Molecular Pharmacology, Vol 6, 172-177, Copyright © 1970 by the American Society for Pharmacology and Experimental Therapeutics

Thioxanthones: Structural Differences between Lucanthone and Its N-Methyl Derivative

¹ Hematology Service, Mount Sinai Hospital Services, Elmhurst, New York 11373, and Departments of Medicine and Pharmacology, The Mount Sinai School of Medicine, New York, New York 10029

Lucanthone (1-diethylaminoethylamino-4-methylthioxanthone) is a bacteriostatic and carcinostatic agent and readily combines with DNA. N¹¹-Methyl substitution results in virtual deletion of these activities. Studies of electronic spectra, vibrational spectra, and ionization constants indicate that N¹¹-methyl substitution precludes coplanarity of the amine side chain and the thioxanthone ring system. The possible relationship of this change in molecular configuration to the strikingly reduced biological and biochemical activities of the N-methyl derivative is discussed.

Note:
ACKNOWLEDGMENTS I thank Dr. I. B. Weinstein and Dr. E. Hirschberg of the Columbia College of Physicians and Surgeons for supplying lucanthone and its N-methyl derivative, and for giving me access to their studies of the bacteriostatic and biochemical activity of the thioxanthones prior to publication. I thank Miss E. Ewald and Mr. N. Cantor for preparing the illustrations.