Síntese de novos derivados da cinetina e do tidiazuron

Abstract

Kinetin and thidiazuron are substances belonging to the cytokinins class, which are plant growth regulators (PGRs). PGRs are an important class of agrochemicals that present the activity of regulating the growth and development of plants and fruits. Cytokinins are divided into adenine-derived compounds (a purine), such as kinetin, and urea compounds such as thidiazuron, which features ring 1,2,3- thiadiazole in their structure. Purine and 1,2,3- thiadiazole heterocycles have a range of biological activities and their derivatives are present in both agrochemicals and medicines. Another very important heterocycle in medicine and agriculture is the nucleus 1,2,3-triazole. Thus, in Chapter I, of this work is described the synthesis of purine (kinetin and adenine) derivatives with the 1,2,3-triazole ring and the synthesis of thiadiazole derivatives with the 1,2,3-triazole ring. In the first part, 22 purine-1,2,3- triazole derivatives were synthesized, 11 kinetin derivatives (1a-k) and 11 adenine derivatives (2a-k), via cycle-addition 1.3-dipolar between azides and terminal alkynes, with global yields ranging from 18- 91%. In the second part, six thiadiazole-1,2,3-triazole derivatives were synthesized with global yields ranging from 4-17%. Chapter II are described the effects presented by the purine-triazole derivatives on dicotyledon plants (cucumber and lettuce). In the preliminary study with the species Cucumis sativus (cucumber), the compounds were tested in two concentrations (100 and 1 µm) and had no phytotoxic effects for the cucumber. From this, a second study was conducted with the species Lactuca sativa (lettuce) in two concentrations (100 and 10 µm). In this study, compounds 2d and 2k had phytotoxic effect on lettuce, different from the others. Chapter III describes the effects presented by the purinetriazole derivatives on the MTT assay against tumor cells (MCF-7 and MDA-MB-231) and normal (MCF-10A) breasts. In this essay, the derivatives of kinetin 1a-e and 1h, and adenine 2a derivative had cytotoxic effect on tumor cells. Compounds 1c [IC50 = 22.3 ± 2.9 µm (MCF7) and IC50 = 9.3 ± 1.7 µm (MDA-MB-231)] and 1d IC50 = 22.9 ± 1.6 µm (MCF-7) and IC50 = 16.7 ± 1.8 µm (MDA-MB-231)] were the most active.