Procyanidin A2 Research Articles

Non-targeted Metabolomic Analysis Based on Ultra-High-Performance Liquid Chromatography Quadrupole Time-of-Flight Tandem Mass Spectrometry Reveals the Effects of Grafting on Non-volatile Metabolites in Fresh Tea Leaves ( Camellia sinensis L.).

To investigate the effects of grafting on non-volatile metabolites in tea, non-targeted metabolomic analyses of fresh leaves were performed on the basis of ultra-high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF/MS). One non-grafted YingHong No. 9 and four grafted tea [grafting scion YingHong No. 9 on four different rootstocks, BaiMao No. 2 (BM2), BaiYeDanCong (BY), HeiYeShuiXian (HY), and WuLingHong (WLH)] were chosen as materials. In total, 32 differential metabolites were identified, including phenolic acids, flavan-3-ols, dimeric catechins, flavonol and flavonol/flavone glycosides, etc. Partial least squares discrimination analysis and hierarchical cluster analysis showed various effects of different rootstocks on metabolites. Thereinto, rootstocks of WLH and BY showed extremely outstanding performance in up- and downregulating these metabolites, respectively. Differential metabolites were enriched into three crucial pathways, including biosynthesis of phenylpropanoids, flavonoid biosynthesis, and flavone and flavonol biosynthesis, which might influence the quality of tea. This study provides a theoretical basis for grafting-related variations of non-volatile metabolites in fresh tea leaves.

VvLAR1 and VvLAR2 Are Bifunctional Enzymes for Proanthocyanidin Biosynthesis in Grapevine.

Proanthocyanidins (PAs) in grapevine (Vitis vinifera) are found mainly in berries, and their content and degree of polymerization are important for the mouth feel of red wine. However, the mechanism of PA polymerization in grapevine remains unclear. Previous studies in the model legume Medicago truncatula showed that 4β-(S-cysteinyl)-epicatechin (Cys-EC) is an epicatechin-type extension unit for nonenzymatic PA polymerization, and that leucoanthocyanidin reductase (LAR) converts Cys-EC into epicatechin starter unit to control PA extension. Grapevine possesses two LAR genes, but their functions are not clear. Here, we show that both Cys-EC and 4β-(S-cysteinyl)-catechin (Cys-C) are present in grapevine. Recombinant VvLAR1 and VvLAR2 convert Cys-C and Cys-EC into (+)-catechin and (-)-epicatechin, respectively, in vitro. The kinetic parameters of VvLARs are similar, with both enzymes being more efficient with Cys-C than with Cys-EC, the 2,3-cis conformation of which results in steric hindrance in the active site. Both VvLARs also produce (+)-catechin from leucocyanidin, and an inactive VvLAR2 allele reported previously is the result of a single amino acid mutation in the N terminus critical for all NADPH-dependent activities of the enzyme. VvLAR1 or VvLAR2 complement the M. truncatula lar:ldox double mutant that also lacks the leucoanthocyanidin dioxygenase (LDOX) required for epicatechin starter unit formation, resulting in increased soluble PA levels, decreased insoluble PA levels, and reduced levels of Cys-C and Cys-EC when compared to the double mutant, and the appearance of catechin, epicatechin, and PA dimers characteristic of the ldox single mutant in young pods. These data advance our knowledge of PA building blocks and LAR function and provide targets for grapevine breeding to alter PA composition.

Cellular evaluation of the antioxidant activity of U.S. Pecans [Carya illinoinensis (Wangenh.) K. Koch

Clinical trials show an inverse relationship between the consumption of antioxidant-rich tree nuts and the development of chronic diseases. This study examined antioxidant efficacy of U.S. pecans using a modified cellular antioxidant activity (CAA) assay with comparisons to data from in vitro antioxidant assays (hydrophilic-oxygen radical absorbance capacity {H-ORACFL} and ferric reducing antioxidant power {FRAP}). Crude phenolic extracts from both raw and roasted pecans were analyzed. In the CAA assay, pecan phenolics were taken up by human colorectal adenocarcinoma (Caco-2) cells and bestowed CAA, determined by monitoring the fluorescence of 2′,7′-dichlorofluorescein. Phenolics (25–100 μg/mL) demonstrated a reduction in fluorescence by 37–69% for raw and 26–68% for roasted pecans. The primary active phenolic constituents were determined by high-performance liquid chromatography–electrospray ionization–mass spectrometry (HPLC–ESI–MS) to be epi(catechin) dimers and trimers. These oligomeric procyanidins, ranging in size from 560 to 840 g/mol appear to be small enough for cellular uptake, showing pecans are an effective antioxidant in biological systems, regardless of roasting.

