Norman Kharasch

A correlation of thyroxine-like activity and chemical structure

Abstract A correlation of structure vs. thyroxine-like activity for 47 analogs of thyroxine, of structure A, has been attempted where X, X′ = halogen, H, CH3, NO2; R′ = H or CH3; R = ionizable groups as alanyl, COOH, etc. It is proposed that: 1. 1. The thyromimetic activities of these analogs in amphibia and mammalia are related to the electronic character of the diphenyl ether nucleus, as affected by the abilities of the groups X, X′, and OR′ to attract or release electrons, with electron-releasing groups favoring higher activity. 2. 2. The abilities of the substituents X and X′ to form hydrogen bonds influence thyromimetic response, activity increasing with enhanced ability to form such bonds. 3. 3. Activity is related to the pK of the side chain, R. The empirical nature of the correlation is stressed and its deficiencies and possible uses are noted.

STRUCTURAL BASIS FOR BIOLOGICAL ACTIVITIES OF DIMETHYL SULFOXIDE

Abstract : In summary, the role of DMSO in reacting with free radicals has been repeatedly emphasized in numerous publications dealing with tumor-inhibition as well as protection against radiation damage to cellular materials. Its ability to react with hydroxyl radicals has also been demonstrated adequately. However, what has not been demonstrated is whether all of such reactions lead to the formation of methane or formaldehyde or methyl radicals or peroxymethyl radicals under all circumstances. It is also not quite clear whether DMSO annihilates hydroxyl radicals by a radical-quenching pathway, or by its reaction with hydroxyl radicals, it produces other free radicals which can multiply the number of ways the original free radical species can interact with cellular components. There appears to be a clear and immediate need for characterizing the products of the reaction of DMSO with hydroxyl radicals.

CHEMISTRY OF BIOLOGICALLY ACTIVE SULFUR COMPOUNDS

Abstract All living organisms require sulfur for various metabolic processes. Sulfur occurs in enzymes, in structural proteins of cells, and in a wide variety of naturally occurring compounds which often play key roles in metabolism. The chemistry and biochemistry of sulfur compounds has been reviewed.1–3.

SULFENIUM IONS AND SULFENYL COMPOUNDS

Abstract The broad scope of the field of sulfenyl compounds is re-emphasized by a general definition of R and X in RSX and by an evaluation of the ionic reactions of such substances. Methods for generating sulfenium ions are described and evidence for the existence of such ions in solution discussed. Brief mention is also made of some free-radical reactions involving sulfenyl compounds. The analogies between displacements from carbon in alkyl and acyl compounds and sulfenyl compounds are noted. A summary of analytical, biochemical, synthetic and theoretical interests in sulfenyl compounds is included. †