Secreted and intracellular phospholipases A2 inhibition by 1-decyl 2-octyl-glycerophosphocholine in rat peritoneal macrophages.

Compounds able to inhibit phospholipases A2 can be considered as potential anti-inflammatory drugs. In this respect, the inhibitory effect of the phospholipid analogue 1-decyl 2-octyl-rac-glycero-3-phosphocholine (decyloctyl-GPC) added to the culture medium of rat peritoneal macrophages stimulated with ionophore A23187 was determined. (a) The substrate of phospholipase A2 1-octadecanoyl 2-[14C]eicosatetraenoyl-sn-glycero-3-phosphocholine ([14C]20:4-GPC) was added to the culture medium. In macrophages + extracellular fluids, its hydrolysis at the 2-position, produced [14C]non-phosphorous lipids which reached 12% of the dose at 0.14 microM, 73% at 0.9 and > 90% at 1.6 microM; in experiments where macrophages and extracellular fluids were analyzed separately, decyloctyl-GPC initially added at 4 microM, significantly inhibited the release of [14C]fatty acids and the eicosanoid synthesis, demonstrating its ability to inhibit secreted and/or intracellular phospholipases A2. (b) Extracellular fluids were separated from the macrophages and incubated with [14C]20:4-GPC: 48% of the dose was hydrolyzed by extracellular fluid-associated secreted phospholipase A2 and decyloctyl-GPC at 3 microM, reduced this hydrolysis by 50%. (c) [3H]arachidonic acid ([3H]20:4) was added to the culture medium and was esterified in the macrophage membrane phospholipids. Activation of intracellular phospholipase A2 induced the release of [3H] fatty acids and eicosanoid synthesis. These releases were inhibited by 50% with decyloctyl-GPC added at 4 microM. (d) [3H]20:4 and [14C]20:4-GPC were added to the culture medium of the macrophages. [3H] and [14C] fatty acids and eicosanoids were released in macrophages or extracellular fluids. They were significantly reduced by the phospholipid analogue added at 4 microM. It is concluded that secreted and intracellular phospholipases A2 were both inhibited by decyloctyl-GPC which extensively reduced the 20:4 release from exogenous and membrane phospholipids and therefore eicosanoid synthesis.

High rate of intestinal absorption of the phospholipid anlaogue 1-dodecyl 2-[1-14C] octanamido-sn-2-deoxy-glycero-3-phosphocholine in the rat.

The phospholipid analogue with two short fatty chains, 1-dodecyl-2-[1-14C] octanamido-sn-2-deoxy-glycero-3-phosphocholine ([14C] phospholipid analogue), with a non-hydrolyzable bond at position 2 of the glycerol, is an inhibitor of phospholipase A2. It was obtained after chemical synthesis and 0.5 micromol was solubilized in Na+ taurocholate with an equimolar amount of 1-octadecanoyl 2-[3H]eicosatetraenoyl-sn- glycero-3-phosphocholine which is the current substrate of phospholipases A2. Both molecules were introduced into the duodenum of rats in order to follow their captations by intestinal mucosa cells for 30, 60 or 90 min. The [14C] phospholipid analogue was poorly split by phospholipases A2 (pancreatic juice and intracellular enzymes). It disappeared from the intestinal contents (87% of the dose gone in 90 min) as rapidly as the tritiated lecithin (81%) but this was later split by the phospholipases at a higher rate.

Structure-activity of three phospholipid analogues towards inhibition of phospholipase A2 in macrophages.

At concentrations 1-20 microns in culture medium of rat peritoneal macrophages which were stimulated with ionophore A23187, the phospholipid analogues 1-decyl-2-octyl-glycerophosphocholine and 1-dodecyl-2-octanamido-2-deoxy glycerophosphocholine were found more potent inhibitors than 1-octyl-2-deoxy glycerophosphocholine to lower the phospholipase A2 activities. The inhibitory effect was measured by [3H] eicosatetraenoic acid ([3H]20:4) release in macrophages and extracellular fluids and synthesis of [3H] eicosanoids after incubation of macrophages with traces of the molecular species of lecithin 1-octadecanoyl-2-[3H] eicosatetraenoyl glycerophosphocholine. The three phospholipid analogues developed higher inhibitory effects than mepacrine, dexamethasone or bromophenacyl bromide, at corresponding concentrations in medium.

