Antibacterial action against food-borne microorganisms and antioxidant activity of carvacrol-rich oil from Lippia origanoides Kunth

Essential Oil of Lippia origanoides Kunth: Nanoformulation, Anticholinesterase Activity, and Molecular Docking

This study investigates the therapeutic potential of Lippia origanoides essential oil (LOEO) in neurological and pharmaceutical applications. The chemical composition of LOEO was analyzed using gas chromatography-mass spectrometry (GC-MS), revealing major constituents, such as carvacrol, thymol, and γ-gurjunene, known for their antioxidant and antimicrobial properties. LOEO demonstrated significant acetylcholinesterase (AChE)-inhibitory activity, particularly in a nanoformulation that enhances bioavailability and stability. Additionally, the major constituent carvacrol, when tested in isolation, also exhibited AChE-inhibitory activity comparable to that of the nanoformulation. Molecular docking analysis indicated strong binding affinities between LOEO compounds and AChE, supporting its therapeutic potential for neurodegenerative diseases like Alzheimer's. Additionally, in silico pharmacokinetic predictions revealed favorable absorption and blood-brain barrier penetration profiles for key constituents. Despite promising results, this study acknowledges the need for in vivo validation and long-term stability assessments of the nanoformulation. Future research should focus on pharmacodynamic studies and evaluating the oil's effectiveness in animal models. These findings highlight LOEO as a valuable candidate for developing natural therapies for neurodegenerative diseases.

Lippia origanoides essential oil increases longevity and ameliorates β-amyloid peptide-induced toxicity in Caenorhabditis elegans

Lippia origanoides essential oil (LOEO) is extensively utilised as food preservative due to its antioxidant and antibacterial activities. In this study, the antioxidant and anti-ageing effects of LOEO was investigated in vivo using the nematode Caenorhabditis elegans. The gas chromatography-mass spectrometry analysis indicated that the main components of LOEO are carvacrol and thymol. LOEO treatment improved physiological parameters such as pharyngeal pumping, locomotion and body size indicating that is not toxic to C. elegans. LOEO treatment showed antioxidant effect in C. elegans by reducing endogenous ROS (Reactive Oxygen Species) production and increasing their survival under oxidative stress. Finally, LOEO treatment significantly extended C. elegans lifespan and alleviated the paralysis induced by β-amyloid peptide overexpression in the muscle. This work demonstrates for the first time LOEO antioxidant and anti-ageing properties on an organism level providing a valuable proof of principle to support further studies in the development of nutraceuticals or antioxidant phytotherapy.

Carvacrol Essential Oil as a Neuroprotective Agent: A Review of the Study Designs and Recent Advances

Neurodegenerative diseases were mostly perceived as diseases of ageing populations, but now-a-days, these diseases pose a threat to populations of all age groups despite significant improvements in quality of life. Almost all essential oils (EOs) have been reported to have some neuroprotective abilities and have been used as supplements for good mental health over the centuries. This review highlights the therapeutic potential of one such monoterpene phenolic EO, carvacrol (CV), that has the potential to be used as a main therapeutic intervention for neurodegenerative disorders. Three libraries, Google Scholar, PubMed, and ScienceDirect, were explored for research studies related to the neuroprotective roles of CV. All the research articles from these libraries were sorted out, with the first article tracing back to 2009, and the latest article was published in 2024. The positive effects of CV in the treatment of Alzheimer's and Parkinson's Diseases, multiple sclerosis, ischemia, and behavioural disorders have been supported with evidence. This review not only focused on study designs and the pharmacological pathways taken by CV for neuroprotection but also focused on demographics, illustrating the trend of CV research studies in certain countries and the preferences for the use of in vitro or in vivo models in studies. Our review provides useful evidence about the neuroprotective potential of CV; however, a lack of studies was observed regarding CV encapsulation in proper dosage forms, in particular nanoparticles, which could be further explored for CV delivery to the central nervous system.

