Chemical composition, toxicological aspects and antifungal activity of essential oil from Lippia sidoides Cham

Antifungal, molecular docking and cytotoxic effect of the essential oil of Cymbopogon citratus (DC) Stapf. and Cymbopogon nardus (L.) Rendle against Candida albicans

Brazil is renowned for its extensive plant biodiversity, with emphasis on Cymbopogon, C. citratus and C. nardus, with broad antimicrobial potential. Candidemias caused by Candida albicans are highly prevalent in immunosuppressed individuals and are associated with infections by biofilms on medical devices. The aim of this study was to evaluate the antimicrobial potential of essential oils C. citratus and C. nardus against C. albicans in planktonic and biofilm forms. Essential oils were obtained by hydrodistillation and chemical composition evaluated by GC-FID and GC-MS. The minimum inhibitory concentration was determined by the broth microdilution method and the synergy effect of essential oils and amphotericin B were evaluated by the checkerboard test. Biofilm activity was determined by the XTT assay. Cytotoxicity assays performed with VERO cells and molecular docking were performed to predict the effect of oil interaction on the SAP-5 enzyme site. The results showed activity of essential oils against planktonic cells and biofilm of C. albicans. Furthermore, the oils had a synergistic effect, and low cytotoxicity. Molecular docking showed interaction between Cadinene, Caryophyllen oxide, Germacrene D with SAP-5. The results indicate that Cymbopogon spp. studied are anti-Candida, with potential for further application in therapy against infections caused by C. albicans.

Unveiling the mechanism of essential oil action against skin pathogens: from ancient wisdom to modern science

Essential oils are among the most well-known phyto-compounds, and since ancient times, they have been utilized in medicine. Over 100 essential oils have been identified and utilized as therapies for various skin infections and related ailments. While numerous commercial medicines are available in different dosage forms to treat skin diseases, the persisting issues include their side effects, toxicity, and low efficacy. As a result, researchers are seeking novel classes of compounds as substitutes for synthetic drugs, aiming for minimal side effects, no toxicity, and high efficacy. Essential oils have shown promising antimicrobial activity against skin-associated pathogens. This review presents essential knowledge and scientific information regarding essential oil's antimicrobial capabilities against microorganisms that cause skin infections. Essential oils mechanisms against different pathogens have also been explored. Many essential oils exhibit promising activity against various microbes, which has been qualitatively assessed using the agar disc diffusion experiment, followed by determining the minimum inhibitory concentration for quantitative evaluation. It has been observed that Staphylococcus aureus and Candida albicans have been extensively researched in the context of skin-related infections and their antimicrobial activity, including established modes of action. In contrast, other skin pathogens such as Staphylococcus epidermidis, Streptococcus pyogens, Propionibacterium acnes, and Malassezia furfur have received less attention or neglected. This review report provides an updated understanding of the mechanisms of action of various essential oils with antimicrobial properties. This review explores the anti-infectious activity and mode of action of essential against distinct skin pathogens. Such knowledge can be valuable in treating skin infections and related ailments.

Wound Healing Effect of Lippia sidoides and Myracrodruon urundeuva Nanogel

Wound healing is a natural regenerative response to tissue injury and the conventional treatments consists of the use wound dressings with local administration of medicines, but, in some cases, are only partially effective and limited by toxicity or ineffective anti-microbial protection. Medicinal plants such as Lippia sidoides and Myracrodruon urundeuva have shown interesting pharmacological activities, allied to this, the association of these medicinal plants and nanotechnology, could mean an advantage in relation to classical approach. This study investigated the effect of a nanogel loaded with Lippia sidoides essential oil and Myracrodruon urundeuva extract (NAA) in an excisional wound healing model in rats. Animals were anesthetized and skin wounds were made using a metal punch. The groups were treated with vehicle, NAA or collagenase gel, for 7, 14 or 21 days and then sacrificed for tissue analysis. NAA did not show acute dermal irritation, further significantly reduced (p<0.05) the final wound area, accelerated the wound contraction and organization of collagen in the group treated for 14 days. The data presented here demonstrate the therapeutic potential for the use of nanotechnology associated with medicinal plants and provides evidence that corroborate with the use of L. sidoides and M. urundeuva as healing medicinal plants.

Antimicrobial activity of essential oils against biofilms formed in dental acrylic resin: a systematic review of in vitro studies

This study aimed to answer the question formulated according to the PICO strategy: 'Which essential oils show antimicrobial activity against biofilms formed on dental acrylic resin?' composed by population (dental acrylic resin), intervention (application of essential oils), comparison (denture cleansers, antifungal drugs, chlorhexidine, and oral mouthwashes), and outcome (antibiofilm activity). In vitro experimental studies evaluating the activity of EOs on biofilm formed on acrylic resin were included. PRISMA guidelines were followed, and the search was performed in the PubMed, Science Direct, Embase, and Lilacs databases and in the gray literature using Google Scholar and ProQuest in December 2023. A manual search of the reference lists of the included primary studies was performed. Of the 1467 articles identified, 37 were selected for full-text reading and 12 were included. Twelve EOs were evaluated, of which 11 showed activity against Candida spp., 3 against Staphylococcus aureus, and 1 against Pseudomonas aeruginosa. The EOs of Cymbopogon citratus, Cinnamomum zeylanicum, and Cymbopogon nardus showed higher action than chlorhexidine, C. nardus higher than Listerine, C. citratus higher than nystatin, and Melaleuca alternifolia higher than fluconazole and nystatin. However, chlorhexidine was more effective than Lippia sidoides and Salvia officinalis, sodium hypochlorite was more effective than L. sidoides, nystatin was more effective than Zingiber officinale, Amphotericin B more effective than Eucalyptus globulus and M. alternifolia. In conclusion, the EOs of C. zeylanicum, C. citratus, C. nardus, and M. alternifolia showed antimicrobial activity to reduce biofilm on dental acrylic resin.

Green Alternatives as Antimicrobial Agents in Mitigating Periodontal Diseases: A Narrative Review

Periodontal diseases and dental caries are the most common infectious oral diseases impacting oral health globally. Oral cavity health is crucial for enhancing life quality since it serves as the entranceway to general health. The oral microbiome and oral infectious diseases are strongly correlated. Gram-negative anaerobic bacteria have been associated with periodontal diseases. Due to the shortcomings of several antimicrobial medications frequently applied in dentistry, the lack of resources in developing countries, the prevalence of oral inflammatory conditions, and the rise in bacterial antibiotic resistance, there is a need for reliable, efficient, and affordable alternative solutions for the prevention and treatment of periodontal diseases. Several accessible chemical agents can alter the oral microbiota, although these substances also have unfavorable symptoms such as vomiting, diarrhea, and tooth discoloration. Natural phytochemicals generated from plants that have historically been used as medicines are categorized as prospective alternatives due to the ongoing quest for substitute products. This review concentrated on phytochemicals or herbal extracts that impact periodontal diseases by decreasing the formation of dental biofilms and plaques, preventing the proliferation of oral pathogens, and inhibiting bacterial adhesion to surfaces. Investigations examining the effectiveness and safety of plant-based medicines have also been presented, including those conducted over the past decade.

