GB1589326A - Pharmacologically active substance from plants belonging to the labiatae family - Google Patents

Description

(54) PHARMACOLOGICALLY ACTIVE SUBSTANCE FROM PLANTS BELONGING TO THE LABIATAE FAMILY (71) WE, HOECHST AKTIENGESELLSCHAFT, a body corporate organised according to the laws of the Federal Republic of Germany, of 6230 Frankfurt/Main 80, Postfach 80 03 20, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to pharmacologically active substance, hereinafter named "Coleforsin", and to its preparation.

We have found that this pharmacologically active substance can be obtained from plants of the Labiatae family.

The Labiatae family comprises 180 genera with about 3,500 plant species. There should especially be mentioned the genera Plectranthus, Coleus, Anisochilus, Lavandula and Leonitis. About 30 Plectranthus species grow in India of which P. macranthus, P. mollis. P.

stocksii, P. coetsa and P. incanus are the more common plants. Moreover, there are about 9 Coleus species to be found in India, i.e. C. amboinicus, C. forskohlii, C. malabraicus, C.

parviflorus, C. Spicatus, C. rotundifolius, C. scutellarioides, C. blumei and C. lacinatus.

Among the 13 species of the Anisochilus group reported to grow in India, A. carnosus and A. verticillatus are the more common plants. The plants of interest in the Lavandula genus are L. bipinatta, L. officinalis, L. gibsoni and L. burmanni. Leonitis nepetaefolia is the more common plant of the two Leonitis species growing in India.

We have found that Coleforsin may be obtained more especially from Coleus forskohlii, an Indian herb belonging to the Labiatae family and synonymous with Coleus barbatus (Benth.). The plants grow in different parts of India and are commonly found in the subtropical Himalayan region, the Deccan peninsula, Gujarat, Bihar and South India. The plants are also cultivated in several places in India, namely Bombay, Gujurat and Saurashtra. The morphological details and distribution of Coleus forskohlii have been described (cf. The Wealth of India, Vol. II, C.S.I.R., India 1950, page 308).

Coleforsin is a pharmacologically effective substance which has mainly blood pressure lowering and positive inotropic properties.

The present invention provides a process for obtaining Coleforsin which comprises (a) extracting a plant of the Labiatae family with a solvent which will dissolve the desired substance to obtain a solution and obtaining a concentrate or residue therefrom by evaporation, (b) subjecting the concentrate or residue to a solvent treatment to effect preliminary purification on the basis of differing solubilities of desired and undesired material, (c) treating the crude product obtained with a base to obtain a crude terpenoid mixture, and (d) purifying the crude terpenoid mixture to obtain Coleforsin.

Usually, for extraction step (a), the plant or part thereof used is ground.

The extraction (a) may be carried out with an aromatic hydrocarbon, aliphatic or aromatic halohydrocarbon. dialkyl ether, dialkyl ketone. alkanol, carboxylic acid or ester thereof, or any other solvent which will dissolve the desired substance, such solvents being for example dimethylformamide, dioxan, tetrahydrofuran, and dimethyl sulphoxide.

A concentrate or residue is then obtained by evaporation.

The solvent treatment (b) may be effected by adding a solvent to the residue or concentrate to dissolve the desired material and precipitating out the crude product needed for step (c), by adding a non-solvent for the crude product. The solvent may be, for example, an aromatic hydrocarbon, an aliphatic halohydrocarbon or an ester. The non-solvent may be, for example, an aliphatic hydrocarbon having, e.g. 5 to 7 carbon atoms. If desired, the concentrate from the previous step may be used directly, a non-solvent for the crude product then being added directly to the concentrate. If desired, the dissolution and precipitation operations may be repeated one or more times using the same or different solvents for each operation. A precipitate may then be separated by filtration.

Treatment with a base (c) is then carried out and, usually, a residue containing the terpenoid mixture obtained or a concentrate is obtained from which the terpenoid mixture may be precipitated.

The purification step (d) may be carried out, for example, by recrystallisation or by chromatographic separation to obtain a semi-pure terpenoid which is subsequently recrystallised to obtain Coleforsin.

The following flow scheme illustrates this process.

Chart I

Ground plant parts Solvent extraction Extract solution Concentration Residue or concentrate Treatment with solvent Crude Product Treatment with base > / Crude Terpenoid Recrystallisation or Chromatography and recrystallisation Coleforsin If desired, one or more additional steps may be included.

For example, before extraction (a), the plant material may be pre-treated with an aliphatic hydrocarbon in which the desired material is insoluble, for example with petroleum ether, to remove plant fats and waxes.

