Catechin molecular weight

The HRP-catalyzed polymerization of (-l-)-catechin was carried out in an equivolume mixture of 1,4-dioxane and buffer (pH 7) to give the polymer with molecular weight of 3.0 x 10 in 30% yield. Using methanol as co-solvent improved the polymer yield and molecular weight. In the polymerization of... 

In addition to all of the expected enzyme systems present in leaf tissue, fresh tea leaves contain a high level of polyphenol oxidase that catalyzes the oxidation of the catechins by atmospheric oxygen. Tea polyphenol oxidase exists as series of copper-containing (0.32%) isoenzymes. The major component has a molecular weight of about 144,000.54 The enzyme is concentrated in the leaf epidermis.55 Soil copper deficiency is sometimes responsible for inadequate oxidation during processing.56... 

The platelet hist UIline release assay demonstrated that cotton mill dust extract, cotton bract extract, cotton leaf extract, dialyzed CMD extract, polyphenols, compound 48/80, rutin, trimethylamine HCl, quercetin, catechin, tannic acid, ellagic acid and sodium metasilicate all release histamine directly (48). Thus not only do tannin compounds induce histamine release, but they may also form higher molecular weight polymers and contain components that survive acid hydrolytic conditions (48). Tannins are widely distributed in the plant kingdom. 

A commercially available decaffeinated mixture of green tea catechins sold as TeGreen 97 (Pharmanex Corporation, Simi Valley, CA). The mixture was arbitrarily assigned the molecular weight of epigallocat-echin gallate as an approximation. 

The on-flow experiment was carried out on a mixture of eight flavonoids (Fig. 2) (20 pg each). MS and NMR data were obtained during this on-flow experiment. The UV chromatogram is depicted in Fig. 3. Table 1 and Fig. 4 show the pseudo-molecular ion information, where M is the molecular weight with all the hydroxyl protons deuterated, in negative mode, for the eight flavonoids obtained in this on-flow experiment. Fig. 5 is the 2-D data set (time vs. chemical shift) where each NMR spectrum was acquired for 16 scans and decreasing the delays (total time per spectrum of 20 s). Fig. 6 depicts the NMR traces of each flavonoid extracted from the 2-D data set. It is notable that catechin... 

There are discordant reports regarding the distribution of the molecular weights (MW) of proanthocyanidins in the seeds. Nevertheless, it has been reported that their mean degree of polymerization (mDP) is lower than 10 and that they are mainly constituted of (+)-catechin and (—)-epicatechin with a minor extent of (—)-epicatechin gallate. (+)-Catechin, (—)-epicatechin and (—)-epicatechin gallate are the terminal monomers (Kennedy and Jones, 2001 Downey et al., 2003 Pastor del Rio and Kennedy, 2006) (—)-epigallocatechin is absent in the seed proanthocyanidins. 

In the polymerization of catechin by using laccase (ML) as catalyst, the reaction conditions were examined in detail [112], A mixture of acetone and acetate buffer (pH 5) was suitable for the efficient synthesis of soluble poly(catechin) with high molecular weight. The mixed ratio of acetone greatly affected the yield, molecular weight, and solubility of the polymer. The polymer synthesized in 20% acetone showed low solubility toward DMF, whereas the polymer obtained in the acetone content less than 5% was completely soluble in DMF. In the UV-Vis spectrum of poly(catechin) in methanol, a broad peak centered at 370 nm was observed. In alkaline solution, this peak was red-shifted and the peak intensity became larger than that in methanol. In the ESR spectrum of the enzymatically synthesized poly (catechin), a singlet peak at g= 1.982 was detected, whereas the catechin monomer possessed no ESR peak. 

The leaves of Kopsia dasyrachis (Apocynaceae) afforded an alkaloid, kopsirachine, derived from units of catechin (75) and two units of skytan-thine (58). By mass spectrometry, the molecular weight was established as 620 amu, and the UV spectrum (256 and 281 nm) indicated a relationship to catechin. The major fragment in the mass spectrum appeared at m/z... 

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