Straight-chain aliphatic seleninic
acids, CH3-(CH2)n-SeOOH, with chain lengths from C4 to C17, a few dibasic
acids of moderate chain length having
seleninic acid groups on both ends of the molecule, HOOSe-(CH2)n-SeOOH, and a series of carbosyseleninic
acids, HOOC-R-SeOOH, comprising chain lengths from C3 to C13 and several branched chains with 5 to 7
carbon atoms were tested for potency in the prevention of dietary liver
necrosis in the rat. Alkylseleninic
acids showed uniformly low activities, ranging from 18% to 56% of that of
selenite selenium which served as a standard. There were no discernible trends or regularities with increasing chain lengths, in c-ntrast to other series of alkylselenium compounds. It is therefore unlikely that alkylseleninic
acids are normal oxidation products of dialkyl mono- or diselenides in the organism. Compounds with
seleninic acid groups at both ends of the chain were practically inactive. Carboxyseleninic
acids carrying a carboxyl group distal to the
seleninic acid group, on the other hand, were highly effective. A maximum of potency occurred at chain lengths C3 and C4, followed by a sharp decline between C4 and C6. A second maximum of activity occurred at C8. There was no alternating effect. This structure/activity pattern is analogous to that of the diselenodicarboxylic
acids. However, the lower carboxyseleninic
acids were, per atom of
selenium, twice as active as the corresponding diseleno-
dicarboxylic acids, of which the higher members were less potent. It is inferred that carboxyseleninic
acids may be metabolically related to diseleno-
dicarboxylic acids and that C3 and C4 carboxyseleninic
acids may play a physiological role.