In addition to the dissolution and precipitation described above for step (b), (b' ) when the extraction (a) is not performed with an alkanol, especially when it is performed with an aromatic hydrocarbon or a halohydrocarbon, a further extraction with an alkanol of the residue or concentrate obtained in (a) may be performed and a residue or concentrate obtained from the alkanol solution, and/or (b") especially when the extraction (a) is performed with an alkanol, the material may be partitioned between two solvents immiscible with each other and a residue or concentrate obtained from the appropriate solution, for example the residue or concentrate is obtained from the organic solution when benzene-water or chlor oform-water are used.

and the residue or concentrate obtained is then further treated by means of the dissolution and precipitation step described above.

Preferably, Coleforsin is obtained from the roots of Coleus forskohlii.

Especially. the dried and ground roots of Coleus forskohlii are subjected to an initial extraction with an aliphatic hydrocarbon in order to remove the main portion of plant fats and waxes contained in the roots. For this purpose, hydrocarbons having from 5 to 7 carbon atoms are preferably used, for example petroleum ether, pentane or hexane, preferably in a ratio of 1 : 2 to 1 : 10 parts by weight of plant material to solvent.

For extracting the desired substance from Coleus forskohlii or other plant in step (a), an aromatic hydrocarbon or an aliphatic halohydrocarbon having from 1 to 3 carbon atoms and up to 3 halogen atoms, preferably up to 3 chlorine atoms, or a lower alkanol having from 1 to 6 carbon atoms, is preferably used. Benzene, toluene or xylene, methylene chloride or chloroform, methanol or ethanol are preferred.

The extraction agent is preferably used in a ratio of 1: 2 to 1:10 parts by weight of plant material to extraction agent.

The extraction is usually carried out at a temperature in the range of from ambient temperature to the boiling point of the solvent used, preferably 30 to 40"C.

The extract solution may be concentrated, suitably under reduced pressure, preferably in vacuo, to give a residue or concentrate.

Various methods may be used to work up the residue, or concentrate. The method chosen depends on the type of solvent used for the extraction and on the solubility properties of the residue, or concentrate. Some of the preferred procedures for the treatment of the residue or concentrate to obtain the crude product are illustrated by the following charts II, III and IV.

Chart 11

Residue or concentrate 1. Repeated precipitation from solution 2. Filtration Crude Product Referring to Chart II, when the plant material is extracted, for example with an aromatic hydrocarbon, for example benzene or toluene or an aliphatic halohydrocarbon, for example chloroform, the residue or concentrate obtained from the extract solution may be repeatedly precipitated out. The residue or concentrate can be dissolved, for example, in the minimum amount of a solvent therefor such, for example as an aromatic hydrocarbon, preferably benzene or toluene, a halohydrocarbon, preferably chloroform, or an ester, preferably ethyl acetate, usually at a temperature ranging from ambient to the boiling point of the solvent used, preferably 30 to 40"C. A non-solvent for the desired material such, for example, as an aliphatic hydrocarbon having from 5 to 7 carbon atoms, preferably petroleum ether, pentane or hexane may then be added to the solution obtained until precipitation is complete. The suspension is suitably allowed to stand until the precipitate settles, the supernatant liquid removed. and the residue is resubjected three times to the procedure of dissolution and precipitation. The precipitate may finally be filtered off to give a crude product.

Chart 111

Residue or concentrate Extraction with alkanol Alkanol solution Evaporated to dryness Residue (further processed as in Chart II) Crude Product Referring to Chart III, the residue or concentrate obtained, for example from the aromatic hydrocarbon extract or a halohydrocarbon extract of the plant is treated with a lower alkanol having from l to 6 carbon atoms, for example methanol or ethanol which are preferred, until all alkanol-soluble material has been dissolved.

The alkanol is preferably used in an amount of from 10 to 40 parts by weight for each part by weight of residue. The extraction is usually carried out at a temperature ranging from ambient to the boiling point of the solvent used, preferably 30 to 400C. The alkanol extracts may be combined, filtered and evaporated to dryness under reduced pressure, preferably in vacuo. To obtain the crude product the residue can be further processed by the procedures described above for Chart II.

Chart IV

Residue or concentrate Partitioned between C6H6-H2O or CHCI3-H20 Organic solvent layer Evaporated to dryness Residue (further processed as in Chart II) Crude Product According to Chart IV, the residue or concentrate obtained, for example by extraction with an alkanol, for example methanol or ethanol, is partitioned between two immiscible solvents, one of which is capable of dissolving the desired substance, for example an aromatic hydrocarbon, preferably benzene, or an aliphatic or aromatic halohydrocarbon, preferably chloroform, and water. Benzene or chloroform and water are preferably used in a ratio of about 1 : l part by volume. The organic layer may be separated and dried and the solution evaporated to dryness under reduced pressure, preferably in vacuo. The residue obtained can be processed further as described for Chart II to a crude product.

The crude product obtained by any of the processes illustrated by Charts II, III and IV is subjected to a treatment with a base according to one of many possible procedures. Some of the preferred procedures are described below.