Study of the mechanism of ε-poly-l-lysine as an antifungal on Candida albicans and Saccharomyces cerevisiae

The antimicrobial activity of ε-poly-l-lysine (EPL) has been documented, but its antifungal activity on yeast is not well defined and its mechanism of action has been vaguely explained. Our studies revealed that on both, Candida albicans and Saccharomyces cerevisiae, the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) were 250 μg·mL^-1; EPL produced a K⁺ and Ca²⁺ efflux, and at higher concentrations also an efflux of material absorbing at 260 nm, small peptides, and phosphate is produced, along with the inhibition of fermentation and extracellular acidification and respiration. Moreover, growth was inhibited, reactive oxygen species (ROS) production increased, and cell viability decreased. The polycation also produced plasma membrane potential hyperpolarization. The effects were dependent both on the cell quantity and polycation concentration, as well as the media used. The plasma membrane disruption was confirmed by TEM and PI staining.

Potential Inhibitors of CYP51 Enzyme in Dermatophytes by Red Sea Soft Coral Nephthea sp.: In Silico and Molecular Networking Studies

In this study, the n-hexane fraction of soft coral Nephthea sp. gathered from the Red Sea was evaluated for its antidermatophyte activity. The antidermatophyte activity was performed versus different fungi, including Microsporum canis, Trichophyton gypseum, and Microsporum mentagrophytes, using a broth microdilution method. The n-hexane fraction showed minimum inhibitory concentrations (MICs) against the tested dermatophytes of 104.2 ± 20.8, 125 ± 0.0, and 83.33 ± 20.83 μg/mL respectively. The chemical constitution of the lipoidal matter (n-hexane fraction) was characterized by gas chromatography coupled with a mass spectrometer (GC-MS). The unsaponifiable fraction (USAP) of Nephthea sp. showed relative percentages of hydrocarbons and vitamins of 69.61% and 3.26%, respectively. Moreover, the percentages of saturated and unsaturated fatty acids were 53.67% and 42.05%, respectively. In addition, a molecular networking study (MN) of the GC-MS analysis performed using the Global Natural Products Social Molecular Networking (GNPS) platform was described. The molecular docking study illustrated that the highest binding energy score for spathulenol toward the CYP51 enzyme was -8.3674 kcal/mol, which predicted the mode of action of the antifungal activity, and then the results were confirmed by the inhibitory effect of Nephthea sp. against CYP51 with an IC₅₀ value of 12.23 μg/mL. Our results highlighted the antifungal potential of Nephthea sp. metabolites.

A Systematic Review of the Potential Effects of Lippia sidoides on Dental Plaque and Periodontal Diseases

Lippia sidoides is a typical shrub from Brazil that has been used in traditional medicine. This is a systematic review on the effect of L. sidoides for controlling dental plaque, gingivitis, and periodontitis. A database search through May 2021 in Medline/PubMed, SCOPUS, BVS, and Web of Science identified 711 reports of which 17 met our inclusion criteria. Five randomized controlled trials and three animal studies were included that compared L. sidoides-based products (toothpaste, mouthrinse, and gel) to cetylpyridinium chloride, chlorhexidine, and placebo products. Among the human studies, a significant antiplaque effect after treatment with L. sidoides-based products was observed in three studies and an antigingivitis effect in two studies, similar to chlorhexidine-based products. One study found superior dental plaque reduction compared to cetylpyridinium chloride mouthrinse. Only one study testing a L. sidoides gel found no antiplaque effect. Among the animal studies, an L. sidoides mouthrinse significantly reduced calculus in two studies, inflammatory infiltrate in one study, and plaque bacteria and gingivitis in one study. An L. sidoides gel significantly reduced alveolar bone loss and inflammatory response in one study in which mice were submitted to ligature-induced periodontal disease. In general, L. sidoides-based products were effective in reducing dental plaque and calculus formation, as well as clinical signs of gingivitis. As most studies present methodological limitations, these results should be interpreted carefully. Further clinical trials with greater methodological accuracy and control of biases are necessary for the use of L. sidoides-based products in humans to be viable in clinical practice.

Can Plant Materials Be Valuable in the Treatment of Periodontal Diseases? Practical Review

Periodontal diseases are one of the most significant challenges in dental health. It is estimated that only a few percent of the worldwide population have entirely healthy teeth, and according to WHO, oral diseases may affect up to 3.5 billion people worldwide. One of the most serious oral diseases is periodontitis, an inflammatory disease affecting periodontal tissues, caused by pathogenic bacteria and environmental factors such as the ageing population, abuse of tobacco products, and lack of adequate oral hygiene due low public awareness. Plant materials are widely and successfully used in the management of many conditions, including periodontitis. Plant materials for periodontitis exhibit antibacterial, anti-inflammatory, antioxidant activities and affect the periodontium structure. Numerous studies demonstrate the advantages of phytotherapy for periodontitis relief and indicate the usefulness of Baikal skullcap root, Pomegranate fruit peel and root cortex, Tea leaves, Chamomile flowers, Magnolia bark, Blackberry leaves and fruits, Cranberry fruits and Lippia sidoides essential oil. This review aims to analyze the use and applicability of selected plant materials in periodontitis management since it is of paramount importance to evaluate the evidence of the traditionally used plant materials in light of continuously growing interest in phytotherapy and its adjuvant role in the treatment of periodontitis.

Do essential oils from plants occurring in the Brazilian Caatinga biome present antifungal potential against dermatophytoses? A systematic review

The Caatinga is an exclusively Brazilian biome where semiarid climatic conditions promote singularities in adaptive biodiversity. Many aromatic species are found in this region possessing antifungal properties, which are attributed to their essential oils. Thus, we questioned whether essential plant oils found in the Caatinga present anti-dermatophytic potential. Dermatophytes are keratinophilic fungi that cause one of the most prevalent mycoses globally, skin infections known as dermatophytoses (tineas). Here, we provide a comprehensive report of the available published information, analyzing the methods used to evaluate the antifungal activity, verifying the quality of the evidence and possible clinical applications, and discussing research trends in this area. The plants studied concentrated in the genera Croton (Euphorbiaceae), Lippia (Verbenaceae), Piper (Piperaceae), and Mentha (Lamiaceae). All of the studies used in vitro tests to analyze antifungal potential, and little evidence was ascertained concerning the mechanism of antifungal action. In addition, the essential oils also evidenced drug modifying activity of conventional antifungal drugs (Ketoconazole and Terbinafine). We believe that the anti-dermatophyte potential of plant essential oils occurring within the Caatinga is underestimated and that this review will encourage future chemical-pharmacological investigations into the plants within this biome.Key points• The essential oils from plants occurring in the Caatinga Biome present unknown anti-dermatophyte potential.• The studies against dermatophyte fungi concentrate on the families Lamiaceae and Verbenaceae.• In vitro assays were used to assess the anti-dermatophyte potential of the essential oils.

