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.

Insecticidal action, repellency, and toxicity mechanism of the essential oil of Lippia turbinata against the stored product pest Rhipibruchus picturatus (F.).

The use of essential oils (EOs) in the development of alternative management methods for bruchid control under storage conditions aroused great interest because they have proven to be effective, less toxic, and less persistent in the ecosystem than synthetic pesticides. In this sense, leaves of Lippia turbinata (Griseb.) Moldenke EO were studied in the present work. The monoterpene limonene and the monoterpenoid eucalyptol were its main constituents. EO showed a potent insecticidal activity, both in contact and fumigant conditions, against Rhipibruchus picturatus (F.) which is one of the main pests of Prosopis alba pods in stored conditions. Moreover, the EO produces repellency in these insects. Additionally, the toxicity mechanism of action was studied. In this regard, the EO inhibits the acetylcholinesterase enzyme in in vitro assays, alters the activity of the antioxidant enzymes superoxide dismutase and catalase, and produces an increase in the lipid peroxidation reactions. This is the first report of the use of the L. turbinata EO against R. picturatus insect pest. The data obtained demonstrate its potential for developing more efficient and natural storage pest control strategies.

Antifungal chemosensitization through induction of oxidative stress: A model for control of candidiasis based on the Lippia origanoides essential oil.

In this work, evaluated the antifungal chemosensitizing effect of the Lippia origanoides essential oil (EO) through the induction of oxidative stress. The EO was obtained by hydrodistillation and analyzed by GC-MS. To evaluate the antifungal chemosensitizing effect through induction of oxidative stress, cultures of the model yeast Saccharomyces cerevisiae ∆ycf1 were exposed to sub-inhibitory concentrations of the EO, and the expression of genes known, due be overexpressed in response to oxidative and mutagenic stress was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) method. Carvacrol and thymol were identified as the main components. The EO was effective in preventing or reducing the growth of the microorganisms tested. The gene expression profiles showed that EO promoted changes in the patterns of expression of genes involved in oxidative and mutagenic stress resistance. The combined use of the L. origanoides EO with fluconazole has been tested on Candida yeasts and the strategy resulted in a synergistic enhancement of the antifungal action of the azolic chemical product. Indeed, in association with EO, the fluconazole MICs dropped. Thus, the combinatorial use of L. origanoides EO as a chemosensitizer agent should contribute to enhancing the efficiency of conventional antifungal drugs, reducing their negative side effects.

Water stress modulates terpene biosynthesis and morphophysiology at different ploidal levels in Lippia alba (Mill.) N. E. Brown (Verbenaceae).

Monoterpenes are the main component in essential oils of Lippia alba. In this species, the chemical composition of essential oils varies with genome size: citral (geraniol and neral) is dominant in diploids and tetraploids, and linalool in triploids. Because environmental stress impacts various metabolic pathways, we hypothesized that stress responses in L. alba could alter the relationship between genome size and essential oil composition. Water stress affects the flowering, production, and reproduction of plants. Here, we evaluated the effect of water stress on morphophysiology, essential oil production, and the expression of genes related to monoterpene synthesis in diploid, triploid, and tetraploid accessions of L. alba cultivated in vitro for 40 days. First, using transcriptome data, we performed de novo gene assembly and identified orthologous genes using phylogenetic and clustering-based approaches. The expression of candidate genes related to terpene biosynthesis was estimated by real-time quantitative PCR. Next, we assessed the expression of these genes under water stress conditions, whereby 1% PEG-4000 was added to MS medium. Water stress modulated L. alba morphophysiology at all ploidal levels. Gene expression and essential oil production were affected in triploid accessions. Polyploid accessions showed greater growth and metabolic tolerance under stress compared to diploids. These results confirm the complex regulation of metabolic pathways such as the production of essential oils in polyploid genomes. In addition, they highlight aspects of genotype and environment interactions, which may be important for the conservation of tropical biodiversity.

In vitro anthelmintic activity of Lippia alba essential oil chemotypes against Haemonchus contortus.

