Extração do óleo de Bidens pilosa L. usando fluido supercrítico: atividade biológica e modelagem matemática

Abstract

Bidens pilosa L. (Asteraceae), better known as Black Jack, is a plant popularly used in the treatment of malaria, inflammation and various types of tumors, and is now widely disseminated throughout the tropical and subtropical region of the world. Among the several components present in the extract of this plant, the presence of flavonoids, polyacetylenes and terpenes are abundant, suggesting that most biological activities are directly linked to the presence of these metabolites. The selective extraction of these compounds with supercritical fluid is an alternative technology to the problems found in the conventional extractions, since there is a strong solvation power, and does not require the use of organic solvents. Therefore, this study had as objective the extraction of the high aggregated value substances present in this plant using supercritical CO2 in different pressure and temperature conditions. For this, 8 g of previously dried and milled Bidens pilosa leaves were fed in an extractor with 42 mL of volume. The unity also contained a high pressure pump, and a micrometric valve for sample removal. Different operating conditions were investigated (150 bar - 60 °C; 179 bar - 46 °C; 179 bar - 74 °C; 250 bar - 40 °C; 250 bar - 80 °C; 321 bar - 46 °C; 321 bar - 74 °C and 350 bar - 60 °C and 250 bar - 60 °C), according to an experimental design. It was observed that the extraction yield increased with increasing pressure. According to the results, the best extraction condition was 321 bar and 74 °C, obtaining a yield of 0.082% (6.6 mg). The analyses of the extracted oils were performed using high performance liquid chromatography (HPLC-DAD) and gas chromatography (GC-MS). Under conditions of 321 bar at 74 °C and 250 bar at 40 °C, signals were found showing ultraviolet spectra of terpenes characteristics of essential oils. The extracts analyzed showed promising inhibition in two tumor cell lines used, melanoma, SK-MEL-28 (68%) and leukemia, K562 (90%), both at a concentration of 150 μg/mL. Subsequently, the experimental data were modeled by the models of Esquivel et al. (1999), Reverchon e Osseo (1994), Zeković et al. (2003), Sovová (1999), Brunner (1984) and Kandiah e Spiro (1999), showing good correlation. The models of Chrastil (1982), Adachi e Lu (1983), Del Valle e Aquilera (1988) and Gordillo (1999) were able to represent the behavior of the solubility of the oils in different conditions of temperature and pressure.