Bactericidal and Synergistic Effects of Lippia origanoides Essential Oil and Its Main Constituents against Multidrug-Resistant Strains of Acinetobacter baumannii

Bacterial resistance in Acinetobacter baumannii is a significant public health challenge, as these bacteria can evade multiple antibiotics, leading to difficult-to-treat infections with high mortality rates. As part of the search for alternatives, essential oils from medicinal plants have shown promising antibacterial potential due to their diverse chemical constituents. This study evaluated the antibacterial, antibiofilm, and synergistic activities of the essential oil of Lippia origanoides (EOLo) and its main constituents against multidrug-resistant clinical isolates of A. baumannii. Additionally, the antibacterial and antibiofilm potential of a nanoemulsion containing carvacrol (NE-CAR) was assessed. EOLo was extracted through hydrodistillation, and its components were identified via gas chromatography coupled with mass spectrometry. The A. baumannii isolates (n = 9) were identified and tested for antimicrobial susceptibility using standard disk diffusion methods. Antibacterial activity was determined by broth microdilution, while antibiofilm activity was measured using colorimetric methods with crystal violet and scanning electron microscopy. Synergism tests with antibiotics (meropenem, ciprofloxacin, gentamicin, and ampicillin+sulbactam) were performed using the checkerboard method. The primary constituents of EOLo included carvacrol (48.44%), p-cymene (14.58%), and thymol (10.16%). EOLo, carvacrol, and thymol demonstrated significant antibacterial activity, with carvacrol showing the strongest effect. They were also effective in reducing biofilm formation, as was NE-CAR. The combinations with antibiotics revealed significant synergistic effects, lowering the minimum inhibitory concentration of the tested antibiotics. Therefore, this study confirms the notable antibacterial activity of the essential oil of L. origanoides and its constituents, especially carvacrol, suggesting its potential as a therapeutic alternative for A. baumannii infections.

Assessment of Antimicrobial and Cytotoxic Activities of Liposomes Loaded with Curcumin and Lippia origanoides Essential Oil

(1) Introduction: Curcumin and Lippia origanoides essential oils have a broad spectrum of biological activities; however, their physicochemical instability, low solubility, and high volatility limit their therapeutic use. Encapsulation in liposomes has been reported as a feasible approach to increase the physicochemical stability of active substances, protect them from interactions with the environment, modulate their release, reduce their volatility, improve their bioactivity, and reduce their toxicity. To date, there are no reports on the co-encapsulation of curcumin and Lippia origanoides essential oils in liposomes. Therefore, the objective of this work is to prepare and physiochemical characterize liposomes loaded with the mixture of these compounds and to evaluate different in vitro biological activities. (2) Methods: Liposomes were produced using the thin-layer method and physiochemical characteristics were calculated. The antimicrobial and cytotoxic activities of both encapsulated and non-encapsulated compounds were evaluated. (3) Results: Empty and loaded nanometric-sized liposomes were obtained that are monodisperse and have a negative zeta potential. They inhibited the growth of Staphylococcus aureus and did not exhibit cytotoxic activity against mammalian cells. (4) Conclusions: Encapsulation in liposomes was demonstrated to be a promising strategy for natural compounds possessing antimicrobial activity.

Lippia grata Essential Oil Acts Synergistically with Ampicillin Against Staphylococcus aureus and its Biofilm

