Avaliação da atividade antioxidante e do potencial antitumoral de extratos de mel

Abstract

Honey is a complex mixture produced by honeybees from floral nectar, supplemented with enzymes and subsequent dehydration. In addition to its use in diet, honey is also used for its various biological properties, or nutraceuticals. In this work liquid-liquid extractions were performed using water plus the organic solvents ethyl acetate and n-hexane, polar and nonpolar, respectively; aiming the production of extractions characterized by the absence of most sugars; the objective was to purify bioactive compounds present in honey which had some sort of biological activity including antioxidant activity and antitumoral potencial. Briefly, thirty grams of crude honey were obtained and mixed with 300 mL of water, consequently the solution was moved to a separatory funnel which contained each solvent. After correct agitation, the solvent fraction was transferred to a rotary evaporator. Following total solvent evaporation, samples were resuspended in ethanol, and the aliquots were moved to test tubes and evaporated in a vacuum centrifuge. Samples were again resuspended in dimethylsulfoxide (DMSO) to future analysis. Ethyl acetate extracts, hexanic extracts and crude honey samples were analysed in High Pressure Liquid Chromatography (HPLC) achieving chromatography peak profiles that were crucial to verify the diversity of molecules present in each extract. Thereafter, each sample had its antioxidant power evaluated in chemical essays like Total Phenolics, FRAP (ferric reducing antioxidant power), and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)]. The antitumor potential was tested through cell viability, using 4L (10 mg/mL) of each sample on K562 and Jurkat leukemic cell lines in RPMI-1640 culture medium containing 10% of fetal bovine serum (FBS). Work results showed a difference between the ethyl acetate extract antioxidant activity and the hexanic extract and crude honey antioxidant powers. Correlations between samples for all the essays revealed statistical difference for the ethyl acetate extract sample owning the highest antioxidant power when compared to hexanic extract and crude honey samples (p<0,001). This result was confirmed by HPLC analysis, where the ethyl acetate extract chromatography profile exhibit itself diversified, displaying multiple peaks, differently from the hexanic extract, which displayed few peaks on the inspected wavelength. The antioxidant chemical essays were able to show purification of antioxidant compounds by the solvent ethyl acetate meaning that the compounds flavonoids and phenolic acids were present, and their activity was measured. Cell viability results showed low cytotoxicity effects for both extracts, although the population scattering indicate that other cellular process might be occurring. Beyond that, more parameters, for instance, cell cycle, cell differentiation, cell proliferation, and expression levels of pro and anti-apoptotic proteins must be tested, and will be decisive to determine honey extracts as potential candidates for prevention of tumorigenesis process. In addition, utter studies of Pampa region honey will be important to obtain comparison data to other region’s honeys, and most of all, to incorporate value to this honey and stimulate region’s beekeeping.