Atividades antioxidante e fungitóxica do óleo essencial de capim-limão e do citral

Abstract

Resumo -Tendo em vista a importância dos óleos essenciais, objetivou-se, com este trabalho, avaliar a atividade antioxidante e os efeitos fungitóxicos do óleo essencial de capim-limão e do seu constituinte majoritário citral sobre a inibição micelial dos fitopatógenos Fusarium oxysporum cubense, Colletotrichum gloeosporioides, Bipolaris sp. e Alternaria alternata. A atividade antioxidante foi realizada, empregando os métodos de redução do radical livre DPPH e o ensaio de oxidação do sistema β-caroteno/ácido linoléico. Para cada metodologia, utilizou-se o delineamento inteiramente casualizado em esquema fatorial de 4 x 5, sendo quatro compostos (óleo essencial, citral, timol e α-tocoferol) e cinco concentrações (5; 10; 25; 50 e 100 μg L Abstract -Given the importance of essential oils, this study evaluated the antioxidant activity and fungitoxic effects of lemongrass essential oil and its main constituent citral on mycelial inhibition of phytopathogens Fusarium oxysporum cubense, Colletotrichum gloeosporioides, Bipolaris sp. and Alternaria alternata. The antioxidant activity was evaluated by employing the DPPH free radical reduction method and oxidation tests of the system β-carotene/linoleic acid. For each method, a completely randomized design in a 4 x 5 factorial arrangement was used with four compounds (essential oil, citral, thymol and α-tocopherol) and five concentrations (5; 10; 25; 50 and 100 Mg L -1 ), with three replicates. The tests to determine fungitoxic activities were performed by applying the in vitro fumigation test on mycelial inhibition of studied phytopathogens. The treatments were arranged in a completely randomized design with three replicates and a factorial arrangement. The essential oil and citral showed little antioxidant activity by the methodology that measures the reduction of the stable radical DPPH; however, by the methodology that employs the emulsified β-carotene/linoleic acid system, these compounds showed significant antioxidant activities. At fungitoxic activities, the essential oil and citral showed greater activity against the phytopathogen Alternaria alternata. When compared to the values of IC 50 , the lowest values presented by the essential (75.83 μg mL -1 ) and citral (58.24 µg mL -1 ) oils were found for Bipolaris sp. Citral caused the greatest mycelial inhibition on all phytopathogens.

Characterization of the Biological Potential of the Essential Oils from Five Species of Medicinal Plants

“…Their data do not match those found in this study. Guimarães et al [28] studied the antioxidant activity of the essential oil from C. citratus and its main constituent, citral, via the capture of the DPPH radical and observed a low antioxidant activity for both. According to the authors, this fact can be justified by the fact that it is difficult for the constituents to donate a hydrogen atom to stabilize the DPPH radical.…”

“…Guimarães et al [28] determined the antioxidant activity of the essential oil from C. citratus and its principal constituent (citral) employing the emulsified β-carotene/linoleic acid system and noted that these substances exhibited an antioxidant activity of 46.45% and 38.00%, respectively, at an essential oil or citral concentration of 100 μg•L −1 . Their data did not corroborate those found in this study.…”

Influence of Plant Extracts and Essential Oils against Panama Disease (Fusarium oxysporum f. sp. cubense) in Banana Seedlings

“…Bajpai et al (2007) found the antifungal effect of the essential oil from Metasequoia glyptostroboides Miki ex Hu, at 1000 μL -1 showing inhibition on mycelial growth of Fusarium oxysporum at 63%. Guimarães et al (2011) showed inhibition of F. oxysporum f. sp. cubense when working with essential oil from Cymbopogon citratus and citral.…”

Ultrasonic assisted extraction to obtain bioactive, antioxidant and antimicrobial compounds from marcela

“…Analyzing antioxidant activity by FRAP, the conventional extraction method was better than ultrasound at all the tested temperatures, as well as in the antioxidant method of IC 50 , where there was only statistical difference at a temperature of 60°C. According to GUIMARÃES et al (2011), there may be variation in antioxidant activity, depending on the compound and the concentration that is used for each methodology. In this case, the ultrasound method probably extracted more compounds, which facilitates the donation of hydrogen by these compounds to neutralize the DPPH radical.…”