Search

This work investigated the biotransformation of ginger constituents (zingerone, [6]-shogaol, [6]-gingerol, and methyl-[6]-gingerol) by the pathogenic fungus Colletotrichum gloeosporioides. Experiments were carried out with and without deuterium-labelled compounds. The product metabolites were analyzed by liquid chromatography coupled to tandem mass spectrometry and liquid chromatography solid phase extraction-nuclear magnetic resonance. Substrates supplied to the fungus were incorporated into metabolic pathways mostly by oxidation reactions, including aromatic carbon���carbon coupling. Zingerone and [6]-gingerol biotransformation products included biphenol dimers. A biodegradation pathway for biphenol formation was proposed based on the presence of the intermediate 4-(2-hydroxyethyl)-2-methoxyphenol, commonly identified from [6]-gingerol and [6]-shogaol biodegradation. This intermediate likely originates from a Baeyer���Villiger reaction followed by hydrolysis. The C���C coupling of molecules could result in phenolic oxidative ortho���ortho coupling, suggesting that biphenol dimers are products of C. gloeosporioides laccase catalysis.

A methanol-soluble fraction of the dichloromethane extract from the culture broth of A. alternata AT4303 strain afforded the following five known mycotoxins: alternariol, alternariol monomethyl ether, altenusin, altenuene and altertoxin I. A hexane-soluble fraction of the dichloromethane extract yielded the steroids ergosterol and ergosterol peroxide, and alternariol monomethyl ether. The concentrated ethyl acetate extract afforded the nucleoside uridine, uracil and inosine. The micro-extracts obtained from this strain in solid media were analyzed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS), and the following five known toxins were identified: ACTG-C, D, E and F and AK-toxin II. The major toxins produced by the tangerine pathotype ACT-toxins appear to be absent in strain AT4303. However, the low concentration of ACT-toxins appears to be responsible for their lack of detection in this study. Some compounds isolated from citrus plants were tested for in vitro activity against this strain. The results indicated that 17.3 µM apigenin-7-O-rutinoside inhibited by 80% conidial germination and appressorium development.

O Brasil é considerado o maior produtor de citros e o maior exportador de suco de laranja. Doenças de pós-colheita representam uma grande perda para a citricultura, sendo que para a exportação de frutos são rígidas as exigências com relação a isenção de resíduos químicos nos mesmos. Patógenos de importância em pós-colheita de citros incluem o Penicillium digitatum, agente causal do bolor-verde e o Colletotrichum gloeosporioides, agente causal da antracnose. Dada a importância econômica que representam estas doenças dos frutos cítricos, tanto em termos de comprometimento da qualidade e dificuldade de controle, a busca de alternativas adicionais que possam viabilizar a capacidade produtiva e garantir a obtenção de frutos com excelentes padrões de qualidade torna-se imprescindível. Portanto, estudou-se os efeitos dos extratos aquosos do flavedo de Citrus aurantifolia var. Tahiti, Lentinula edodes, Agaricus subrufescens (syn. Agaricus brasiliensis), albedo de Citrus sinensis var. Valência e do ácido jasmônico no controle póscolheita do bolor verde e da antracnose e na indução de resistência em frutos de laranjeira Valência (Citrus sinensis). Foi possível observar que o extrato aquoso do flavedo (C. aurantifolia) apresentou efeito inibitório sobre os patógenos, quando tratados em pós-colheita, em função da redução dos sintomas e esporulação. Porém, os extratos de albedo (C. sinensis), L. edodes, A. subrufescens e o ácido jasmônico não apresentaram efeitos sobre P. digitatum e C. gloeosporioides. Brazil is considered to be the biggest citrus producer and orange juice exporter. Post-harvest diseases represent a great loss in the citriculture, and for many fruits to be exported they should be free of chemical residues. In relation to some pathogens of importance in post-harvest, it can be mentioned Penicillium digitatum (green-mold) and Colletotrichum gloeosporioides (anthracnose). Because of the economical importance of these diseases for citric fruits, in terms of compromising quality and control difficulties, the search for alternative control measures that can make possible to improve the producing capacity of the producers and the obtaining of fruits with excellent quality are indispensable. Therefore, it was studied the viability of the control of post-harvest diseases in Valência orange fruits (Citrus sinensis) by using the biotic agents flavedo (Citrus auratifolia cv. Tahiti), Lentinula edodes, Agaricus subrufescens (syn. Agaricus brasiliensis), albedo (Citrus sinensis cv. Valência) and the abiotic agent jasmonic acid. It was possible to observe that the aqueous extracts from the flavedo (C. aurantifolia) inhibited the pathogens in Valência orange fruits when treated in post-harvest, based upon symptom and sporulation reduction. On the other hand, the albedo (C. sinensis), L. edodes, A. subrufescens and jasmonic acid had no effects on P. digitatum and C. gloeosporioides in the fruits.

