Microalga Haematococcus pluvialis na produção de astaxantina: otimização da produção e nanoencapsulamento dos extratos para aumento da estabilidade

Abstract

Haematococcus pluvialis is a microalga of high commercial value because it is the greatest source of astaxanthin, a strong natural antioxidant. Thus, the development of processes aimed at optimizing the production of astaxanthin by microalgae is a biotechnological challenge. This work proposes a new strategy to enhance the production of astaxanthin and increase the biomass of H. pluvialis using carrot juice in the culture medium. Three experiments of microalgae cultivation were carried out, two of them with media supplemented with carrot juice (SC) in different stages of microalgae growth [experiment 1: beginning of the vegetative phase (day 1); experiment 2: at the peak of cell growth (day 26)] and the control experiment (without SC). Analysis of cell morphology showed that cells treated with SC (1.62 g.mL) differ from control cells by the development of vacuoles, which are associated with the storage of secondary metabolites. As for the biomass production, it was observed that both experiments produce higher values than the control. Furthermore, the astaxanthin content also varied with the introduction of SC, resulting in a content of 4.79, 8.54 and 7.71 ppm in control experiments, 1 and 2, respectively. Another topic addressed in this work is the development of polymeric nanocapsules from extracts and fractions of H. pluvialis, aiming to improve the stability of astaxanthin and enhance its use as a dye and bioactive compound in a cosmetic application. Thus, after preparation and chromatographic fractionation of the ethanolic extract of the microalgae H. pluvialis (EEMHP), the antioxidative and photoprotective potential of EEMHP and the dichloromethane/methanol 5%_1 (FDM5%_1) and methanol (FMeOH) fractions were investigated. By showing satisfactory results in both activities, nanocapsules of Pluronic F127-bPEI containing the active EEMHP and FDM5%_1 were synthesized through polymeric reticulation or crosslinking, using the nanoemulsion process as a methodological strategy. The characterization of the nanocapsules (NC) regarding the parameters of particle size and zeta potential revealed that NC-FDM5%_1 presents greater stability against storage time and pH variation in relation to NC-EEMHP. In summary, this work is the first report on the use of carrots as a source of secondary metabolites of astaxanthin biosynthesized by H. pluvialis and the use of Pluronic F127-bPEI nanocapsules for nanoencapsulation of extracts and fractions from the microalgae under study.