Multidrug-resistant Escherichia coli in Raw Milk: Molecular Characterization and the potential impact of camel's Urine as an Antibacterial Agent

Raw milk is one of the most important vehicles for transmitting various pathogens, especially Escherichia coli (E. coli). Multidrug-resistant pathogens are highly prevalent among mastitic cows in various dairy farms worldwide. Therefore, our current study is based on the identification of E. coli from mastitic cow’s milk and their resistance to various antibacterial agents. As well, the impact of camel’s urine on multi-drug resistant E. coli were also evaluated. Thirty-three E. coli isolates were recovered from 254 milk samples. All strains were initially identified phenotypically by culturing on specific media and Vitek 2 Compact System. The protein fingerprinting technique was used as a confirmatory method. The Stx1, Stx2 and eae genes were also verified by polymerase chain reaction (PCR). The antimicrobial resistance of E. coli strains was tested by the Vitek 2 AST-GN69 cards. Thirty multi-drug resistant E. coli strains (20 from mastitic milk and 10 from clinical samples) were laboratory tested with different concentrations (100%, 75%, 50% and 25%) of virgin and breeding camel’s urine, using the paper disc diffusion method. Our findings showed that 93.94% of E. coli strains were recognized by the Vitek™ 2 system. The results of proteomic investigation illustrated that 100% of E. coli strains were identified at log values ≥2.00. The genotypic identification of the three virulence genes illustrated that 90.1%, 63.64%, and 30.55% of E. coli strains were able to carry the Stx1, eae, and Stx2 genes, respectively. Most strains of E. coli showed strong resistance against cefazolin (78.79%), ceftazidime (66.67%), cefotaxime (60.61%), ceftriaxone (54.55%), and cefepime (39.40%). The results of the antibacterial effect of camel’s urine revealed that the mean inhibitory zones of virgin camel’s urine were 28 mm, 17 mm, and 14 mm, for the concentrations of 100%, 75%, and 50%, respectively. Whereas; the inhibitory zones for the breeding camel’s urine were 18 mm, 0 mm, and 0 mm, for the concentrations of 100%, 75%, and 50%, respectively. We concluded that the majority of E. coli strains were able to harbor some virulence genes and resist many antibiotics. Our study also provided a robust evidence that the camel’s urine, particularly from the virgin camels has robust antimicrobial activity against multidrug-resistant E. coli strains.

Microbiological evaluation of an experimental denture cleanser containing essential oil of Lippia sidoides

The antimicrobial activity of an experimental solution containing essential oil of Lippia sidoides for denture cleaning was evaluated by (1) minimum inhibitory (MIC) and fungicidal/bactericidal concentration (MFC/MBC) tests against Candida albicans, Staphylococcus aureus, and Pseudomona aeruginosa; (2) the metabolic activity of C. albicans biofilm formed on flat-bottom microplates and denture base specimens based on the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT); and (3) scanning electron microscopy, to evaluate the fungal biofilm morphology. The solution showed antimicrobial action against the pathogens tested (C. albicans - MIC and MFC: 19.53 µg ml^-1, S. aureus - MIC and MBC: 78.12 µg ml^-1, P. aeruginosa - MIC: 625 µg ml^-1, MBC: 2,500 µg ml^-1), reduced the metabolic activity of C. albicans biofilm up to 97%, and caused cell wall damage at low concentrations (195.3-390.6 µg ml^-1) and in short time periods (20 min). Therefore, the experimental solution has the potential to be used as an alternative in the prevention and treatment of denture-induced infections.

Use of Essential Oils in Veterinary Medicine to Combat Bacterial and Fungal Infections

Essential oils (EOs) are secondary metabolites of plants employed in folk medicine for a long time thanks to their multiple properties. In the last years, their use has been introduced in veterinary medicine, too. The study of the antibacterial properties of EOs is of increasing interest, because therapies with alternative drugs are welcome to combat infections caused by antibiotic-resistant strains. Other issues could be resolved by EOs employment, such as the presence of antibiotic residues in food of animal origin and in environment. Although the in vitro antimicrobial activity of EOs has been frequently demonstrated in studies carried out on bacterial and fungal strains of different origins, there is a lack of information about their effectiveness in treating infections in animals. The scientific literature reports some studies about in vitro EOs' activity against animal clinical bacterial and fungal isolates, but in vivo studies are very scanty. The use of EOs in therapy of companion and farm animals should follow careful studies on the toxicity of these natural products in relation to animal species and route of administration. Moreover, considering the different behavior of EOs in relation to both species and strain pathogen, before starting a therapy, an aromatogram should be executed to choose the oil with the best antimicrobial activity.

The regulatory role of dietary factors in skeletal muscle development, regeneration and function

Skeletal muscle plays a crucial role in motor function, respiration, and whole-body energy homeostasis. How to regulate the development and function of skeletal muscle has become a hot research topic for improving lifestyle and extending life span. Numerous transcription factors and nutritional factors have been clarified are closely associated with the regulation of skeletal muscle development, regeneration and function. In this article, the roles of different dietary factors including green tea, quercetin, curcumin (CUR), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and resveratrol (RES) in regulating skeletal muscle development, muscle mass, muscle function, and muscle recovery have been summarized and discussed. We also reviewed the potential regulatory molecular mechanism of these factors. Based on the current findings, dietary factors may be used as a potential therapeutic agent to treat skeletal muscle dysfunction as well as its related diseases.

Using the plants of Brazilian Cerrado for wound healing: From traditional use to scientific approach

ETHNOPHARMACOLOGICAL RELEVANCE

The Brazilian Cerrado is a biome with a remarkable diversity of plant species, many of which are used mainly by local communities as a source of treatment to several pathologic processes, especially for the treatment of wounds. However, no systematic review exists focusing on the plants used in this respect and on the appropriate pharmacological investigations that substantiate the actions that are reported. This study revisits the traditional use of medicinal plants from the Brazilian Cerrado in the treatment of wounds and the pharmacological characteristics of the reported plant species.

METHOD

ology: For the present article, previous studies on plants of the Brazilian Cerrado used for wound healing carried out between 1996 and 2018 were researched on various academic databases (PubMed, Elsevier, Springer, Lilacs, Google Escolar, and Scielo).

RESULTS

A total of 33 studies were carried out on 29 plant species distributed into 18 families, mainly Fabaceae or Leguminosae (9), Bignoniaceae (2), Asteraceae (2), Euphorbiaceae (2). Considering the great diversity of Cerrado plants, only a small number of wound healing studies were carried out between 1996 and 2018. It was observed that there is a large gap between experimentation assay and traditional use. There are only few connections between the form of use by the population and the experiments conducted in the laboratory. We found that only about 12% of these studies considered to use the methodologies, or at least in parts, to obtain extracts such as those used in folk medicine. Approximately 37% of the experiments were performed using the bark as well as the same ratio for leaves, 6% using the fruits, and 9% using the seeds, roots or flowers. In several studies, there are reports of chemical constituents such as flavonoids and tannins, followed by steroid terpenes, saponins, and fatty acids, and alkaloids. However, approximately 35% of the studies did not supply information about compounds present in the preparation or the effect which could be attributed to these agents in respect to wound healing. Regarding treatment, most of the studies employed a topical treatment, though intraperitoneal and oral treatment were also described using either topical, oil-based formulations, but also gel- or saline-based formulations.

CONCLUSIONS

Although, there has been an increase in knowledge about the biological actions of plants from Cerrado biome, the scientific basis for the traditional use of these local medicinal plants in wound healing does not provide sufficient information on the efficacy of the treatment, the molecular mechanisms, or, in particular, the effective doses used and the drug interactions. Thus, focused research investigating these hypotheses from traditional knowledge is necessary to prove the evidence of the potential pharmacological action.

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.