Antimicrobial resistance (AMR) presents a global challenge as microorganisms evolve to withstand the effects of antibiotics. In addition, the improper use of antibiotics significantly contributes to the AMR acceleration. Essential oils have garnered attention for their antimicrobial potential. Indeed, essential oils extracted from plants contain compounds that exhibit antibacterial activity, including against resistant microorganisms. Hence, this study aimed to evaluate the antimicrobial and antibiofilm activity of the essential oil (EO) extracted from Lippia grata and its combination with ampicillin against Staphylococcus aureus strains (ATCC 25923, ATCC 700698, and JKD6008). The plant material (leaves) was gathered in Mossoro, RN, and the EO was obtained using the hydrodistillation method with the Clevenger apparatus. The antimicrobial activity of the EO was assessed through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. Antibiofilm activity was evaluated by measuring biomass using crystal violet (CV) staining, viable cell counting, and analysis of preformed biofilms. In addition, the synergistic effects of the EO in combination with ampicillin were examined by scanning electron and confocal microscopy. The EO displayed a MIC value of 2.5 mg/mL against all tested S. aureus strains and an MBC only against S. aureus JKD6008 at 2.5 mg/mL. L. grata EO caused complete biofilm inhibition at concentrations ranging from 10 to 0.312 mg/mL against S. aureus ATCC 25923 and 10 to 1.25 mg/mL against S. aureus ATCC 700698 and S. aureus JKD6008. In the viable cell quantification assay, there was a reduction in CFU ranging from 1.0 to 8.0 logs. The combination of EO with ampicillin exhibited a synergistic effect against all strains. Moreover, the combination showed a significantly inhibiting biofilm formation and eradicating preformed biofilms. Furthermore, the EO and ampicillin (individually and in combination) altered the cellular morphology of S. aureus cells. Regarding the mechanism, the results revealed that L. grata EO increased membrane permeability and caused significant membrane damage. Concerning the synergy mechanism, the results revealed that the combination of EO and ampicillin increases membrane permeability and causes considerable membrane damage, further inhibiting bacteria synergistically. The findings obtained here suggest that L. grata EO in combination with ampicillin could be a viable treatment option against S. aureus infections, including MRSA strain.

Chemical Composition and Antibacterial Activity of the Lippia origanoides Kunth Essential Oil from the Carajás National Forest, Brazil

Species of the genus Lippia are rich in essential oils and have shown antibacterial properties, which may be related to oils' chemical composition. The present work aimed to evaluate the antimicrobial potential of Lippia origanoides Kunth against two bacteria strains: Escherichia coli and Staphylococcus aureus. Leaf essential oils were obtained by hydrodistillation in a modified Clevenger-type apparatus, and their chemical composition was determined by gas chromatography coupled to mass spectrometry (GC/MS) and flame ionization detection (GC/FID). We identified 28 compounds, representing 98.87% of the total concentration of the essential oil. The compounds identified at the highest concentrations were 1,8-cineole (35.04%), carvacrol (11.32%), p-cymene (8.53%), α-pinene (7.17%), and γ-terpinene (7.16%). The leaf essential oil of L. origanoides showed antibacterial action on biological isolates of Escherichia coli and Staphylococcus aureus. For Escherichia coli, the oil presented bactericidal action at concentrations of 5-20 μL/mL. Regarding Staphylococcus aureus, the bactericidal effect was noted at 20 μL/mL and the bacteriostatic action was noted around 2.5-10 μL/mL. Given the results obtained, L. origanoides essential oil showed promising biological potential against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, thus encouraging further studies on substances isolated from this species to contribute to the development of new antimicrobial drugs.

Effect of Essential Oils on the Inhibition of Biofilm and Quorum Sensing in Salmonella enteritidis 13076 and Salmonella typhimurium 14028

The emergence of multidrug-resistant microorganisms represents a global challenge that has led to a search for new antimicrobial compounds. Essential oils (EOs) from medicinal aromatic plants are a potential alternative for conventional antibiotics. In this study, the antimicrobial and anti-biofilm potential of 15 EOs was evaluated on planktonic and biofilm-associated cells of Salmonella enterica serovar Enteritidis ATCC 13076 (S. enteritidis) and Salmonella enterica serovar Typhimurium ATCC 14028 (S. typhimurium). In total, 4 out of 15 EOs showed antimicrobial activity and 6 EOs showed anti-biofilm activity against both strains. The EO from the Lippia origanoides chemotype thymol-carvacrol II (LTC II) presented the lowest minimum inhibitory concentration (MIC₅₀ = 0.37 mg mL^-1) and minimum bactericidal concentration (MBC = 0.75 mg mL^-1) values. This EO also presented the highest percentage of biofilm inhibition (>65%) on both microorganisms, which could be confirmed by scanning electron microscopy (SEM) images. Transcriptional analysis showed significant changes in the expression of the genes related to quorum sensing and the formation of the biofilm. EOs could inhibit the expression of genes involved in the quorum sensing mechanism (luxR, luxS, qseB, sdiA) and biofilm formation (csgA, csgB, csgD, flhD, fliZ, and motB), indicating their potential use as anti-biofilm antimicrobial agents. However, further studies are needed to elucidate the action mechanisms of essential oils on the bacterial cells under study.

