PENETRATION OF LIPID MONOLAYERS BY PSYCHOACTIVE DRUGS

Liquid membrane phenomena in chlorpromazine action

Chlorpromazine has been shown, in the present study, to generate a liquid membrane at an interface in accordance with Kesting's hypothesis [5]. The specific orientation of chlorpromazine molecules in a liquid membrane with hydrophobic ends facing the permeable substances has been found to reduce the permeability of catecholamines and neurotransmitter amino acids. This observation is discussed in the light of the orientation of receptor proteins in general. The data on transport of catecholamines and neurotransmitter amino acids are discussed in the context of the mechanism of action of chlorpromazine.

Antihemolytic and anticonvulsant activities of 1-(2,4-dichloro/2,4,5-trichlorophenoxyacetyl)-4-alkyl/arylthiosemicarbazides and their inhibition of NAD-dependent oxidations and monoamine oxidase

Several 1-(2,4-dichloro and 2,4,5-trichlorophenoxyacetyl)-4-alkyl/arythiosemicarbazides were synthesized and characterized by their sharp melting points and elemental analyses. All substituted thiosemicarbazides protected in vitro hypoosmotic hemolysis of dog red blood cells. These thiosemicarbazides selectively inhibited nicotinamide adenine dinucleotide (NAD)-dependent oxidation of pyruvate and alpha-ketoglutarate, while NAD-independent oxidation of succinate was not affected. These compounds inhibited the activity of monamine oxidase in rat brain homogenate, and the degree of inhibition ranged from 26.5 to 89.2 percent at a final concentration of 0.03mM, with kynuramine as the substrate. Almost all thiosemicarbazides possessed anticonvulsant activity; protection against pentylenetetrazol-induced convulsions in mice ranged from 10 to 70 percent at a dose of 100 mg/kg ip. These results provided evidence of some similarity between the membrane-stabilizing property of these substituted thiosemicarbazides with their ability to exhibit selective inhibition of NAD-dependent oxidations and inhibition of monoamine oxidase. On the other hand, the anticonvulsant activity possessed by these substituted thiosemicarbazides was unrelated to their in vitro antihemolytic and enzyme inhibitory properties.

In vitro antibacterial activity of drugs against human intestinal anaerobic bacteria

The in vitro antibacterial activity, against the major groups of anaerobic fecal bacteria, of a series of drugs was examined by an agar diffusion test and the minimum inhibitory concentration (MIC) test. Only the phenothiazines and amitriptyline showed any marked antibacterial activity, the MIC's being in the 40-640-mu-g/ml range. It is suggested that the detergent nature of the molecules of these drugs in aqueous solution is responsible for the observed antibacterial activity.

Characteristics of penicillinase release by washed cells of Bacillus licheniformis

Saline-washed cells of Bacillus licheniformis strain 749/C (constitutive for penicillinase) were able to release exopenicillinase in the presence of concentrations of chloramphenicol that prevented protein synthesis completely. The release reaction was strongly pH-dependent, occurring at a faster rate at alkaline pH in anionic or cationic buffers than at neutral pH. A strongly pH-dependent release reaction was noted in growing cells also. The reaction in washed cells can be stopped completely by changing the pH to 6.0. Within 30 min at pH 9.0, about 55% of the cell-bound penicillinase was released; thereafter, release continued at a greatly reduced rate. Suspensions of washed cells retained their capacity to release penicillinase at pH 9.0 for 90 min. Penicillinase released at pH 9.0 from either cells or protoplasts was not readsorbed over a 60-min period after changing the pH to 6.0. The release reaction was strongly temperature-dependent. We examined the effect of a large number of metabolic inhibitors and other compounds on the pH-dependent release phenomenon. Quinacrine hydrochloride, chloroquine diphosphate, and chlorpromazine hydrochloride reduced secretion substantially at 10(-4)m. Deoxycholate and Triton X-100 were active at 10(-3)m, but tungstate, arsenate, and molybdate had small effects at 10(-1)m. The rate of exopenicillinase release at pH 9.0 from fully stabilized protoplasts was one-half that of intact cells. Protoplasts lysed in hypotonic media or detergents showed even greater reduction in releasing activity. Penicillinase released from washed cells at pH 7.5 or 9.0 appeared to be derived from the periplasmic tubule and vesicle fraction that was released by protoplast formation.