Síntese de heterociclos derivados de aminoácidos e anilinas aromáticas como inibidores de ureases

Abstract

Ureases are nickel-dependent hydrolytic enzymes, which negatively impact both agricultural production and human and animal health. These enzymes hydrolyze urea – the most widely used nitrogen fertilizer in the world – leading to the formation of ammonia and carbon dioxide, which are gases associated with greenhouse effects and acid rain. Urea is also used by ureolytic bacteria as a survival strategy for these microorganisms in extremely hostile environments – such as the stomach (pH 1.5-2.0). In these contexts, the development of new urease inhibitors may eventually mitigate the production of harmful gases to the environment, in addition to combating pathogenic microorganisms for humans and animals. This work aimed to obtain and evaluate anti-ureolytic heterocyclics derived from amino acids and aromatic anilines in vitro tests against the urease enzyme isolated from Canavalia ensiformis. The motivation for choosing amino acid derivatives in the form of thioidantoins was due to the recognized antibacterial activity of these compounds and the ease of obtaining them, not requiring complex purification procedures. Thirteen thioidantoins derived from valine (Val), tryptophan (Trp) and threonine (Thr) were synthesized and evaluated, with yields ranging from 48 to 94%. In relation to anti-ureolytic activity, in addition to amino acid derivatives, precursor amino acids were tested: (i) L-valine, D-valine, L/D-valine (ii) L-tryptophan, D-tryptophan, L/D- tryptophan (iii) L-Threonine. All amino acids and seven of their derivatives showed IC50 values comparable to the reference inhibitor, hydroxyurea (HU, IC50 = 559 M), with the valine-derived thioidantoins being significantly more potent (IC50 = 332, 433, 448 M). The motivation for choosing aniline derivatives in the form of benzimidazole-benzoylthioureas and benzothiazol-benzoylthioureas hybrids was given by the recognized ability of both classes to inhibit urease enzymes. Thus, a viable synthetic route for the synthesis of the first precursor, 2-aminobenzothiazole, with 88% yield was established. Among the proposed products, only the benzothiazol-benzoylthioureas (HBTs) hybrids with meta and para substituents were obtained with yields ranging from 47 to 78%. Most of the synthesized compounds had IC50 values comparable to the reference inhibitor, hydroxyurea. This work also aimed to develop an experiment to quantify ammonia, volatilized from urea, in a continuous air flow system in a closed chamber, in which one compound of each class synthesized in this work was evaluated.