Natural Compounds as a Strategy to Optimize "In Vitro" Expansion of Stem Cells

The efficient use of stem cells for transplantation is often limited by the relatively low number of stem cells collected. The ex vivo expansion of human stem cells for clinical use is a potentially valuable approach to increase stem cell number. Currently, most of the procedures used to expand stem cells are carried out using a 21% oxygen concentration, which is about 4- to 10-fold greater than the concentration characteristic of their natural niches. Hyperoxia might cause oxidative stress with a deleterious effect on the physiology of cultured stem cells. In this review, we investigate and critically examine the available information on the ability of natural compounds to counteract hyperoxia-induced damage in different types of stem cells ex vivo. In particular, we focused on proliferation and stemness maintenance in an attempt to draw up useful indications to define new culture media with a promoting activity on cell expansion in vitro.

Taxonomy and Broad-Spectrum Antifungal Activity of Streptomyces sp. SCA3-4 Isolated From Rhizosphere Soil of Opuntia stricta

Actinobacteria are important producers of bioactive compounds. Extreme ecosystems cause evolution of novel secondary metabolic pathways of Actinobacteria and increase the possible discovery of new biological functions of bioactive compounds. Here, we isolated 65 Actinobacteria from rhizosphere soil samples of Opuntia stricta. An Actinobacteria strain (named SCA3-4) was screened against Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4, ATCC 76255). The strain produced pink-white aerial mycelia and brown substrate mycelium on Gause No. 1 agar. Biverticillate chains of cylindrical spores were observed by scanning electron microscopy (SEM). Based on alignment of 16S rRNA sequences, a constructed phylogenetic tree showed that strain SCA3-4 shared a 99.54% similarity with Streptomyces lilacinus NRRL B-1968T. The morphological, biochemical, physiological, and molecular characteristics further indicated that strain SCA3-4 belongs to the Streptomyces sp. It can grow well on medium with the following antibiotics chloramphenicol, streptomycin, penicillin-G, gentamicin, erythromycin, nystatin or neomycin sulfate. The polymerase chain reaction (PCR) amplification of types I and II polyketide synthase genes (PKS-I and PKS-II) suggested its bioactive potential. Under treatment with 100 μg/ml of ethyl acetate extracts isolated from Streptomyces sp. SCA3-4, growth of Foc TR4 was inhibited and cell membrane was destroyed. Crude extracts also showed a broad-spectrum antifungal activity against 13 phytopathogenic fungi including Foc TR4 and displayed the lowest minimum inhibitory concentration (MIC) (0.781 μg/ml) against Colletotrichum fragariae (ATCC 58718). A total of 21 different compounds identified by gas chromatography-mass spectrometry (GC-MS) were composed of phenolic compound, pyrrolizidine, hydrocarbons, esters, and acids. Besides the known active compounds, Streptomyces sp. SCA3-4 possesses antimicrobial or other biological activities. Further attention will be paid on other compounds with no functional annotation, aiming at the discovery of new bioactive substances.

Evaluation of the antimicrobial and antioxidant activity of 7-hydroxy-4', 6-dimethoxy-isoflavone and essential oil from Myroxylon peruiferum L.f

This study evaluated the antibacterial, antifungal, and antioxidant effect of 7-hydroxy-4',6-dimethoxy-isoflavone and essential oil of Myroxylon peruiferum. The compound was isolated and its structure elucidated by NMR. The chemical composition of essential oil determined by GC-MS analysis. To evaluation of antimicrobial activity, the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC) were performed. In addition to analysis of antioxidant activity, DPPH radical scavenging tests, iron chelating assay (FIC), antioxidant reducing power assay (FRAP) and β-carotene bleaching assay (BCB) were performed. For the essential oil were identified 24 organized compounds having as main constituents; Germacrene D (17.2%), α-pinene (14.8%) and E-caryophyllene (10.8%). The results showed that isoflavone (2000 to 156 μg/mL) and essential oil (5.0 to 1.25%) present antibacterial and antifungal activity against Gram-positive bacteria and filamentous fungi. The isoflavone and the essential oil also presented antioxidant activity in all the tests, mainly on inhibition of the oxidation of β-carotene test concentrations ranging from 60 to 100%. In conclusion, isoflavone and essential oil from M. peruiferum present an antimicrobial alternative against Gram-positive bacteria, especially of the genus Staphylococcus and dermatophyte fungi of the genus Trichophyton, as well as a natural compound antioxidant.

Genetic diversity and chemical variability of Lippia spp. (Verbenaceae)

Background

The genus Lippia comprises 150 species, most of which have interesting medicinal properties. Lippia sidoides (syn. L. origanoides) exhibits strong antimicrobial activity and is included in the phytotherapy program implemented by the Brazilian Ministry of Health. Since species of Lippia are morphologically very similar, conventional taxonomic methods are sometimes insufficient for the unambiguous identification of plant material that is required for the production of certified phytomedicines. Therefore, genetic and chemical analysis with chemotype identification will contribute to a better characterization of Lippia species.

Methods

Amplified Length Polymorphism and Internal Transcribed Spacer molecular markers were applied to determine the plants’ genetic variability, and the chemical variability of Lippia spp. was determined by essential oil composition.

Results

Amplified Length Polymorphism markers were efficient in demonstrating the intra and inter-specific genetic variability of the genus and in separating the species L. alba, L. lupulina and L. origanoides into distinct groups. Phylogenetic analysis using Amplified Length Polymorphism and markers produced similar results and confirmed that L. alba and L. lupulina shared a common ancestor that differ from L. origanoides. Carvacrol, endo-fenchol and thymol were the most relevant chemical descriptors.

Conclusion

Based on the phylogenetic analysis it is proposed that L. grata should be grouped within L. origanoides due to its significant genetic similarity. Although Amplified Length Polymorphism and Internal Transcribed Spacer markers enabled the differentiation of individuals, the genotype selection for the production of certified phytomedicines must also consider the chemotype classification that reflects their real medicinal properties.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3839-y) contains supplementary material, which is available to authorized users.

Circadian Rhythm, and Antimicrobial and Anticholinesterase Activities of Essential Oils from Vitex gardneriana

Vitex gardneriana, popularly known as “jaramataia”, is a shrub commonly found in the caatinga biome located in northeast Brazil. In folk medicine, its leaves have been used as analgesic and anti-inflammatory agents. Here we describe, for the first time, the chemical composition of the leaf essential oils extracted at 8.00, 12.00 and 17.00 h from V. gardneriana and report on their circadian rhythm, and antimicrobial and anticholinesterase activities. The essential oils’ antifungal activity was evaluated by a broth microdilution method using strains of dermatophytes, fungi and yeasts. The modulatory activity assays were performed by the checkerboard technique using ketoconazole as a standard drug, and acetylcholinesterase inhibitory activity was performed using Ellman's colorimetric method and compared with a reference acetycholinesterase inhibitor (physostigmine). The essential oils extracted from the leaves were analyzed by GC/MS and GC/FID. Twenty-five constituents (94.7%) were identified in the 8 o'clock oil, these being 2 monoterpenes (0.4%) and 23 sesquiterpenes (94.3%). For the essential oil extracted at 12 o'clock, 26 constituents (91.8%) were identified, of which 2 were monoterpenes (0.3%) and 24 sesquiterpenes (91.5%). For the essential oil extracted at 17.00 h, 32 constituents (91.4%) were identified, of which 5 were monoterpenes (3.4%) and 27 sesquiterpenes (88%). The main constituents of the 8.00, 12.00 and 17.00 h essential oils were the sesquiterpenes cis-calamenene (27.9, 24.5 and 25.8%), 6,9-guaiadiene (21.8, 11.2 and 18.4%) and caryophyllene oxide (16.7, 26.3 and 13.8%), respectively. The essential oils showed activity against strains of Trichophyton rubrum.

