Abstract
Rice blast disease preventive activities of seven amino acid derivatives were examined by using rice seedlings of the 4- or 5- leaf stage. Because N-lauroyl-L-valine (No.5) showed the most constant activity among them, it was used as the test compound in further experiments, and the following experimental results were obtained.
Lauric acid, L-valine and their mixture showed lower activities than that of No.5.
In comparison with activities of optical isomers of valine, no significant difference was found among them.
Among various salts and esters of N-lauroyl-L-valine tested, only sodium and potassium salts were as effective as the free compound, whereas calcium salt, and methyl and ethyl esters had low preventive activity.
In case of substituting other amino acids for valine residue in N-lauroyl-L-valine, L-proline, L-methionine, L-leucine and DL-alanine derivatives were as effective as No.5, whereas in case of replacing lauric acid (C12) with other fatty acids, the protective effects reduced as increasing or decreasing the number of carbon atoms of substituted fatty acids.