Litchi (Litchi chinensis Sonn.) flower proanthocyanidin fraction exhibited protective efficacy to suppress nickel-induced expression for vascular endothelial growth factor in HepG2 cells.

The protective efficacy of litchi (Litchi chinensis Sonn.) flower proanthocyanidin fraction (LFPF) composed of (-)-epicatechin and proanthocyanidin A2 against vascular endothelial growth factor (VEGF) generation induced by nickel (Ni) in hepatocellular carcinoma (Hep G2) cells was studied. VEGF is an angiogenic inducer, which promotes tumor angiogenesis, leading to rapid tumor growth and metastasis. VEGF could be substantially induced in the Ni-mediated Hep G2 cells. Through LFPF treatment, the Ni-induced VEGF generation could be suppressed significantly. The inhibition of HIF-1α expression by blocking phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathways, and the suppression of Janus kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT 3), and Raf-1 proto-oncogene, serine/threonine kinase (RAF1)/mitogen-activated protein kinase (MEK1/2)/extracellular-signal-regulated kinase (ERK1/2) pathways are important molecular mechanisms for the LFPF action. LFPF should probably reduce the risk of liver cancer in Ni-contaminated environments by inhibiting VEGF expression. PRACTICAL APPLICATIONS: LFPF mainly contained (-)-epicatechin and proanthocyanidin A2. Our results demonstrated that LFPF considerably suppressed the Ni-induced VEGF expression through inhibition of JAK2/STAT 3 and RAF1/MEK1/2/ERK1/2 pathways and prohibited HIF-1α expression through blocking PI3K/AKT/mTOR pathway. Litchi flowers might have the potential to diminish the liver cancer risk in a Ni-contaminated environment through suitable treatment.

Evaluation of the Degree of Polymerization of the Proanthocyanidins in Cranberry by Molecular Sieving and Characterization of the Low Molecular Weight Fractions by UHPLC-Orbitrap Mass Spectrometry.

4-dimethylammino-cinnamaldehyde (DMAC) assays quantify total proanthocyanidins (PACs) but do not provide qualitative PAC molecular weight distribution information and cannot discriminate between A- and B-type PACs. We developed an efficient method for assessing PAC molecular weight distributions. The PACs from three commercial cranberry extracts (A1–A3) were fractionated by molecular sieves with cut-offs of 3, 10, 30, 50, and 100 kDa, and each fraction was analyzed by DMAC assays. A1, A2, and A3 contained 27%, 33%, and 15% PACs, respectively. Approximately 28 PACs, 20 flavonols, and 15 phenolic acids were identified by UHPLC-DAD-Orbitrap MS in A1 and A3, while A2 contained only flavan-3-ols. Epicatechin was the main monomer in A1 and A3, and catechin was the main in A2. Procyanidin A2 was the main dimer in A1 and A3, representing more than 85% of the total dimers, while it constituted approximately only 24% of A2. A1 and A3 contained quercetin, isorhamnetin, myricetin, and their glycosides, which were totally absent in A2. In A1 and A3 the PACs were mainly distributed in the fractions 30–3 and <3 kDa, while in A2 more than 70% were present in the fraction less than 3 kDa. Overall, obtained data strongly suggests that A2 is not cranberry-derived, or is adulterated with another source of PACs.

