Factorial design in optimization of phenolic compounds in Psidium cattleianum Sabine leaves and evaluation of its antichemotactic activity

Popularly known as “araçá”, Psidium cattleianum Sabine is a native species from Brazil. It has two cultivars registered, Ya-ci and Irapuã, known as yellow and red araçá, respectively. Most studies report the presence of tannins, flavonoids, saponins and catechins in extracts obtained from the leaves. Also, the literature reports antioxidant, antimicrobial and anti-inflammatory activities for the species [1; 2]. Therefore, the aim of this study was to optimize the extraction of phenolic compounds, and evaluate the anti-inflammatory activity. The species were collected in Campestre da Serra (red araçá) and Vacaria (yellow araçá), RS, and the extraction was optimized in two steps: fractional factorial design (FFD) and central composite design (CCD), through the statistical software MiniTab 17® [3]. Preliminarily, it was tested the variables method of extraction, temperature and time. With that stablished, four variates were selected for FFD, and to estimate the experimental error, Dong algorithm was associated with factorial design. In the CDD model, the parameters were evaluated in two levels (-1 and +1): number of extractions and solvent percentage. The phenolic content was estimated by high performance liquid chromatography (HPLC Shimadzu Prominence LC-2030C), using the peak area of the phenolic compounds as response. The antichemotactic activity was carried out with the optimized extracts, according to the modified Boyden chamber method [4]. It was evaluated the leucocytes migration through the filter using a microscope. The extracts were tested at concentrations of 0,001 to 10 μg/mL, using indomethacin as a positive control and a neutrophil suspension without treatment as a negative control. The results indicated ultrasound, temperature of 60ºC and 60 min extraction as previous best conditions. In the FFD, 75% Dong algorithm and CCD, the optimal extraction obtained was: ≤ 180 μm of particle size, 3 extractions, 43% methanol as solvent and the ratio plant: solvent as 1:40 (w/v). In the anti-inflammatory assay, the results indicated, for yellow araçá, 100.0%, 65.4%, 49.4%, 46.6% and 22.6% inhibition of leukocyte migration at concentration of 10, 1, 0.1, 0.01 and 0.001 μg/mL, respectively. And for red araçá, 69.7%, 39.9%, 28.6%, 21.7% and 5.6% inhibition at the same concentrations. All samples in the different concentrations, except the lowest concentration of red araçá, inhibited significantly leukocyte migration (p <0.05) when compared to the negative control. The results imply that the optimization increased the concentration of phenolic compounds in the extracts, and the species shows a potential anti-inflammatory activity through the inhibition of the process of neutrophil migration at the initial stage.