Metabolomics of heat-treated Tudela artichoke (poly)phenolic compoundsEffect of the gastrointestinal digestion and gut microbiota on their bioaccesibility and bioavailability

Resumen

Tudela artichokes (Cynara Scolymus cv. Blanca de Tudela), commonly eaten cooked, are rich in (poly)phenolic compounds, in particular caffeoylquinic acids, which can be modified by heat treatments but also by gastrointestinal digestion and human gut microbiota, affecting their bioaccessibility and further bioavailability and metabolism. Therefore, the aim of this work was to investigate how bioaccessibility of heat-treated Tudela artichoke (poly)phenols is modulated as they pass through the gastrointestinal tract and to determine their bioavailability and the metabolites produced after consumption. A total of 31 (poly)phenolic compounds were identified by HPLC-MS/MS in Tudela artichokes, with caffeoylquinic acids accounting for more than 95% of total (poly)phenols. Frying, griddling and boiling decreased the (poly)phenolic content of artichokes by a 51%, 49% and 25%, mainly due to high temperature (frying and griddling) and leaching of compounds into the water (boiling). On the contrary, microwaving maintained and sous-vide cooking even augmented the total content by a 15%. Considering these results, artichoke (poly)phenol bioaccessibility was evaluated in boiled, sous-vide cooked and microwaved artichokes as well as in raw artichokes. Heat-treated artichokes showed a higher (poly)phenol bioaccessibility (>38%) than raw samples (1.6%) after gastrointestinal digestion. It seems that heat treatment exerted a positive effect on artichoke (poly)phenols. Sous-vide and boiled artichoke (poly)phenols presented similar bioaccessibility (59%), probably due to the similar heating mechanism (boiling water), but it was higher than in microwaved artichokes (38%). After in vitro fecal fermentation, similar profiles of (poly)phenol degradation and formation were described in the different samples, suggesting that heat treatments do not have much influence in the colonic catabolism of (poly)phenols. According to the amounts of the 11 newly formed colonic catabolites, a major pathway was proposed with 3-phenylpropanoic acid and phenylacetic acid as the main end-products at 48 h. With the aim of investigating the bioavailability and metabolism of dietary (poly)phenols, a high throughput targeted UHPLC-MS/MS method using authentic standards was validated for the identification and quantification of more than 100 (poly)phenol metabolites in plasma and urine. The method was fast (16 min single run), sensitive (LOQ 26 nM in urine and 7.2 nM in plasma), precise and accurate, and showed good linearity for all compounds. Thus, it was suitable for the analysis of plasma and urine samples of healthy participants after consumption of sous-vide artichokes (5776 µmol of (poly)phenols). Artichoke metabolites found in plasma and urine of participants included acyl-quinic acids and metabolites: cinnamic acids, benzoic acids, phenylacetic acids, propanoic acids, hippuric acids, benzene diols and triols and benzaldehydes, as well as their phase II metabolites. Late-absorbed compounds (Tmax &#8805; 6 h) were the major ones excreted in urine, particularly dihydroferulic acid-4&#697;-glucuronide, dihydroferulic acid, dihydroisoferulic acid-3&#697;-glucuronide, 3-(3&#697;-hydroxyphenyl)propanoic acid, hippuric and 3&#697;-hydroxyhippuric acid. From the early absorbed ones (Tmax < 4 h), ferulic acid, ferulic acid-4&#697;-sulfate, and caffeic acid-3&#697;-sulfate were the most abundant excreted. The 24 h urinary recovery with respect to the amount of (poly)phenols consumed was 9%.