Seleção de ésteres do ácido (e)-cinâmico ativos contra meloidogyne incognita

Abstract

Phytoparasitic nematodes generate large losses for world agricultural production. Among these organisms is Meloidogyne incognita, which can parasitize approximately 2000 species of plants, causing great economic damage to farmers. This is the case, for example, of the tomato crop, which has world productions of 170 million tons per year and can lose up to 10% only due to phytonematodes. As the most used methods for the control of such parasites are the use of chemical nematicides, with high toxicity against non-target organisms, there is a need to develop efficient alternatives with less environmental impact, for use as nematicides. An example of this is the work previously done with (E)-cinamaldehyde, which was shown to be very active against M. incognita in in vitro tests and in tomato plants. However, this aldehyde showed low persistence in the soil, which can be attributed to its high susceptibility to oxidation. Consequently, in order to contribute to solve this problem of low persistence, this study aimed to select, through in vitro and in vivo tests, esters of (E) -cinamic acid active against M. incognita. In addition, it also aimed to identify the enzymatic target of the most

active esters through in silico study. The best results were obtained for methyl (E)-p- fluorocinamate (13), methyl (E)-p-chlorocinamate (14) and methyl (E)-p-bromocinamate

(15), which showed lethal concentrations for 50% (LC50) of nematodes of the second stage (J2) of M. incognita, in vitro, equal to 168, 95 and 216 μg mL-1

, respectively. Under the same conditions, the LC50 values for the commercial nematicides carbofuran and fluensulfone were equal to 160 and 34 μg mL-1

. Substances 13-15 were also active against nematode eggs and,

when used at a concentration of 200 μg mL-1

in experiments with tomato plants inoculated with J2, reduced the number of galls of the nematode in plants by about 23% the number of galls of the nematode in the plants. Through the in silico study, it was observed that the probable enzymatic target of substances 13-15 in M. incognita was histone deacetylase, which is an enzyme responsible for epigenetic expression and can intervene in the embryonic formation of nematodes. As a pre-study aimed at the development of more active molecules against the nematode, analogous chemical structures, with more affinities for histone deacetylase, were selected and proposed as potential nematicides. In conclusion, esters 13-15 are potentially useful for the development of new nematicides for the control of M. incognita, mainly because histone deacetylase, which is the enzymatic target of these substances in the nematode, according to the in silico study, can be used to if you find similar substances with more nematicidal activity.