# US 5,710,260 A · Method of extracting sennosides A, B and A1

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- Number: US 5,710,260 A
- Document ID: US5710260A
- Status: Granted
- Kind: A
- Application number: 08/614,772
- Filed: 1995-12-21
- Granted: 1998-01-20
- Earliest claimed: 1991-06-25
- Assignees: Madaus AG
- Inventors: Alfons Carcasona; Wolf Grimminger; Pentti Hietala; Helga Zaeske; Klaus Witthohn
- Web page: https://patentgrep.com/patent/US5710260A

## CPC

- C07H 15/24: Condensed ring systems having three or more rings
- C07H: SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS (derivatives of aldonic or saccharic acids C07C, C07D; aldonic acids, saccharic acids C07C59/105, C07C59/285; cyanohydrins C07C255/16; glycals C07D; compounds of unknown constitution C07G; polysaccharides, derivatives thereof C08B; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; sugar industry C13)

## Abstract

Sennosides A, B and Al of the formula: ##STR1## which are substantially free from sennosides C, D and Dl, and from aloe-emodin derivatives, are prepared by a process wherein a) a sennoside mixture is reduced to rhein-9-anthrone-8-glucoside and aloe-emodin-9-anthrone-8-glucoside, b) a liquid-liquid partitioning of the compounds obtained is carried out between a polar organic solvent which is only partly miscible with water and an aqueous phase and c) the rhein-9-anthrone-8-glycosides contained after the partitioning in the aqueous phase is again oxidized to the corresponding sennosides and these are recovered.

## Claims

### Claim 1

A process for obtaining sennosides A, B and Al of the formula: ##STR6## which are substantially free from sennosides C, D and Dl and from aloe-emodin derivatives, wherein
a) a sennoside mixture is reduced to rhein-9-anthrone-8-glucoside and aloe-emodin-9-anthrone-8-glucoside,
b) a liquid-liquid partitioning of the compounds obtained is carried out between a polar organic solvent which is only partly miscible with water and an aqueous phase and
c) the rhein-9-anthrone-8-glucoside contained after partitioning in the aqueous phase is again oxidized to the corresponding sennosides and these are recovered.

### Claim 2 (depends on 1)

The process of claim 1, wherein the sennoside mixture is obtained by extraction of senna drug with aqueous methanol.

### Claim 3 (depends on 2)

The process of claim 2, wherein the extraction with methanol is carried out in the presence of a buffer.

### Claim 4 (depends on 1)

The process of claim 1, wherein an alkali metal dithionite is used as reducing agent in step a).

### Claim 5 (depends on 4)

The process of claim 4, wherein the process is performed at a pH value of 5 to 10.5.

### Claim 6 (depends on 1)

The process of claim 1, wherein butan-2-ol or acetone is used as polar organic solvent in step b).

### Claim 7 (depends on 1)

The process of claim 1, wherein an aqueous phase is used in step b), the redox potential of which is -210 mV or more negative.

### Claim 8 (depends on 1)

The process of claim 1, wherein the liquid-liquid partitioning in step b) is carried out in a countercurrent mode.

### Claim 9 (depends on 1)

The process of claim 1, wherein the oxidation in step c) is carried out with oxygen or a ferric salt.

### Claim 10 (depends on 9)

The process of claim 9, wherein the oxidation with oxygen is carried out at a weakly acidic pH value.

### Claim 11 (depends on 10)

The process of claim 10, wherein the oxidation is carried out in the presence of a catalyst.

### Claim 12 (depends on 11)

The process of claim 11, wherein the catalyst is a ferric salt.

### Claim 13

A composition comprising sennosides A, B and Al which are substantially free from sennosides C, D and Dl and from aloe-emodin components.

### Claim 14 (depends on 13)

The composition of claim 13 wherein the composition is a pharmaceutical composition.

### Claim 15 (depends on 14)

The pharmaceutical composition of claim 14 further comprising one or more carriers or adjuvants.