Physico-chemical characteristics of D-I, a hypotensive factor occurred in acetone extract of bovine brain.

Abstract

Stability of D-I preparation on standing at low temperature was examined. Standing in saline solution at 4.degree., the hypotensive activity was stable for the first 45 days, then was lost completely the following week. Standing as CHCl3-MeOH (2:1, vol/vol) solution at 4.degree., the decomposition began 75 days later and reached a plateau maintaining about 20% of the initial activity. At -20.degree., in syrup form the activity could be stored unaltered for 120 days. In the partition experiments, n-hexane and ethylether could extract little active component at all pH values tested (pH 4, 7 and 10). n-Butanol or Folch''s solvent could extract unilaterally without any pH effects. The NMR spectrum of D-I strongly resembles that of lysophosphatidyl choline (LPCh). Specific optical rotation was also similar to that of LPCh. In the assessment of MW on Sephadex LH-20 column eluting with 80% EtOH, the active substance was eluted in the neighborhood of L-dipalmitoylphosphatidyl choline or L-palmitoyl-LPCh. Its MW was estimated at .apprx. 500-800. The ratio of phosphorus, glycerol, choline and fatty acid was .apprx. 1:1:1:1; oleic acid shared about half of the fatty acid composition. D-I may be a LPCh or a closely related compound.