The aim of the present study was to evaluate the effects of the essential oils of Lippia alba chemotypes carvone and citral on H. contortus. Chemical characterization was performed by means of gas chromatography coupled to mass spectrometry (GC/MS). The anthelmintic effects of the essential oils were assessed through the egg hatch test (EHT) and the adult worm motility test (AWMT) using a multidrug-resistant H. contortus Kokstad isolate. Confocal laser scanning microscopy (CLSM) of eggs and adults of H. contortus and scanning electron microscopy (SEM) of adults were performed after treatment with oils for qualitative observations of their effects. The carvone chemotype of L. alba (LaCV) presented 70% carvone, and the citral chemotype of L. alba (LaCT) presented 29.4% geranial and 20.4% neral, respectively. In the EHT, the EC50 values of LaCV and LaCT were 0.2 and 0.3 mg/mL, respectively. In AWMT, after 12 h of exposure to 2 mg/mL LaCV and 2 mg/mL LaCT, 100% of adult nematodes were immobile. CLSM showed changes in larval motility inside the egg caused by LaCV, while LaCT promoted changes in larval formation. In adults exposed to both chemotypes, alterations in the anterior portion of the oesophagus were observed. In SEM, morphological changes were observed in the buccal capsule and in the medial portion of H. contortus adults. It is concluded that the two essential oils of L. alba, the chemotypes carvone and citral, caused morphological changes and inhibited the hatching of eggs and the motility of adult H. contortus nematodes.

Cytotoxic Activity of Polyphenol Extracts from Three Oregano Species: Hedeoma patens, Lippia graveolens and Lippia palmeri, and Antiproliferative Potential of Lippia graveolens against Two Types of Breast Cancer Cell Lines (MDA-MB-231 and MCF-7).

Oregano infusions have traditionally been used to treat some diseases related to inflammation and cancer; also, some species have shown antiproliferative activity on cancer cell lines, for example, colon and liver, and this has been attributed to its phytochemical profile, mainly its phenolic compounds. This study aimed to evaluate the cytotoxicity and antiproliferative potential of the polyphenols-rich extracts (PRE) of the oregano species H. patens, L. graveolens, and L. palmeri on breast cancer cell lines. The PRE of the three oregano species were obtained from dried leaves. The extract was characterized by determining antioxidant activity, total phenols content, and identifying the profile of phenolic acids and flavonoids by chromatography UPLC-MS/MS. Furthermore, the cytotoxicity of the extracts was evaluated in vitro on a non-cancer cell line of fibroblast NIH3T3 and the antiproliferative potential on the breast cancer cell lines MDA-MB-231 and MCF-7. L. graveolens showed the highest antioxidant capacity and significantly inhibited the proliferation of MCF-7 and MDA-MB-231 cells at non-cytotoxic concentrations in normal cells, with a similar effect to that cisplatin in MDA-MB-231 cells. Therefore, the polyphenol-rich extract from L. graveolens showed the greatest potential to guide future research on the antiproliferative mechanism of action.

In Silico Evaluation of the Antimicrobial Activity of Thymol-Major Compounds in the Essential Oil of Lippia thymoides Mart. & Schauer (Verbenaceae).

In this paper, we evaluated the drug-receptor interactions responsible for the antimicrobial activity of thymol, the major compound present in the essential oil (EO) of Lippia thymoides (L. thymoides) Mart. & Schauer (Verbenaceae). It was previously reported that this EO exhibits antimicrobial activity against Candida albicans (C. albicans), Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli). Therefore, we used molecular docking, molecular dynamics simulations, and free energy calculations to investigate the interaction of thymol with pharmacological receptors of interest to combat these pathogens. We found that thymol interacted favorably with the active sites of the microorganisms' molecular targets. MolDock Score results for systems formed with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli) were -77.85, -67.53, and -60.88, respectively. Throughout the duration of the MD simulations, thymol continued interacting with the binding pocket of the molecular target of each microorganism. The van der Waals (ΔEvdW = -24.88, -26.44, -21.71 kcal/mol, respectively) and electrostatic interaction energies (ΔEele = -3.94, -11.07, -12.43 kcal/mol, respectively) and the nonpolar solvation energies (ΔGNP = -3.37, -3.25, -2.93 kcal/mol, respectively) were mainly responsible for the formation of complexes with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli).

