Estudo químico do fungo fitopatogênico Lasiodiplodia theobromae (Sphaeropsidaceae).

Abstract

This work reports the chemical investigation of Lasiodiplodia theobromae (Sphaeropsidaceae). The fatty acid profile, secondary metabolites production and application of this fungus in biotransformation of ketones were investigated. The fatty acid composition of L. theobromae in several culture broth produced hexadecanoic acid (C16:0), octadecanoic acid (C18:0), 9-octadecenoic acid (C18:1) and 9,12-octadienoic acid (C18:2) as main compounds. The identification of these fatty acid was done by GC/MS. L. theobromae was grown in liquid (Czapeck and peptone) and solid (rice) medium and allowed the isolation of 4-hydroxymellein, 2,4,6-trimethyloct-2-enoic acid and the eremophilane sesquiterpene 1,2,6,8atetrahydro-7-hydroxy-1,8a-dimethyl-6-oxo-2-naphtalenyl ester from the Czapeck broth. From the fungus culture in peptone it was isolated a mixture of fatty acids, 2-amino-trans-4-hexenoic acid and ergosterol. This steroid was also isolated from the culture of L. theobromae in rice, as well as D-glucose and cellobiose as products of starch degradation. The eremophilane sesquiterpene isolated from the Czapeck broth is being reported for the first time in the literature. The production of jasmonic acid by L. theobromae was investigated by mass spectrometry (MS/ESI). This fungus was grown for 32 days and revealed the presence of jasmonic acid from the 16th day. Biotransformation of (R)-carvone by L. theobromae yielded neodihydrocarveol, 8(9)-p-menthene-2,10-diol and p-menthane-2,8,9-triol as products. The same results was obtained when (S)-carvone was used as starting material. Biotransformation of acetophenone and four p-substituted derivatives provided the corresponding alcohols in varied yields (16.4 – 74.0 %) and ee (31.7 – 98.0 %).