Chemical Composition and In Vitro Antimicrobial Activity of the Essential Oil Obtained from Eugenia pyriformis Cambess. (Myrtaceae)

Abstract Our study aimed to evaluate the chemical composition of the essential oil from the leaves of Eugenia pyriformis Cambess., belonging to the Myrtaceae family and native to the Brazilian Atlantic forest. The volatile compounds in the essential oil were extracted by hydrodistillation and analyzed using GC-MS; 36 compounds accounted for 78.80% of the total oil content. The major compounds were β-caryophyllene, bicyclogermacrene, globulol, and (δ-cadinene. We evaluated their antimicrobial potential of the essential oil and toxicity to Artemia salina. The antimicrobial activity of the essential oil was evaluated against 12 microorganisms using the broth microdilution method. Our results showed moderate inhibition of Staphylococcus aureus and methicillin-resistant S. aureus (MIC, 250 and 125 μg.mL-1, respectively) and toxicity to A. salina (LC50, 125.64 μg.mL-1). Our results establish the biological activity of the essential oil obtained from E. pyriformis.

Biocidal potential of Eugenia pyriformis essential oil in the control of Rhipicephalus (Boophilus) microplus in the free-living cycle / Potencial biocida do óleo essencial de Eugenia pyriformis Cambess no controle de Rhipicephalus (Boophilus) microplus no ciclo de vida livre

Brazil has one of the largest commercial cattle herds in the world, which naturally coexist with an enormous number of parasitic species. Southern cattle tick, Rhipicephalus (Boophilus) microplus, is among these species, interfering with animal productivity and causing losses to the beef and dairy cattle sector. The use of chemical acaricides in the control of this mite has resulted in the emergence of resistant populations. In this sense, alternative control measures using plants as sources of botanical acaricides have shown to be effective. Eugenia pyriformis Cambess is a Brazilian plant with antioxidant and antimicrobial activity; however, there are no reports on its acaricidal activity in the literature. The present study aimed to evaluate the acaricidal and larvicidal potential of E. pyriformis leaf essential oil (EO) on southern cattle tick at different stages of the reproductive cycle. E. pyriformis leaves were collected and dried, and had their EO extracted by hydrodistillation (3h) using a modified Clevenger apparatus. Chemical analysis was performed by gas chromatography coupled with mass spectrometry (GC/MS), and 32 compounds belonging to the sesquiterpene class were identified: hydrocarbons (17.98%) and oxygenated forms (81.96%), with spathulenol (43.65%) and caryophyllene oxide (12.17%) as the most common. The EO was evaluated by the Adult Immersion Test at the concentrations (500.00 to 3.12mg/mL) in which the following parameters were measured: mortality of females (%), hatchability of eggs (%), and product efficiency (%). Larvae were assessed by the Larval Packet Test at concentrations ranging from 25.00 to 0.00004mg/mL. Lethal concentrations (LC) required for killing 50 and 99.9% of adult females and larvae were determined using Probit analysis. LC50 and LC99.9 of EO were 0.06 and 24.60mg/mL and 1,208.80 and 2,538mg/mL for larvae and adult females, respectively. Action of the EO in the free-living cycle of R. (B.) microplus larvae was another parameter assessed. To this end, the larvae were deposited in pots containing Brachiaria decumbens and, after migration to the leaf apex, a solution containing LC99.9 (24.60mg/mL) of the EO was sprayed. After 24h, 72.25% of the larvae had died, indicating stability of the EO when subjected to uncontrolled temperature and humidity conditions. The mechanism of action through which the EO killed the larvae and adult females was investigated by the Bioautographic Method, which showed inhibition of 3.15mg/mL of the EO on the acetylcholinesterase (AChE) enzyme. The results found in the present experiment indicate that E. pyriformis essential oil is an alternative in the control of southern cattle tick in the larval (parasitic) and free-living cycle (non-parasitic) stages under field conditions.(AU)

O Brasil dispõe de um dos maiores rebanhos bovinos comerciais do mundo, sendo natural que junto a esse rebanho, coexista uma enorme quantidade de espécies parasitárias; dentre estes o carrapato Rhipicephalus (Boophilus) microplus que interfere na produtividade animal, causando prejuízos à pecuária de corte e leite. A utilização de acaricidas químicos no controle deste ácaro tem causado o surgimento de populações resistentes e neste sentido, controles alternativos utilizando plantas como fontes de acaricidas botânicos têm se mostrado eficazes. Eugenia pyriformis Cambess é uma planta brasileira com atividades antioxidante e antimicrobiana, entretanto não há relatos da atividade acaricida. O objetivo do presente estudo consistiu na avaliação do potencial acaricida e larvicida do óleo essencial das folhas de E. pyriformis sobre o carrapato bovino nos diferentes estágios do ciclo reprodutivo. As folhas foram coletadas, secas e o OE extraído por hidrodestilação (3 horas) em aparelho Clevenger modificado. A análise química foi realizada por cromatografia gasosa acoplada à espectrometria de massas (CG/EM) sendo identificados 32 compostos, pertencentes à classe sesquiterpenos: hidrocarbonetos (17.98%) e oxigenados (81.96%); tendo como majoritários o spathulenol (43,65%) e caryophylene oxide (12,17%). O OE foi avaliado pelo teste de imersão de adultos nas concentrações (500,00 a 3,12mg/mL) onde foram mensurados os parâmetros: mortalidade das fêmeas (%), eclodibilidade dos ovos (%) e eficiência do produto (%). As larvas foram avaliadas pelo teste de imersão larval (Larval Packet Test) nas concentrações que variaram de 25,00 a 0,00004mg/mL. Foram determinadas as concentrações letais (CLs) necessárias para matar 50 e 99,9% das fêmeas adultas e das larvas utilizando a análise de Probitos. As CL50 e CL99,9 do OE foram (0,06 e 24,60mg/mL) para as larvas e (1.208,80 e 2.538mg/mL) para as fêmeas adultas, respectivamente. Outro parâmetro avaliado em nossa pesquisa foi mensurar a ação do OE no ciclo de vida livre das larvas de R.(B.) microplus; onde as larvas foram depositadas em vasos com Brachiaria decumbens e após migração destas para o ápice das folhas, foi aspergido solução contendo a CL99,9 (24,60mg/mL) do OE. Após 24 horas, 72,25% das larvas morreram indicando que houve estabilidade do OE quando submetido a condições de temperatura e umidade não controladas. O mecanismo de ação pelo qual o OE matou as larvas e fêmeas adultas foi investigado pelo método bioautográfico, indicando uma inibição de 3,15mg/mL do óleo essencial sobre a enzima acetilcolinesterase (AChE). Os resultados encontrados no presente experimento indicaram que o óleo essencial de E. pyriformis é uma alternativa no controle do carrapato bovino no estágio larval (parasitário) e no ciclo de vida livre (estágio não parasitário) em condições de campo.(AU)

