# US 2008/0306286 A1 · Isolation, Purification and Synthesis of Procyanidin B2 and Uses Thereof

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- Number: US 2008/0306286 A1
- Document ID: US20080306286A1
- Status: Published application
- Kind: A1
- Application number: 12/124,929
- Filed: 2008-05-21
- Published: 2008-12-11
- Earliest claimed: 2002-10-11
- Inventors: Alan Snow; Gerardo Castillo; Paula Choi; Beth Nguyen; Stephen Lorimer; Lesley Larsen
- Web page: https://patentgrep.com/patent/US20080306286A1

## CPC

- C07D 407/04: directly linked by a ring-member-to-ring-member bond
- A61P 1/00: Drugs for disorders of the alimentary tract or the digestive system
- A61P 11/00: Drugs for disorders of the respiratory system
- A61P 13/08: of the prostate
- A61P 19/02: for joint disorders, e.g. arthritis, arthrosis
- A61P 25/04: Centrally acting analgesics, e.g. opioids
- A61P 25/16: Anti-Parkinson drugs
- A61P 25/28: for treating neurodegenerative disorders of the central nervous system, e.g. nootropic agents, cognition enhancers, drugs for treating Alzheimer's disease or other forms of dementia
- A61P 29/00: Non-central analgesic, antipyretic or antiinflammatory agents, e.g. antirheumatic agents; Non-steroidal antiinflammatory drugs [NSAID]
- A61P 31/04: Antibacterial agents
- A61P 31/12: Antivirals
- A61P 31/18: for HIV
- A61P 35/00: Antineoplastic agents
- A61P 37/08: Antiallergic agents (antiasthmatic agents A61P11/06; ophthalmic antiallergics A61P27/14)
- C07D 311/62: with oxygen atoms directly attached in position 3, e.g. anthocyanidins
- C07D 321/10: condensed with carbocyclic rings or ring systems
- C07D 323/00: Heterocyclic compounds containing more than two oxygen atoms as the only ring hetero atoms
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)
- A61P: SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS

## Abstract

Methods for the synthesis, isolation, and purification of procyanidin B2 are disclosed. The synthetic methods utilize epicatechin as a starting material and produce procyanidin B2 in high yields. The isolation methods extract procyanidin B2 from a sample of bark powder from plant matter of the genus Uncaria. The isolated and/or synthesized procyanidin B2 is used to treat amyloid disease, such as Alzheimer's disease and Parkinson's disease as well as improve cognitive performance and increase learning and memory in Alzheimer's patients. Pharmaceutical compositions containing the synthesized and/or isolated procyanidin B2 are also disclosed.

## Claims

### Claim 1

A method for synthesizing procyanidin B2 comprising the steps of:
a) esterification of an epicatechin to form a 5,7,3′,4′,3″-penta-O-acyl-epicatechin;
b) protecting the 5,7,3′,4′,3″-penta-O-acyl-epicatechin to form a 5,7,3′,4′-tetra-O-protected epicatechin;
c) coupling an adduct precursor with a first portion of the 5,7,3′,4′-tetra-O-protected epicatechin to form a 4″-substituted, 5,7,3′,4′-tetra-O-protected epicatechin;
d) dimerizing a second portion of the 5,7,3′,4′-tetra-O-protected epicatechin with the 4″-substituted, 5,7,3′,4′-tetra-O-protected epicatechin to form a 5,7,3′,4′-tetra-O-protected epicatechin-4β→8-5,7,3′,4′-tetra-O-protected epicatechin; and
e) deprotecting the 5,7,3′,4′-tetra-O-protected epicatechin-4β→8-5,7,3′,4′-tetra-O-protected epicatechin to form procyanidin B2.

### Claim 2 (depends on 1)

The method of claim 1, wherein the esterification step comprises the step of acetylation of an epicatechin to form a 5,7,3′,4′,3″-penta-O-acetyl-epicatechin.

### Claim 3 (depends on 1)

The method of claim 1, wherein the protection step comprises the step of protecting the 5,7,3′,4′,3″-penta-O-acyl-epicatechin to form a 5,7,3′,4′-tetra-O-benzylepicatechin.

### Claim 4 (depends on 3)

The method of claim 3, wherein the protecting step comprises the step of reacting the 5,7,3′,4′,3″-penta-O-acyl-epicatechin with benzylchloride in the presence of water to form the 5,7,3′,4′-tetra-O-benzylepicatechin.

### Claim 5 (depends on 4)

The method of claim 4, wherein the protecting step comprises the step of reacting the 5,7,3′,4′, 3″-penta-O-acyl-epicatechin with between about 4.0 and about 4.2 equivalents of benzylchloride for between about 24 hours and about 72 hours to form a reaction mixture comprising the 5,7,3′,4′-tetra-O-benzylepicatechin.

