Tyrosine and proline conjugated trolox, hydroxy-cinnnamic acid and diclofenac hybrids as strong hypolipidemic and anti-inflammatory agents.

Abstract

Oxidative stress induces the signaling of inflammatory and apoptotic pathways leading to the progression of degenerative disorders, whilst lipid increase and oxidation is an important factor for their development and propagation. L-tyrosine and L-proline amino acids and their derivatives have shown to be implicated in several of these aspects in a positive manner. In this prospect, methyl esters of these amino acids, amidated with the antioxidants trolox and (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid (hydroxylated cinnamic acid compound), as well as the classical NSAID diclofenac, were prepared and evaluated as antioxidant, anti-inflammatory and anti-hyperlipidemic agents. Almost all compounds presented high or moderate 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation inhibitory activity, reaching up to 12 fold (in the lipid peroxidation inhibition) that of the parent antioxidant acids, such as trolox, whilst the insertion of the tyrosine moiety seemed to offer additional antioxidant potency, especially in the case of the NSAID derivative (compound 3). The majority of them displayed significant in vivo acute inflammation reduction (decrease of paw oedema, induced by carrageenan, 33–78 % at 150 μmol/kg) ability. The most active trolox-proline hybrid (compound 4) exhibited more than two fold increased inhibition in comparison to the well-established NSAIDs ibuprofen and diclofenac. They were also moderate inhibitors of soybean lipoxygenase, however active, in several cases, compared to their parent acid molecules. The most profound activity of the compounds was the reduction of the plasma lipidemic indices (Triton-induced hyperlipidemia in rats). Compound 5 was the most potent, with decrease in triglycerides, total cholesterol and low density lipoprotein, by 56 %, 87 %, and 72 %, respectively at 150 μmol/kg (i.p.), slightly better than that of simvastatin. Thus, the insertion of proline and tyrosine moieties seem to improve the anti-inflammatory activity of parent acids and NSAIDs, resulting in compounds with two or more pharmacological features (including hypolipidemic activity), which might be beneficial in cases characterized by inflammatory, oxidative, hyperlipidemic and degenerative conditions.