Study of the Cellular Action of Drugs with Protozoa. II. Comparative Study of the Inhibitions Induced by Hypocholesteremic Agents on Ochromonas danica Multiplication; Annulment by Oleic Acid*

SYNOPSIS. Several hypocholesteremic agents inhibit multiplication of Ochromonas danica, Euglena grucilis, and Tetrahy‐menu pyriformis. Inhibiting O. danica are benzmalecene, triparanol, diazacholestanol. 3‐β‐(2‐diethylaminoethoxy) androst‐5‐en‐17‐one, α‐phenylbutyric acid, β‐diethylaminoethyldiphenyl‐n‐propylacetate (SKF‐525A) 2,2‐diphenyl‐1‐ (β‐dimethylaminoethoxy)pentane (SKF‐3301A), trans‐3‐(p‐chlorophenyl)‐2‐[p‐(2‐diethylaminoethoxy)phenyll‐2‐pentenenitrile (P‐3429), frans‐3‐[p‐(2‐diethylaminoethoxy) phenyll‐2‐pentenenitrile (P‐3013), vanadyl SO† and L‐thyroxine but not nicotinic acid, 3‐pyridylacetic acid, 3‐pyridylacetamide, nicotinuric acid, p‐aminosalicylic acid. tris‐(2‐dimethylaminoethyl) phosphate (SKF‐7732‐A3), tris‐ (2‐diethylaminoethyl) phosphate (SKF‐7997‐A3), 2,3‐bis[p‐(2‐diethylaminoethoxy) phenyl] acrylonitrile bis (P‐2681). Inhibition of Ochromonas multiplication by benzmalecene, triparanol, diazacholestanol, SKF‐525A. SKF‐3301A, P‐3013, and P‐3429 was annulled by lecithin, TEM, and specifiically by oleic acid. The following compounds equimolar with oleic acid were ineffective: stearic, palmitic, myristic, and lauric acids; cholesterol, stigmasterol, ergosterol, lanosterol, and β‐sitosterol; mevalonic acid lactone, geranyl acetate, farnesol, and squalene. Evidence is presented for the usefulness of protozoa as detectors of toxicity and possible harmful side effects of inhibitors of lipid metabolism in mammals.