Essential oil composition, total phenolic content, antioxidant and antibiofilm activities of four Origanum species from southeastern Turkey

Formulation of sustainable, biodegradable chitosan films enriched with Origanum majorana extract as an eco-friendly antimicrobial food packaging for possible food preservation

In this work, chitosan (Cs) was blended with different concentrations of Origanum majorana extract (OmE) that extracted using ethyl acetate and used for the formation of food packaging films. Based on the utilized volumes of OmE (2.5, 5, and 7.5 mL) that were mixed with 27.5, 25, and 22.5 mL of Cs, these different film samples (2.5 OmE loaded Cs film, 5 OmE loaded Cs film and 7.5 OmE loaded Cs film) were obtained and compared with the film of pure Cs. The extraction yields of OmE were found to be 13 g and 10.4 g % when using ethyl acetate (OmE) and methanol (OmME), respectively, with total phenolic content measured at 889.30 μg GAE/g for the ethyl acetate extract and 810.21 μg GAE/g for the methanol extract, indicating a substantial amount of bioactive compounds available for formulation. Antimicrobial activity was assessed against various foodborne pathogens, with the 7.5 OmE loaded Cs film demonstrating the highest efficacy, achieving inhibition zones of 27 mm against E. coli and 25 mm against S. aureus. This research underscores the potential of Cs-based films loaded with O. majorana extract as a viable solution for active food packaging, addressing environmental concerns and food safety.

Identification of compounds from Origanum compactum and Origanum elongatum using HPLC/UV-ESI-MS and comparative analysis of their antioxidant, antimicrobial, anticoagulant, and antidiabetic properties

The aim was to assess the phytochemical composition, phenolic component levels, and biological properties of the flowering tops of Origanum compactum and Origanum elongatum. The study employed phytochemical assays, spectrophotometric techniques for quantitative analysis of polyphenols, flavonoids, and tannins, and compound identification using HPLC/UV-ESI-MS. The antimicrobial, antioxidant, anticoagulant, and antidiabetic properties were examined both in vitro and in vivo. The results showed that the O. compactum extract had significantly high levels of total polyphenols, measuring 47.368 mg gallic acid equivalents per gram, and flavonoids, measuring 14.839 mg quercetin equivalents per gram. The phytochemical examination of O. compactum revealed that lithospermic acid accounted for 36.82 % of the chemicals detected, followed by salvianolic acid C at 12.57 % and ros-marinic acid at 6.01 %. The main constituents of O. elongatum are salvianolic acid C (14.46 %), luteolin-3-O-glucuronide (13.51 %), salvianolic acid B (12.24 %), rosmarinic acid (7.83 %), and rutin (6.18 %). The results demonstrated different levels of effectiveness against the investigated microorganisms, with the extract from O. compactum exhibiting better activity, particularly against Gram-negative bacteria, certain yeasts, and the fungus Aspergillus niger. The aqueous extracts of both Origanum species demonstrate significant antioxidant activity. O. compactum has a higher total antioxidant capacity (IC50 of 35.083 μg/mL) compared to O. elongatum (IC50 of 77.080 μg/mL). However, O. elongatum has a higher reducing power (35.697 μg/mL) compared to O. compactum (42.563 μg/mL). In vivo evaluations revealed that the aqueous extracts of O. compactum and O. elongatum possess significant antihyperglycemic and anticoagulant properties. The extracts demonstrated a marked reduction in blood glucose levels during the oral glucose tolerance test (OGTT) in Wistar rats and effectively prolonged both prothrombin time (PT) and activated partial thromboplastin time (aPTT), highlighting their ability to inhibit coagulation pathways. Moreover, their comparable efficacy to standard antihyperglycemic medications and absence of severe toxicity, even at high doses, underscore their therapeutic potential for safe and effective treatment applications. Between the two species, O. compactum exhibited superior efficacy in key biological activities such as antioxidant, antimicrobial, and anticoagulant properties, making it a strong candidate for therapeutic applications. This study underscores the value of Origanum species as a rich source of bioactive compounds, offering significant potential in pharmaceuticals, nutraceuticals, and agri-food industries. The findings pave the way for further exploration of their diverse applications.

