current study, we successfully encapsulated oregano essential oil (OEO) into Poly (l-lactic acid-co-e-caprolactone) /Silk Fibroin (PLCL/SF) polymers through electrospinning. The nanofibrous membrane (NF) was fabricated and characterized for various physico-chemical and biological attributions. Homogenous and bead free morphology was confirmed by scanning electron microscopy (SEM). Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) confirmed the successful loading of OEO and its physical interaction with the blend of PLCL/SF. Moreover, thermogravimetric analysis (TGA) also confirmed the successful loading and thermostability of the OEO. Although a significant change was noted in tensile strength due to the loading of OEO, the mechanical behaviour still falls into the acceptable ranges required for skin tissue engineering. Similarly, fabricated material was evaluated for its biological significance. Liquid chromatography-mass spectrometry (LC-MS) was employed to determine the release behaviour of OEO from electrospun membranes. LC-MS data, noted for 48 h, confirmed the biphasic release of OEO. Furthermore, NF membranes have shown strong antioxidant and anti-tumor activities. This material is promising and can be implanted to avoid the recurrence of the tumor after its surgical removal.

Oregano (Origanum vulgare) extract for food preservation and improvement in gastrointestinal health

The Mediterranean diet has long been known to provide a variety of health benefits such as cardiovascular protection, cancer prevention, and lowering gastrointestinal inflammation. Oregano (Origanum vulgare) is an herb prominent in the Mediterranean diet, and has been shown to possess several bioactive properties including anti-oxidant, anti-microbial, anti-inflammatory, and analgesic properties. The anti-oxidant and anti-microbial properties of oregano also make it a strong candidate as a natural food preservative. Because of the recent public concern with synthetic food preservatives, natural alternatives are increasingly being evaluated for effective food preservation. Oregano extract (OE) and essential oil (OEO) are two such agents that have shown promise as natural food preservatives. Additionally, oregano is being evaluated for its positive effect on gastrointestinal health, suggesting an additional benefit of food preservation with oregano. This review will describe in vitro studies related to the anti-microbial and anti-oxidant properties of oregano along with food preservation studies with oregano in various model food matrices. The major phytochemical content reported for OE and OEO will also be outlined to highlight the importance of characterizing the extract that is used, since the extraction process can have a significant effect on the phytochemicals therein. Finally, in vivo studies that investigate the gastrointestinal health benefits of oregano, specifically against inflammation, will be addressed to show the impact of oregano on gastrointestinal health.

Chemical composition and antioxidant activities of essential oils from different parts of the oregano

This research was undertaken in order to characterize the chemical compositions and evaluate the antioxidant activities of essential oils obtained from different parts of the Origanum vulgare L. It is a medicinal plant used in traditional Chinese medicine for the treatment of heat stroke, fever, vomiting, acute gastroenteritis, and respiratory disorders. The chemical compositions of the three essential oils from different parts of the oregano (leaves-flowers, stems, and roots) were identified by gas chromatography-mass spectrometry (GC-MS). The antioxidant activity of each essential oil was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and reducing the power test. Among the essential oils from different parts of the oregano, the leaf-flower oils have the best antioxidant activities, whereas the stem oils are the worst. The results of the DPPH free radical scavenging assay showed that the half maximal inhibitory concentration (IC₅₀) values of the essential oils were (0.332±0.040) mg/ml (leaves-flowers), (0.357±0.031) mg/ml (roots), and (0.501±0.029) mg/ml (stems), respectively. Interestingly, the results of reducing the power test also revealed that when the concentration exceeded 1.25 mg/ml, the leaf-flower oils had the highest reducing power; however, the stem oils were the lowest.

Essential Oils of Oregano: Biological Activity beyond Their Antimicrobial Properties

Essential oils of oregano are widely recognized for their antimicrobial activity, as well as their antiviral and antifungal properties. Nevertheless, recent investigations have demonstrated that these compounds are also potent antioxidant, anti-inflammatory, antidiabetic and cancer suppressor agents. These properties of oregano essential oils are of potential interest to the food, cosmetic and pharmaceutical industries. The aim of this manuscript is to review the latest evidence regarding essential oils of oregano and their beneficial effects on health.