138663-01-1Relevant academic research and scientific papers
Phytotoxic and Antimicrobial Activities of Catechin Derivatives
Veluri, Ravikanth,Weir, Tiffany L.,Bais, Harsh Pal,Stermitz, Frank R.,Vivanco, Jorge M.
, p. 1077 - 1082 (2007/10/03)
(±)-Catechin is a potent phytotoxin, with the phytotoxicity due entirely to the (-)-catechin enantiomer. (+)-Catechin, but not the (-)-enantiomer, has antibacterial and antifungal activities. Tetramethoxy, pentaacetoxy, and cyclic derivatives of (±)-catechin retained phytotoxicity. The results indicate that antioxidant properties of catechins are not a determining factor for phytotoxicity. A similar conclusion was reached for the antimicrobial properties. Centaurea maculosa (spotted knapweed) exudes (±)-catechin from its roots, but the flavanol is not re-absorbed and hence the weed is not affected. The much less polar tetramethoxy derivative may, however, be absorbed and hence be able to cause toxicity. Because of the combination of phytotoxicity and antimicrobial activity, (±)-catechin could be a useful natural herbicide and antimicrobial.
A-type proanthocyanidins from peanut skins
Lou, Hongxiang,Yamazaki, Yoshimitsu,Sasaki, Tsutomu,Uchida, Masaru,Tanaka, Hideoki,Oka, Syuichi
, p. 297 - 308 (2007/10/03)
Six A-type proanthocyanidins were isolated from the water-soluble fraction of peanut skins. On the basis of spectral data, reductive cleavage with sodium cyanoborohydride, and chiral HPLC analysis, three new compounds, epicatechin-(2β → O → 7, 4β → 6)-catechin, epicatechin-(2β → O → 7, 4β → 6)-ent-catechin and epicatechin-(2β → O → 7, 4β → 6)-ent- epicatechin were unambiguously identified, together with the three known compounds, proanthocyanidin A-1, proanthocyanidin A-2 and epicatechin-(2β → O → 7, 4β → 8)-ent-epicatechin. 13C NMR chemical shift rules to distinguish between [2 → O → 7, 4 → 8] and [2 → O → 7,4 → 6] double- linked heptamethyl ethers of A-type proanthocyanidins are proposed. Bioassay experiments showed that these six compounds possess substantial activity against hyaluronidase.
On the Radical Deoxygenation of Secondary Alcohols
Weinges, Klaus,Schick, Hartmut,Zoellner, Peter
, p. 293 - 296 (2007/10/02)
The derivatives 1c - 1f were prepared from tetramethyl-(+)-catechin (1b).Their radical reduction with tri-n-butyltin hydride or tris(trimethylsilyl)silane in the presence of azobis(isobutyronitrile) as initiator led to (2R)-(-)-3',4',5,7-tetramethoxyflava
Proton magnetic resonance spectra of catechin and bromocatechin derivatives: C6- vs. C8-substitution
Kiehlmann, E.,Tracey, A. S.
, p. 1998 - 2005 (2007/10/02)
The 1Hmr spectra of 20 catechin derivatives substituted at C-6/C-8 by bromine and/or hydrogen and at oxygen by methyl, acetyl, and/or hydrogen have been analyzed in deuterated acetone, acetonitrile, and chloroform.Because of its dependence on the nature o
Synthesis of Biflavonoids in which the Flavan Units are linked through Oxygen from C-2 to C-3 or C-4
Brown, Ben R.,Stuart, Ian A.,Tyrrell, A. William R.
, p. 2563 - 2572 (2007/10/02)
Flav-2-enes have been utilised via 2,3-cis-2-acetoxy-3-bromoflavans for the synthesis of C-2-O-C-3- and C-2-O-C-4-linked biflavonoids.For example, 2,3-cis-2-acetoxy-3-bromoflavans react with (+/-)-tetra-O-methylcatechin (18) to give
Novel Bioflavonoids, Chalcan-flavan Dimers from Gambir
Nonaka, Gen-Ichiro,Nishioka, Itsuo
, p. 3145 - 3149 (2007/10/02)
The homologous series of novel chalcan-flavan dimers, gambiriin A1, A2, A3, B1, B2 and B3, along with a proanthocyanidin dimer, gambiriin C (epiafzelechin-catechin), have been isolated from Gambir.Keywords---tannin, Gambir; Uncaria Gambir; Rubiaceae; chalcan-flavan dimer; proanthocyanidin; astringency
