Fungal growth in fruits may cause spoilage and result in a reduction of their quality and quantity. The aim of the current study was to investigate the antifungal activity and the metabolism of thymol and carvacrol by Colletotrichum acutatum and Botryodiplodia theobromae. The results showed that both compounds provided relatively good control against these plant pathogenic fungi. Mycelial growth of C. acutatum and B. theobromae was inhibited at 50 µg/mL and above. At 150 µg/mL, thymol and carvacrol inhibited the radial growth of fungi completely and this effect remained for 240 h. Furthermore, thymol and carvacrol were metabolized by the plant pathogenic fungi in low proportion to several compounds, including thymoquinone, thymohydroquinone, thymyl- and carvacryl acetate, thymyl- and carvacryl methyl ether. The transformations affect the structural requirements of thymol and carvacrol related to their antimicrobial activity and mode of action. The relatively high antifungal activity of thymol and carvacrol against C. acutatum and B. theobromae and the low levels of microbial transformation indicate that both compounds could be an alternative to traditional chemical fungicides for control of pre- and postharvest phytopathogenic fungi on fruits or vegetables.

El crecimiento de los hongos en frutas puede causar el deterioro de los alimentos y resultar en una reducción de la calidad y la productividad. El objetivo del presente estudio fue investigar la actividad antifúngica, y el metabolismo de timol y carvacrol por Colletotrichum acutatum y Botryodiplodia theobromae. Los resultados muestran que ambos compuestos despliegan un relativo buen control contra los hongos fitopatogénicos; el crecimiento micelial de C. acutatum y B. theobromae se inhibió a concentraciones de 50 µg/mL y mayores. A 150 µg/mL, timol y carvacrol inhibieron el crecimiento radial de los hongos completamente y este efecto permaneció durante 240 h. Además, los hongos fitopatogénicos metabolizaron timol y carvacrol a varios compuestos en una baja proporción, incluyendo timoquinona, timohidroquinona, timil- y carvacril acetato, timil- y carvacril metil eter, entre otros. Las transformaciones afectan los requerimientos estructurales del timol y carvacrol relacionados con su actividad antimicrobiana y modo de acción. La actividad antifúngica relativamente alta de timol y carvacrol contra C. acutatum and B. theobromae y los niveles de transformación microbiana bajos, indican que ambos compuestos pueden ser una alternativa a los fungicidas químicos tradicionales para el control de los hongos fitopatogénicos en pre- y poscosecha de frutas y vegetales.

The aims of the present study were to evaluate the antifungal properties of Colombian propolis extracts against Colletotrichum gloeosporioides and Botryodiplodia theobromae, and to isolate and identify the main constituents from the active extracts. Therefore, propolis samples were thoroughly extracted with n-hexane/methanol (EPEM), dichloromethane, ethyl acetate, and methanol. Experimental results indicated that mycelial growth of all selected microorganisms was reduced in culture media containing EPEM and dichloromethane fractions. Furthermore, through antifungal bioassay-guided fractionation, three known labdane-type diterpenes: isocupressic acid (1), (+)-agathadiol (2) and epi-13-torulosol (3) were isolated as the main constituents from the active fractions.

En este estudio se evaluaron las biotransformaciones realizadas por el hongo fitopatógeno Colletotrichum acutatum, sobre los sustratos 2-feniletanol 1 y acetofenona 2; los procesos se realizaron en el medio de cultivo líquido Czapeck-Dox a temperatura promedio de 24 oC, humedad relativa entre 45 y 60%, y agitación a 150 rpm en un agitador orbital tipo shaker. En la biotransformación a partir del sustrato 1 se obtuvieron los productos metabólicos 1-fenil-1,2-etanodiol 3, (2-metoxietil) benceno 4 y acetato de 2-feniletilo 5, y desde el sustrato 2 los compuestos 1-fenil-1,2-etanodiol 3, 1-feniletanol 6 y 2-feniletanol 1. Los productos de la transformación microbiana se identificaron mediante cromatografía de gases acoplada a espectrometría de masas (CG-EM), y resonancia magnética nuclear de protón y carbono (RMN 1H y 13C). Se observó una tendencia marcada del patógeno a producir hidroxilaciones sobre el sustituyente del anillo aromático; igualmente, tiene la capacidad de reducir el grupo carbonilo y esterificar los grupos hidroxilo de alcoholes primarios. Se discute una posible ruta metabólica para la transformación de los sustratos.

The microbial transformation of 2-phenilethanol 1 and acetophenone 2 was investigated using the plant pathogenic fungus Colletotrichum acutatum; the process was carried out in liquid media culture Czapeck-Dox at an average temperature of 24 oC, a relative humidity between 45% and 60% and with agitation in a shaker at 150 rpm. The biotransformation of the substrate 1 produced the metabolic products 1-phenyl-1,2-ethanediol 3, (2- methoxyethyl)benzen 4 and 2-phenylethyl acetate 5, and from substrate 2 were obtained the compounds 1-phenyl- 1,2-ethanediol 3, 1-phenylethanol 6 and 2-phenylethanol 1. The structures of metabolic products were determined by gas chromatography coupled with mass spectrometry (GC-MS) and nuclear magnetic resonance of proton and of carbon (1H and 13C NMR). The process has a strong tendency of the pathogen to produce hydroxylations on the substituents attached to the aromatic ring. Additionally, C. acutatum was effective to reduce the carbonyl group and produce esterification reactions in the hydroxyl groups from primary alcohols. The metabolic pathway of both substrates is discussed.