Morphometry of bovine blastocysts produced in vitro in culture media with antioxidants cysteamine or oily extract of Lippia origanoides

ABSTRACT This study aimed to evaluate the ultrastructural morphometry of bovine embryos produced in vitro grown at different concentrations of antioxidants. After in vitro maturation and fertilization, the presumptive zygotes were assigned into five treatments. T1) without the addition of any antioxidants (negative control); T2) addition of 50μM/mL cysteamine; and T3, T4 and T5) adding 2.5μg/mL, 5.0μg/mL or 10.0μg/mL of the antioxidants derived from the oily extract from Lippia origanoides, respectively. On D7 of culture, the embryos in the blastocyst stage were fixed and prepared for electron transmission microscopy. These were evaluated for the proportion of cytoplasm-to-nucleus, cytoplasm-to-mitochondria, cytoplasm-to-vacuoles, cytoplasm-to-autophagic vacuoles and cytoplasm-to-lipid droplets. Blastocysts cultured in media containing oily extract of Lippia origanoides presented morphological characteristics such as high cell:mitochondria ratio and low cell:vacuoles and cell:autophagic vacuole ratio, possibly been morphological indicators of embryonic quality. Inner cell mass (ICM) from blastocysts cultured in media without any antioxidants had the highest cell:vacuole ratio. Similar results were found in the trophectoderm (TE) cells of blastocysts from treatment 2. Embryo culture media supplemented with antioxidants derived from Lippia origanoides oil produced embryos with a higher cytoplasmic proportion of organelles, such as mitochondria. Also, treatments without any antioxidants or with the addition of cysteamine presented cytoplasmic vacuolization, a characteristic related to production of poor-quality embryos.

R, Rocha P, López Rodilla JM. Chemical Composition and Antibacterial Activity of Lippia multiflora Moldenke Essential Oil from Different Regions of Angola

The purpose of the study was to determine the chemical composition and antibacterial activity of Lippia multiflora Moldenke essential oils (EOs) collected in different regions of Angola. Antibacterial activity was evaluated using the agar wells technique and vapour phase test. Analysis of the oils by GC/MS identified thirty-five components representing 67.5 to 100% of the total oils. Monoterpene hydrocarbons were the most prevalent compounds, followed by oxygenated monoterpenes. The content of the compounds varied according to the samples. The main components were Limonene, Piperitenone, Neral, Citral, Elemol, p-cymene, Transtagetone, and Artemisia ketone. Only one of the eleven samples contained Verbenone as the majority compound. In the vapour phase test, a single oil was the most effective against all the pathogens studied. The principal component analysis (PCA) and hierarchical cluster analysis (HCA) of components of the selected EOs and inhibition zone diameter values of agar wells technique allowed us to identify a variability between the plants from the two provinces, but also intraspecific variability between sub-groups within a population. Each group of essential oils constituted a chemotype responsible for their bacterial inhibition capacity. The results presented here suggest that Angolan Lippia multiflora Moldenke has antibacterial properties and could be a potential source of antimicrobial agents for the pharmaceutical and food industry.