Evaluating Antibiofilm, Cytotoxic and Apoptotic Activities of Scutellaria brevibracteata subsp. brevibracteata Essential Oil

Essential oils have many important biological properties, including antibacterial and antibiofilm activities. These unique properties make, essential oils good alternatives to synthetic chemical drugs, which have many side effects. In this study, we aimed to determine the chemical composition and biological activity of the essential oil obtained from Scutellaria brevibracteata subsp. brevibracteata. Specifically, its antibiofilm activity against Pseudomonas aeruginosa PAO1 and Staphylococcus aureus ATCC 29213 biofilms using XTT assay. Cytotoxic and apoptotic properties of the essential oil were investigated in human lung cancer cells (A540 and H1299) using MTT assay, Annexin V-FITC and propidium iodide staining and q-PCR. Thirty-two different compounds were identified from the essential oil, of which elemol (20.42 %), γ-eudesmol (20.12 %) and β-eudesmol (14.85 %) were the main components. The essential oil was more effective against P. aeruginosa PAO1 biofilm (79 %) than S. aureus ATCC 29213 biofilm (27 %). The specific activity of the essential oil against P. aeruginosa biofilm may be related to its high terpene contents. In addition, the essential oil showed high cytotoxic activity towards A549 (IC50 9.09 μg/ml) and H1299 (IC50 55.04 μg/ml) cell lines, inducing apoptosis in these cancer cells. These results demonstrate the antibiofilm and anticancer activities of S. brevibracteata subsp. brevibracteata essential oil.

Origanum majorana L. protects against neuroinflammation-mediated cognitive impairment: a phyto-pharmacological study

BACKGROUND

Neuroinflammation and oxidative stress are critical players in the pathogenesis of numerous neurodegenerative diseases, such as Alzheimer's disease (AD) which is responsible for most cases of dementia in the elderly. With the lack of curative treatments, natural phenolics are potential candidates to delay the onset and progression of such age-related disorders due to their potent antioxidant and anti-inflammatory effects. This study aims at assessing the phytochemical characteristics of Origanum majorana L. (OM) hydroalcohol extract and its neuroprotective activities in a murine neuroinflammatory model.

METHODS

OM phytochemical analysis was done by HPLC/PDA/ESI-MSⁿ. Oxidative stress was induced in vitro by hydrogen peroxide and cell viability was measured using WST-1 assay. Swiss albino mice were injected intraperitoneally with OM extract at a dose of 100 mg/kg for 12 days and with 250 μg/kg LPS daily starting from day 6 to induce neuroinflammation. Cognitive functions were assessed by novel object recognition and Y-maze behavioral tests. Hematoxylin and eosin staining was used to assess the degree of neurodegeneration in the brain. Reactive astrogliosis and inflammation were assessed by immunohistochemistry using GFAP and COX-2 antibodies, respectively.

RESULTS

OM is rich in phenolics, with rosmarinic acid and its derivatives being major constituents. OM extract and rosmarinic acid significantly protected microglial cells against oxidative stress-induced cell death (p < 0.001). OM protected against the LPS-induced alteration of recognition and spatial memory in mice (p < 0.001) and (p < 0.05), respectively. Mice that received OM extract prior to the induction of neuroinflammation showed comparable histology to control brains, with no overt neurodegeneration. Furthermore, OM pre-treatment decreased the immunohistochemistry profiler score of GFAP from positive to low positive and COX-2 from low positive to negative in the brain tissue, compared to the LPS group.

CONCLUSION

These findings highlight the potential preventive effects of OM phenolics against neuroinflammation and pave the way toward drug discovery and development for neurodegenerative disorders.

Exploration of Antibiofilm and In Vivo Wound Healing Activity of p-Cymene-Loaded Gellan/PVA Nanofibers

Wound dressings with outstanding biocompatibility, antimicrobial, and tissue regeneration activities are essential to manage emerging recalcitrant antifungal infections to speed up healing. In this study, we have engineered p-cymene-loaded gellan/PVA nanofibers using electrospinning. Morphological and physicochemical properties of the nanofibers were characterized using a multitude of techniques to validate the successful integration of p-cymene (p-cym). The fabricated nanomaterials exhibited strong antibiofilm activity against Candida albicans and Candida glabrata compared to pure p-cymene. In vitro biocompatibility assay demonstrated that nanofibers did not possess any cytotoxicity to the NIH3T3 cell lines. In vivo, full-thickness excision wound healing study showed that the nanofibers were able to heal skin lesions faster than the conventional clotrimazole gel in 24 days without forming any scar. These findings unraveled p-cymene-loaded gellan gum (GA)/poly(vinyl alcohol) (PVA) nanofibers as an effective biomaterial for cutaneous tissue regeneration.

Constant-Current Coulometry with Electrogenerated Titrants as a Novel Tool for the Essential Oils Screening Using Total Antioxidant Parameters

Essential oils are widely used in aromatherapy, medicine, and food industries due to a wide spectrum of bioactivity. Their antioxidant properties can be considered as markers of therapeutic effect and quality. Constant–current coulometry with electrogenerated titrants has been successfully applied for these purposes for the first time. Fifteen types of essential oils from various plant materials have been studied. Their composition has been identified by gas chromatography with mass-spectrometric detection (GC-MS). The reactivity of individual antioxidants of essential oils towards electrogenerated titrants (bromine and ferricyanide ions) has been estimated. Total antioxidant parameters, in particular total antioxidant capacity (TAC) and ferric reducing power (FRP) based on the reactions of essential oil antioxidants with electrogenerated bromine and ferricyanide ions, respectively, have been evaluated. Positive correlations (r = 0.7051–0.9558) with common antioxidant tests (antioxidant activity by reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) and total phenolic content by the Folin–Ciocalteu method) have been obtained. Coulometric approaches overcome the limitations of spectrophotometry and are applicable to a wider range of essential oils.

