Epigenetic modulation of mechanisms involved in inflammation: Influence of selected polyphenolic substances on histone acetylation state

In the present study, we have investigated the influence of low concentrations of polyphenols (5 μM) on histone acetyltransferase (HAT) and histone deacetylase (HDAC) activity, a monocyte cell system related to the inflammatory process. We selected gallic acid, ellagic acid, oenothein B, valoneic acid dilactone and penta-O-galloyl-β-d-glucose, which are known to affect inflammatory responses, such as IL-6 secretion and/or NF-κB down-regulation and polyphenol metabolites (urolithins A, B and C). TNF-α stimulation resulted in a reduction of THP-1 cell viability by 28.9%, reduced HDAC activity from 25.2 to 13.5 pmol/μg protein and increased HAT activity from 24.0 to 45.5 pmol/μg protein. The coincubation with ellagic acid and oenothein B restored the viability and reversed the effect of TNF-α on HAT and HDAC activities. Urolithins B and C, gallic acid and penta-O-galloyl-β-d-glucose only showed significant reductions of HAT activity, by 40-50%. Our results prove that polyphenols act as epigenetic modulators.     

Changes of porcine pancreas α‐amylase in activity and secondary conformations under inhibition of tea polyphenols

To investigate two‐sided functions of tea polyphenols (TP) in antinutrition and energy balance modulation, TP were extracted from Chinese green tea and used to complex porcine pancreas α‐amylase (PPA). Changes of PPA in activity and secondary conformations were analysed. Porcine pancreas α‐amylase was found sensitive to TP treatment. Tea polyphenols exhibited IC₅₀ at 0.41 mg mL^?1 against PPA and maximum inhibitory rate (98.17%) at 3.0 mg mL^?1. Tea polyphenols inhibition was concluded as noncompetitive pattern based on its unchanged Km value (0.98 mg mL^?1) for soluble starch substrate. Tea polyphenols inhibition arose from pH 1.5 to 10.14, covering gastric and intestinal environments inside body. Circular dichroism spectra analysis revealed regular changes of PPA in secondary conformations (increased proportions of α‐helix and β‐sheet) prior to its inactivation at low TP concentrations. Tea polyphenols‐inhibited PPA had distinct double‐negative peaks at 204 nm and 208 nm. Porcine pancreas α‐amylase was inactivated by TP in ways of complexation and modification of secondary conformations.     

Nonextractable polyphenols,usually ignored,are the major part of dietary polyphenols: A study on the Spanish diet

Scope: Dietary polyphenols (PP) can be divided into two groups: extractable polyphenols (EPP) or compounds solubilized by aqueous organic solvents, and nonextractable polyphenols (NEPP) or compounds that remain in their corresponding extraction residues. Most studies on food polyphenols and dietary intakes address exclusively EPP. The objective of this work was to determine the actual amount of PP, including NEPP, in food and in a whole diet. Methods and results: HPLC‐MS analyses were performed to identify EPP in methanol–acetone extracts and NEPP in the acidic hydrolyzates of their extraction residues in cereals, fruits, vegetables, nuts, and legumes. NEPP contents, estimated as hydrolyzable PP plus nonextractable proanthocyanidins (PA), ranged from 880 mg/100 g dry weight in fruits to 210 mg/100 g in cereals and were substantially higher than the contents of EPP. NEPP intake (day/person) in the Spanish diet (942 mg) is higher than EPP intake (258 mg) fruits and vegetables (746 mg) are the major contributors to the total PP intake (1201 mg). Conclusion: Non extractable polyphenols are the major part of dietary polyphenols. The knowledge of intakes and physiological properties of NEPP may be useful for a better understanding of the potential health effects of dietary PP.     

白藜芦醇对SIRT1的调节作用及SIRT家族对代谢综合征的防治意义

代谢综合征是由一系列代谢紊乱所导致的心血管疾病和Ⅱ型糖尿病等疾病的统称,是饮食紊乱和不正确的生活方式所造成的。随着人们年龄的增长发病率逐渐升高,并且在全球呈现流行趋势。二氢尿嘧啶脱氢酶(NAD+)依赖的SIRT家族调节细胞和器官的代谢,对代谢综合征具有明显的调节作用。本文重点从分子水平阐述白藜芦醇介导的SIRT1,以及SIRT家族其他成员对代谢的调节作用,为开发白藜芦醇类的功能性食品提供科学依据。SIRT家族的乙酰化调节也为由于代谢和饮食紊乱所导致的代谢综合征和癌症治疗方法的发展提供新的途径。