Phytochemical analysis and fungicide potential of Pouteria ramiflora against Lasiodiplodia theobromae

Fitoquímica e potencial fungistático de extratos e frações de Pouteria ramiflora contra Lasiodiplodia theobromae

ABSTRACT

The use of plant extracts can be an alternative to reduce the use of pesticides, to control diseases and pests that affect agricultural production. The aim of this study was the chemical characterization of the extract and fractions of Pouteria ramiflora leaves and to determine its fungistatic potential on Lasiodiplodia theobromae. The ethanolic extract of dried and crushed leaves was obtained by maceration. Part of this extract was sequentially partitioned and the following fractions were obtained: hexane, dichloromethane, chloroform, ethyl acetate, n-butyl, and hydromethanol for subsequent bioassay, and qualitative and quantitative phytochemical analysis. Experimental development comprises of adding a L. theobromae mycelial disk (5 mm), obtained from pure colonies, in the middle of Petri dishes with PDA culture growth (potato-dextrose-agar) plus the aforementioned substances in different concentrations (800; 1,200; 1,600; 2,000, and 2,400 µg/mL), and a control treatment (PDA). The plates were incubated in B.O.D. (25±2°C), and the assessment was performed by measuring the diameter of the colonies until it reaches the edge of the board. The experimental design was completely randomized with five replications, and the treatments were constituted of a factorial of seven extracts/fractions and six concentrations. For the Mycelial Growth Rate Index (MGRI) obtained, the analysis of variance was performed, and when significant, the regression analysis was performed. All extract/fractions decreased MGRI of L. theobromae, as the concentrations were increased. The best MGRI reduction occurred in n-butanolic fraction, and the efficiency of this fraction may be related to the presence of flavonoids and anthraquinones. The extract and fractions of P. ramiflora, a tree from the Cerrado biome in Mato Grosso do Sul, was effective in the control of L. theobromae, which can be used as a control option in organic farming or in integrated management systems.

Keywords:
Pathogen; natural products; organic farming; flavonoids