Abstract
Methylation of mycobacillin with dimethyl sulfate and methyl iodide produced respectively mono- and di-methyl derivatives. The products were inactive against fungal spores and erythrocytes. Tyrosine hydroxyl groups only were methylated; in the monomethyl derivative, the hydroxyl of the tyrosine residue in position 6 is methylated, whereas the hydroxyl of the tyrosine in position 4 remains free; both hydroxyl groups are methylated in the dimethyl
derivative. The results indicate that the hydroxyl group of the tyrosine residue in position 6 is essential for the biological activity of mycobacillin.