Yields, chemical composition, and antimicrobial activity of two Algerian essential oils against 40 avian multidrug-resistant Escherichia coli strains

AIM

The aim of this study is to investigate, in vitro, a possible antibacterial activity of Algerian essential oils (EOs) of Thyme (Thymus vulgaris L.) and that of Coriander (Coriandrum sativum L.) against multidrug-resistant avian Escherichia coli strains and this in a perspective of their future use as a substitute for antibiotics (ATBs).

MATERIALS AND METHODS

In addition to the reference strain of E. coli ATCC 25922, 40 strains of avian E. coli have been isolated (24 strains of broilers and 16 of turkeys), their antimicrobial resistance profile was determined by antibiogram tests against 21 ATBs whereupon they were subjected to the action of two Algerian EOs; the EO of Thyme (T. vulgaris L.) and that of Coriander (C. sativum L.), which oils were extracted by hydrodistillation and analyzed by Gas Chromatography coupled to Mass Spectrometry (GC-MS) and this for the determination of their chemical composition. The antibacterial activity, resulting in zones of inhibition, was evaluated by carrying out, in triplicate, aromatograms for both pure EO and that which has been diluted to 15% in Dimethyl Sulfoxide (DMSO), while the minimum inhibitory concentrations (MIC) of the two EOs were highlighted by the method of liquid macrodilution.

RESULTS

Antibiogram performance demonstrated an alarming state of antimicrobial resistance, the multidrug resistance rate was estimated at 100% for the broilers chicken strains and at 81.25% for strains isolated from turkeys, hydrodistillation allowed to obtained EOs with yields estimated at 1.22±0.26% for Thyme EO and 0.23±0.15% for the essence of Coriander, the GC-MS analysis identified 19 main compounds and showed that the majority chemical components were Carvacrol (73.03%) for Thyme volatile oil and Linalool (60.91%) for Coriander EO, aromatograms and the determination of MIC concluded that the EO of Thyme showed a greater antibacterial activity with an average of the zones of inhibition estimated at 26.75±0.426 mm and MIC ranging from 0.07 to 0.93 mg/ml against an average of the inhibition zones evaluated at 17.05±0.383 mm and MICs evaluated between 0.6 and 10 mg/ml for the EO of Coriander.

CONCLUSION

In aviculture, these results seem to be very promising in the case where we think about the replacement of ATBs by EOs, in vivo studies would be very interesting to confirm or invalidate this hypothesis.

Composition and cytotoxic and antioxidant activities of the oil of Piper aequale Vahl

Background

Piper aequale Vahl is a small shrub that grows in the shadow of large trees in the Carajás National Forest, Municipality of Parauapebas, Para state, Brazil. The local people have used the plant against rheumatism and inflammation.

Methods

The essential oil of the aerial parts was extracted and analyzed by GC and GC-MS. The MTT colorimetric assay was used to measuring the cytotoxic activity of the oil against human cancer lines. The determination of antioxidant activity of the oil was conducted by DPPH radical scavenging assay.

Results

The main constituents were δ-elemene (18.92 %), β-pinene (15.56 %), α-pinene (12.57 %), cubebol (7.20 %), β-atlantol (5.87 %), and bicyclogermacrene (5.51 %), totalizing 65.63 % of the oil. The oil displayed a strong in vitro cytotoxic activity against the human cancer cell lines HCT-116 (colon) and ACP03 (gastric) with IC₅₀values of 8.69 μg/ml and 1.54 μg/ml, respectively. The oil has induced the apoptosis in a gastric cancer cells in all tested concentration (0.75–3.0 μg/ml), after 72 h of treatment, when compared to negative control (p < 0.001). Also, the oil showed a significant antioxidant activity (280.9 ± 22.2 mg TE/ml), when analyzed as Trolox equivalent, and a weak acetylcholinesterase inhibition, with a detection limit of 100 ng, when compared to the physostigmine standard (1.0 ng).

Conclusion

The higher cell growth inhibition induced by the oil of P. aequale is probably due to its primary terpene compounds, which were previously reported in the proliferation inhibition, in stimulation of apoptosis and induction of cell cycle arrest in malignant cells.