Enzymatic activity of cell-free extracts from Burkholderia oxyphila OX-01 bio-converts (+)-catechin and (−)-epicatechin to (+)-taxifolin

This study characterized the enzymatic ability of a cell-free extract from an acidophilic (+)-catechin degrader Burkholderia oxyphila (OX-01). The crude OX-01 extracts were able to transform (+)-catechin and (?)-epicatechin into (+)-taxifolin via a leucocyanidin intermediate in a two-step oxidation. Enzymatic oxidation at the C-4 position was carried out anaerobically using H₂O as an oxygen donor. The C-4 oxidation occurred only in the presence of the 2R-catechin stereoisomer, with the C-3 stereoisomer not affecting the reaction. These results suggest that the OX-01 may have evolved to target both (+)-catechin and (?)-epicatechin, which are major structural units in plants.     

(+)-Catechin is more bioavailable than (−)-catechin: Relevance to the bioavailability of catechin from cocoa

Catechin is a flavonoid present in fruits, wine and cocoa products. Most foods contain the (+)-enantiomer of catechin but chocolate mainly contains ( ? )-catechin, in addition to its major flavanol, ( ? )-epicatechin. Previous studies have shown poor bioavailability of catechin when consumed in chocolate. We compared the absorption of ( ? ) and (+)-catechin after in situ perfusion of 10, 30 or 50 μmol/l of each catechin enantiomer in the jejunum and ileum in the rat. We also assayed 23 samples of chocolate for (+) and ( ? )-catechin. Samples were analyzed using HPLC with a Cyclobond I-2000 RSP chiral column. At all concentrations studied, the intestinal absorption of ( ? )-catechin was lower than the intestinal absorption of (+)-catechin (p < 0.01). Plasma concentrations of ( ? )-catechin were significantly reduced compared to (+)-catechin (p < 0.05). The mean concentration of ( ? )-catechin in chocolate was 218 ± 126 mg/kg compared to 25 ± 15 mg/kg (+)-catechin. Our findings provide an explanation for the poor bioavailability of catechin when consumed in chocolate or other cocoa containing products.     

Cyclohexene epoxides, (+)-pandoxide, (+)β-senepoxide and (−)-pipoxide,from Uvaria pandensis

The new cyclohexene epoxide (+)-pandoxide along with (+)-β-senepoxide and (−)-pipoxide were isolated from the stembark, roots and leaves of the new Uvaria species U. pandensis. Their structures and stereochemical configurations were determined by spectroscopic methods. The pipoxide has an absolute configuration opposite to the one previously isolated from Uvaria species. The absolute stereochemical configuration of (+)-β-senepoxide was assigned unambiguously by an X-ray diffraction analysis.     

Biological activities of (−)-epicatechin and (−)-epicatechin-containing foods: Focus on cardiovascular and neuropsychological health

Recent studies have suggested that certain (?)-epicatechin-containing foods have a blood pressure-lowering capacity. The mechanisms underlying (?)-epicatechin action may help prevent oxidative damage and endothelial dysfunction, which have both been associated with hypertension and certain brain disorders. Moreover, (?)-epicatechin has been shown to modify metabolic profile, blood's rheological properties, and to cross the blood-brain barrier. Thus, (?)-epicatechin causes multiple actions that may provide unique synergy beneficial for cardiovascular and neuropsychological health. This review summarises the current knowledge on the biological actions of (?)-epicatechin, related to cardiovascular and brain functions, which may play a remarkable role in human health and longevity.     

Potential α-glucosidase inhibitors from thermal transformation of (+)-catechin

Thermal transformation of the (+)-catechin (1) with heating processing afforded a new oxidation product, gambiriin D (2), along with catechin [6′–8]-catechin (3), and (+)-epicatechin (4). The structure of a new catechin dimer with C–C linkage was determined on the basis of spectroscopic data interpretation. The catechin dimers 2 and 3 exhibited significantly improved inhibitory activities against α-glucosidase, with IC₅₀ values of 0.16 ± 0.2 and 0.14 ± 0.2 μM, respectively, when compared to parent (+)-catechin. Kinetic analysis showed that the two effective compounds 2 and 3 have noncompetitive modes of action.     

A New Keto-alcohol, (−)-Mintlactone, (+)-isoMintlactone and Minor Components in Peppermint Oil

Eighty-one constituents were newly identified from the oil of Mentha piperita L., including a new keto-alcohol, (?)-mintlactone and (+)-isomintlactone. They were determined by spectral data and syntheses to be 4-hydroxy-4-methyl-2-cyclohexen-1-one (8), (6R, 7aR) (10) and (6R, 7aS)-3,6-dimethyl-5,6,7,7a-tetrahydro-2(4H)-benzofuranone (11), respectively.     