Comportamiento fenológico ex situ de Lippia integrifolia "incayuyo" (Verbenaceae) de una población de base genética amplia / Ex situ phenological behavior of Lippia integrifolia "incayuyo" (Verbenaceae) from a population with a broad genetic base

Abstract: Lippia integrifolia "incayuyo" is an aromatic, sub - woody shrub used in popular medicine, aperitit drinks and compound herb s. Its choleretic, antispasmodic, biocidal, antibacterial and larvicidal activity has been proven. The objective of the work was to register the phenology of a sample of 70 genotypes from a population with a broad genetic base. The phenophases studied were : vegetative growth, flower bud, flowering and fruiting fortnightly for two years. The initiation, intensity and prolongation of the phenophases were evaluated. The moment of full bloom occurs during the second half of December. Taking this date as a refer ence, a differentiated beginning of flowering was evidenced. The results of two campaigns were compared, observing that 70% of the specimens had a similar behavor, standing out some genotypes for presenting an early flowering and longer duration. The recor ded variability suggests that much of it could be due to intrinsic factors of the plant, and therefore, feasible to be selected .

Resumen: Lippia integrifolia "incayuyo" es un arbusto aromático, subleñoso empleado en la medicina popular, bebidas aperitivas y yerbas compuestas. Se ha comprobado su actividad colerética, antiespasmódica, biocida, antibacteriana y larvicida. El objetivo del trabajo fue registrar la fenología d e una muestra de 70 genotipos de una población de base genética amplia. Las fenofases estudiadas fueron: crecimiento vegetativo, botón floral, floración y fructificación quincenalmente durante dos años. Se evaluó inicio, intensidad y prolongación de las fe nofases. El momento de plena floración ocurre durante la segunda quincena de diciembre. Tomando esta fecha como referencia, se evidenció un inicio de floración diferenciada. Se compararon los resultados de dos campañas, observando que el 70% de los ejempla res tuvo un compartimiento semejante, destacándose algunos genotipos por presentar una floración temprana y de prolongación superior. La variabilidad registrada sugiere que gran parte de ésta podría deberse a factores intrínsecos de la planta, y por ello, factible de ser seleccionados.

Lippia alba and Lippia gracilis essential oils affect the viability and oviposition of Schistosoma mansoni.

Schistosomiasis is a neglected tropical disease that affects millions of people around the world. Currently, the only drug available for the treatment of this disease is praziquantel, which has low efficacy against immature helminth stages and there are reports of drug resistance. In this study, the chemical composition and the in vitro effect of essential oils (EOs) and major compounds from Lippia gracilis and Lippia alba against schistosomula and adult Schistosoma mansoni worms were evaluated. Adult S. mansoni worms cultured for 8h in the presence of L. gracilis EO (50 and 100 µg/mL) or for 2h with its major compound, carvacrol (100 µg/mL), had a 100% reduction in viability. After interaction with L. alba EO (100µg/mL), there was a reduction of approximately 60% in the viability of adult worms after 24 hours of exposure; citral (50 and 100 µg/mL), its major compound, reduced the viability after 24 hours by more than 75%. Treatment of schistosomula with 100 µg/mL of L. gracilis or L. alba EOs for 6h led to a reduction in parasite viability of 80% and 16% respectively. Both EOs and their major compounds significantly reduced the oviposition of adult worms exposed to a non-lethal concentration (5 µg/mL). In addition, morphological changes such as the destruction of the tegument and disorganization of the reproductive system of male and female worms were visualized. Both EOs showed low cytotoxicity at a concentration of 50 µg/mL. The results encourage further investigation of these plants as a potential source of bioactive compounds against S. mansoni.

Comparative analysis of chemical profiles and antioxidant activities of essential oils obtained from species of Lippia L. by chemometrics.

