Thymol and carvacrol: biotransformation and antifungal activity against the plant pathogenic fungi Colletotrichum acutatum and Botryodiplodia theobromae

Abstract

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, thymyland 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. Key words: Alternative control, arylpropanoids, fungal detoxification, metabolic pathways, thymoquinone. RESUMEN Timol y carvacrol: biotransformación y actividad antifúngica contra los hongos fitopatogénicos Colletotrichum acutatum y Botryodiplodia theobromaeEl 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 g/mL y mayores. A 150 µg/mL, timol y carvacrol inhibieron el crecimiento radial de los hongos 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 fruta...

The effects of essential oils carvacrol and thymol on growth of Penicillium digitatum and P. italicum involved in lemon decay

“…Accordingly, thyme and clove oils inhibited the growth of P. digitatum and P. italicum completely when added to culture medium at 600 μL L −1 , or by using their volatiles at 24 μL per 8 cm-diameter Petri dish (Yahyazadeh et al, 2009). In addition, the antifungal effect of thymol was higher than that of carvacrol, according to previous reports using Colleotrichum acutatum (Numpaque et al, 2011). An earlier report revealed that other essential oils, apart from thymus and clove oil, such as oregano and cinnamon essential oils, completely inhibited P. digitatum and P. italicum when added to the medium at 1 mL L −1 (Plaza et al, 2004).…”

Synthesis, Larvicidal and Acetylcholinesterase Inhibitory Activities of Carvacrol/Thymol and Derivatives

“…25 The hydrophobic nature of carvacrol and thymol interact with the lipid bilayer of cytoplasmic membranes cause loss of integrity and leakage of cellular material such as ions, ATP and nucleic acid. 26 Generally, the derivatization of hydroxylated monoterpenes results in enhancement of larvicidal activity against Aedes aegypti of newly obtained compounds, because the presence of hydroxyl groups on their parent structures results in decreased potency, preventing substance penetration in the larva cuticle, [27][28][29][30][31] although this may also result in a decreased activity.…”

Chemical composition and antifungal activity of Piper auritum Kunth and Piper holtonii C. DC. against phytopathogenic fungi

“…However, some plant pathogens, such as C. acutatum and C. gloeosporioides possess resistant strains to carbendazim (Zhang and Huang, 2007). Meanwhile, thymol has been recognized for its potent antifungal activity (Numpaque et al, 2011).…”