Antimicrobial Activity and Chemical Composition of Essential Oils from Verbenaceae Species Growing in South America

The Verbenaceae family includes 2600 species grouped into 100 genera with a pantropical distribution. Many of them are important elements of the floras of warm-temperature and tropical regions of America. This family is known in folk medicine, and its species are used as digestive, carminative, antipyretic, antitussive, antiseptic, and healing agents. This review aims to collect information about the essential oils from the most reported species of the Verbenaceae family growing in South America, focusing on their chemical composition, antimicrobial activity, and synergism with commercial antimicrobials. The information gathered comprises the last twenty years of research within the South American region and is summarized taking into consideration the most representative species in terms of their essential oils. These species belong to Aloysia, Lantana, Lippia, Phyla, and Stachytarpheta genera, and the main essential oils they contain are monoterpenes and sesquiterpenes, such as β-caryophyllene, thymol, citral, 1,8-cineole, carvone, and limonene. These compounds have been found to possess antimicrobial activities. The synergism of these essential oils with antibiotics is being studied by several research groups. It constitutes a resource of interest for the potential use of combinations of essential oils and antibiotics in infection treatments.

Chemical composition, antioxidant and antifungal activities of essential oils and extracts from Plectranthus spp. against dermatophytes fungi

SUMMARY Resistance to use antifungal drugs is a great concern seeking for scientists to discover new products to treat fungal infections. The aim of this study was to evaluate the antioxidant and antifungal activities of essential oils and extracts of Plectranthus grandis and Plectranthus ornatus against Trichophyton rubrum and Microsporum canis dermatophytes strains. Extracts were obtained from leaves by maceration in ethanol (96%) during 7 days. The oils were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry. A total of 25 components were identified, as major constituents the sesquiterpenes β-caryophyllene, α-copaene, germacrene, β-caryophyllene and caryophyllene oxide. Antioxidant activities were evaluated using DPPH scavenging assay and antifungal action was determined by the broth microdilution method. The decocts obtained from the extraction of essential oil presented a greater antioxidant action when compared with the essential oils, with IC50 values of 12.35 μg/mL and 15.69 μg/mL to P. ornatus and P. grandis, respectively. Natural products presented significant antifungal activity, with MIC values ranging from 0.078 mg/mL to 0.31 mg/mL for all strains. The synergistic activity between Plectranthus spp. extracts and ketoconazole demonstrated a fungal growth inhibitory action when combined with a standard antifungal drug, indicating its potential for use in preventive veterinary medicine to treat dermatophytoses.

Antifungal and Anti-Biofilm Activity of Essential Oil Active Components against Cryptococcus neoformans and Cryptococcus laurentii

Cryptococcosis is an emerging and recalcitrant systemic infection occurring in immunocompromised patients. This invasive fungal infection is difficult to treat due to the ability of Cryptococcus neoformans and Cryptococcus laurentii to form biofilms resistant to standard antifungal treatment. The toxicity concern of these drugs has stimulated the search for natural therapeutic alternatives. Essential oil and their active components (EO-ACs) have shown to possess the variety of biological and pharmacological properties. In the present investigation the effect of six (EO-ACs) sourced from Oregano oil (Carvacrol), Cinnamon oil (Cinnamaldehyde), Lemongrass oil (Citral), Clove oil (Eugenol), Peppermint oil (Menthol) and Thyme oil (thymol) against three infectious forms; planktonic cells, biofilm formation and preformed biofilm of C. neoformans and C. laurentii were evaluated as compared to standard drugs. Data showed that antibiofilm activity of the tested EO-ACs were in the order: thymol>carvacrol>citral>eugenol=cinnamaldehyde>menthol respectively. The three most potent EO-ACs, thymol, carvacrol, and citral showed excellent antibiofilm activity at a much lower concentration against C. laurentii in comparison to C. neoformans indicating the resistant nature of the latter. Effect of the potent EO-ACs on the biofilm morphology was visualized using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), which revealed the absence of extracellular polymeric matrix (EPM), reduction in cellular density and alteration in the surface morphology of biofilm cells. Further, to realize the efficacy of the EO-ACs in terms of human safety, cytotoxicity assays and co-culture model were evaluated. Thymol and carvacrol as compared to citral were the most efficient in terms of human safety in keratinocyte- Cryptococcus sp. co-culture infection model suggesting that these two can be further exploited as cost-effective and non-toxic anti-cryptococcal drugs.

Effects of Lippia sidoides essential oil, thymol, p-cymene, myrcene and caryophyllene on rat sciatic nerve excitability

Lippia sidoides Cham is a typical herb species of Northeast Brazil with widespread use in folk medicine. The major constituents of the essential oil of L. sidoides (EOLs) are thymol, p-cymene, myrcene, and caryophyllene. Several studies have shown that the EOLs and its constituents have pharmacological effects, including antibacterial, anti-inflammatory, antioxidant and neuroprotective activity. Therefore, this work aimed to investigate the effects of the EOLs and their main constituents on rat sciatic nerve excitability. The sciatic nerves of adult Wistar rats were dissected and mounted in a moist chamber. Nerves were stimulated by square wave pulses, with an amplitude of 40 V, duration of 100 μs to 0.2 Hz. Both EOLs and thymol inhibited compound action potential (CAP) in a concentration-dependent manner. Half maximal inhibitory concentration for CAP peak-to-peak amplitude blockade were 67.85 and 40 µg/mL for EOLs and thymol, respectively. CAP peak-to-peak amplitude was significantly reduced by concentrations ≥60 µg/mL for EOLs and ≥30 µg/mL for thymol. EOLs and thymol in the concentration of 60 µg/mL significantly increased chronaxie and rheobase. The conduction velocities of 1st and 2nd CAP components were also concentration-dependently reduced by EOLs and thymol in the range of 30-100 µg/mL. Differently from EOLs and thymol, p-cymene, myrcene and caryophyllene did not reduce CAP in the higher concentrations of 10 mM. These data demonstrated that EOLs and thymol inhibited neuronal excitability and were promising agents for the development of new drugs for therapeutic use.

Growth-arresting Activity of Acmella Essential Oil and its Isolated Component D-Limonene (1, 8 P-Mentha Diene) against Trichophyton rubrum (Microbial Type Culture Collection 296)

Background:

Spilanthes acmella is used as a remedy in toothache complaints by the tribal people of Western part of Odisha, India.

Objective:

The objective of this study was to study the growth-arresting activity of an indigenous Acmella essential oil (EO) (S. acmella Murr, Asteraceae) and its isolated component, d-limonene against Trichophyton rubrum (microbial type culture collection 296).

Materials and Methods:

The EO was extracted from flowers of indigenous S. acmella using Clevenger's apparatus and analyzed by gas chromatography–mass spectrometry (GC-MS). High pressure liquid chromatography (HPLC) was carried out to isolate the major constituent. The isolated fraction was subjected to fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The antidermatophytic activity was screened for using “disc diffusion” and “slant dilution” method followed by optical, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies. The molecular dockings were made between d-limonene with cell wall synthesis-related key enzymes (14 methyl deaminase and monooxygenase).