Effects of simulated digestion on the phenolic composition and antioxidant activity of different cultivars of lychee pericarp

BackgroundLychee pericarp is rich in phenolic and has good antioxidant activity. The effects of simulated gastric (SGF) and intestinal fluid (SIF) digestion on the contents, composition, and antioxidant activities of the phenolic substances in the pericarp of different lychee cultivars (cv Jizui, Lizhiwang, Guiwei, Yuhe, Nuomici and Guihong) were investigated.ResultsCompared with distilled water (DW) treatment, the total phenolic content (TPC) and total flavonoid content (TFC) in the pericarp of different lychee cultivars decreased after SGF digestion; especially, the TFC in “Lizhiwang” decreased by 41.5%. The TPC and TFC of lychee pericarp also decreased after SIF digestion. However, the TPC in “Jizui”, “Guiwei” and “Yuhe” increased. The SGF and SIF also had different effects on the FRAP and ABTS antioxidant activities of different lychee cultivars. The SGF digestion decreased the ABTS antioxidant capacity of lychee pericarp but enhanced the FRAP value of some lychee cultivars. However, the SIF digestion decreased the FRAP antioxidant activity of different lychee cultivar pericarps but enhanced the ABTS antioxidant capacity of lychee. The HPLC results showed that lychee pericarp had relatively high contents of procyanidin B2 and procyanidin A2. After SIF digestion, caffeic acid and isoquercitrin could not be detected in any of the lychee varieties. However, quercetin-3-rutinose-7-rhamnoside and isoquercitrin were increased after SGF digestion.ConclusionsLychee pericarp could be used as an inexpensive functional food ingredient.

Transport of Flavanolic Monomers and Procyanidin Dimer A2 across Human Adenocarcinoma Stomach Cells (MKN-28).

It has been proven that A-type procyanidins, containing an additional ether bond, compared to B-type procyanidins are also bioavailable in vitro and in vivo. However, their bioavailability and absorption in the gastrointestinal tract remain uncertain. In this study, a model of the human adenocarcinoma stomach cell line (MKN-28) was established to explore the cellular transport of flavanolic monomers and procyanidin dimer A2, which were isolated from the litchi pericarp extract. After the integrity and permeability of the cell monolayer were ensured by measurement of the transepithelial electrical resistance and the apparent permeability coefficient for Lucifer yellow, the transportation of procyanidins A2 and B2, (-)-epicatechin (EC), and (+)-catechin (CC) was studied at pH 3.0, 5.0, or 7.0 in the apical side, with compound concentrations of 0.05 and 0.1 mg/mL based on the cytotoxicity test. High-performance liquid chromatography and liquid chromatography-mass spectrometry analyses indicated that EC, CC, and A2 were transported in the MKN-28 cell line from 30 to 180 min, while B2 showed no transport. The maximal transport efficiencies of EC, CC, and A2 were 23 ± 0.81, 13.16 ± 1.53, and 16.41 ± 1.36%, respectively, existing at 120, 180, and 120 min of transportation. Laser scanning confocal microscopy analysis presented the dynamic transmission of EC, in accordance with the result of concentration determination, suggesting that the A-type procyanidins are possibly absorbed through the stomach barrier, which is pH- and time-dependent.

Guaraná (Paullinia cupana) catechins and procyanidins: Gastrointestinal/colonic bioaccessibility, Caco-2 cell permeability and the impact of macronutrients

Abstract Guarana (Paullinia cupana) seeds are rich in flavan-3-ols (catechins) and reduce oxidative stress in humans. We determined the concentration and in vitro bioaccessibility of catechins in guarana seeds from two geographical origins, and measured their Caco-2 permeability. The effect of macronutrients on catechins’ bioaccessibility and Caco-2 permeability was also evaluated. Guarana seeds from southern Bahia and Maues contained, respectively, 30.0 and 26.8 mg catechin/g, 20.2 and 20.0 mg epicatechin/g, 3.7 and 3.8 mg procyanidin B1/g, and 3.3 and 4.9 mg procyanidin B2/g. Bioaccessibility ranged between 65 and 95% for catechin monomers and 50–140% for dimers. Casein inhibited bioaccessibility of catechin dimers, while vegetable oil improved bioaccessibility of total procyanidins. Guarana catechin monomers and dimers were able to permeate through Caco-2 cell monolayers (Papp 0.31–0.35 × 10−6 cm/s) without effect from co-digested macronutrients. Guarana seeds are a source of highly bioaccessible catechins, which can permeate the intestinal epithelium with negligible effect from macronutrients.