Due to the importance of diseases associated with oxidative stress, the search for natural antioxidants proves to be essential. This work aimed to compare the chemical composition and antioxidant potential of essential oils from the genus Lippia L. through chemometric analysis. The essential oils were characterized by gas chromatography coupled with mass spectrometry. Antioxidant potentials were determined by DPPH, ABTS, Deoxyribose and ß-carotene protection, Iron chelation and reduction methods. All data were related by multivariate analyzes. Essential oils showed low similar chemical compositions and no statistically significant relationship. These showed relevant antioxidant activity, especially for L. sidoides that obtained IC50 of 5.22 ± 0.08 µg/mL in ABTS capture. Multivariate analyzes showed the effectiveness of L. alba compounds to DPPH scavenging, Fe3+ reduction and ß-carotene protection, and L. gracilis components to deoxyribose protect. Thus, studies proving the antioxidant potential of Lippia compounds against oxidative stress and their use in food conservation are fundamental.

Long-Term Refrigerated Storage of Beef Using an Active Edible Film Reinforced with Mesoporous Silica Nanoparticles Containing Oregano Essential Oil (Lippia graveolens Kunth).

Beef is a fundamental part of the human diet, but it is highly susceptible to microbiological and physicochemical deterioration which decrease its shelf life. This work aimed to formulate an active edible film (AEF) incorporated with amino-functionalized mesoporous silica nanoparticles (A-MSN) loaded with Mexican oregano (Lippia graveolens Kunth) essential oil (OEO) and to evaluate its effect as a coating on fresh beef quality during refrigerated storage. The AEF was based on amaranth protein isolate (API) and chitosan (CH) (4:1, w/w), to which OEO emulsified or encapsulated in A-MSN was added. The tensile strength (36.91 ± 1.37 MPa), Young's modulus (1354.80 ± 64.6 MPa), and elongation (4.71%) parameters of AEF made it comparable with synthetic films. The antimicrobial activity of AEF against E. coli O157:H7 was improved by adding 9% (w/w) encapsulated OEO, and interactions of glycerol and A-MSN with the polymeric matrix were observed by FT-IR spectroscopy. In fresh beef, after 42 days, AEF reduced the population growth (Log CFU/cm2, relative to uncoated fresh beef) of Brochothrix thermosphacta (5.5), Escherichia coli (3.5), Pseudomonas spp. (2.8), and aerobic mesophilic bacteria (6.8). After 21 days, odor acceptability of coated fresh beef was improved, thus, enlarging the shelf life of the beef and demonstrating the preservation capacity of this film.

Effects of the healing activity of rosemary-of-Chapada (Lippia gracilis Schauer) on cutaneous lesions in rats

Purpose: To evaluate the effects of rosemary leaf essential oil-based ointments on the healing of rat skin lesions. Methods: Sixty adult male rats, with dorsal excisional skin wounds made surgically under anesthesia, were divided into three groups (n = 20): Sham group (untreated wounds); control group (CG, wounds treated with vehicle); and essential oil (EO) treated group (wounds treated with essential oil-based ointments), administered topically once daily. Skin wounds were evaluated at 4, 7, 14, and 21 days after EO or vehicle treatments. Lesions were analyzed macroscopically for the contraction degree. Formalin-fixed paraffin-embedded sections of skin wounds were used for histopathological evaluation. Results: Macroscopic evaluation showed wounds edges with thin crust without firmness and yellowish color, along with an improvement in wound contraction in EO group when compared to the other groups. A reduced inflammatory reaction, along with newly formed small diameter capillaries and more organized and elongated collagen fibers, were more frequently observed in EO group than in the other groups. Moreover, blood vessel number and collagen fibers density were significantly higher in EO group. Conclusions: Skin lesion treatment with rosemary leaf essential oil-based ointments accelerates the initial stages of healing, reduces inflammation, and increases angiogenesis, collagen fibers density, and wound contraction in rats.

Drying Effects on Chemical Composition and Antioxidant Activity of Lippia thymoides Essential Oil, a Natural Source of Thymol.