Effects of (−)-epicatechin and derivatives on nitric oxide mediated induction of mitochondrial proteins

Impaired mitochondrial function represents an early manifestation of endothelial dysfunction and likely contributes to the development of cardiovascular diseases (CVD). The stimulation of mitochondrial function and/or biogenesis is seen as a means to improve the bioenergetic and metabolic status of cells and thus, reduce CVD. In this study we examined the capacity of the flavanol (?)-epicatechin and two novel derivatives to enhance mitochondrial function and protein levels in cultured bovine coronary artery endothelial cells. As nitric oxide production by endothelial cells is suspected in mediating mitochondria effects (including biogenesis), we also examined the dependence of responses on this molecule using an inhibitor of nitric oxide synthase. Results indicate that the flavanol (?)-epicatechin and derivatives are capable of stimulating mitochondrial function as assessed by citrate synthase activity as well as induction of structural (porin, mitofilin) and oxidative phosporylation protein levels (complex I and II). Effects were blocked by the use of the chemical inhibitor of the synthase thus, evidencing a role for nitric oxide in mediating these effects. The results observed indicate that the three agents are effective in enhancing mitochondria function and protein content. The effects noted for (?)-epicatechin may serve to explain the healthy effects on cardiometabolic risk ascribed to the consumption of cocoa products.     

Synthesis of novel (−)-epicatechin derivatives as potential endothelial GPER agonists: Evaluation of biological effects

To potentially identify proteins that interact (i.e. bind) and may contribute to mediate (?)-epicatechin (Epi) responses in endothelial cells we implemented the following strategy: 1) synthesis of novel Epi derivatives amenable to affinity column use, 2) in silico molecular docking studies of the novel derivatives on G protein-coupled estrogen receptor (GPER), 3) biological assessment of the derivatives on NO production, 4) implementation of an immobilized Epi derivative affinity column and, 5) affinity column based isolation of Epi interacting proteins from endothelial cell protein extracts. For these purposes, the Epi phenol and C3 hydroxyl groups were chemically modified with propargyl or mesyl groups. Docking studies of the novel Epi derivatives on GPER conformers at 14?ns and 70?ns demostrated favorable thermodynamic interactions reaching the binding site. Cultures of bovine coronary artery endothelial cells (BCAEC) treated with Epi derivatives stimulated NO production via Ser1179 phosphorylation of eNOS, effects that were attenuated by the use of the GPER blocker, G15. Epi derivative affinity columns yielded multiple proteins from BCAEC. Proteins were electrophoretically separated and inmmunoblotting analysis revealed GPER as an Epi derivative binding protein. Altogether, these results validate the proposed strategy to potentially isolate and identify novel Epi receptors that may account for its biological activity.     

Myeloperoxidase-mediated LDL oxidation and endothelial cell toxicity of oxidized LDL: attenuation by (−)-epicatechin

Recent data suggest an inverse epidemiological association between intake of flavanol-rich cocoa products and cardiac mortality. Potential beneficial effect of cocoa may be attributed to flavanol-mediated improvement of endothelial function, as well as to enhancement of bioavailability and bioactivity of nitric oxide in vivo. ( ? )-Epicatechin is one bioactive flavanol found in cocoa. This review deals with protective actions of ( ? )-epicatechin on two key processes in atherogenesis, oxidation of LDL and damage to endothelial cell by oxidized LDL (oxLDL), with emphasis on data from this laboratory. ( ? )-Epicatechin not only abrogates or attenuates LDL oxidation but also counteracts deleterious actions of oxLDL on vascular endothelial cells. These protective actions are only partially shared by other vasoprotective agents such as vitamins C and E or aspirin. Thus, ( ? )-epicatechin appears to be a pleiotropic protectant for both LDL and endothelial cells.     

Conversion of (−)-Carvotanacetone and (+)-Carvotanacetone by Pseudomonas ovalis,Strain 6–1

As a part of series on the biochemical reduction of terpenes, the conversion of (?)-carvotanacetone (I) and (+)-carvotanacetone (II) by Pseudomonas ovalis, strain 6–1, has been studied.

By the action of the microorganism, I was reduced to give (+)-carvomenthone (III), (+)-neocarvomenthol (IV), and (?)-carvomenthol (V), whereas II was also reduced to (?)-isocarvomenthone (VI), (?)-carvomenthone (VII), (?)-isocarvomenthol (VIII), and (?)-neoisocarvomenthol (IX); of which III, VI and IX are the major products.