Synthesis and preliminary in vitro evaluation of antitumor nitrosoureido cholesterol derivatives.

A new class of chloroethyl nitrosourea analogues of cholesterol has been synthetized from the corresponding 7-amino and 7-aminoalkylcholesterol derivatives. Compounds III-V inhibited L1210 cell growth in culture much more effectively than N,N'-bis(2-chloroethyl)-N'-nitrosourea (BCNU) after 48 h incubation. Stability and cytotoxic activity of these prodrugs are promising for brain tumor treatments and as lymphotropic vectors for tumor cells spreading along the lymphatic pathways.

Influence of alkyl chain lengths in dialkylglycerophosphocholines towards phospholipase A2 inhibition in macrophages.

Rat peritoneal macrophages were cultured with a specific and potent phospholipase A2 activator A 23187, with 1-stearoyl-2-[3H]arachidonoyl-sn-GPC as source of [3H] arachidonic acid, and with a dialkyl-GPC, at 2, 10 or 20 microM. Four dialkyl-GPCs were prepared by chemical synthesis. Position 2 of rac-glycerol was alkylated with an alkane chain of 8 carbons and position 1 was alkylated with various alkane chains (8, 10, 12, or 16 carbons). [3H] arachidonic acid was split, then recovered with cell nonesterified fatty acids and nonphosphorous glycerolipids after endocellular phospholipase A2 activity. It was also recovered with fatty acids and eicosanoids isolated from culture medium. Inhibition of fatty acid release and eicosanoid synthesis depended on mixed chain dialkyl-GPC structures. The highest inhibitory effect on arachidonic acid release was reached with 1-decyl-2octyl-GPC and was practically as high in culture medium (IC50 at 5 microM) as in cells (IC50 at 4 microM). 1,2-di-octyl-GPC and 1-dodecyl-2-octyl-GPC had weaker inhibitory effects (but higher in culture medium than in cells). The asymmetrical 1-hexadecyl-2-octyl-GPC poorly affected enzyme activity.

Synthesis and orally macrofilaricidal evaluation of niclosamide lymphotropic prodrugs.

The development of new macrofilaricidal drugs is described following a strategy for the promotion of the lymphatic transport of anthelminthic drugs by-passing the liver. The selected compound was niclosamide (CAS 50-65-7) which is very effective in vitro against infective larvae but has no significant antifilarial activity when orally administered at 200 mumol/kg. To estimate the interest of such an approach, the synthesis of 5 prodrugs was achieved in a first stage. The intrinsic antifilarial activity and the delayed effect of these compounds were evaluated in vitro. Then, in vivo tests were performed with Molinema dessetae infective larvae to select the best ligands. The prodrug V 1,3-dihexadecanamido-2-[4-chloro(2- chloro-4-nitroanilinocarbonyl)phenyloxy-carbonylpropanoyl oxy]propane (having a diamide function) was responsible for an in vitro delayed effect and an orally in vivo activity (200 mumol/kg when administered in a single dose). The biological improvement of this easily micellizable prodrug which is stable to intestinal enzymes in respect to Niclosamide confirms such a strategy.

Amino- and aminomethylcholesterol derivatives with fungicidal activity.

Among a series of aminocholesterol derivatives synthesized, 7-aminocholesterol is the strongest inhibitor of yeast cell growth. Using sterol auxotrophic mutant strains, we showed that this compound inhibits cell proliferation by interfering with ergosterol biosynthesis. The sterol pattern of treated cells revealed that 7-aminocholesterol inhibits delta 8-->delta 7-sterol isomerase and delta 14-sterol reductase as morpholine inhibitors. However, the novel feature of this compound is a strong cytotoxicity to yeast.