Triagem fitoquímica e avaliação de propriedades biológicas do extrato alcoólico das folhas de eugenia pyriformis cambess. (myrtaceae) / Phytochemical screening and evaluation of biological properties of alcoholic extract of eugenia uvalha cambess. (myrtaceae) leaves

O extrato alcoólico (EUFO) das folhas da espécie nativa Eugenia pyriformis Cambess (Myrtaceae), popularmente conhecida como uvaia, uvalha ou uvaieira, foi avaliado no presente trabalho quanto às atividades citotóxicas, antioxidantes, antibacterianas e anticolinesterásicas, e quanto à constituição fitoquímica. O extrato EUFO mostrou baixa toxicidade pelo bioensaio de letalidade frente à náuplios de Artemia salina Leach (CL50 > 1000 µg mL-1), não sendo considerado citotóxico. As propriedades antioxidantes foram investigadas in vitro pelo método de DPPH e foram consideradas bastante significativas (IC50 = 2,8 µg mL-1), com valor bem próximo ao obtido para o controle positivo quercetina (IC50 = 1,1 µg mL-1). EUFO não mostrou atividade anticolinesterásica pelo ensaio enzimático de inibição de acetilcolinesterase, nem atividade antimicrobiana frente às bactérias Escherichia coli e Staphylococcus aureus. Estes resultados sugerem que as folhas E. pyriformis apresentam baixa toxicidade e possuem componentes com elevado potencial antioxidante, especialmente taninos e flavonoides, podendo ser indicadas em terapias de doenças relacionadas com a presença de radicais livres.

The alcoholic extract (EUFO) of leaves from the native species Eugenia uvalha Cambess (Myrtaceae), popularly known in Brazil as uvaia, uvalha or uvaieira, were evaluated in this study for the cytotoxic, antioxidant, antibacterial and anticholinesterase activities and phytochemical characterization. Its EUFO extract showed low toxicity by the lethality bioassay using Artemia salina Leach (LC50> 1000µg mL-1) and it did not show cytotoxicity. The antioxidant properties were investigated by in-vitro DPPH method and found to be very significant (CI50 = 2.8 µg mL-1), very close to the value obtained for the positive control quercetin (CI50 = 1.1 µg mL-1). The EUFO did not show anticholinesterase activity by enzyme assay of acetylcholinesterase inhibition, or antimicrobial activity against Escherichia coli and Staphylococcus aureus. These results suggest that E. uvalha leaves present low toxicity and have presence of high potential antioxidant components, particularly tannins and flavonoids, which may be indicated in disease therapies associated with the presence of free radicals. This is the first report for the antioxidant activity of E. uvalha.

Morpho-anatomy of the leaf and stem of Eugenia pyriformis

Eugenia pyriformis Cambess., known as uvaia, is a species of Myrtaceae native to Brazil. Its leaves are used in folk medicine to treat gout because they possess the property of inhibiting xanthine oxidase, an enzyme involved in the conversion of xanthine into uric acid. The objective of this work was to study the leaf and stem morpho-anatomy of E. pyriformis, in order to contribute to what is known about the Brazilian flora, and this medicinal plant and potential vegetal drug. Samples of mature leaves and young stems were fixed and sectioned by freehand, or embedded in glycol methacrylate and sectioned with a microtome, and then stained. In addition, microchemical tests and scanning electron microscopy were performed. The leaf is simple, symmetric, elliptic-lanceolate, with an acute apex and base, and an entire margin. The epidermis is uniseriate and coated with a moderately thick cuticle. The stomata are anomocytic and inserted at the same level as the adjacent cells. Unicellular non-glandular trichomes are abundant on the abaxial surface. The mesophyll is dorsiventral. In transverse section, the midrib is plano-convex and the petiole is circular, and both of these structures have a single bicollateral vascular bundle. In the stem, the vascular cylinder consists of external phloem, xylem and internal phloem, traversed by narrow rays. Phenolic compounds, druses and prismatic crystals of calcium oxalate are also present in the leaf and stem.