Antioxidant Properties of Ergosterol and Its Role in Yeast Resistance to Oxidation.

Although the functions and structural roles of sterols have been the subject of numerous studies, the reasons for the diversity of sterols in the different eukaryotic kingdoms remain unclear. It is thought that the specificity of sterols is linked to unidentified supplementary functions that could enable organisms to be better adapted to their environment. Ergosterol is accumulated by late branching fungi that encounter oxidative perturbations in their interfacial habitats. Here, we investigated the antioxidant properties of ergosterol using in vivo, in vitro, and in silico approaches. The results showed that ergosterol is involved in yeast resistance to tert-butyl hydroperoxide and protects lipids against oxidation in liposomes. A computational study based on quantum chemistry revealed that this protection could be related to its antioxidant properties operating through an electron transfer followed by a proton transfer mechanism. This study demonstrates the antioxidant role of ergosterol and proposes knowledge elements to explain the specific accumulation of this sterol in late branching fungi. Ergosterol, as a natural antioxidant molecule, could also play a role in the incompletely understood beneficial effects of some mushrooms on health.

Comparison of the antioxidant property of acerola extracts with synthetic antioxidants using an in vivo method with yeasts.

In this study, we compared the antioxidant activity of ripe and unripe acerola extracts with synthetic antioxidants (BHA and BHT). This activity was assessed by classical approaches (DPPH and ABTS) and by an in vivo method using yeasts. Acerola extracts contain phenolic compounds and ascorbic acid that exhibit radical scavenger capacity and reducing power. The results obtained with yeasts revealed that the acerola extracts and BHT either acted as antioxidants or presented no activity depending on the nature of the oxidant molecule used. BHA decreased yeast resistance to oxidative treatments and also showed deleterious effects even when oxidative treatments were not applied. The unripe acerola was the most efficient antioxidant in the in vitro experiments but not necessarily in the in vivo assays, showing the weakness of in vitro systems in predicting antioxidant responses for biological purposes. BHA presented cell damaging effects even in the absence of oxidizing reagents.

In vitro and in vivo antioxidant properties of bioactive compounds from green propolis obtained by ultrasound-assisted extraction.

Green propolis presents a potential source of bioactive compounds, responsible for its antioxidant capacity. The effects of ethanol concentration, solid-solvent ratio, and extraction time were evaluated in regard to the total phenolic content (TPC) and antioxidant capacity of the extracts by the use of central composite rotatable designs. Optimum extraction conditions lead to significant reduction of extraction time compared to conventional extraction methods. Under optimum conditions, extracts were composed of 1614.80 mg GAE. g-1 and 807 mg artepillin C. g-1. Extracts were effective in retarding the oxidation in oil-in-water emulsions subjected to accelerated tests. Green propolis extracts (up to 200 mg.kg-1) did not increase Saccharomyces cerevisiae cell damage after 4 h of exposure, indicating its antioxidant effect and potential innocuity. Results demonstrated the antioxidant properties of the propolis extract was similar or better than the ones from synthetic antioxidants and warrant further investigation to determine its potential industrial application.

Can lychee reducing the adipose tissue mass in rats?

ABSTRACT Lychee fruit has been studied owing to the presence of several bioactive compounds that can contribute to weight loss in obese individuals. However, the anti-obese potential of the fruit has not been explored yet. The aim of this study was to investigate the effect of different parts of lychee in reducing the adipose tissue mass of cafeteria diet-fed rats. Phenolic compounds and scavenging capacities were quantified. The food intake, apparent digestibility, weight of the body and liver, body mass, Lee Index, and the mass of epididymal and visceral adipose tissues were evaluated. The results were estimated by Tukey's Test at 5% probability. A higher amount of phenolic compounds and scavenging capacity were observed in the peel of lychee as compared to the other parts of the fruit. The hypercaloric diet with lychee flour resulted in a higher apparent digestibility. There was no difference between groups control (C), hypercaloric (H), hypercaloric with lychee flour - 50.00% peel and 50.00% seeds (H2F), and hypercaloric with lychee flour - 33.33% peel, 33.33% pulp and 33.34% seeds (H3F) with respect to body and liver weight, corporal mass, and Lee Index. The hypercaloric diet-fed group exhibited an increase in visceral and epididymal adipose tissue mass, whereas the group fed with hypercaloric diets and flour made from the peel and seed of lychee presented a lower visceral adipose tissue mass. In conclusion, the use of lychee flour was considered viable because it decreased visceral adipose tissue mass in rats.