Bicho-mineiro do cafeeiro: anÃlise da digestÃo e inibiÃÃo de tripsina por extratos de folhas de mamona. / Coffee leaf miner: Digestion and trypsin inhibition using castor beam leaves extracts.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Coffee is a crop of great social and economic importance to Brazil and its production is affected by a number of pests and diseases. One of those pests is the coffee leaf miner, Leucoptera coffeella (GuÃrin-MÃneville, 1842) (Lepidoptera: Lyonetiidae) which can cause great losses in production. The forms of controlling the coffee leaf miner known and utilized at present show several troubles, which motivates the search for new forms of control of this insect. A possible point of attack to the pests aiming at their control is the use of digestive enzyme-inhibiting agents which take part in the primary digestion. The tests of inhibiting trypsin were chosen by this enzyme taking part in the primary digestion of proteins and their poor functioning resulting into the reduction of aminoacids available to the insect. Castor bean leaf extracts were utilized, since previous studies on cassava hornworm - Erinnyis ello (Linneaus, 1758) (Lepidoptera: Sphingidae) â showed the presence of a trypsin inhibitor in castor bean leaves. The objective of this work was to study the digestive enzymes of the coffee leaf miner and investigate the inhibition of its trypsin by utilizing castor bean leaf extracts. The experiment was conducted in Lavras-MG and the enzymes -glucosidase (13.7 + 3.4 U/g of insect; optimum pH = 6.0), amylase (2.2 + 0.11 U/g of insect; optimum pH = 10.0), aminopeptidase (6.8 + 0.86 U/g of insect; optimum pH = 8.3), -glucosidase (0.38 + 0.16 U/g of insect; optimum pH = 6.0), acidic phosphatase (0.79 + 0.19 U/g of insect; optimum pH = 5.5), saccharase (6.7 + 0.78 U/g of insect; optimum pH = 6.5), trehalase (2.2 + 0.43 U/g of insect; optimum pH = 6.0) and trypsin (0.70 + 0.2 U/g of insect; optimum pH = 9.7). The analysis of the optimum pHÂs of enzymes could suggest that the digestive environment of the coffee leaf miner is highly similar to the one of the other lepidopterans. The tests of inhibition of the coffee leaf miner trypsin activity indicated an inhibition of about 2.12 UTI/g of fresh castor bean leaves. The purification procedures and the treatments of boiling and boiling plus addition of -mercaptoethanol in the castor bean leaf extract showed that the inhibitor is a non-protein molecule and heat-resistant which was purified by adsorption chromatography (silica gel 60) and analyzed by mass spectrometry.

ASSUNTO(S)

trypsin inhibition enzimas digestivas agronomia digest enzymes coffee leaf miner inibiÃÃo de tripsina bicho-mineiro do cafeeiro

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