New insights into antioxidant activity of Prunus spinosa flowers: Extracts, model polyphenols and their phenolic metabolites in plasma towards multiple in vivo-relevant oxidants

Prunus spinosa L. flowers are a traditional herbal medicine recommended for the adjunctive treatment of oxidative stress-related diseases. In search of the main bioactive constituents of the flowers, the antioxidant activity of dry extracts obtained thereof by fractionated extraction was tested in vitro towards primary in vivo-relevant reactive oxygen species (O2–, OH, NO, H2O2, ONOO–, HOCl) and juxtaposed with the activity of eight model native polyphenols and five compounds considered to be their main metabolites in human plasma. All extracts exhibited concentration- and phenolic-dependent scavenging potential towards the tested oxidants, and the highest responses were observed for O2–, OH, ONOO–, and HOCl. The total antioxidant capacity of the extracts towards the six oxidants, expressed as sum of ascorbic acid (AA) equivalents, was in the range of 4.8–29.2 μmol AA/mg dw. The most active model polyphenols were quercetin, avicularin, procyanidin A2 and chlorogenic acid (44.5–72.5 μmol AA/mg), while the prevalent in the extracts kaempferol derivatives exhibited relatively weak capacity (11.8–27.0 μmol AA/mg). Among the metabolites, dihydrocaffeic acid (68.8 μmol AA/mg) and 2-(3′,4′-dihydroxyphenyl)acetic acid (63.2 μmol AA/mg) were particularly active – in some tests exhibited stronger activity than their parent compounds. The work gives an insight into the role of native and metabolised phenols as contributory factors to systemic activity of flower extracts and proposes the analytical markers for their standardisation.

Procyanidin A2, an anti-diabetic condensed tannin extracted from Wendlandia glabrata, reduces elevated G-6-Pase and mRNA levels in diabetic mice and increases glucose uptake in CC1 hepatocytes and C1C12 myoblast cells.

To reduce the global burden of diabetes in an affordable way great attention has been paid to the search for functional foods and herbal remedies. One of the most popularly used functional foods in the North Eastern region of India is tender shoots of Wendlandia glabrata DC. In the current study identification of active anti-diabetic constituent of the tender shoots of W. glabrata was guided through α-glucosidase inhibition and procyanidin A2 was identified with IC50 0.27 ± 0.01 μg mL−1 making it potential source for postprandial management of DM type 2. The study has also demonstrated procyanidin A2 as a potent anti-diabetic agent that exhibits significant glucose-6-phosphatase inhibitory activities and downregulated mRNA level in diabetic mice as well as increases glucose uptake in hepatocytes and myoblast cells. This study revealed that easily available tender shoots of W. glabrata could be used to make specific dietary recommendations for consumption for affordable management of diabetes.

Maturation and Maceration Effects on Tropical Red Wines Assessed by Chromatography and Analysis of Variance - Principal Component Analysis

Effects of grape maturity, maceration length during winemaking and interaction of both of them on physicochemical parameters, phenolic and volatile composition were investigated in tropical Syrah wines with the aim of finding the best conditions to produce wines that are rich in phenols and positive aroma active compounds. A headspace solid phase micro extraction and gas chromatography with mass spectrometry (HS-SPME-GC-MS) method was improved and validated for the analysis of 41 volatiles. Principal component analysis (PCA) and analysis of variance (ANOVA)-PCA coupled with inspection of statistically significant loadings were important to access the effects of maturation and maceration on wine composition. Wines made from riper grapes (21-23 oBrix) stood out in relation to color intensity, total phenolic compounds, and presented high levels of anthocyanins, flavonols, procyanidin A2, and linalool (floral). Thirty days of maceration were linked to higher levels of some flavan-3-ols, gallic acid, a few esters (fruity) and alcohols, (E)-nerolidol (floral), while nonanoic acid (unpleasant aroma) reduced its concentration with prolonged maceration.

