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Cholesteryl esters in the hydrophobic core of low-density lipoprotein (LDL) particles constitute a major molecular target during copper-mediated oxidation. To facilitate the rapid analysis and quantitation of the oxidative degradation of LDL cholesteryl esters, we describe a new approach based on light scattering detection following separation by HPLC. We have applied this approach to the evaluation of the protective capacity of a new synthetic antioxidant, S20478, during oxidation of LDL in the presence of copper ions. HPLC separation of cholesterol and the four major molecular species of cholesteryl esters (C16:0, C18:1, C18:2 and C20:4) of LDL was achieved in a single run of 20 min with high sensitivity (50 ng) and low background. Time course studies of the oxidative modification of LDL (ratio LDL protein: copper, 100 micrograms/mL: 1 microM) revealed that the content of unsaturated cholesteryl esters (C20:4 and C18:2) decreased (-30% and -15%, respectively) within 90 min of copper-mediated oxidation, while only minor degradation (up to 15%) of monounsaturated (C18:1) and saturated (C16:0) esters occurred. At 24 hours of oxidation, only traces (< 5%) of the C20:4 and C18:2 esters were detectable; whereas 52% of the C18:1 ester remained (P < 0.01). Of the saturated esters, only minor proportions (35% or less) underwent oxidative modification. In addition, some 81% of free cholesterol was conserved as the native sterol. The synthetic antioxidant, S20478 (50 microM) was capable of inhibiting the initiation and the propagation of copper-mediated LDL oxidation as determined by the time- and dose-dependent inhibition of the formation of conjugated dienes and thiobarbituric acid-reactive substances, as well as the conservation of the net electrical charge of LDL; indeed S20478 conserved cholesteryl esters in their native form up to 24 hours. However, after prolonged exposure to copper ions (48 hours), only 47% of the unsaturated esters remained (C18:2, P < 0.05). Nonetheless, S20478 (10 microM) was more efficient in inhibiting copper-mediated LDL oxidation as compared to probucol at the same concentration. These findings suggest that S20478 may be of potential interest in a new antioxidant approach to therapeutic stabilisation and regression of atherosclerotic plaques. Moreover, this method should prove useful in the assessment of the integrity of native LDL, and provides a new chemical marker of the degree of LDL oxidation.

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The structure-activity relationships of nine products of the acrylophenone family have been studied. In a previous report 2-(4-methyl-1-piperazinylmethyl)acrylophenone was shown to be an antimicrotubular drug. The effects of these drugs on the bovine brain tubulin polymerization were determined by a turbidimetric assay. The median inhibitory concentrations (ID50) ranged from 1.5 X 10(-5) to 5 X 10(-5) mol/l. Their action on the inhibition of 3H-colchicine binding to tubulin was determined by DEAE (diethylaminoethyl)cellulose filter assay. These compounds are weak inhibitors of colchicine binding. Pharmacological studies of these drugs revealed a strong inhibition of the human ADP-induced platelet aggregation. Moreover, they markedly decreased the serum cholesterol, triglycerides and phospholipids levels of rats after injection of Triton WR 1339 (4-(1,1,3,3-tetramethylbutyl)phenol polymer with formaldehyde and oxirane). They inhibited Candida albicans, Penicillium notatum and Aspergillus versicolor growth. Thus, these nine compounds possess interesting pharmacological properties which are very likely to be related to the acrylic moiety of the molecules.

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Nine (amino-methyl)-2 acrylophenone derivatives having in vitro antimicrotubular activities very similar to those of colchicine are tested on Triton WR 1339-induced hyperlipidemia in rats. By producing a disorganization of the microtubular system, these drugs reduce the lipoprotein secretory process from hepatocytes, and more particularly the triglyceride-rich VLDL secretory process, such that the serum triglyceride, cholesterol and phospholipid levels are decreased. On the other hand, HDL-cholesterol and HDL-phospholipids are increased in a significant manner. Other studies show that serum apoprotein B levels are decreased while serum apoprotein A1 levels are increased. These results are interesting since atherogenous risk is now known to be dyslipemia-related, and is not the same according to the fact that lipids are bound to one or another lipoprotein. Among the four most effective compounds (5,7,8 and 9) three of them possess a methoxy group on the aromatic ring, which seems to distinguish that series from the other two.

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Acrylophenone derivatives with in vitro antimicrotubular activities very similar to those of colchicine were tested on Triton WR 1339-induced hyperlipidemia in rats. They exhibit high normolipemic activity on plasmatic apolipoproteins AI and B, contrasting with inactivity on plasmatic lipids and lipoproteins.

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With the relation between chemical structure and pharmacological activity as a guide, we have been for some time synthetizing a wide range of beta-amino-ketone derivatives. One of them, 2-(4-methyl-1-piperazinylmethyl) acrylophenone, MPMAP, possesses antimicrotubular activities. This product inhibits 50% of the microtubule polymerization at a 3.10(-5) M concentration. It does not prevent tubulin paracrystal formation induced by vinblastine, and binding experiments reveal that this product is a weak inhibitor of colchicine binding. The structure of this compound is different from the other antimicrotubular agents and has the advantage of being far less complex, highly soluble and easy to synthesize. Thus, this product and related compounds should be a new tool for the study of antimicrotubular activities and tubulin assembly.

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Acrylophenone derivatives having in vitro antimicrotubular activity very similar to that of Colchicine were tested on Triton WR 1339 induced hyperlipidemia in rats. By inducing a disorganization of the microtubular system these compounds decreased the movement of very low density lipoproteins (VLDL) to the extracellular space and consequently decreased hypertriglyceridemia. On the other hand, contrary to Colchicine, these derivatives decreased cholesterolemia more significantly and this could be explained by a second action mechanism.

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Chemical and pharmacological properties of potent anorectic compounds with phenylpiperazinyl structure were studied. Among them, the three derivatives having the most interesting anorectic activity are product VI obtained by pharmacomodulation from amfepramone and the compounds IV and V, analogs of GABA. The derivative VI possesses an anorectic activity very similar to that of fenfluramine, namely: modification of feeding behaviour in treated rats, wasting away and decrease of adipose tissue. The two other compounds and more particularly compound V seem to be effective even when treatment is over. Perhaps this is in relation with metabolic effects modifying the regulation of feeding behaviour in the central nervous system. In fact, these compounds have substituents able to interfere with GABA systems.

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