Uso de solventes eutéticos profundos na recuperação de bioativos obtidos a partir de rhodotorula mucilaginosa e aplicação em sistemas nanoemulsionados

Abstract

The present study aimed to obtain lipo-molecules by a bioprocess using Rhodotorula mucilaginosa CCT3892 cells as catalyst and sugarcane molasses as carbon source, evaluated a green extraction process of them using Deep Eutectic Solvents and lastly to obtain nanoemulsioned systems containing these biosubstances in view of a future application in the cosmetic industry. The results obtained in the first part of this work showed that the use of molasse (CM) in the bioactive simultaneous production by the yeast was able to produce the same content of total lipids and total carotenoids (16.50 % ± 0.68% e 0.053 ± 0.001 mg.g-1) as a synthetic medium (CS) (15.36 ± 1.36 % e 0.051 ± 0.001 mg.g-1). With regards to the fatty acids production, the CM cultivation showed the most interesting profile once it present a great content of oleic acid (74,05%). The yeast extract supplementation (CMEL) did not provide an improvement in microbial oil-production once it redirected the yeast metabolism to others actives instead of secondary metabolites obtainment. In the second part of this research, the use of four choline chloride based Deep Eutectic Solvents was verified in relation to their ability in to improve the yeast cell permeability and total carotenoids recuperation. The best result for the total carotenoid recovery (0.110 ± 0.005 mg.mL-1) was achieved using the solvent synthetized with glycerol (ChGy). The results of the fatty acids analysis showed that DES treatments did not influence in the oil composition. The thermogravimetric analysis of the yeast cells, before and after the treatments, revealed that the solvent interaction with the cells were conditioned to the chemical specie used in DES synthesis. An experimental design (2³) evidenced the process dependence in relation to the temperature, etanol addition in the solvent and extraction time. In the last part of this research, it was found a strong antioxidant activity for the eutectic extract obtained from the Rhodotorula cells and it was conclude that this characteristic was not only due the carotenoid presence (0.10 ± 0.02 mg.g-1) but also because of the content of reducing sugars, such as: xylose (2.19 ± 0.02 mg.g-1), glucose (1.03 ± 0.00 mg.g-1) and arabinose (0.36 ± 0.00 mg. g-1). After the determination of the inhibitory concentration for oxidative species (IC50) (10.84 mg.mL-1), the extract was added at 2,5% in an oil phase formed by caprylic/capric triglycerides and preservative. The phase was emulsified with distilled water (aqueous phase) and Tween 20 (surfactant) and the formation of nanoemulsions was noticed, F1 (42.90 ± 8.17 nm) and F2 (118.85 ± 1.44 nm). Both systems were characterized in relation to their pH, zeta potential and polydispersity index (PDI). After the stability tests, the systems showed to be stable in relation to the centrifugal action and variant in kinetic terms according to the storage temperature (30 days). The rheology of the nanoemulsions was also investigated and it revealed that the behavior in ration to a shear stress was conditioned to the oil content, which varied from Newtonian (F1) to non-Newtonian (F2) as a function of the oil phase content. At leats, the results present here were able to show that the bioproduction of oleaginous compounds can be attached to a fractional recovery and cosmetical application.