Este trabalho objetivou avaliar a incidência da mancha preta dos citros (MPC) em frutos de laranja 'Valência' e tangor 'Murcott', destinados à exportação, e em laranjas 'Pêra', 'Lima' e 'Natal' e em tangor 'Murcott', destinados ao mercado interno, após diferentes etapas do beneficiamento em packinghouses, nas safras 2004/05 e 2005/06, assim como a incidência da MPC em laranjas 'Pêra' e 'Lima' e em tangor 'Murcott' comercializados na Ceagesp-SP, em 2006. Frutos foram coletados na chegada ao packinghouse, após a pré-lavagem, após o desverdecimento, na banca, no palete e na Ceagesp, e armazenados durante 14 a 21 dias a 25ºC e 85-90% de UR. A incidência da MPC foi avaliada visualmente após um dia e ao final do armazenamento. A incidência da MPC nos frutos do packinghouse de exportação foi decrescente, com valores médios abaixo de 2,0% na chegada e nenhum sintoma em frutos do palete. A incidência média da MPC em laranjas 'Pêra', 'Lima' e 'Natal' e em tangor 'Murcott' no packinghouse destinado ao mercado interno foi de 64,1; 39,0; 32,1 e 19,3%, respectivamente, após um dia de armazenamento e manteve-se constante em todas as etapas do beneficiamento. A incidência de frutos com MPC na Ceagesp foi baixa nos meses de inverno e crescente na primavera. O aumento médio na incidência da doença após o armazenamento (21 dias) não foi significativo nos frutos cítricos amostrados. The purposes of this work were a) to evaluate citrus black spot (CBS) incidence in 'Valência' oranges and 'Murcott' tangors aimed at the export market, and in 'Pêra', 'Lima' and 'Natal' oranges, and 'Murcott' tangors, aimed at the domestic market after different processing stages in packinghouses in 2004/05 and 2005/06; b) to evaluate CBS incidence in 'Pêra' and 'Lima' oranges and 'Murcott' tangors sold at Ceagesp-SP, the biggest wholesale market in the State of São Paulo, in 2006. Citrus fruits were collected at the packinghouse, on their arrival, after pre-washing and de-greening, from the packing table, from the pallet and at Ceagesp. They were stored for 14 to 21 days at 25ºC and 85-90% RH. The incidence of CBS was visually evaluated after one day and at the end of the storage period. CBS incidence in fruits aimed at the export market decreased, with values under 2.0% on arrival and no CBS symptoms observed on fruits from the pallet. The average incidence of CBS in 'Pêra', 'Lima' and 'Natal' oranges, and 'Murcott' tangors in the packinghouse aimed at the domestic market were 64.1, 39.0, 32.1 and 19.3%, respectively, after one day of storage, then remaining constant in all processing stages. The incidence of CBS in Ceagesp fruits was low in winter months and increased in the spring. The increase in disease incidence during the storage period (21 days) was not significant in collected fruits.