Phenolic profile and effects of acetone fractions obtained from the inflorescences of Calluna vulgaris (L.) Hull on vaginal pathogenic and non-pathogenic bacteria.

The phenolic profile and the antibacterial activity against pathogenic commensal vaginal bacteria exhibited by different fractions of the acetone extract of heather were assessed. The acetone extract of Calluna vulgaris (L.) Hull was fractionated by silica gel column chromatography through an eluent system of increasing polarity, and 10 different fractions (Fr 1 to Fr 10) were obtained. The phenolic profile was analyzed by HPLC-DAD-ESI/MS. Type B (epi)catechin dimers, (-)-epicatechin and (+)-catechin, were the main phenolic compounds present in the fractions. The antibacterial activity was also analyzed against pathogenic bacteria and the effect on the beneficial microflora was also assessed. Some of the obtained fractions revealed the capacity to inhibit pathogenic microorganisms without affecting the beneficial microflora, especially Fr 7 and Fr 8. For instance, Neisseria gonorrhoeae was inhibited by both of the fractions, while Fr 7 was more active against Klebsiella pneumoniae and Morganella morganii, and Fr 8 was active against methicillin resistant Staphylococcus aureus (MRSA) and methicillin susceptible Staphylococcus aureus (MSSA), without affecting the Lactobacillus strains. This study corroborates the therapeutic use of this matrix in traditional medicine.

Syntheses of doubly linked proanthocyanidins using free flavan units as nucleophiles: insight into the origin of the high regioselectivity of annulation.

A synthesis method of doubly linked flavan dimers is reported via the acid-promoted annulation reaction using nascent catechins, (+)-catechin or (-)-epicatechin, as a dianionic partner and an ethylenedioxy-bridged flavan as a dicationic partner. Procyanidins A1 and A2 were synthesized. On the high regioselectivity of the annulation reactions, model experiments and computational studies were carried out.

Size Exclusion Coupled to Reversed Phase Liquid Chromatography for the Characterization of Cranberry Products

A combination of solvent extraction, size exclusion purification, and reversed-phase liquid chromatography with UV absorption and fluorescence detection was here used for the determination of flavan-3-ols and related oligomeric compounds in cranberry products. The method relied on robust, simple, and inexpensive instrumental equipment present in most of routine analytical laboratories. Sample extracts in methanol/water/hydrochloric acid solution (60:39:1, v/v/v) were subjected to size-exclusion chromatography (SEC) using Sephadex LH-20 as the sorbent to separate simple phenolic and oligomeric components. As a novel aspect of this work, the implementation of the SEC process in a reusable packed column was practically and economically highly advantageous. Fractions were analyzed by reversed-phase chromatography using a C18 core-shell analytical column and 0.1% formic acid aqueous solution and methanol as the components of the mobile phase. Chromatograms were recorded by UV absorption spectroscopy at 280 nm and by fluorescence spectroscopy at λex 280 nm/λem 347 nm. The method was applied to the determination of flavan-3-ols in various cranberry samples. Catechin, epicatechin, and procyanidins A2 and B2 were found in different amounts depending on the cranberry varieties.

Chemical characterization and evaluation of gastric antiulcer properties of the hydroethanolic extract of the stem bark of Virola elongata (Benth.) Warb.