Results:

The GC-MS analysis EO had inferred the presence of 7 number of major (≥2%) components. The component with highest peak area (%) was found to be 41.02. The HPLC-isolated fraction was identified as d-limonene (1,8 p-Mentha-diene) by FTIR and NMR. Qualitative and quantitative assays had suggested the growth inhibitory activity of Acmella EO and its component. Shrinkage, evacuation, cell wall puncture, and leakage of cellular constituents by the activity of Acmella oil and d-limonene were evidenced from optical, SEM, and TEM studies. The computer simulation had predicted the binding strengths of d-limonene and fluconazole with dermatophyte cell wall enzymes.

Conclusion:

There could have been synergistic action of all or some of compounds present in indigenous Acmella EO.

SUMMARY

There was presence of seven number of (d-limonene, ocimene, β-myrcene, cyclohexene, 3-(1, 5-dimethyl-4-hexenyl)-6-methylene, β-caryophyllene, and β-sesquiphellandrene and β-phellandrene) major components in the indigenous Acmella essential oil

The d-limonene content was 41.02% in the indigenous oil

The antidermatophytic activity of Acmella essential oil could have been attributable to its chemotypes.

Abbreviations used: °C: Degree centigrade; w/v: Weight/volume; TS: Transverse section; min: minute; Hz: hertz: h: Hr.

Effect of essential oils from Mangifera indica L. cultivars on the antifungal susceptibility of Candida spp. strains isolated from dogs

SUMMARY This work reports the chemical study, and anti-Candida spp. activity of leaf essential oil from Mangifera indica cultivars. The essential oils were obtained by hydro-distillation and analyzed by gas chromatography/mass spectroscopy. The anti-Candida spp. activity was evaluated against strains isolated from dogs by the agar-well diffusion method and the minimum inhibitory concentration (MIC) by the broth microdilution method. Tommy Atkins cultivar presented β–selinene (29.49%), caryophyllene oxide (12.40%) and humulene II epoxide (8.66%) as main constituents, while the main constituents of Rosa, Moscatel and Jasmim varieties were caryophyllene oxide (23.62, 48.42 and 30.77%, respectively) and humulene epoxide II (11.56, 23.45, and16.27%, respectively). The means of inhibition zones were 11 ± 0.71, 13.5 ± 3.54, 10.5 ± 0.71 and 13.5 ± 0.71mm to Tommy Atkins, Rosa, Moscatel and Jasmim varieties, respectively. For Tommy Atkins, the MIC ranged from 0.62 to 1.25 mg/mL; for Rosa, ranged from 0.31 to 1.25 mg/mL; for Jasmim ranged from 0.31 to 0.62 mg/mL; while for the Moscatel variety the MIC value was 1.25 mg/mL for all Candida strains. Essential oils of four M. indica cultivars were active in vitro against Candida spp., demonstrating good antifungal activity and can be a useful source of antifungal compounds for veterinary medicine.

Effect of dietary Lippia citriodora extract on reproductive and productive performance and plasma biochemical parameters in rabbit does

Two doses of natural extract from Lippia citriodora (titrated in verbascoside) were assessed in New Zealand White rabbit does evaluating selected reproductive, productive and plasma biochemical parameters. After 1 week of adaptation period, the trial on 45 rabbit does for three consecutive reproductive cycles was conducted; does were divided into three groups of 15 animals each, homogenous by age (1 year ± 2 weeks), bodyweight (4.77 ± 0.21 kg) and parity (2 ± 1). A control group (CON) did not receive the dietary supplement in the feed and the other two groups received 1 g of natural extract supplement in the feed (5 mg verbascoside/kg feed; LNE) and 2 g of natural extract (10 mg verbascoside/kg feed; HNE). The use of a dietary NE supplement improved kit bodyweight at weaning (934 vs 1104 g; P < 0.001), and average daily weight gain from birth to weaning (24.7 vs 29.7 g/day; P < 0.001), with no NE dose effect. In the LNE and HNE groups serum triglycerides, total cholesterol, low density lipoprotein cholesterol, bilirubin, and activities of alkaline phosphatase, alanine aminotransferase (P < 0.05) and aspartate aminotransferase (P < 0.01) decreased and high density lipoprotein cholesterol (P < 0.01) increased, according to the cycle effect. The dietary supplement also improved blood oxidative status markers in the experimental groups due to an increase in the concentrations of plasma vitamin A and E (P < 0.01) and a decrease in plasma reactive oxygen metabolites and thiobarbituric acid reactive substances values (P < 0.01). In conclusion, the dietary Lippia NE supplement improved selected productive and reproductive parameters and the animal welfare of does, expressed by a general improvement of blood profile, with no effect of the dose.

Antiparasitic activity, histopathology and physiology of Colossoma macropomum (tambaqui) exposed to the essential oil of Lippia sidoides (Verbenaceae)

In vivo and in vitro antiparasitic activity of the essential oil of Lippia sidoides and blood and histological alterations were assessed in Colossoma macropomum (tambaqui). Essential oil concentrations of 10, 20, 40, 80, 160 and 320mg/L were assayed in vitro against monogenoideans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri from fish gills. Lippia sidoides essential oil concentrations of 320 and 160mg/L were 100% effective against monogenoideans in 10min and 1h of exposure, respectively. However, the effectiveness of 100% concentrations of 80mg/L and 40mg/L occurred in 3 and 6h, respectively. In the in vivo tests, juvenile fish were submitted to 60min of baths with 10mg/L and 15min of baths with 20mg/L of the essential oil of L. sidoides. These therapeutic baths were not efficient against Ichthyophthirius multifiliis, and monogenoideans present in the gills of C. macropomum. In addition, 10 and 20mg/L of the essential oil of L. sidoides caused an anesthetic effect on the fish and did not influence total glucose and protein plasma levels; however, it decreased the number of total erythrocytes in fish exposed to the higher concentration of this essential oil. Severe alterations and irreversible damage were observed in the fish gills just after L. sidoides essential oil baths and after 24h of recovery. The most recurrent lesions found were hyperplasia and fusion of the lamellar epithelium, vasodilation, detachment of the gill epithelium and lamellar aneurism, epithelial breakdown with hemorrhage, congestion, edema and necrosis, proliferation of the mucous cells and chloride cells and lamellar hypertrophy. Therefore, since the essential oil of L. sidoides has in vitro antiparasitic activity and low concentrations of it have shown toxic effects, the bioactive potential of its main chemical components should be investigated, as well as more efficient forms of its administration in therapeutic baths in order to eliminate fish parasites.

