Bioaccessibility of phenolic compounds in Psidium guajava L. varieties and P. friedrichsthalianum Nied. after gastrointestinal digestion.

Psidium guajava L. and Psidium friedrichsthalianum Nied are part of the Psidium species native to America. Nowadays, it is essential to study the phenolic compound (PC) profile and their changes during digestion and the fractions available for absorption. This study aimed to characterize the PC profile in some Psidium species and their bioaccessibility (BA). Fifty-seven compounds were identified, and forty-six belonged to ten different phenolic classes. PC profiles showed significant differences between the species and the intestinal fraction P. friedrichsthalianum Nied. showed the highest PC content, although it mostly belonged to non-extractable polyphenols. This leads to the lowest BA (37%); P. guajava L. 'Morada' showed the highest (47%). Hydroxycinnamic acids were the most stable PC after gastrointestinal digestion. This study showed relevant differences in the PC content and profile of different Psidium species and changes between the PC in the original matrix and those released in the different stages of gastrointestinal digestion.

A macroporous resin purification process to obtain food-grade phlorotannin-rich extracts with α-glucosidase inhibitory activity from Chilean brown seaweeds: An UHPLC-MSn profiling.

An efficient macroporous resin purification process was designed to obtain food-grade phlorotannin-rich extracts from the seaweeds Durvillaea incurvata and Lessonia spicata. Phlorotannins were profiled to relate structures with the α-glucosidase inhibitory activity of the extracts. Liquid chromatography-mass spectrometry was applied for tentative identification. The best phlorotannin purification performance was achieved with HP-20 resin and elution with 80% v/v ethanol. This is the first study that demonstrates the effectivity of HP-20 resin for removing potentially toxic elements (As, Cd) from seaweed extracts. Fucols/phlorethols/fucophlorethols isomers up to 4 phloroglucinol units (PGU) were the most representative phlorotannins. High molecular weight species (11-21 PGU), although in low abundances, were detected in D. incurvata for the first time. Eckols, carmalols, fuhalols, phenolic acids, and flavonoids were also detected. Some extracts' potent α-glucosidase inhibitory activities were related to their high phlorotannin abundances, the presence of phlorotannins of a high degree of polymerization, and the phlorotannins class.

Study of the impact of a dynamic in vitro model of the colon (TIM-2) in the phenolic composition of two Mexican sauces.

Husk tomato (Physalis ixocarpa Brot. ex. Horm) is mainly used in the preparation of many Mexican sauces due to its unique and slightly acidic flavor, both in raw and cooked forms. These sauces also usually contain Serrano hot pepper (Capsicum annuum L), onion (Allium cepa L.), garlic (Allium sativum L.), coriander (Coriandrum sativum L.) and salt. Mexican sauces are a pre-Hispanic staple food, yet there is scarce knowledge on the phenolic compounds (PC) that reach the colon bound to the indigestible fraction (IF) after intestinal digestion. Thus, the aim of the present work was to evaluate the indigestible fraction of two types of Mexican sauces made with cooked and raw husk tomato: cooked green sauce (CGS) and raw green sauce (RGS). IF of CGS and RGS were fermented in the in vitro model of the human colon (TIM-2) to investigate the PC bioconversion by the gut microbiota after 24, 48 and 72 h. PC of the original sauces and their predigested fractions, as well as the formed metabolites were identified and monitored by HPLC-ESI-QToF-MS. Cooking husk tomato significantly increased the total indigestible fraction (TIF), mainly due to its insoluble indigestible fraction (IIF), and diminished PC. Flavonoids (flavonols and flavones) were the most abundant phenolic group in digested sauces followed by capsaicinoids (a characteristic group derived from hot pepper), hydroxycinnamic acids, and hydroxybenzoic acids. The metabolites 3-(ρ-hydroxyphenyl) propionic acid, 3-(3-hydroxyphenyl) propionic acid and 4-hydroxyphenylacetic acid were the most abundant colonic metabolites identified, which are thought to be derived from the biotransformation of flavonoids and hydroxycinnamates. These results are the first obtained on in vitro colonic fermentation of Mexican sauces and should be considered in future studies on the health effects related to consuming this staple food.

Improved LC-MSn characterization of hydroxycinnamic acid derivatives and flavonols in different commercial mate (Ilex paraguariensis) brands. Quantification of polyphenols, methylxanthines, and antioxidant activity.

Yerba mate is a beverage rich in bioactive compounds popular in South America. Polyphenols and methylxanthines were qualitatively and quantitatively analyzed in four commercial brands of yerba mate, as well as the antioxidant capacity of the beverages. Using LC/MSn analysis, 58 polyphenols were observed of which 4-sinapoylquinic acid, di- and tri-methoxycinnamoylquinic acids, two isomers of trimethoxycinnamoylshikimic acid and four isomers of caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosonic acid were identified for the first time in mate. Additionally, 46 polyphenols and 2 methylxanthines were quantified by HPLC-DAD. Hydroxycinnamic acid derivatives and flavonols comprised 90% and 10% of mate phenols, respectively, 3-caffeoylquinic (26.8-28.8%), 5-caffeoylquinic (21.1-22.4%), 4-caffeoylquinic (12.6-14.2%) and 3,5-dicaffeoylquinic acids (9.5-11.3%) along with rutin (7.1-7.8%) were the most abundant polyphenols, whereas caffeine was the main methylxanthine (90%). Ilex paraguariensis is an important source of polyphenols with moderate methylxanthines content; therefore its high antioxidant capacity was mainly associated to its polyphenolic composition.

Effects of consuming diets containing Agave tequilana dietary fibre and jamaica calyces on body weight gain and redox status in hypercholesterolemic rats.

Dietary fibre (DF) obtained from Agave tequilana, which is rich in fructans and insoluble DF, and jamaica calyces (Hibiscus sabdariffa), which is rich in DF and phenolic compounds, were assessed as new potential functional ingredients using the hypercholesterolemic animal model. Wistar rats (200-250 g) were divided into 3 groups (n=8) and fed with cholesterol-rich diets supplemented with cellulose (CC, control), agave DF (ADF) or ADF with jamaica calyces (ADF-JC). After consuming the test diets for 5 weeks, weight gain in the ADF-JC group was significantly lower than in the other groups. The ADF and ADF-JC groups had a reduced concentration of cholesterol transporters in the caecum tissue, although no changes were observed in the plasma lipid profile. Both treatments improved the redox status by reducing the malondialdehyde serum levels and protein oxidative damage, compared to the CC group. DF from A. tequilana alone, or in combination with jamaica calyces, shows promising potential as a bioactive ingredient.