Procyanidin B-2 3,3 -di-

Procyanidin B-2 3,3 -di-0-gallate (condensed tannin) Rheum palmatum (Polygonaceae) ACE (2 pM) [SlF... 

Scheme 15 Synthesis of the 3,3-di-O-gallate (98) of procyanidin B-2 (5). Reagents and conditions (a) TiCi4, CH2Ci2/THF, RT (b) 20% Pd(OH)2/C, H2, THF/Me0H/H20, RT (c) 3,4,5-tris(benzyioxy)benzoyi chioride, 4-DMAP, pyridine, RT.

Controlled acid-catalyzed degradation of the proanthocyanidins in grape seeds with L-cysteine as the capture nucleophile, gave a series of mono-, di-, and tri-meric-L-cysteine complexes. The flavan-3-ol adducts included the L-cysteine derivatives (173), (174), and (175) of epicatechin (3), catechin (2), and epigallocatechin, respectively. The dimers comprise the derivatives of procyanidin B-2 (176) and its C-ring... 

The synthesis protocols shown in Schemes 15—19 afforded access to 10—100 mg quantities of some of the procyanidins shown, permitting assessment of their in vitro biological activities. " With a view to fully develop the potential clinical applications for this class of compounds, and to address pharmacological and toxicological requirements, Romanczyk and coworkers recently reported the process scale-up conditions required for the multigram synthesis of procyanidin B-1 (90) and the 3,3-di-O-gallate (98) of procyanidin B-2... 

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