Toxicity of twenty-two plant essential oils against pathogenic bacteria of vegetables and mushrooms

ASBTRACT Toxicity of twenty-two essential oils to three bacterial pathogens in different horticultural systems: Xanthomonas campestris pv. phaseoli (causing blight of bean), Clavibacter michiganensis subsp. michiganensis (bacterial wilt and canker of tomato), and Pseudomonas tolaasii (causal agent of bacterial brown blotch on cultivated mushrooms) was tested. Control of bacterial diseases is very difficult due to antibiotic resistance and ineffectiveness of chemical products, to that essential oils offer a promising alternative. Minimal inhibitory and bactericidal concentrations are determined by applying a single drop of oil onto the inner side of each plate cover in macrodilution assays. Among all tested substances, the strongest and broadest activity was shown by the oils of wintergreen (Gaultheria procumbens), oregano (Origanum vulgare), and lemongrass (Cymbopogon flexuosus. Carvacrol (64.0-75.8%) was the dominant component of oregano oils, while geranial (40.7%) and neral (26.7%) were the major constituents of lemongrass oil. Xanthomonas campestris pv. phaseoli was the most sensitive to plant essential oils, being susceptible to 19 oils, while 11 oils were bactericidal to the pathogen. Sixteen oils inhibited the growth of Clavibacter michiganensis subsp. michiganensis and seven oils showed bactericidal effects to the pathogen. The least sensitive species was Pseudomonas tolaasii as five oils inhibited bacterial growth and two oils were bactericidal. Wintergreen, oregano, and lemongrass oils should be formulated as potential biochemical bactericides against different horticultural pathogens.

Thymol accelerates the recovery of the skeletal muscle of mice injured with cardiotoxin

OBJECTIVES

The aim of this study was to investigate the preventive effect of thymol in in vivo muscle inflammation and regeneration on cardiotoxin-induced injury.

METHODS

Mice were pretreated (p.o.) with thymol (10-100 mg/kg), and after 1 h, cardiotoxin (25 μM, 40 μl) was administrated into the gastrocnemius muscle. The quantification of the areas of inflammation and regeneration of muscle tissue (3, 7 and 10 days) in HE-stained slides as well as the count of total mast cells and different phenotypes of mast cells were made. Sirius red staining was used to analyse total collagen expression.

KEY FINDINGS

The pretreatment with thymol significantly reduced the area of inflammation (30 and 100 mg/kg) and increased the area of regeneration (100 mg/kg) 3 days after the cardiotoxin injection. Thymol at 30 and 100 mg/kg increased the area of collagen in 3 days and also decreased this area in 7 and 10 days, compared to the injured group. The pretreatment with thymol did not affect the number of total mast cells; however, it was able to change the number of mucosal mast cells within 10 days.

CONCLUSIONS

This study suggests that thymol ameliorates inflammatory response and accelerates regeneration in cardiotoxin-induced muscle injury.

General Characteristics, Phytochemistry and Pharmacognosy of Lippia sidoides

Lippia sidoides Cham. is a plant that belongs to the family Verbenaceae and is commonly known as “alecrim-pimenta”. It was first found in northeastern Brazil, where it is extensively used in traditional medicine. Many studies have been made with the essential oil of L. sidoides, which has a high content of the isomeric compounds thymol and carvacrol. L. sidoides extracts, and particularly the essential oil extracted from its aerial parts, have shown many biological activities such as antifungal, antibacterial, and insecticidal. Given the great biological potentialities of L. sidoides and the amount of recent studies about this plant, the present study aimed to make a survey of its general attributes, cultivation methods, chemical characterization of its extracts and essential oil, as well as its different biological activities.

Antimicrobial activity and acute and chronic toxicity of the essential oil of Lippia origanoides

Currently, there is a growing interest in medicinal plants, because of an increased demand for alternate therapies. In this study, the antimicrobial activity and toxicity of the essential oil of Lippia origanoides (L. origanoides) were investigated. The essential oil of L. origanoides was extracted by steam-dragging distillation and its constituents were identified by chromatography coupled with mass spectrometry. Among the 15 compounds identified, the most abundant were carvacrol (29.00%), o-cymene (25.57%), and thymol methyl ether (11.50%). The essential oil was studied in antimicrobial assays to determine the MIC and MBC. The results indicated that a concentration of 120μL/mL of oil was sufficient to inhibit the growth of the following microorganisms: Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Salmonella cholerasuis (ATCC 10708). Acute and chronic toxic effects of orally administered oil were investigated in Wistar rats by using standard methods. Doses of 30, 60 and 120mg/kg of the essential oil did not induce significant changes in weight, behavior or hematological and biochemical parameters in the animals. There were no signs of any histopathological changes to the liver, kidneys or heart of the treated rats, suggesting that Lippia origanoides oil is non-toxic after oral administration in acute or chronic toxicity studies. The results obtained in this study show that the essential oil of L. origanoides has a high safety margin, with no detectable toxic effects in rats treated with doses to 120mg/kg. In addition, L. origanoides oil demonstrated potent antimicrobial activity against S. aureus, E. coli and S. cholerasuis. Based on these findings, this essential oil may have practical application as a veterinary antimicrobial.

The efficacy of three formulations of Lippia sidoides Cham. essential oil in the reduction of salivary Streptococcus mutans in children with caries: a randomized, double-blind, controlled study

Essential oils of many plants have been previously tested in the treatment of oral diseases and other infections. This study was a randomized, double-blind, in parallel with an active control study, which aimed to evaluate the efficacy of three formulations of the Lippia sidoides Cham. essential oil (LSO) in the reduction of salivary Streptococcus mutans in children with caries. 81 volunteers, aged 6-12 years, both genders, with caries, were recruited to participate in this study, and randomly assigned to either one of five different groups. Each group received topical treatment with either 1.4% LSO toothpaste, 1.4% LSO gel, 0.8% LSO mouthwash, 1% chlorhexidine gel, or 0.12% chlorhexidine mouthwash. A 5-ml volume of each gel was placed inside disposable trays, and applied for 1 min, every 24h, for 5 consecutive days. The mouthwash groups used 5-ml volume of a mouthwash inside disposable syringes. In the toothpaste group, children brushed their teeth for 1 min, once a day for 5 days. Saliva was collected before and after treatment. MS colonies were counted, isolated and confirmed through biochemical tests. Differences in MS levels measured in different days within the same treatment group was only verified with LSO toothpaste, chlorhexidine gel and chlorhexidine mouthwash. Comparison between groups of LSO mouthwash, toothpaste and gel showed that the toothpaste group expressed significantly lower MS levels than the mouthwash and gel groups at day-30. Chlorhexidine significantly reduced MS levels after 5 days of treatment, but these levels returned to baseline in other periods of the study. LSO toothpaste reduced MS levels after 5 days of treatment, and MS levels remained low and did not return to baseline during subsequent analysis. Hence, LSO toothpaste demonstrated the most long-lasting MS reduction in saliva, whereas other LSO formulations did not effectively reduce MS levels in children with dental caries.

Chemical composition and evaluation of modulatory of the antibiotic activity from extract and essential oil of Myracrodruon urundeuva

CONTEXT

The combination of antibiotics with natural products has demonstrated promising synergistic effects in several therapeutic studies.

OBJECTIVE

The aim of this study was to determine the effect of a combination of an ethanol extract of Myracrodruon urundeuva Fr. All. (Anacardiaceae) (aroeira plant) and its essential oil with six antimicrobial drugs against multiresistant strains of Staphylococcus aureus and Escherichia coli from clinical isolates.

MATERIALS AND METHODS

After identification of the chemical components by GC-MS, the antibacterial activity of the natural products and antibiotics was assessed by determining the minimal inhibitory concentration (MIC) using the microdilution method and concentrations ranging 8-512 μg/mL and 0.0012-2.5 mg/mL, respectively. Assays were performed to test for a possible synergistic action between the plant products and the antimicrobials, using the extract and the oil at a sub-inhibitory concentration (128 μg/mL) and antibiotic at concentrations varying between 8 and 512 μg/mL.