### Claim 6 (depends on 5)

The method of claim 5, wherein the protecting step comprises the step of combining the reaction mixture with an acid.

### Claim 7 (depends on 6)

The method of claim 6, wherein the acid is hydrochloric acid.

### Claim 8 (depends on 7)

The method of claim 7, wherein the hydrochloric acid is between about 0.01 M and about 3 M.

### Claim 9 (depends on 7)

The method of claim 7, wherein the hydrochloric acid is between about −10° C. and about +10° C.

### Claim 10 (depends on 4)

The method of claim 4, wherein the protecting step comprises the steps of:
a) reacting the 5,7,3′,4,3″-penta-O-acyl-epicatechin with between about 4.0 and about 4.2 equivalents of benzylchloride for between about 24 hours and about 72 hours in the presence of water to form a reaction mixture comprising 5,7,3′,4′-tetra-O-benzylepicatechin; and
b) combining the reaction mixture with hydrochloric acid, wherein the hydrochloric acid is between about 0.01 M and about 3 M, and between about −10° C. and about +10° C.

### Claim 11 (depends on 1)

The method of claim 1, wherein the coupling step comprises the step of coupling an ethylene glycol with the first portion of the 5,7,3′,4′-tetra-O-protected epicatechin to form a 5,7,3′,4′-tetra-O-protected 4-(2-hydroxyethoxy)epicatechin.

### Claim 12 (depends on 1)

The method of claim 1, wherein the dimerization step comprises the steps of:
a) crystallizing the 5,7,3′,4′-tetra-O-protected epicatechin-4β→8-5,7,3′,4′-tetra-O-protected epicatechin; and
b) isolating the 5,7,3′,4′-tetra-O-protected epicatechin-4β→8-5,7,3′,4′-tetra-O-protected epicatechin using column chromatography.

### Claim 13

A method for synthesizing procyanidin B2 comprising the steps of:
a) acetylation of an epicatechin to form a 5,7,3′,4′,3″-penta-O-acetyl-epicatechin;
b) reacting the 5,7,3′,4′,3″-penta-O-acetyl-epicatechin with between about 4.0 and about 4.2 equivalents of benzylchloride for between about 24 hours and about 72 hours in the presence of water to form a reaction mixture comprising a 5,7,3′,4′-tetra-O-benzylepicatechin;
c) combining the reaction mixture with hydrochloric acid to form purified 5,7,3′,4′-tetra-O-benzylepicatechin, wherein the hydrochloric acid is between about 0.01 M and about 3 M, and between about −10° C. and about +10° C.;
d) coupling an ethylene glycol with a first portion of the purified 5,7,3′,4′-tetra-O-benzylepicatechin to form a 5,7,3′,4′-tetra-O-benzyl 4-(2-hydroxyethoxy)epicatechin;
e) dimerizing a second portion of the 5,7,3′,4′-tetra-O-benzylepicatechin with the 5,7,3′,4′-tetra-O-benzyl 4-(2-hydroxyethoxy)epicatechin to form a 5,7,3′,4′-tetra-O-benzylepicatechin-4β→8-5,7,3′,4′-tetra-O-benzylepicatechin;
f) crystallizing the 5,7,3′,4′-tetra-O-benzylepicatechin-4β→8-5,7,3′,4′-tetra-O-benzylepicatechin;
g) isolating the 5,7,3′,4′-tetra-O-benzylepicatechin-4β→8-5,7,3′,4′-tetra-O-benzylepicatechin using column chromatography; and
h) deprotecting the 5,7,3′,4′-tetra-O-benzylepicatechin-4β→8-5,7,3′,4′-tetra-O-benzylepicatechin to form procyanidin B2.

### Claim 14

A method for synthesizing a 5,7,3′,4′-tetra-O-protected epicatechin comprising the steps of:
a) esterification of an epicatechin to form a 5,7,3′,4′,3″-penta-O-acyl-epicatechin; and
b) protecting the 5,7,3′,4′,3″-penta-O-acyl-epicatechin to form a 5,7,3′,4′-tetra-O-protected epicatechin.

### Claim 15 (depends on 2)

The method of claim 2 where suitable acyl groups for acetylation of epicatechin are selected from acetyl, other short chain acyl groups (C1-C6), benzoyl and substituted benzoyl groups.

### Claim 16 (depends on 1)

The method of claim 1 where the adduct precursors are selected from C1-C6 alkanols, ethylene glycol, other alcohols, water and thiols.

### Claim 17 (depends on 1)

The method of claim 1 further including the steps of crystallization and isolation using column chromatography.