Pascal Dubé

Modulation of Strawberry/Cranberry Phenolic Compounds Glucuronidation by Co-Supplementation with Onion: Characterization of Phenolic Metabolites in Rat Plasma Using an Optimized μSPE–UHPLC-MS/MS Method

Plant phenolic compounds are suggested to exert pharmacological activities in regards to obesity and type-2 diabetes, but their mode of action is poorly understood due to a lack of information about their bioavailability. This work aimed to study the bioavailability of GlucoPhenol phenolic compounds, a strawberry-cranberry extracts blend, by characterizing plasma phenolic profile in obese rats. A comparison was performed by co-supplementation with an onion extract. Using an optimized μSPE-UHPLC-MS/MS method, 21 phenolic metabolites were characterized, mostly conjugated metabolites and microbial degradation products of the native phenolic compounds. Their kinetic profiles revealed either an intestinal or hepatic formation. Among identified metabolites, isorhamnetin glucuronide sulfate was found in greater amount in plasma. Three glucuronidated conjugates of strawberry-cranberry phenolic compounds, p-hydroxybenzoic acid glucuronide, catechins glucuronide, and methyl catechins glucuronide were found in higher quantities when GlucoPhenol was ingested together with onion extract (+252%, +279%, and +118% respectively), suggesting a possible induction of glucuronidation processes by quercetin. This work allowed the characterization of actual phenolic metabolites generated in vivo following a phenolic intake, the analysis of their kinetics and suggested a possible synergistic activity of phenolic compounds for improving bioavailability.

Comprehensive phenolic composition analysis and evaluation of Yak-Kong soybean (Glycine max) for the prevention of atherosclerosis

Yak-Kong (YK) (Glycine max), a small black soybean cultivar with a green embryo, was evaluated for functional constituents with a focus on atherosclerosis prevention. In comparison to common yellow and black soybean cultivars, YK contains significantly higher concentrations of antioxidants, particularly in its seed coat. A comprehensive phenolic composition analysis revealed that proanthocyanidins were the major phenolic group in YK. In contrast to other proanthocyanidin-rich foods, YK was rich in bioavailable proanthocyanidins (with a degree of polymerization ≤3) specifically with A-type dimers. Significant concentrations of phloridzin and coumestrol were also exclusively found in YK seed coat and the embryo, respectively. Extracts of both the proanthocyanidin-rich seed coat and isoflavonoid-rich embryo of YK attenuated adhesion of THP-1 to LPS-stimulated human umbilical vascular endothelial cells, suggesting that they are important sources of coronary heart disease-preventive phenolics. YK has promising potential for further development as a functional food source targeted at atherosclerosis prevention.

The high content of β-carotene present in orange-pulp fruits of Carica papaya L. is not correlated with a high expression of the CpLCY-β2 gene

We investigated the transcriptional regulation of six genes involved in carotenoid biosynthesis, together with the carotenoid accumulation during postharvest ripening of three different papaya genotypes of contrasting pulp color. Red-pulp genotype (RPG) showed the lowest content of yellow pigments (YP), such as β-cryptoxanthin, zeaxanthin, and violaxanthin, together with the lowest relative expression levels (REL) of CpLCY-β2 and CpCHX-β genes. On the contrary, the yellow-pulp genotype (YPG) showed the highest content of YP and the highest REL of CpLCY-β2 and CpCHX-β genes. Interestingly, the orange-pulp genotype (OPG) showed intermediate content of YP and intermediate REL of CpLCY-β2 and CpCHX-β genes. The highest content of β-carotene shown by OPG despite having an intermediate REL of the CpLCY-β2 genes, suggests a post-transcriptional regulation. Thus, the transcriptional level of the genes, directing the carotenoid biosynthesis pathway, can partially explain the accumulation of carotenoids during the postharvest ripening in C. papaya genotypes of contrasting pulp color.

Persistent negative temperature response of mesophyll conductance in red raspberry (Rubus idaeus L.) leaves under both high and low vapour pressure deficits: A role for abscisic acid?: Persistent negative temperature response of mesophyll conductance in red raspberry (Rubus idaeus L.) leaves under both high and low vapour pressure de

The temperature dependence of mesophyll conductance (gm) was measured in well-watered red raspberry (Rubus idaeus L.) plants acclimated to leaf-to-air vapour pressure deficit (VPDL) daytime differentials of contrasting amplitude, keeping a fixed diurnal leaf temperature (Tleaf) rise from 20°C to 35°C. Contrary to the great majority of gm temperature responses published to date, we found a pronounced reduction of gm with increasing Tleaf irrespective of leaf chamber O2 level and diurnal VPDL regime. Leaf hydraulic conductance was greatly enhanced during the warmer afternoon periods under both low (0.75 to 1.5 kPa) and high (0.75 to 3.5 kPa) diurnal VPDL regimes, unlike stomatal conductance (gs), which decreased in the afternoon. Consequently the leaf water status remained largely isohydric throughout the day, and therefore cannot be evoked to explain the diurnal decrease of gm. However, the concerted diurnal reductions of gm and gs were well correlated with increases in leaf abscisic acid (ABA) content, thus suggesting that ABA can induce a significant depression of gm under favourable leaf water status. Our results challenge the view that the temperature dependence of gm can be explained solely from dynamic leaf anatomical adjustments and/or from the known thermodynamic properties of aqueous solutions and lipid membranes.

Liver and plasma lipid changes induced by cyclic fatty acid monomers from heated vegetable oil in the rat

Abstract Cyclic fatty acid monomers (CFAM) generated through domestic or industrial heating of vegetable oils may alter liver enzymes and induce hepatomegaly and steatosis, but the underlying mechanisms are not clearly understood. This study aimed to assess the effects of CFAM on liver and plasma lipids and to determine whether these effects are modulated by dietary lipids. Thirty‐six (36) male Wistar rats were fed either of the four isoenergetic diets consisting of canola oil or soybean oil with/without 500 mg/100 g CFAM of total fat for 28 days. Rats fed CFAM had higher liver total lipids (p = 0.03) and triacylglycerols (TAG) (p = 0.02), but less hepatic phosphatidylcholine (p = 0.02) compared to those fed the non‐CFAM diets. CFAM did not alter liver phosphatidylethanolamine N‐methyltransferase (PEMT) activity and CTP: phosphocholine cytidylyltransferase (CT‐α) protein levels. Rats fed CFAM diets had higher levels of plasma total cholesterol (TC), VLDL + LDL cholesterol, higher ratio of TC to HDL cholesterol, and lower levels of HDL cholesterol compared with rats fed non‐CFAM diets (p < 0.05). Plasma alanine transaminase (ALT) was decreased with CFAM, but plasma insulin, glucose, and TAG did not vary among the four diet groups (p < 0.05). Rats fed canola oil and CFAM had higher plasma levels of aspartate transaminase (AST) and AST/ALT ratio compared with the other three diet groups. These results indicate that CFAM may provoke an accumulation of TAG in the liver related to a decrease in phosphatidylcholine (PC) levels, but the effect of CFAM on PC concentrations may not occur through impairment of the two main PC biosynthesis pathways.