RESULTS

The GC-MS analysis identified the main compound as δ-carene (80.41%). The MIC of the natural products was >1024 μg/mL, except against S. aureus ATCC25923. Only the combinations of the natural products with gentamicin, amikacin and clindamycin were effective against S. aureus 358, enhancing the antibiotic activity by reducing the MIC.

CONCLUSIONS

The extract from aroeira showed a higher antibacterial activity and the oil was more effective in potentiating the activity of conventional antibiotics.

Topical continuous use of Lippia sidoides Cham. essential oil induces cutaneous inflammatory response, but does not delay wound healing process

ETHNOPHARMACOLOGICAL RELEVANCE

The essential oil of Lippia sidoides (EOLS) has been used in Brazilian folk medicine as a topical antiseptic agent in skin for treatment of wounds and superficial infections of the body. The aim of this study was to investigate the effects of EOLS on intact and damaged skin, including its action on expression of mediators, COX-2 and VEGF, involved in healing full-thickness cutaneous lesions in vivo.

MATERIAL AND METHODS

EOLS was analyzed chemically and used at different concentrations to dose-response experiments in skin mice. Skin irritation tests by one-dosage and multiple-dosages and irritation to damaged skin were assessed by macroscopy, morphometry and histological and immunohistochemical analyses. To evaluate the effects of EOLS on wound healing, excision wounds were surgically created on the dorsum of rats, and the ointments at 6% and 12% were applied daily to the wound area. Cutaneous lesions were assessed by planimetric (wound contraction) and macroscopic parameters.

RESULTS

Skin irritation tests showed that topical application of EOLS promoted cutaneous inflammation in varying degrees, which was demonstrated by increase of skin thickness and formation of cutaneous edema and erythema. Topical administration of EOLS in high concentrations presented an irritant response to skin, but this irritation is lighter when low concentrations this oil were used. Histological evaluation supported the outcome of these models, which revealed accentuated presence of inflammatory cells infiltration. In wound healing process, the lesions treated with EOLS showed intense edema and exsudation up to day 5, but there were not significant differences in the wound contraction on days 14 and 21. No immunohistochemical staining was verified to COX-2 and VEGF mediators in skin treated with EOLS 12%.

CONCLUSION

The continuous application of EOLS in adequate concentrations on cutaneous wounds increases inflammatory response without delay the lesions closure. The association of these results with antimicrobial action previously related to EOLS allows its indication as an alternative therapeutic modality for topical treatment of infected cutaneous wound. Nevertheless, further studies need to be performed to determine the mechanism of action and support its application in clinical practice.

Antimicrobial effect of Lippia sidoides and thymol on Enterococcus faecalis biofilm of the bacterium isolated from root canals

The species Lippia sidoides Cham. (Verbenaceae) is utilized in popular medicine as a local antiseptic on the skin and mucosal tissues. Enterococcus faecalis is the bacterium isolated from root canals of teeth with persistent periapical lesions and has the ability to form biofilm, where it is responsible for the failure of endodontic treatments. Essential oil of L. sidoides (EOLS) and its major component, thymol, were evaluated for reducing the CFU in biofilms of E. faecalis in vitro. The essential oil was obtained by hydrodistillation and examined with respect to the chemical composition, by gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis has led to the identification of thymol (84.9%) and p-cymene (5.33%). EOLS and thymol reduced CFU in biofilms of E. faecalis in vitro (time of maturation, 72 h), with an exposure time of 30 and 60 min at concentrations of 2.5 and 10%. There was no statistical difference in effect between EOLS and thymol, demonstrating that this phenolic monoterpene was the possible compound responsible for the antimicrobial activity of EOLS. This study provides a basis for the possible utilization of EOLS as an adjuvant in the treatment of root canals that show colonization by E. faecalis.

Chemical composition of the essential oil of Lippia gracilis Schauer leaves and its potential as modulator of bacterial resistance

Lippia gracilis Schauer (Verbenaceae) is an aromatic plant widely used in folk medicine in the Brazilian semi-arid region. This work aims at evaluating the anti-microbial activity of essential oils from the leaves of L. gracilis (EOLG) when associated with commercial antibiotics against bacterial resistance. The essential oil obtained by hydrodistillation has 38 chemical constituents with thymol (44.4%), carvacrol (22.2%), p-cymene (6.2%) and α-pinene (5.6%) as major constituents. Microbiological assays were conducted by direct and gaseous contacts. We demonstrated that EOLG has significant synergism with all antibiotics tested. EOLG decreased the minimal inhibitory concentration of the aminoglycosides and improved their zone of inhibition more than 300% against Staphylococcus aureus and 270% against Pseudomonas aeruginosa. These results demonstrate that natural substances present in EOLG have the capacity to modulate bacterial resistance and can be used as an adjuvant therapy against multi-resistant microorganisms such as S. aureus, Escherichia coli and P. aeruginosa.

In vitro efficacy of Coriandrum sativum, Lippia sidoides and Copaifera reticulata against Leishmania chagasi

The increased incidence of visceral leishmaniasis (VL) in Brazil is due to a lack of effective disease control measures. In addition to that, no effective treatment exists for canine VL in response to synthetic drugs. Thus, the objective of this study was to evaluate the effect of the essential oils of Coriandrum sativum and Lippia sidoides, and oleoresin from Copaifera reticulata, on Leishmania chagasi promastigotes and amastigotes. We also examined the toxicity of these treatments on the murine monocyte cell line RAW 264.7. To determine the IC50 a MTT test (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was performed on promastigotes, and an in situ ELISA assay was conducted on amastigotes. Here, we demonstrate that oleoresin from C. reticulata was effective against both promastigotes (IC50 of 7.88 µg.mL-1) and amastigotes (IC50 of 0.52 µg.mL-1), and neither of the two treatments differed significantly (p > 0.05) from pentamidine (IC50 of 2.149 µg.mL-1) and amphotericin B (IC50 of 9.754 µg.mL-1). Of the three plant oils tested, only oleoresin showed no toxicity toward monocyte, with 78.45% viability after treatment. Inhibition of promastigote and amastigote growth and the lack of cytotoxicity by C. reticulata demonstrate that oleoresin may be a viable option for analyzing the in vivo therapeutic effects of leishmanicidal plants.

Antifungal activity, toxicity and chemical composition of the essential oil of Coriandrum sativum L. fruits

The aims of this study were to test the antifungal activity, toxicity and chemical composition of essential oil from C. sativum L. fruits. The essential oil, obtained by hydro-distillation, was analyzed by gas chromatography/mass spectroscopy. Linalool was the main constituent (58.22%). The oil was considered bioactive, showing an LC₅₀ value of 23 μg/mL in the Artemia salina lethality test. The antifungal activity was evaluated against Microsporum canis and Candida spp. by the agar-well diffusion method and the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) were established by the broth microdilution method. The essential oil induced growth inhibition zones of 28 ± 5.42 and 9.25 ± 0.5 for M. canis and Candida spp. respectively. The MICs and MFCs for M. canis strains ranged from 78 to 620 and 150 to 1,250 μg/mL, and the MICs and MFCs for Candida spp strains ranged from 310 to 620 and 620 to 1,250 μg/mL, respectively. C. sativum essential oil is active in vitro against M. canis and Candida spp. demonstrating good antifungal activity.