Effect of polycaprolactone nanocapsules loaded with essential oils on biofilm formation by Staphylococcus aureus strains isolated from bovine mastitis cases

Abstract Bovine infectious mastitis is largely resistant to antibacterial treatment, mainly due to mechanisms of bacterial resistance in the biofilms formed by Staphylococcus aureus. Melaleuca (MEO) and citronella essential oils (CEO) are promising agents for reducing or eliminating biofilms. Free melaleuca oil presented a medium Minimum Inhibitory Concentration (MIC) of 0.625% and a Minimum Bactericidal Concentration (MBC) of 1.250%, while free citronella oil showed medium MIC and MBC of 0.313%. Thus, free CEO and MEO demonstrate bacteriostatic and bactericidal potential. We generated polymeric nanocapsules containing MEO or CEO and evaluated their efficacy at reducing biofilms formed by S. aureus. Glass and polypropylene spheres were used as test surfaces. To compare the responses of free and encapsulated oils, strains were submitted to 10 different procedures, using free and nanoencapsulated essential oils (EOs) in vitro. We observed no biofilm reduction by MEO, free or nanoencapsulated. However, CEO nanocapsules reduced biofilm formation on glass (p=0.03) and showed a tendency to diminish biofilms on polypropylene (p=0.051). Despite nanoencapsulated CEO reducing biofilms in vitro, the formulation could be improved to modify the CEO component polarity and, including MEO, to obtain more interactions with surfaces and the biofilm matrix

Antifungal activity of the essential oil of cymbopogon citratus (DC) stapf: an in vitro study

Aim. to evaluate the antifungal potential of the essential oil of cymbopogon citratus by determining the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) for candida albicans (ATCC 90029), candida albicans (CBS 562), candida tropicalis (ATCC 705) and candida tropicalis strains (CBS 94), as well as to analyze the possible mechanism of action of the oil through the addition of sorbitol to the culture medium. methods. for the MIC determination, inocula were previously adjusted through spectrophotometry and 100µL were added to the wells of plates already containing the culture medium and 100µL of the serial dilutions of the oil, incubating them in aerobiosis for 24 hours, with subsequent staining by 1 percent TCT. for the MFC, 50µL of the supernatant from the MIC assay wells were dripped onto petri dishes and incubated in aerobiosis for 24 hours. tests were performed in triplicate and data analysed by descriptive statistics. results. It was determined that the MIC for C. albicans was 125 µg/mL while MIC for C. tropicalis was 250 µg/mL, with the essential oil presenting fungicidal effect for both analyzed yeasts. conclusion. the essential oil of cymbopogon citratus does not act at the cellular wall level and demonstrated an antimicrobial effect on candida albicans and candida tropicalis, therefore acting as a fungicide.

Antimicrobial activity of the essential oil of Cymbopogon citratus (DC) Stapf. on Staphylococcus spp., Streptococcus mutans and Candida spp. / Atividade antimicrobiana do óleo essencial de Cymbopogon citratus (DC) Stapf. sobre Staphylococcus spp., Streptococcus mutans e Candida spp.

Medicinal plants with fungicide action, antibacterial and anti-inflammatory effects are under investigation. The main purpose of this work was to evaluate the antimicrobial activity of the essential oil from Cymbopogon citratus (DC) Stapf. on strains of Staphylococcus spp., Streptococcus mutans and Candida spp. with planktonic and biofilm growth. To study the micro-organisms in planktonic cells, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined by using 9 clinical strains for each species and 1 ATCC (American Type Culture Collection) from C. albicans, C. tropicalis, C. glabrata, S. aureus, S. epidermidis and S. mutans. In order to evaluate the effects of the essential oils on biofilms, strains of S. aureus (ATCC 6538), S. mutans (ATCC 35688) and C. albicans (ATCC 18804) were used. The biofilm was formed on acrylic resin discs with isolated micro-organisms or in associations. The number of colony-forming-units (CFU) obtained in each biofilm (CFU/ml) was submitted to Student's t statistical test. The results demonstrated that the essential oil of Cymbopogon citratus showed microbiostatic and microbicidal activity against all tested strains. The average CFU/ml for the biofilm of S. aureus, S. mutans and C. albicans, whether isolated or in association, was lower in the group treated with essential oil than in the control group.

As ações fungicida, antibacteriana e anti-inflamatória são propriedades importantes que vêm sendo investigadas em espécies medicinais. O objetivo do presente trabalho foi o de avaliar a atividade antimicrobiana do óleo essencial de Cymbopogon citratus (DC) Stapf. (capim-limão) sobre cepas de Staphylococcus spp., Streptococcus mutans e Candida spp. em crescimento planctônico e em biofilme. Para estudo dos micro-organismos em crescimento planctônico foram determinadas a Concentração Inibitória Mínima (CIM) e a Concentração Microbicida Mínima (CBM) de 9 cepas clínicas e, para cada espécie, uma ATCC (American Type Culture Collection) de: C. albicans, C. tropicalis, C. glabrata, S. aureus, S. epidermidis e S. mutans. Para a avaliação dos efeitos dos óleos essenciais em biofilme foram utilizadas cepas padrão de S. aureus (ATCC 6538), S. mutans (ATCC 35688) e C. albicans (ATCC 18804). O biofilme foi formado em corpos-de-prova de resina acrílica com os micro-organismos isolados ou em associações. O número de unidades formadoras de colônias obtidas em cada biofilme (UFC/ mL) foi submetido ao teste t de Student. Os resultados demonstraram que o óleo essencial de Cymbopogon citratus apresentou atividade microbiostática e microbicida para todas as cepas analisadas. As médias de UFC/ml para o biofilme de S. aureus, S. mutans e C. albicans, isolados ou associados, foram menores no grupo tratado com óleo essencial em relação ao grupo controle.

