Phenolic compounds and antioxidant capacity of Pediastrum boryanum (Chlorococcales) biomass.

Bioactive compounds, synthesized by photosynthetic microorganisms, have drawn the attention of the pharmaceutical field. This study aimed at evaluating synthesis and in vitro antioxidant capacity of phenolic compounds produced by a microalgae species P. boryanum, which was grown in six different culture media (standard BG11, modified BG11/MBG11, standard WC, modified WC, WC*2 and basal). The highest concentrations of biomass (1.75 ± 0.01 g.L-1) and phenolic content (3.18 ± 0.00 mg.g-1) were obtained when P. boryanum was grown in MBG11 and phenolic acids were identified: gallic, protocatechuic, chlorogenic, hydroxybenzoic and vanillic ones. All extracts exhibited scavenger activity in the ABTS assay and inhibited peroxidase. However, phenolic compounds from P. boryanum grown in BG11 and MBG11 had the most potent scavenger activity in the DPPH assay. In sum, P. boryanum can be a new source of free phenolic compounds with potential antioxidant activity when grown in MBG11, since it yields high amounts of biomass and phenolic compounds.

Fungal diversity and natural occurrence of deoxynivalenol and zearalenone in freshly harvested wheat grains from Brazil.

This study investigated the fungal diversity and presence of deoxynivalenol and zearalenone in 150 samples of freshly harvested wheat grains collected in three regions of Brazil (Sao Paulo, Parana, and Rio Grande do Sul). Analysis of the mycobiota showed a predominance of Alternaria sp., Fusarium sp. and Epicoccum sp. Microdochium nivale (23%), a fungus rarely found in Brazilian crops, was detected in Sao Paulo. Four members of the Fusarium graminearum species complex were isolated: F. graminearum s.s. (37%), Fusarium meridionale (46%), Fusarium cortaderiae (13%), and Fusarium austroamericanum (3%). Toxin analysis revealed 99% contamination with deoxynivalenol (mean 706 µg/kg). The frequency of zearalenone varied greatly across regions: wheat grains from Rio Grande do Sul (84%) and Sao Paulo (12%) had median concentrations of 70.9 and 57.9 µg/kg, respectively. ZEA was not detected in the samples from Parana. A total of six samples were above the maximum tolerated level recommended by the European Commission for ZEA in wheat grains. This study provided new insights into the natural mycobiota of Brazilian wheat, demonstrating contamination of most samples with deoxynivalenol and high frequency of zearalenone in samples from Rio Grande do Sul.