Lipoaldehydes: With a carbonyl as polar group, the lipoidic properties appear with propanal in the homologous series of the aliphatic aldehydes. With the carbonyl less dissociated than the carboxyl, the lipoaldehydes represent negative lipoids able to act for a longer time than the respective acids. We were especially interested in three groups of aldehydes. In one, with a nonsaturated short nonpolar chain, we searched a conjugated formation between the double bond of the oxygen of the carbonyl and the double bond of the nonpolar chain. Another group of the lipoaldehydes corresponded to long chain fatty acids, while the third was formed by saturated short chain aldehydes with an odd number of carbons. From the energetic point of view, there were the first and especially the third groups which appeared as the most interesting. In the last group the opposite influence exerted by the carbonyl and methyl groups upon the intermediary carbons of the chain gives the entire molecule an especially high reactivity. This opposite influence is seen at its maximum in propanal, where C2 suffers the influence energetically opposite of the carbonyl and methyl group. The fact that, due to its relatively high solubility in water, propanal— which is a lipoid—can be administered in aqueous solutions and still act upon the lipidic system—makes of it an especially interesting agent.

We have investigated these groups of lipoaldehydes from the point of view of their influence exerted upon the two offbalances. In the group with unsaturated short chains, we studied acrolein and crotonic and maleic aldehyde without seeing any special effect upon the other levels than the cellular one, where a vacuolation was obtained. Furthermore their toxicity has represented an handicap. More interesting has appeared the group of the saturated short molecules with odd number of carbons. While with heptanal we have obtained besides an influence upon pain, also a manifest inhibitory effect upon the growth of experimental tumors, it was propion aldehyde which has shown the most interesting effects upon pain.

This was seen for the group of aldehydes with aliphatic saturated chain such as propionic and heptylic aldehydes or with cyclic, as salicylic aldehydes. In adequate doses—from %0 cc. to 2 cc. of the 10% solution of propionic aldehyde, or of the 1 % solution of the heptylic or salicylic aldehydes—a manifest influence was obtained upon the systemic condition as well as upon pain. Patients in oflbalance A with pain and general discomfort, were seen to have a decrease of the symptoms after the administration of propionic aldehyde. The effect upon tumors was reduced and propionic aldehyde did not change the evolution of the tumors in spite of the marked improvement of the general condition and even of the cessation of pain.