サルフア剤の化学構造と抗菌作用に就いて (第4報)

サルフア剤の酸解離恒数と抗菌作用に就いて

抄録

The curve which shows the relationship between acidity and antibacterial activity of N¹-substituted derivative of sulfanilamides has been found to have one maximum. The reason is thought to be due to the fact that, though SO₂-radical in ionic type is more negative, the negativity of ionic or molecular type decreases as the acid dissociation constant decreases. Therefore, the relationship between acid dissociation and antibacterial activities of sulfa drugs is thought to be directly relative to the negativity of SO₂-radical. The theory of Bell and Roblin is thought to be applicable under the condition of pH 7.0. In spite of the general weakness or disappearance of antibacterial action in N⁴-substituted compounds of sulfa drugs, the fact that the acid dissociation constant is almost the same as that of the original, shows that the relationship between chemical structure and antibacterial activities cannot be explained only by acid dissociation. The theories which explain the relationship between chemical structure and antibacterial activities of sulfa drugs by ionic-type or resonance-type theory present some doubts.