Chemical Composition, Antioxidant, Antibacterial, and Antibiofilm Activities of Backhousia citriodora Essential Oil

The essential oil of Backhousia citriodora, commonly known as lemon myrtle oil, possesses various beneficial properties due to its richness in bioactive compounds. This study aimed to characterize the chemical profile of the essential oil isolated from leaves of Backhousia citriodora (BCEO) and its biological properties, including antioxidant, antibacterial, and antibiofilm activities. Using gas chromatography-mass spectrometry, 21 compounds were identified in BCEO, representing 98.50% of the total oil content. The isomers of citral, geranial (52.13%), and neral (37.65%) were detected as the main constituents. The evaluation of DPPH radical scavenging activity and ferric reducing antioxidant power showed that BCEO exhibited strong antioxidant activity at IC50 of 42.57 μg/mL and EC50 of 20.03 μg/mL, respectively. The antibacterial activity results showed that BCEO exhibited stronger antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) than against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). For the agar disk diffusion method, S. epidermidis was the most sensitive to BCEO with an inhibition zone diameter of 50.17 mm, followed by S. aureus (31.13 mm), E. coli (20.33 mm), and K. pneumoniae (12.67 mm). The results from the microdilution method showed that BCEO exhibited the highest activity against S. epidermidis and S. aureus, with the minimal inhibitory concentration (MIC) value of 6.25 μL/mL. BCEO acts as a potent antibiofilm agent with dual actions, inhibiting (85.10% to 96.44%) and eradicating (70.92% to 90.73%) of the biofilms formed by the four tested bacteria strains, compared with streptomycin (biofilm inhibition, 67.65% to 94.29% and biofilm eradication, 49.97% to 89.73%). This study highlights that BCEO can potentially be a natural antioxidant agent, antibacterial agent, and antibiofilm agent that could be applied in the pharmaceutical and food industries. To the best of the authors' knowledge, this is the first report, on the antibiofilm activity of BCEO against four common nosocomial pathogens.

Antifungal Activity and Chemical Composition of Seven Essential Oils to Control the Main Seedborne Fungi of Cucurbits

Essential oils represent novel alternatives to application of synthetic fungicides to control against seedborne pathogens. This study investigated seven essential oils for in vitro growth inhibition of the main seedborne pathogens of cucurbits. Cymbopogon citratus essential oil completely inhibited mycelial growth of Stagonosporopsis cucurbitacearum and Alternaria alternata at 0.6 and 0.9 mg/mL, respectively. At 1 mg/mL, Lavandula dentata, Lavandula hybrida, Melaleuca alternifolia, Laurus nobilis, and two Origanum majorana essential oils inhibited mycelia growth of A. alternata by 54%, 71%, 68%, 36%, 90%, and 74%, respectively. S. cucurbitacearum mycelia growth was more sensitive to Lavandula essential oils, with inhibition of ~74% at 1 mg/mL. To determine the main compounds in these essential oils that might be responsible for this antifungal activity, they were analyzed by gas chromatography–mass spectrometry (GC-MS). C. citratus essential oil showed cirtal as its main constituent, while L. dentata and L. nobilis essential oils showed eucalyptol. The M. alternifolia and two O. majorana essential oils had terpinen-4-ol as the major constituent, while for L. hybrida essential oil, this was linalool. Thus, in vitro, these essential oils can inhibit the main seedborne fungi of cucurbits, with future in vivo studies now needed to confirm these activities.

Bioactive properties of hydroalcoholic extract from Origanum onites L. as affected by glycerol incorporation

In the current study, the effect of glycerol -as a green solvent- addition into solvent mixture (50:50 ethanol:distilled water), on some biofunctional properties of Origanum onites L. was investigated. Response surface methodology (RSM) was used to detect the optimum conditions for the extraction process. Three variables namely glycerol concentration (X₁: 1–9 g), extraction temperature (X₂: 25–75 °C) and time (X₃:10–30 min) were selected and also total phenolic content, total flavonoid content, antioxidant capacity and antiradical activity of O. onites extracts were determined. Analysis of variance (ANOVA) showed that glycerol incorporation significantly increased the total phenolic content and antioxidant activity (p < 0.05) of the samples. Maximum levels to obtain the highest bioactive properties (highest total phenolic content and antioxidant activity) were determined as to be 9 g of glycerol addition for the extraction conditions as 45.4 °C and 75 min. This study reports the effect of glycerol on bioactive properties of O. onites and suggests that glycerol can be used to produce hydroalcoholic extracts having higher bioactivity from Origanum genus.

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.