Influence of microbial fermentation on the antioxidant activity of phenolic substances in Saccharomyces cerevisiae.

AIM: Using in vitro assay and eukaryotic cell model of Saccharomyces cerevisiae, we investigated the impact of microbial fermentation on the antioxidant activity of phenolic substances. METHODS AND RESULTS: Caffeic acid phenethyl ester (CAPE) and mangiferin were fermented by lactic acid bacteria (LAB), and the antioxidant activity of the fermented products was compared to that of the pure substances. This comparison was assessed using high-performance liquid chromatography (HPLC), in vitro by 2,2-Diphenyl-1-picrylhydrazyl (DPPH), and in vivo in yeast cells. The wild-type strain (BY4741) and its isogenic mutants in glutathione (Δgsh1), catalase (Δctt1), and superoxide dismutase (Δsod1) were treated with CAPE and mangiferin, fermented or not, and exposed to hydrogen peroxide (H2O2)-induced stress. The antioxidant activity was evaluated by cellular viability, intracellular oxidation, and lipid peroxidation. We expected that fermentation would change the antioxidant activity of phenolic substances. While HPLC analysis revealed changes in the composition of fermented products, significant alterations in antioxidant activity were only observed when using mutant strains. The fermentation of mangiferin increased dependency on GSH compared to the respective pure phenolic substance to resolve H2O2-induced stress. Additionally, CAPE appeared to act as a preconditioning agent, enhancing antioxidant responses, and promoting increased tolerance to H2O2 stress, and this mechanism was maintained after fermentation. CONCLUSIONS: This study highlights that fermentation impacts the enzymatic mechanism of oxidative stress resolution, even though differences could not be observed in in vitro assays or in the wild-type strain.

Aroeira fruit (Schinus terebinthifolius Raddi) as a natural antioxidant: Chemical constituents, bioactive compounds and in vitro and in vivo antioxidant capacity.

Schinus terebinthifolius Raddi fruit, known as Brazilian pepper or aroeira, is a natural source of bioactive compounds. However, studies about the antioxidant and nutritional contribution of this fruit in food systems are limited. Regarding the presence of bioactive compounds, flavonoids showed the highest level (10.33 ± 0.34 mg QE/g), and potential antioxidant components such biflavonoids were determined by ultra-high performance liquid chromatography/electrospray ionization mass spectrometry. The aroeira fruit extract showed antioxidant potential in DPPH (42.68 ± 0.05%), ORAC (43.40 ± 6.22 µM TE/g) and ß- carotene/linoleic acid (61.41 ± 5.30%) assays. Besides that, in vivo analyses demonstrated the ability of aroeira extracts to decrease the damage caused by oxidative stress promoted by H2O2 in Saccharomyces cerevisiae cells. Thus, the presence of phytochemicals with functional properties and the antioxidant capacity of aroeira fruit indicate its use as a potential natural antioxidant for the food industry.