Neste estudo foi analisada as biotransformaçoes feitas pelo fungos fitopatogênico Colletotrichum acutatum, nos substratos 2-feniletanol 1 e acetofenona 2; os processos forem feitos no meio de cultura Czapeck-Dox a uma temperatura média de 24 °C, umidade relativa entre 45 e 60% e agitação 150 rpm em um agitador orbital tipo shaker. Na biotransformaçao do substrato 1 é obtido os produtos metabólicos 1-fenil-1,2-etanodiol 3, (2-metoxietil) benceno 4 e acetato de 2-feniletilo 5, e do substrato 2 os compostos 1-fenil- 1,2-etanodiol 3, 1-feniletanol 6 e 2- feniletanol 1. Os produtos da transformação microbial forem identificados por meio do cromatografia de gás acoplada ao espectrometria da massas (CG-EM) e ressonância magnética nuclear de hidrogênio e de carbono (RMN 1H e 13C). Uma tendência marcada do patógeno é observada para produzir hidroxilaçoes na cadeia lateral do anel aromático; também tem a capacidade de reduzir ao grupo carbonilo e esterificar dos grupos hidroxilo da função álcool primária. Uma rota metabólica possível para a transformação das substratos é discutida.

Se evaluaron las propiedades del color y la estabilidad a diferentes factores (temperatura y pH) de soluciones de los antranoides prenilados ferruginina A (FRA) y ?-hidroxiferruginina A (HFA), obtenidos a partir de las bayas de las especies Vismia guianensis y V. baccifera ssp. ferruginea. El estudio de la influencia de la temperatura sobre las características espectrales reveló que las soluciones en propilenglicol de la FRA y la HFA son relativamente estables al calor a las temperaturas de 50 y 80 °C , mientras que a 100 y 150 °C presentaron cambios ligeros en la intensidad (e) y tonalidad (?vis-max, coordenadas colorimétricas CIE L* a* b*). Adicionalmente, las variaciones del color (?vis-max, e) para los antranoides en el rango de pH 1,0-11,0 durante 60 días de almacenamiento a 4 y 25 °C , demostraron una mayor estabilidad del color en condiciones de refrigeración y pH 6,0 y 8,0, la cual fue superior para las soluciones de HFA. Las buenas características de los compuestos los hacen potencialmente útiles como colorantes naturales en la industria de los cosméticos, textil y farmacológica.

Colour properties and stability to different factors (temperature and pH) of solutions of prenylated anthranoids ferruginin A (FRA) and ? -hydroxyferruginin A (HFA), obtained from berries of Vismia guianensis and V. baccifera ssp. ferruginea, were evaluated. Spectral characteristics influenced by different temperatures, revealed that the solutions in propylenglycol of the FRA and HFA were relatively stable to the heat to temperatures of the 50 and 80 °C , whereas to temperatures of 100 and 150 °C they displayed slight changes in the intensity ( e ) and tonality ( ? vis-max, colorimetric co-ordinates in the CIE L* a* b* scale). Additionally, colour variation ( ? vis-max, e ) for both anthranoids in the pH range 1.0 - 11.0 during a period of 60 days storage at 4 and 25 °C , showed higher colour stability in refrigerated conditions and pH values of 6.0 and 8.0, being better for solutions of HFA. The good characteristics of compounds make them potentially useful like natural colourants in the textile, cosmetic and pharmacological industry.

Foram avaliadas as propriedades da cor e a estabilidade de fatores diferentes (temperatura e pH) de soluções dos antranoides prenilados ferruginina A (FRA) e ? -hidroxiferruginina A (HFA), obtidos das bagas das espécies Vismia guianensis e V. baccifera ssp. ferruginea. O estudo da influência da temperatura nas características espectrais mostra que as soluções em etilenglicol da FRA e a HFA foram relativamente estáveis ao calor para as temperaturas de 50 e 80 °C , enquanto para temperaturas de 100 e 150 °C apresentaram mudanças leves na intensidade ( e ) e tonalidade ( ? vis-max, coordenadas CIE L* a* b*). Além do mais, as variações da cor ( ? vis-max, e ) dos antranoides no rango de pH 1,0-11,0 durante 60 dias de armazenamento a 4 e 25 °C mostraram uma estabilidade maior em condições refrigerasão e em valores de pH de 6,0 e de 8,0, sendo melhor para soluções do HFA. As características boas dos compostos os fazem potencialmente úteis como corantes naturais nas indústrias das cosméticas, têxtil e farmacêutica.