This study investigated and compared the absorption, metabolism, and subsequently, the tissue distribution and excretion of hydroxytyrosol (HT) administered either in its free form or through its naturally occurring esterified precursors, namely oleuropein (OLE) and its aglycone forms known as secoiridoids (SEC). Here, rats were fed a diet supplemented with the equivalent of 5 mg phenol/kg/day for 21 days and the HT metabolites in the gastrointestinal digesta (stomach, small intestine and caecum), plasma, urine and metabolic tissues (liver and kidney) were analysed. Compared to HT and SEC, OLE showed greater stability during digestion, and, consequently, the bioavailability based on the urine excretion of HT metabolites was higher. OLE, as a glycoside molecule, reached the colon unaltered generating more diverse microbial metabolites. In terms of bioavailability, findings suggest that OLE might be the most suitable precursor of HT for incorporation into foods or nutraceutical formulations.
A recent paper published in the journal Food and Chemical Toxicology presents the results of a long-term toxicity study related to a widely-used commercial herbicide (Roundup™) and a Roundup-tolerant genetically modified variety of maize, concluding that both the herbicide and the maize varieties are toxic. Here we discuss the many errors and inaccuracies in the published article resulting in highly misleading conclusions, whose publication in the scientific literature and in the wider media has caused damage to the credibility of science and researchers in the field. We and many others have criticized the study, and in particular the manner in which the experiments were planned, implemented, analyzed, interpreted and communicated. The study appeared to sweep aside all known benchmarks of scientific good practice and, more importantly, to ignore the minimal standards of scientific and ethical conduct in particular concerning the humane treatment of experimental animals.
After the sustained consumption of virgin olive oil (VOO), the unabsorbed native phenols (mainly hydroxytyrosol (HT)) are transformed into its catabolites in the intestine by microbials. The role of these catabolites in preventing colon cancer has not been sufficiently investigated. This work aims to study the antiproliferative and apoptotic activities in colon (Caco-2; HT-29) cancer cell lines of the main catabolites detected in human feces (phenylacetic, phenylpropionic, hydroxyphenylpropionic, and dihydroxyphenylpropionic acids and catechol), after the sustained VOO intake. Additionally, an assessment of the ability of these colonic cells to metabolize the studied compounds was performed. The results showed that HT and phenylacetic and hydroxyphenylpropionic acids produce cell cycle arrest and promote apoptosis. HT-29 cells were more sensitive to phenol treatments than Caco-2. In synthesis, the results of the present study represent a good starting point for understanding the potential apoptotic and antiproliferative effects of VOO phenolic compounds and their colonic metabolites.
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