Leaves of Lippia thymoides (Verbenaceae) were dried in an oven at 40, 50 and 60 °C and the kinetic of drying and the influence of the drying process on the chemical composition, yield, and DPPH radical scavenging activity of the obtained essential oils were evaluated. The composition of the essential oils was determined with gas chromatography-mass spectrometry and gas chromatography-flame ionization detection analyses. The influence of drying on the chemical composition of the essential oils of L. thymoides was evaluated by multivariate analysis, and their antioxidant activity was investigated via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The Midilli model was the most appropriate to describe the behavior of drying kinetic data of L. thymoides leaves. Thymol was the major compound for all analyzed conditions; the maximum content was obtained from fresh leaves (62.78 ± 0.63%). The essential oils showed DPPH radical scavenging activity with an average of 73.10 ± 12.08%, and the fresh leaves showed higher inhibition (89.97 ± 0.31%). This is the first study to evaluate the influence of drying on the chemical composition and antioxidant activity of L. thymoides essential oils rich in thymol.

Antibacterial activity of Lippia alba, Myrcia lundiana and Ocimum basilicum essential oils against six food-spoiling pathogenic microorganisms / Actividad antibacteriana de los aceites esenciales de Lippia alba, Myrcia lundiana y Ocimum basilicum contra seis microorganismos patógenos que estropean los alimentos

The aim of this study was to undertake a screening experiment on essential oils (EO) of Myrcia lundiana, Ocimum basilicum and Lippia alba against six food-spoiling pathogenic bacteria. Seventy-two (72) samples were initially analyzed fo antimicrobial activity based on the agar diffusion test. The minimum inhibitory (MIC) and bactericidal (MBC) concentrations were determined for the 12 samples which showed greatest antimicrobial potential in this stage. Two samples of L. alba, three samples of M. lundiana and seven samples of O. basilicum showed a MIC of 0.12-125 µL/mL for the six tested bacteria. Of these, the EO of O. basilicum cultivar Maria Bonita stood out with the lowest MIC and MBC. Thus, a mixture simulating this essential oil was prepared from commercial standards of the compounds (±)-linalool, geraniol and 1,8-cineole. Significantly higher MIC and MBC were detected in the simulation compared to the respective EO, suggesting a synergistic effect between compounds.

El objetivo de este estudio fue realizar un experimento de detección en aceites esenciales (AE) de Myrcia lundiana, Ocimum basilicum y Lippia alba contra seis bacterias patógenas que estropean los alimentos. Setenta y dos (72) muestras fueron analizadas inicialmente para la actividad antimicrobiana basada en la prueba de difusión en agar. Se determinaron las concentraciones mínimas inhibitoria (CMI) y bactericida (CMB) para las 12 muestras que mostraron el mayor potencial antimicrobiano en esta etapa. Dos muestras de L. alba, tres muestras de M. lundiana y siete muestras de O. basilicum mostraron un CMI de 0.12-125 µL/mL para las seis bacterias analizadas. De estos, el AE de O. basilicum cultivar Maria Bonita se destacó con el CMI y CMB más bajos. Por lo tanto, se preparó una mezcla que simula este aceite esencial a partir de los estándares comerciales de los compuestos de (±)-linalol, geraniol y 1,8-cineol. Se detectaron CMI y CMB significativamente más altos en la simulación en comparación con el AE respectivo, lo que sugiere un efecto sinérgico entre los compuestos.

A Randomized, Double-Blind, Placebo-Controlled Trial to Determine the Effectiveness of a Polyphenolic Extract (Hibiscus sabdariffa and Lippia citriodora) for Reducing Blood Pressure in Prehypertensive and Type 1 Hypertensive Subjects.

Hypertension is an important factor of cardiovascular diseases and contributes to their negative consequences including mortality. The World Health Organization estimated that 54% of strokes and 47% of cases of ischemic heart illness are related to high blood pressure. Recently, Hibiscus sabdariffa (HS) and Lippia citriodora (LC) have attracted scientific interest, and they are recognized for their high content of polyphenols as these may prevent several disease factors, such as hypertension. The aim of the present study is to determine if supplementation with an HS-LC blend (MetabolAid®) may be effective for the treatment of type 1 hypertensive sedentary populations. A total of 80 type 1 hypertensive subjects of both sexes were included in the study and were treated with placebo or the HS-LC extract, and both groups were treated over 84 days. The blood pressure (diastolic, systolic, and pulse pressure) was measured throughout the day, for each of the days of the study duration and determined using Ambulatory Blood Pressure Monitoring (ABPM). Physical activity was determined throughout the study to ensure similar conditions related to exercise. The results showed the capacity for reducing the blood pressure parameters in the case of the HS-LC extract. The daily consumption of the HS-LC extract but not the placebo over 84 days was able to reduce the daytime parameters related to blood pressure. The most remarkable results were observed in the measurements performed during the daytime, especially in the systolic blood pressure showing statistically significant variation.