Viabilidade de sementes de feijão caupi após o tratamento com óleo essencial de citronela (Cymbopogon winterianus Jowitt) / Viability of Vigna unguiculata bean seeds treated with essential oil of Java grass (Cymbopogon winterianus Jowitt)

O tratamento de sementes com óleos essenciais é um método alternativo que auxilia o manejo integrado de pragas. O objetivo deste trabalho foi avaliar a influência do tratamento de sementes de feijão Vigna unguiculata (L.) Walp. com o óleo essencial de citronela (Cymbopogon winterianus Jowitt). Foi avaliado o efeito do óleo essencial de C. winterianus sobre V. unguiculata nas dosagens 20 µL, 15 µL, 10 µL, 5 µL e testemunha. A qualidade fisiológica das sementes foi determinada pela porcentagem de emergência, velocidade de emergência e índice de velocidade de emergência. A análise dos dados foi realizada no delineamento inteiramente casualizado, disposto em esquema fatorial 5 x 2 com cinco repetições. As sementes fumigadas apresentaram diferenças estatísticas entre os parâmetros avaliados em relação à testemunha. O óleo essencial de citronela revelou potencialidade alelopática sobre a germinação de sementes de feijão que variou de acordo com a concentração do óleo.

Seed treatment with essential oils is an alternative method tool in integrated pest management. The objective of this study was to evaluate the effect of treating Vigna unguiculata (L.) Walp. bean seeds with essential oil of Java grass (Cymbopogon winterianus Jowitt). The effect of C. winterianus essential oil on P. vulgaris was evaluated at levels of 20 µL, 15 µL, 10 µL, 5 µL and control. The physiologic quality of the seeds was determined by percentage emergence, speed emergence and speed emergence index. The data analysis was carried out using an entirely randomized design, in a 5 x 2 factorial scheme with five repetitions. The fumigated bean seeds showed the statistics differences among the analyzed parameters when was compared with the no treated check. The essential oil of Java grass revealed allelopathic potentiality on bean seed germination which varied according to the oil concentration.

Avaliação in vitro da ação do óleo essencial de capim limão (Cymbopogon citratus) sobre o carrapato bovino Rhipicephalus (Boophilus) microplus / In vitro evaluation of the action of lemon grass (Cymbopogon citratus) essential oil on the cattle tick Rhipicephalus (Boophilus) microplus

O uso indiscriminado de produtos químicos no controle do carrapato bovino constitui a principal causa do gradativo aumento do número de cepas resistentes deste parasita às bases disponíveis no mercado. A utilização de óleos essenciais e extratos vegetais é uma prática antiga no controle de carrapatos, porém só recentemente tem recebido a devida atenção dos pesquisadores. O objetivo deste experimento foi avaliar a eficácia in vitro do óleo de capim limão (Cymbopogon citratus) sobre fêmeas ingurgitadas de Rhipicephalus (Boophilus) microplus através do exame de biocarrapaticidograma. Foram testadas seis diluições do óleo de C. citratus (1; 5; 10; 25; 50 e 100%) em uma população de carrapatos resistentes a amidínicos e piretróides sintéticos. A inibição de postura foi de 3; 23; 46; 66; 46 e 46%, a eclosão larval foi de 83; 58; 31; 0; 38 e 25% e a eficácia do tratamento foi de 32; 64; 83; 100; 88 e 82%, respectivamente. O óleo de C. citratus apresentou controle parcial do carrapato R. microplus in vitro, mesmo frente a populações resistentes a produtos químicos.

The indiscriminate use of chemical products to control the cattle tick is the main cause of the gradual increase in the number of strains of this parasite that are resistant to the bases currently available in the market. The use of essential oils and plant extracts is an ancient practice for tick control; however, only recently has it received due attention by researchers. The aim of this experiment was to evaluate the in vitro efficacy of lemongrass (Cymbopogon citratus) essential oil on engorged females of Rhipicephalus (Boophilus) microplus through immersion test. Six concentrations of Cymbopogon citratus oil (1; 5; 10; 25; 50 and 100%) were tested against a tick population resistant to synthetic formamidines and pyrethroids. The inhibition of egg-laying was 3; 23; 46; 66; 46 and 46%, the hatching was 83; 58; 31; 0; 38 and 25%, and the treatment efficacy was 32; 64; 83; 100; 88 and 82%, respectively. C. citratus oil showed partial control of the tick R. microplus in vitro, even against populations resistant to chemical products.