Ethnopharmacological relevanceVirola elongata is a tree species belonging to the Myristicaceae family, distributed in the North and Midwest regions of Brazil, in the phytogeographic domain of the Amazon. The aqueous infusion or the hydroethanolic macerate of the stem bark of V. elongata are used in Brazilian and Ecuadorian indigenous folk medicine for several ethnopharmacological purposes, principally, in the treatment of stomach pain, indigestions, and gastric ulcers. This study was aimed to investigate the gastroprotective activity of this plant in order to support its popular use with scientific evidence. Materials and methodsThe stem bark hydroethanolic extract of the plant (HEVe) was prepared by maceration. Its qualitative and quantitative phytochemical constituents were investigated by classical colorimetric techniques, HPLC, and electrospray ionization-multiple stage fragmentation (ESI-MSn). The gastroprotective and antiulcer activity of HEVe at doses of 100, 300 and 900 mg/kg p.o. were tested using three acute (acidified ethanol, piroxicam, and in-water-restrain stress), and one chronic (acetic acid) animal ulcer models. The probable mode of action of the HEVe was evaluated by analyzing gastric acid secretion, mucus content, nitric oxide effect, and its antioxidant properties (on catalase, myeloperoxidase, and GSH content) in experimental rodents. The direct extract's activity on the growth of Helicobacter pylori was also investigated. ResultsTotal phenolic content in the HEVe was of 146.20 ± 1.07 mg, being flavonoids about 50% (71.79 ± 0.70 mg) of it. Comparative HPLC fingerprint analysis revealed the presence of known phenolic antiulcer compounds, such as gallic acid, catechin, and rutin. Also, methanol/water fractionation and ESI-MSn analysis of the HEVe reveals the presence of quinic acid, 3,3′,4-trihydroxystilbene, juruenolid D, one catechin dimer, one C-glycosyl flavonoid, one polyketide and two neolignans as the major components of the extract. The HEVe attenuated gastric ulceration in all the different models of acute gastric ulcer, by enhancing gastroprotection through its antioxidant properties in vivo, and reducing also considerably the gastric secretion and total acidity. The HEVe also presented healing properties against the induced chronic ulceration process. On the other hand, the HEVe did not exhibit direct activity against H. pylori. ConclusionThe HEVe exhibited significant gastroprotective/antiulcer effects and contain a relative high proportion of phenolic compounds, especially flavonoids, that could likely account, at least in part, for its pharmacological properties. The results justify its traditional usage and provided scientific evidence for its potential as a new herbal medicine to treat gastric ulcers.

Disentangling the Complexity of a Hexa-Herbal Chinese Medicine Used for Inflammatory Skin Conditions-Predicting the Active Components by Combining LC-MS-Based Metabolite Profiles and in vitro Pharmacology.

Objectives: The purpose of this study is to investigate the anti-inflammatory activity of a hexa-herbal Chinese formula (HHCF) using spontaneously immortalized human epidermal keratinocytes (HaCaT) and to predict the active components by correlating the LC-MS-based metabolite profiles of the HHCF and its 12 varied formulae with their anti-inflammatory activity using partial least-squares regression analysis.Methods: The HHCF comprises the rootstock of Scutellaria baicalensis, Rheum tanguticum, Sophora flavescens, the root bark of Dictamnus dasycarpus, the bark of Phellodendron chinense, and the fruit of Kochia scoparia in equal proportions. Its 12 varied formulae were developed by uniform design with varied proportions of the component botanical drugs. The decoctions of the HHCF and its 12 varied formulae were profiled using liquid chromatography (LC) combined with triple quadrupole mass spectrometry (MS) and their effects on tumor necrosis factor (TNF)-α -plus-interferon (IFN)-γ-induced C-C motif chemokine ligand 17 (CCL17) production in HaCaT were investigated. Partial least-squares regression analysis was conducted to assess the relationship between the LC-MS-based metabolite profiles of the decoctions to anti-CCL17 production in HaCaT.Results: Compounds with potential to promote anti-CCL17 production in HaCaT were identified (e.g., berberine, pyrogallol and catechin dimers) as a result of the developed model and their potential to act as anti-inflammatory agents were also supported by relevant literature.Conclusion: This promising approach should assist in the screening process of active components from complex Chinese herbal preparations and will better inform the necessary pharmacological experiments to take forward.

Effect of Storage Conditions on Phenolic Profiles and Antioxidant Activity of Litchi Pericarp.

