Propriedades bioquímicas e biológicas de proteínas de sementes de leguminosas arbóreas da Amazônia

Abstract

Seeds of leguminous have a high concentration of proteins, including proteinases inhibitors and lectins. Such proteins are involved in several metabolic processes in plants comprising the mechanism of defense against phytopathogenous fungi. The aim of this work was to detect the presence of these two classes of proteins in seeds of four tree species of Amazonian leguminous (Caesalpinia ferrea var. cearensis, Cedrelinga catenaeformis, Swartzia polyphylla and Peltogyne venosa), as well as to characterize the effect of crude extracts in the mycelial growth and the sporulation of Colletotrichum guaranicola, Corynespora cassiicola, Fusarium oxysporum and Sclerotium rolfssii. Crude extracts of the seeds were used in detection, partial purification and characterization of trypsin inhibitors and AHE and in assays in vitro of phytopathogenous fungi. The inhibitors partially purified were designated CfTI and SpTI of C. ferrea var. cearensis and S. polyphylla, respectivelly. C. catenaeformis fractions with AHE were designated CeCL and those of P. venosa of PeVL. In the presence of 3,8 μg of CfTI and 12 μg of SpTI, the activity of the enzyme was reduced in approximately 99 % and 62 %, respectivelly. Fractions with AHE of CeCL were inhibited by glucose, lactose, sucrose, manose, maltose, D-galactosamine, -methyl-mannopyranosil and in contact with fractions of PeVL, there was also inhibition of sugars maltose and N-acetil-galactosamine. When it was added EDTA in concentrations of 3,1 mM and 50 mM, there was not inhibition AHE of CeCL and PeVL, however, when it processed the serial dilution of EDTA an inhibition of AHE was detected. The protein content of the extracts was of approximately 52, 48, 269 and 82 μg.mL-1 for extracts of C. ferra var. cearensis, C. catenaeformis, S. polyphylla and P. venosa, respectivelly. The electrophoretic profile revealed a single band in CfTI, eight bands in SpTI and three bands in PeVL. Proteins bands of CeCL were little evident. The presence of DTT did not modify the pattern of migration of proteins in the gel. Whereas in bio assays crude extracts of C. ferrea var. cearensis, C. catenaeformis and S. polyphylla had a significant effect in decreasing the sporulation of the tested fungi, and for S. rolfssi just C. ferrea var. cearensis and C. catenaeformis had a significant effect. But decreasing the micelial growth, the three extracts had an effect on F. oxysporum, while the effect on C. guaranicola was just caused by the extract of S. polyphylla, in C. cassiicola it was the extract of C. ferrea var. cearensis and C. catenaeformis and in S. rolfssi the extract of C. ferrea var. cearensis and S. polyphylla. Therefore it is concluded that only C. ferrea var. cearensis and S. polyphylla have specific inhibitors for bovine trypsin, while C. catenaeformis and P. venosa can present lectins in their seeds. This evidences that the subfamilies Caesalpinioideae, Papilionoideae and Mimosoideae can differ in the presence and specificity of the proteinases inhibitors and lectins. The in vitro bio assays revealed that nor all of these extracts reduced the micelial growth and the sporulation of C. guaranicola, C. cassiicola, F. oysporum and S. rolfssi.