Essential Oils of New Lippia alba Genotypes Analyzed by Flow-Modulated Comprehensive Two-Dimensional Gas Chromatography (GC×GC) and Chemometric Analysis.

Lippia alba (Mill.) N. E. Br. (Verbenaceae) is an aromatic shrub whose essential oils have stood out as a promising source for application in several industrial fields. In this study, the essential oils chemical characterization of eight new L. alba genotypes was performed. The selected materials were collected from the Active Germplasm Bank of the Agronomic Institute and the essential oils were extracted by hydrodistillation. Flow-modulated comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS) was employed for chemical characterization and evaluation of possible co-eluted compounds. In addition, the chemical analyses were submitted to multivariate statistical analyses. From this investigation, 73 metabolites were identified in the essential oils of the genotypes, from which α-pinene, ß-myrcene, 1,8-cineole, linalool, neral, geranial, and caryophyllene oxide were the most abundant compounds among the accessions. This is the first report disclosing α-pinene in higher amounts in L. alba (19.69%). In addition, sabinene, trans-verbenol, myrtenol, (E)-caryophyllene, α-guaiene, germacrene D, and α-bulnesene were also found in relevant quantities in some of the genotypes, and myrtenal and myrtenol could be well separated through the second dimension. Such results contributed to the understanding of the chemical composition of those new genotypes, being important to drive a future industrial applicability and studies in genetic breeding.

Combination of entomopathogenic nematodes with acaricides or essential oil of Lippia triplinervis against Rhipicephalus microplus (Acari: Ixodidae).

This study aimed to evaluate the combination effect of Heterorhabditis bacteriophora HP88 and H. indica LPP1, with the acaricides deltamethrin, amitraz and chlorfenvinphos, and the essential oil (EO) of Lippia triplinervis, against engorged females of Rhipicephalus microplus. In order to verify the effect of acaricides and EO, the adult immersion test was used, and in the groups treated only with entomopathogenic nematodes (EPNs), 150 infective juveniles were used per female. In the treatments with nematodes in combination with the acaricides or EO, the females were immersed in the solutions (acaricide or EO) and then transferred to Petri dishes for application of the nematodes. The treatment with acaricides resulted in a control percentage lower than 70%, except in the group treated with chlorfenvinphos in the second experiment (84.3%). The control percentage was 73% for L. triplinervis EO, and greater than 90% in all the groups treated with nematodes. For treatments with EPNs combined with the acaricides or EO, the efficacy was greater than 95% (except for deltamethrin + HP88), and reached 100% in the treatment with LPP1 + amitraz. It can be concluded that the EPNs at the concentrations tested were compatible with the acaricides deltamethrin, amitraz and chlorfenvinphos, and with the EO of L. triplinervis. These combinations enhance the effect of these control agents.

Composition, antioxidant capacity, intestinal, and immunobiological effects of oregano (Lippia palmeri Watts) in goats: preliminary in vitro and in vivo studies.

