Caracterização química e biológica de extratos de própolis vermelha do nordeste do Brasil obtidos por diferentes métodos de extração

Abstract

Propolis is a natural compound of wide application in the food, pharmaceutical and cosmetic areas, being a complex resin produced by bees through the mixture of exudates from different plants, wax and salivary secretions. Variations in the chemical composition, and consequently, in the biological activity of propolis extracts, are associated with many factors, such as type, geographic origin, seasonality, among others. Within this context, the objective of this study was to evaluate the influence of different extraction methods on the chemical and biological composition of red propolis extracts from different geographic origins, as well as to determine the process conditions for obtaining red propolis extracts using the technology extraction with supercritical fluid (SFE). Initially, conventional (ethanolic) and ultrasound-assisted extraction methods were used to extract active compounds from propolis from different regions of Northeastern Brazil (Sergipe, Alagoas, Bahia, and Rio Grande do Norte). Contents of phenolic compounds, flavonoids, in vitro antioxidant activity, concentration of markers (formononetin and kaempferol) and cytotoxicity to human tumor cell lines (HCT116 - human colon, HL60 - leukemia, PC3 - carcinoma of prostate and SNB19 - glioblastoma) were evaluated comparatively for the twelve extracts obtained from six different samples. Additionally, red propolis extracts were obtained by SFE from a sample from Alagoas using different process conditions. To determine the process parameters applying SFE, the Overall Extraction Curves (OEC - Overall Extraction Curves), the S/F (CO2 mass/propolis mass), the percentage of co-solvent (ethanol – 0, 1, 2 and 4%) and the global yield isotherms (GYI - Global Yield Isotherms) as a function of different pressures (250, 350 and 450 bar) and temperatures (31.7, 40 and 50°C). The total phenolic compounds, antioxidant activity and the content of formononetin, naringenin and kaempferol in the extracts obtained under different conditions (SFE) were investigated. As a result of this study, significant variations (p>0.05) were identified in the content of the compounds investigated in red propolis extracts, confirming that the chemical composition varies according to the region where the samples were collected. The highest concentration of the compounds of interest and the highest in vitro antioxidant activity were shown by extracts obtained from samples from the state of Alagoas (A1, A2, B1 and B2), which is currently the only one in Brazil that has certification of origin. The biomarkers formononetin and kaempferol were identified in all samples, regardless of origin or extraction method used. The highest concentrations of formononetin were identified in the extracts obtained by ultrasound, indicating a greater selectivity for the extraction of this compound by this method. Regarding cytotoxic activity, for the HCT-116 strain, all extracts showed inhibition greater than 90%, while for the HL-60 and PC3 strains, the lowest inhibition identified was 80%. In general, there was no significant difference (p>0.05) in the antiproliferative potential when comparing the extraction methods. The results showed that the composition of Brazilian red propolis varies significantly depending on the geographic origin and that the method used influences the resulting compounds that are present in the propolis. Regarding the application of SFE as an extractive method, within the parameters investigated, the best conditions found were a S/F of 131 and the use of ethanol in the highest concentration (4%), which resulted in higher yields of extract and higher content of antioxidant compounds. Formononetin, the main biomarker of red propolis, was the compound found in greater amounts in the extracts obtained by SFE under all conditions used. As expected, the temperature and pressure conditions also influenced the process yield, with 350 bar and 40°C being the best conditions for obtaining bioactive compounds from a red propolis sample. The new results for red propolis found in this study show that it is possible to obtain extracts with high antioxidant potential using alternative technologies, as well as that the geographic origin, the type of method used and the process conditions influence the quality of the extract obtained.