Molecular Pharmacology, Vol 6, 61-66, Copyright © 1970 by the American Society for Pharmacology and Experimental Therapeutics

Correlation of the Potencies of Tetracyclines in Vitro with a D-Ring Substituent Index

¹ Temple University School of Pharmacy, Philadelphia, Pennsylvania 19140

Inhibitory and inactivation potencies of tetracyclines toward nonsynchronous and synchronous cultures, respectively, of Escherichia coli can be correlated with the same substituent index for groups placed on the D-ring. The implication gained from this pair of correlations is that the bacteriostatic and bactericidal effects of tetracyclines are controlled by a conmmon electronic factor. Similarly, aim equivalent electronic index and the lipophilic index may be used to correlate the inhibitory potencies of a series of chloramphenicols, whose mode of action is similar to but at a site different from that of the tetracyclines.