Physiological effects of γ-linolenic acid and sesamin on hepatic fatty acid synthesis and oxidation.

Interrelated effects of γ-linolenic acid (GLA) and sesamin, a sesame lignan, on hepatic fatty acid synthesis and oxidation were examined. Rats were fed experimental diets supplemented with 0 or 2 g/kg sesamin (1:1 mixture of sesamin and episesamin) and containing 100 g/kg of palm oil (saturated fat), safflower oil rich in linoleic acid, or oil of evening primrose origin containing 43% GLA (GLA oil) for 18 days. In rats fed sesamin-free diets, GLA oil, compared with other oils, increased the activity and mRNA levels of various enzymes involved in fatty acid oxidation, except for some instances. Sesamin greatly increased these parameters, and the enhancing effects of sesamin on peroxisomal fatty acid oxidation rate and acyl-CoA oxidase, enoyl-CoA hydratase and acyl-CoA thioesterase activities were more exaggerated in rats fed GLA oil than in the animals fed other oils. The combination of sesamin and GLA oil also synergistically increased the mRNA levels of some peroxisomal fatty acid oxidation enzymes and of several enzymes involved in fatty acid metabolism located in other cell organelles. In the groups fed sesamin-free diets, GLA oil, compared with other oils, markedly reduced the activity and mRNA levels of various lipogenic enzymes. Sesamin reduced all these parameters, except for malic enzyme, in rats fed palm and safflower oils, but the effects were attenuated in the animals fed GLA oil. These changes by sesamin and fat type accompanied profound alterations in serum lipid levels. This may be ascribable to the changes in apolipoprotein-B-containing lipoproteins.

Boron-based inhibitors of acyl protein thioesterases 1 and 2.

Ras proteins are of importance in cell proliferation, and hence their mutated forms play causative roles in many kinds of cancer in different tissues. Inhibition of the Ras-depalmitoylating enzyme acyl protein thioesterases APT1 and -2 is a new approach to modulating the Ras cycle. Here we present boronic and borinic acid derivatives as a new class of potent and nontoxic APT inhibitors. These compounds were detected by extensive library screening using chemical arrays and turned out to inhibit human APT1 and -2 in a competitive mode. Furthermore, one of the molecules was demonstrated to inhibit Erk1/2 phosphorylation significantly.

Glyoxalase I and glyoxalase II from Aloe vera: purification, characterization and comparison with animal glyoxalases.

Glyoxalase I and glyoxalase II from the outer green rind of Aloe vera leaves were purified by (matrix) affinity ligand-enzyme binding methods. The purified enzymes exhibited single protein bands on SDS-PAGE electrophoresis, with MW values of approximately 44,000 and 27,000 for glyoxalase I and glyoxalase II, respectively. The glyoxalase I is a basic protein (pI 7.8), while the glyoxalase II (3 protein bands) is acidic (pI 4.7, 4.8 [prevalent form], and 5.0). The kinetic constants, Km and Vmax, and Ki values for certain inhibitors are reported for both glyoxalase I and glyoxalase II. The glyoxalase enzymes from Aloe vera were compared with reported animal and plant glyoxalases.