Changes of phenolic profiles and antioxidant activity of litchi pericarp during storage at 4 °C for seven days and at room temperature (RT) for 72 h were evaluated in this study. The contents of total phenolic and procyanidin decreased by 20.2% and 24.2% at 4 °C and by 37.8% and 47.8% at RT, respectively. Interestingly, the corresponding reductions of anthocyanins were 41.3% and 73%, respectively. Four phenolic compounds, including epicatechin, procyanidin A2, procyanidin B2, and quercetin-3-O-rutinoside-7-O-α-l-rhamnosidase were detected in litchi pericarp. Their contents after storage at 4 °C and at RT were decreased by 22.1–49.7% and 27.6–48.7%, respectively. The oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) of litchi pericarp decreased by 17.6% and 58.7% at 4 °C, and by 23.4% and 66.0% at RT, respectively. The results indicated that storage at 4 °C preserved more phenolics and retained higher antioxidant activity in litchi pericarp compared to storage at RT, suggesting that storage at 4 °C should be considered as a more effective method for slowing down the degradation of litchi pericarp phenolics.

Polyphenols Derived from Lychee Seed Suppress Aβ (1-42)-Induced Neuroinflammation.

Amyloid-β (Aβ) is commonly recognized as the most important factor that results in neuronal cell death and accelerates the progression of Alzheimer’s disease (AD). Increasing evidence suggests that microglia activated by Aβ release an amount of neurotoxic inflammatory cytokines that contribute to neuron death and aggravate AD pathology. In our previous studies, we found that lychee seed fraction (LSF), an active fraction derived from the lychee seed, could significantly improve the cognitive function of AD rats and inhibit Aβ-induced neuroinflammation in vitro, and decrease neuronal injuries in vivo and in vitro. In the current study, we aimed to isolate and identify the specific components in LSF that were responsible for the anti-neuroinflammation effect using preparative high performance liquid chromatography (pre-HPLC), liquid chromatography-mass spectrometry (LC-MS), and nuclear magnetic resonance (NMR) methods. To this end, we confirmed two polyphenols including catechin and procyanidin A2 that could improve the morphological status of BV-2 cells and suppress the release, mRNA levels, and protein expression of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) through downregulating the nuclear factor-κB (NF-κB) signaling pathway using ELISA, RT-PCR, and Western blotting methods. Furthermore, catechin and procyanidin A2 could inhibit Aβ-induced apoptosis in BV-2 cells by upregulating Bcl-2 and downregulating Bax protein expression. Therefore, the current study illustrated the active substances in lychee seed, and first reported that catechin and procyanidin A2 could suppress neuroinflammation in Aβ-induced BV-2 cells, which provides detailed insights into the molecular mechanism of catechin and procyanidin A2 in the neuroprotective effect, and their further validations of anti-neuroinflammation in vivo is also essential in future research.

Effects of Blue-Light-Induced Free Radical Formation from Catechin Hydrate on the Inactivation of Acinetobacter baumannii, Including a Carbapenem-Resistant Strain.

Catechin is a flavan-3-ol, a derivative of flavans, with four phenolic hydroxyl groups, which exhibits a wide range of physiological properties. Chromatographic analyses were employed to examine the effects of blue light irradiation on the changes of catechin hydrate in an alkaline condition. In particular, the detection of a superoxide anion radical (O2•−), a reactive oxygen species (ROS), and the inactivation of Acinetobacter baumannii (A. baumannii)—including a carbapenem-resistant A. baumannii (CRAB)—was investigated during the photoreaction of catechin hydrate. Following basification with blue light irradiation, the transparent solution of catechin hydrate turned yellowish, and a chromogenic catechin dimer was separated and identified as a proanthocyanidin. Adding ascorbic acid during the photolytic treatment of catechin hydrate decreased the dimer formation, suggesting that ascorbic acid can suppress the photosensitive oxidation of catechin. When catechin hydrate was irradiated by blue light in an alkaline solution, O2•− was produced via photosensitized oxidation, enhancing the inactivation of A. baumannii and CRAB. The present findings on the photon-induced oxidation of catechin hydrate provides a safe practice for the inactivation of environmental microorganisms.

Choushenosides A-C, three dimeric catechin glucosides from Codonopsis pilosula collected in Yunnan province, China

Choushenosides A-C, three dimeric catechin glucosides, were isolated from the roots of Codonopsis pilosula cultivated at high elevations in Yunnan province of the People's Republic of China. The structures of these substances were determined by using spectroscopic and chemical methods. Biological evaluation showed that choushenoside C is a dose-dependent inhibitor of SIRT1.