Procyanidin B4

Catechol-Type Flavonoids from the Branches of Elaeagnus glabra f. oxyphylla Exert Antioxidant Activity and an Inhibitory Effect on Amyloid-beta Aggregation.[Pubmed:33114256]

Molecules. 2020 Oct 23;25(21). pii: molecules25214917.

Elaeagnus glabra f. oxyphylla (Elaeagnaceae) is a small evergreen tree with narrow lanceolate leaves that is native to Korea. In this work, we studied the chemical composition of E. glabra f. oxyphylla branches (EGFOB) for the first time. Additionally, we evaluated the effects of the ethanol extract of EGFOB and each of its chemical components on key mediators of Alzheimer's disease (AD), namely, amyloid-beta (Abeta) aggregation and oxidative stress. The ethanol extract of EGFOB decreased Abeta aggregation (IC50 = 32.01 microg/mL) and the levels of the oxidative free radicals 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 = 11.35 and 12.32 microg/mL, respectively). Sixteen compounds were isolated from EGFOB. Among them, procyanidin B3 (8), Procyanidin B4 (9), and helichrysoside (13) significantly inhibited Abeta aggregation (IC50 = 14.59, 32.64, and 44.45 muM, respectively), indicating their potential as bioactive compounds to control Abeta aggregation. Furthermore, these compounds markedly enhanced in vitro scavenging activity against ABTS (IC50 = 3.21-4.61 microM). In the DPPH test, they showed lower scavenging activity than in the ABTS test (IC50 >/= 54.88 microM). Thus, these results suggest that EGFOB and specifically compounds 8, 9, and 13 may be beneficial in AD prevention and treatment through their antioxidant and anti-Abeta aggregation activities.

Interaction of polyphenols with model membranes: Putative implications to mouthfeel perception.[Pubmed:31785236]

Biochim Biophys Acta Biomembr. 2020 Feb 1;1862(2):183133.

Food polyphenols in fruits juices, tea, coffee, wine and beer confer sensory properties such as colour, astringency and bitterness. The development of functional healthy drinks without the unpleasant sensory feeling is boosting research for a clearer understanding on the interactions of polyphenols within the oral mucosa. In this study we investigated the interaction of astringent polyphenols, namely ECG, EGCG, Procyanidin B4 and PGG, with lipids in model membranes by spectroscopic techniques. The membrane model was built varying the cholesterol content to mimic mouth regions and experiments were conducted at pH 5 to mimic the pH drop at the moment of beverage (e.g. green tea, red wine) intake. Fluorescence quenching results conducted on LUVs with cholesterol molar fractions ranging between 0.34 < chichol < 0.74 and similar size distributions (122.9 +/- 3.7 nm) showed that interaction of polyphenols is structure- and concentration-dependent. Also, the decrease of partition constants (Kp) with increasing cholesterol content (chichol) suggest that the affinity of polyphenols is weaker in cholesterol-rich liposomes. STD results revealed that the interaction of EGCG and PGG with membrane lipids involved mainly galloyl residues. Overall, spectroscopic data show that polyphenols interact to higher extent with more polar regions found in buccal, flour of the mouth and gingiva regions than with more hydrophobic regions located in the palate and tongue supporting that lipid microenvironments play a role in oral sensory perception.

Flavan-3-ols Content in Red Raspberry Leaves Increases under Blue Led-Light Irradiation.[Pubmed:30901937]

Metabolites. 2019 Mar 21;9(3). pii: metabo9030056.

Berry fruits are well known to contain large amounts of polyphenol compounds. Among them, flavan-3-ol derivatives are a group of secondary metabolism compounds currently attracting a great deal of attention owing to their health benefits. Not only the fruits, but also the leaves of raspberry plants, are highly esteemed for tea making around the world and are largely used for food. In this report, we discuss the results of our study on the effect of light and temperature on polyphenol accumulation in raspberry leaves. When raspberry was cultivated in a plant factory unit and light intensity, wavelength, and temperature were varied, the amount of total polyphenol increased under blue light. Quantitative determination of (+)-catechin, ((-))-epicatechin, Procyanidin B4, flavan-3-ol trimer, which are flavan-3-ol derivatives, was carried out using HPLC, whereby we confirmed their increase under blue light. Semi-quantitative RT-PCR showed correlation between chalcone synthase (CHS) gene expression and the amounts of the compounds measured in the leaves.

Lotus seed skin proanthocyanidin extract exhibits potent antioxidant property via activation of the Nrf2-ARE pathway.[Pubmed:30544155]

Acta Biochim Biophys Sin (Shanghai). 2019 Jan 1;51(1):31-40.

Lotus seed is well known as traditional food and medicine, but its skin is usually discarded. Recent studies have shown that lotus seed skin contains a high concentration of proanthocyanidins that have multi-functions, such as antioxidation, anti-inflammation, and anti-cancer effects. In the present study, we aimed to isolate and purify the proanthocyanidins from lotus seed skin by acetone extraction and rotary evaporation, identify their chemical structures by HPLC-MS-MS and NMR, and further investigate the antioxidant properties of the extract purified by macroporous resin (PMR) from lotus seed skin both in vitro and in vivo. The results showed that PMR mainly contained oligomeric proanthocyanidins, especially dimeric procyanidin B1 (PB1), procyanidin B2 and Procyanidin B4. Although it had limited ability to directly scavenge radicals in vitro, PMR could significantly enhance the expressions of antioxidant proteins via activation of nuclear factor-E2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway in HepG2 cells. Molecular data revealed that PB1, a major component in PMR, stabilized Nrf2 by inhibiting the ubiquitination of Nrf2, which led to subsequent activation of the Nrf2-ARE pathway, including the enhancements of Nrf2 nuclear translocation, Nrf2-ARE binding and ARE transcriptional activity. Moreover, the in vivo results in high fat diet-induced mice further verified the powerful antioxidant property of PMR. These results revealed that lotus seed skin is a promising resource for functional food development.

Comparison of compounds of three Rubus species and their antioxidant activity.[Pubmed:26781923]

Drug Discov Ther. 2015 Dec;9(6):391-6.

Rubus amabilis, Rubus niveus Thunb., and Rubus sachalinensis are three Rubus species that are alternatively found in Manubzhithang, a Tibetan medicine, in different areas of China. The current study analyzed HPLC/UV chromatograms and it compared compounds of these three Rubus species in contrast to reference substances such as 2,6-dimethoxy-4-hydroxyphenol-1-O-beta-D-glucopyranoside, Procyanidin B4, and isovitexin-7-O-glucoside. The three Rubus species produced similar peaks in chromatograms. The antioxidant activity of the three Rubus species was determined using an assay for DPPH free radical scavenging activity. Results indicated that the three Rubus species extracts had almost the same level of free radical scavenging activity. Thus, findings indicated the rationality of substituting these species for one another as an ingredient in Manubzhithang.