The metabolic pathways of I and II and mechanism of stereospecific hydrogenation are also discussed.     

Different responses of CR(−) and CR(+) B cells to LPS stimulation

Proliferative response of B cells with or without CR [CR(+) or CR(?) B cells] was compared in their polyclonal response when they were stimulated with lipopolysaccharide (LPS). CR(+) B cells responded better in proliferation and more poorly in polyclonal antibody formation than did CR(?) B cells. The dissociation between proliferation and antibody formation in LPS response was not due to the shift of the time kinetics nor the exhaustion of the culture medium. T cells and macrophages did not take part in the dissociation, since macrophage depletion from nu/nu mouse spleen cells could not modify the dissociation. The polyclonal antibody response of CR(?) B cells was more resistant to irradiation than that of CR(+) B cells. These results suggest that among LPS-responsive B cells there are CR(?) B-cell subset(s) more mature than CR(+) B cells.     

Semi-preparative chromatographic purification of the enantiomers S-(−)-amlodipine and R-(+)-amlodipine

Pharmacokinetic studies of optically pure compounds after single enantiomer administration are becoming increasingly important. The process of racemization in vivo can diminish all expected advantages of single enantiomer treatment. Amlodipine, one of the calcium channel blockers, currently used in therapy as a racemate, is one of such drugs under study. In order to administer single enantiomers of amlodipine to healthy volunteers both were chromatographically purified and characterised. The two optical isomers of amlodipine, active S-(−)- and non-active R-(+)-amlodipine, were purified using chromatographic procedure adopted from the analytical separation. Enantiomers were successfully converted to benzenesulphonic salt without any racemization. All semi-preparative purifications were monitored with complementary analytical methods, HPLC and CE, along with the determination of optical activity so that the final product was sufficiently defined for further in vivo studies. The analytical method developed for the determination of plasma concentrations of each enantiomer of amlodipine in these studies is also briefly described.     

Proteomic analysis of CD44(+) and CD44(−) gastric cancer cells

CD44 is a cell surface protein and it is widely used as a cancer stem cell marker in various cancer types including gastric cancer. We conducted proteomic analysis in CD44(+) and CD44(?) gastric cancer cells to understand characteristics of CD44(+) and CD44(?) cells. In the present study, we sorted cells from the gastric cancer cell line MKN45 according to CD44 expression to separate out CD44(+) and CD44(?) cells. And we conducted RT-PCR to identify mRNA expression of cancer stem cell markers in CD44(+) and CD44(?) cells. Cancer stem cell markers showed upregulated expression in CD44(+) cells. Next, we performed two-dimensional electrophoresis analysis to determine the differential expression pattern of proteins in each group; control, CD44(+), and CD44(?) MKN45 cells. We found a total of 113 spots that varied in expression between CD44(+) and CD44(?) cells, and subjected 20 of those protein spots to MALDI-MS. We selected the three proteins (HSPA8; heat shock cognate 71 kDa protein isoform 1, ezrin, α-enolase) upregulated in CD44(+) cells than CD44(?) cells and one protein (prohibitin) showed increased expression in CD44(?) cells. We validated the protein expression levels of four selected proteins by Western blot. We suggest that our study could be a helpful background to study CD44(+) cancer stem-like cells and differences between CD44(+) and CD44(?) cells in gastric cancer.     

(+)-Kuraramine,a possible metabolite of (−)-N-methylcytisine in flowers of Sophora flavescens

From the flowers of Sophora flavescens, a new dipiperidine-type alkaloid, (+)-kuraramine, has been isolated together with (+ )-mamanine and the oth     

Monogenic basis for reduction of (+)-pulegone to (−)-menthone in Mentha oil biogenesis

A chemotype of Mentha arvensis, having the genotype AA pp rr FF with 79% (+)-pulegone, less than 6% (?)-menthone and less than 0.1% menthofur     

Trisporic acid biosynthesis in cultures ofBlakeslea trispora with (+) and (−) mycelia separated by a filter

Cultures ofBlakeslea trispora in which (+) and (−) mycelia were separated by membrane filters for 152 h made 4.5, 13.3, and 25.5% of the trisporic acids (102 μg/ml of medium) made by combined (+) and (−) cultures. Control studies indicate that the extent of trisporic acid biosynthesis in cultures with membrane-separated mycelia is proportional to the rate of diffusion of small molecules through the membrane.