This study investigated Lippia palmeri Watt (oregano) phytochemical compounds, their antioxidant capacity, and immunological effects on goat peripheral blood leukocytes (PBL), and on the presence of intermediate polar compounds in goat feces fed dietary oregano. The polar and nonpolar fractions of L. palmeri W. were characterized and phytochemical contents and antioxidant capacity were determined. Twelve healthy Anglo-Nubian goats were used for the in vivo trials, which were randomly assigned to control fed with basal diet, or oregano group fed with basal diet + 2.6% (DM basis) dried oregano leaves. Goat peripheral blood leukocytes (PBL) were isolated for the in vitro study, and PBL were stimulated with oregano extracts at 100 and 150 µg/mL after 24 h. For the in vivo trial, dietary oregano (2.6% on DM basis) was evaluated in the goats for 90 days. Relatively high abundance of carvacrol and thymol phytochemical compounds was found in oregano. The highest antioxidant capacity of oregano extracts was detected at 100 and 150 µg/mL. Nitric oxide production, phagocytosis, and superoxide dismutase activities increased (p < 0.05) in stimulated PBL with oregano extracts, whereas the pro-inflammatory (TNF-α and IL-1ß) transcription and antioxidant (CAT and GPX-4) genes downregulated. In the in vivo experiment, dietary oregano enabled the detection of nine compounds found in goat feces, from which caproic (C6) was in a high relative quantity compared with the control group. Oregano has phytochemical compounds with strong antioxidant capacity that protect cells against oxidative stress damage and could modulate immune response and feces composition in goats.

Essential oil from Lippia microphylla Cham. modulates nitric oxide pathway and calcium influx to exert a tocolytic effect in rat uterus.

The essential oil of Lippia microphylla (LM-OE) presents several pharmacological activities. This work evaluates the tocolytic effect of LM-OE on rats. LM-OE inhibited phasic contractions and relaxed tonic contractions on rat uterus. Considering that nitric oxide (NO) pathway regulates uterine contraction, LM-OE potency was attenuated in the presence of NO synthase (NOS) inhibitor and this reduction was reversed in the presence of a NOS substrate. Similarly, the relaxant potency of LM-OE was reduced in the presence of soluble guanylyl cyclase (sGC) and protein kinase G (PKG) inhibitors. LM-OE also demonstrates a positive modulation of large and small conductance calcium-activated, voltage-gated and adenosine triphosphate-sensitive potassium channels and inhibited curves to CaCl2 as well as relaxed the uterus pre-contracted by S-(-)-Bay K8644, suggesting voltage-gated calcium channels type-1 (CaV1) blockade. Thus, the tocolytic effect of LM-OE on rat involves positive modulation of NO/NOS/sGC/PKG/K+-channels pathway and Ca2+ influx blockade through CaV1.[Formula: see text].

Antifungal and antibiofilm activities of the essential oil of leaves from Lippia gracilis Schauer against phytopathogenic fungi.

AIMS: This study aimed to evaluate the antifungal and antibiofilm effects of essential oil (EO) from leaves of Lippia gracilis and its major constituents, thymol and carvacrol, against phytopathogenic fungi. METHODS AND RESULTS: The leaves of L. gracilis were hydrodistilled to obtain the EO and the chemical composition was determined by GC/MS analysis. The antifungal activity of EO of L. gracilis was evaluated on the vegetative and mycelial growth of Colletotrichum gloeosporioides, Colletotrichum lindemuthianum, Fusarium oxysporum and Fusarium solani. In addition, the ability of the oil to inhibit fungal biofilm formation was assessed by total biomass quantification using crystal violet staining, analysis of metabolic activity, and scanning electron microscopy (SEM). Moreover the antifungal and antibiofilm activities of the monoterpenes, thymol and carvacrol, present in EO of L. gracilis were evaluated against F. oxysporum. The analysis of the chemical composition of EO extracted from L. gracilis, revealed the presence of monoterpenes (94·13%), which included carvacrol (48·57%) and thymol (7·78%), and 4 sesquiterpenes (3·74%). In general, EO showed significant antifungal activity and inhibited the formation of fungal biofilms. Furthermore, thymol and carvacrol showed significant antifungal and antibiofilm activities against F. oxysporum. SEM images showed structural changes in fungal morphology upon treatment with EO of L. gracilis. CONCLUSION: The results presented in this study showed promising antifungal and antibiofilm effects of EO of L. gracilis and its major components, carvacrol and thymol. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings indicate that the EO extracted from L. gracilis, and the monoterpenes, carvacrol and thymol have a great potential as antifungal and antibiofilm agents. Furthermore, this is the first report of the antibiofilm activity of the EO of L. gracilis and its major components against phytopathogenic fungi.