Bioaccessibility of polyphenols associated with dietary fiber and in vitro kinetics release of polyphenols in Mexican 'Ataulfo' mango (Mangifera indica L.) by-products.

The biological properties of polyphenol (PP) depend on its bioaccessibility and bioavailability. Therefore, part of PP released from the food matrix in the gastrointestinal tract through enzymatic hydrolysis is at least partially absorbed. The aim of this study is to determine the bioaccessibility of PP associated with dietary fiber (DF) and the kinetics release of PP in mango (Mangifera indica L.) 'Ataulfo' by-products by an in vitro model. Soluble and insoluble DF values were 7.99 and 18.56% in the mango paste and 6.98 and 22.78% in the mango peel, respectively. PP associated with soluble and insoluble DF was 6.0 and 3.73 g GAE per 100 g in the paste and 4.72 and 4.50 g GAE per 100 g in the peel. The bioaccessibility of PP was 38.67% in the pulp paste and 40.53% in the peel. A kinetics study shows a release rate of 2.66 and 3.27 g PP min(-1) in the paste and peel, respectively. The antioxidant capacity of the paste increased as digestion reached a value of 2.87 mmol TE min(-1) at 180 min. The antioxidant capacity of the peel had its maximum (28.94 mmol TE min(-1)) between 90 and 120 min of digestion; it started with a value of 2.58 mmol TE min(-1), and thereafter increased to 4.20 mmol TE min(-1) at 180 min. The major PPs released during the digestion of paste were gallic and hydroxybenzoic acids, while in the peel, they were hydroxycinnamic and vanillic acids. It was concluded that these phenolic compounds are readily available for absorption in the small intestine and exert different potential health benefits.

Phytosteryl sinapates and vanillates: chemoenzymatic synthesis and antioxidant capacity assessment.

Phytosterols and their derivatives have attracted much attention because of their health benefits to humans and are widely used in food, pharmaceuticals, and cosmetics in the past decades. While most of the research has focused on free phytosterols and phytosteryl esters of fatty acids, few researches reported on phytosteryl phenolates, the esters of phytosterols with phenolic acids. Two novel group phytosteryl phenolates, namely phytosteryl sinapates and vanillates, were successfully chemoenzymatically synthesised in this work and their structures confirmed. Fourier transform infrared (FTIR) and high performance chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) using atmospheric pressure chemical ionisation (APCI) under both positive and negative ion modes were employed for this purpose. High antioxidant capacity of phytosteryl sinapates was observed using both oxygen radical absorbance capacity (ORAC) assay and cooked ground meat model system. Although phytosteryl vanillates showed lower antioxidant capacity than phytosteryl sinapates, they were stronger antioxidants than vanillic acid and vinyl vanillate in both assays employed. Conjugation of phytosterols with sinapic or vanillic acid rendered higher antioxidant capacity. Further studies on health benefits of phytosteryl sinapates and vanillates are necessary.

Prediction model based on decision tree analysis for laccase mediators.

A Structure Activity Relationship (SAR) study for laccase mediator systems was performed in order to correctly classify different natural phenolic mediators. Decision tree (DT) classification models with a set of five quantum-chemical calculated molecular descriptors were used. These descriptors included redox potential (ɛ°), ionization energy (E(i)), pK(a), enthalpy of formation of radical (Δ(f)H), and OH bond dissociation energy (D(O-H)). The rationale for selecting these descriptors is derived from the laccase-mediator mechanism. To validate the DT predictions, the kinetic constants of different compounds as laccase substrates, their ability for pesticide transformation as laccase-mediators, and radical stability were experimentally determined using Coriolopsis gallica laccase and the pesticide dichlorophen. The prediction capability of the DT model based on three proposed descriptors showed a complete agreement with the obtained experimental results.

Vanillic acid as a novel specific inhibitor of snake venom 5'-nucleotidase: a pharmacological tool in evaluating the role of the enzyme in snake envenomation.

Vanillic acid has been investigated for its inhibitory effect on Naja naja, Daboia russellii, and Trimeresurus malabaricus venom 5'-nucleotidase activity. Trimeresurus malabaricus venom 5'-nucleotidase activity was 1.3- and 8.0-fold higher than that of N. naja and D. russellii venoms, respectively. Substrate specificity studies showed that for all the venoms tested, 5'-AMP was the preferred substrate for 5'-nucleotidase. This indicates the central role of adenosine in snake envenomation. Vanillic acid selectively and specifically inhibited 5'-nucleotidase activity among several enzymes present in the three venoms tested. The inhibitor was competitive, as the inhibition was relieved by increased substrate concentration. It appears that the COOH group in vanillic acid is the determining factor for inhibition as vanillin, a structurally similar compound with respect to vanillic acid, had no inhibitory activity. This study for the first time exemplifies vanillic acid as a pharmacological tool in evaluating the role of 5'-nucleotidase in snake envenomation.