Metabólicos secundários da goiabeira (Psidium guajava L.) como potenciais fatores de resistência às pragas

Abstract

The guava tree Psidium guajava L. stands out in the fruit market, mainly because it presents a socioeconomic alternative in Brazilian agribusiness. However, the presence of insect pests such as Triozoida limbata (Enderlein) (Hemiptera: Sternorrhyncha: Triozidae) considerably affects the productivity of guava. However, there are guava cultivars not preferred by T. limbata. In this sense, the objective of this work was to analyze and identify the compounds referred to as secondary metabolites, present in eight different guava cultivars, aiming to contribute to a program of genetic improvement of the culture or as a recommendation of Integrated Pest Management. Guava leaves were collected from the orchard located in Embrapa Agropecuária Oeste, Dourados, Mato Grosso do Sul, Brazil, with eight cultivars of P. guajava. The leaves were dried and ground for extraction, identification and analysis of the compounds in the laboratory. The contents of the extracts' constituents were determined as Total phenols (mg gallic acid/g of extract) flavonoids (mg quercetin/g of extract) and flavonol (mg catechin/g of extract) and antioxidant activity by the method of elimination of the extract stable free radical 1,1- diphenyl-2-picrylhydrazyl (DPPH). Through the analyses, the secondary metabolites were identified, in terms of phenolic compounds contents, being phenols, flavonoids, flavonol and antioxidant activity in the different cultivars. The identification of these compounds leads us to infer about their actions in the interaction of plants with insects and how these components can act in the constitutive defense of plants against insects.