Effects of in vitro gastrointestinal digestion and colonic fermentation on a rosemary (Rosmarinus officinalis L) extract rich in rosmarinic acid

The potential phytochemical losses occurring throughout the sequential steps of in-vitro gastrointestinal digestion and colonic fermentation of a rosemary aqueous extract were investigated. Crude (CE), digested (DE) and fermented (FE) extracts were characterized in terms of their phenolic profile and biological activities. Rosmarinic acid was the phytochemical that underwent the most significate transformation during digestion and fermentation, which amounted to 60% compared to the 26% degradation of the total phenolics. Overall, the simulated digestion step decreased the antioxidant activity estimated by DPPH, ABTS, FRAP, ORAC and TBARS assays. Both CE and DE did not present antiproliferative potential, however, FE exhibited a pronounced cytotoxic activity (GI50 = 116 µg/mL) against HeLa cells. CE and DE showed to be moderate inhibitors of methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible S. aureus (MSSA), S. aureus, Listeria monocytogenes, whilst the FE acted as a moderate inhibitor of MRSA and MSSA.

Effects of in vitro digestion and in vitro colonic fermentation on stability and functional properties of yerba mate (Ilex paraguariensis A. St. Hil.) beverages

Yerba mate (Ilex paraguariensis) is a plant that grows naturally in South America. From its leaves and thin stems different kinds of beverages are prepared (chimarrão, tererê and tea mate), all of them rich in bioactive substances. The aim of this study was to evaluate the influence of in vitro gastrointestinal digestion and colonic fermentation on the stability of the polyphenols and on the antioxidant, antimicrobial and antitumoral activities of the yerba mate beverages. The phenolic chromatographic profile revealed that both the in vitro digestion and the colonic fermentation caused a pronounced decrease in 3,5-O-dicaffeoylquinic acid and 5-O-caffeoylquinic acid in the preparations. However, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid and salvianolic acid I were only barely affected in all preparations. Despite the decrease in the phytochemicals content, yerba mate beverages maintain their functional properties such as antioxidant, antibacterial and antitumoral activities.

Liquid nitrogen pretreatment of eucalyptus sawdust and rice hull for enhanced enzymatic saccharification

In this work, liquid nitrogen was used for the first time in the pretreatment of plant biomasses for purposes of enzymatic saccharification. After treatment (cryocrushing), the initial rates of the enzymatic hydrolysis of eucalyptus sawdust and rice hull were increased more than ten-fold. Cryocrushing did not modify significantly the contents of cellulose, hemicellulose and lignin in both eucalyptus sawdust and rice hulls. However, substantial disorganization of the lignocellulosic materials in consequence of the pretreatment could be observed by electron microscopy. Cryocrushing was highly efficient in improving the saccharification of the holocellulose component of the plant biomasses (from 4.3% to 54.1% for eucalyptus sawdust and from 3.9% to 40.6% for rice hull). It is important to emphasize that it consists in a simple operation with low requirements of water and chemicals, no corrosion, no release of products such as soluble phenolics, furfural and hydroxymethylfurfural and no waste generation.