The dry crude product is treated with an alkali metal alkoxide, preferably sodium methoxide or sodium ethoxide in the presence of a solvent, for example an ether, preferably dioxan, tetrahydrofuran or diethyl ether, usually at a temperature in the range of from ambient to the boiling point of the solvent used, preferably 30 to 40"C. The pH of the solution may then be adjusted to 5 to 7 by adding an organic acid, for example acetic acid, or an inorganic acid, for example hydrochloric acid, the solution thus obtained is concentrated, diluted with water and the mixture of crude terpenoids is filtered off.

According to another method the crude product is treated with an alkali metal carbonate, preferably sodium or potassium carbonate or an alkali metal bicarbonate, preferably potassium bicarbonate, in the presence of a solvent, for example an alkanol having from 1 to 6 carbon atoms, preferably methanol or ethanol, at a temperature in the range of from ambient to the boiling point of the solvent used, preferably 30 to 40"C. The solution obtained is concentrated, diluted with water and the mixture of crude terpenoids is filtered off.

According to a third method, the crude product is treated with a basic metal oxide, for example basic alumina, in the presence of a solvent. preferably an aromatic hydrocarbon, especially benzene or toluene. or an ether, preferably diethyl ether, dioxane, or tetrahydrofuran, usually at a temperature in the range of from ambient to the boiling point of the solvent used, preferably 30 to 4() C. The suspension obtained may then be filtered and the metal oxide treated repeatedly with an organic solvent, preferably ethyl acetate, acetone, chloroform, methanol, ethanol and/or a mixture of any two or more of these solvents, and the resulting extracts evaporated to dryness under reduced pressure, preferably iii vacua. to give a mixture of crude terpenoids.

The mixture of crude terpenoids obtained by any one of the processes described above can be subjected to chromatographic separation. Due to the difference in chromatographic mobility and by the visualisation of terpenoids with spray reagents, for example vanillin-sulphuric acid or anisaldehyde-sulphuric acid, a semi-pure terpenoid can be obtained.

The mixture of crude terpenoids obtained prior to chromatographic separation or the semi-pure terpenoid after chromatographic separation can be recrystallised from solvents, for example ethyl acetate, chloroform or benzene, each in admixture with an aliphatic hydrocarbon having from 5 to 7 carbon atoms, preferably petroleum ether, hexane or pentane, to obtain Coleforsin, the compound of the invention, having a melting point of 208 to 211"C.

The active substance Coleforsin has the molecular formula C22H3407, which has been computed from the molecular weight of 410 mass units determined by mass spectroscopy and the following elemental analysis data: found C = 64 to 65%; H = 8 - 8.5; calculated C = 64.37%; H = 8.35%.

The ultraviolet spectrum show absorption maxima at wavelengths of 208 to 210 m (Emax, 1,000 to 1,200) and 305 to 310 nm (Emax 45 to 50).

In the accompanying drawing are shown in the infrared spectrum (Figure 2) and the nuclear magnetic resonance spectrum (Figure 1). The optical rotation [a]D depends on the solvent in which the measurements are performed, the values in methanol being in the range of from + 15 to + 25 (c = 2.8 in CHSOH).

Coleforsin is soluble in organic solvents such, for example, as methanol, ethanol, propanol, acetone, chloroform, methylene chloride, ethyl acetate, benzene, ether, dioxan, tetrahydrofuran, dimethylformamide and dimethyl sulphoxide.

Coleforsin has physical and chemical properties usually shown by terpenoids. The results of spectral and chemical analysis reveal that Coleforsin is a terpenoid possessing the following carbon skeleton

and having oxygen-containing functional groups and substituents corresponding to the following structural elements: a) two secondary hydroxy groups, b) one tertiary hydroxy group, c) one oxa group, d) one acetoxy group and e) one keto group.

The spectroscopical and chemical data indicate for Coleforsin the following structure

Accordingly, the present invention provides a compound of the formula I shown above.

It should be understood that when used herein, the name Coleforsin and the formula therefor include all possible stereoisomers of the compound and mixtures thereof.

The invention also provides a salt, especially a physiologically tolerable salt, of the above compound of the invention.

The compound of the invention has a very good hypotensive effect. Moreover, it has a vasodilating effect on peripheral vessels and a positive inotropic activity.

Accordingly, the present invention provides a pharmaceutical preparation which comprises Coleforsin or a physiologically tolerable salt thereof, in admixture or conjunction with a pharmaceutically suitable carrier.

Owing to its hypotensive effect Coleforsin can be used in the treatment of heart and circulatory diseases, for example essential and malignant hypertonia, myovascular insufficiency, Angina pectoris, and disorders in the peripheral circulation. In therapy, the compound can be used in combination with other pharmacologically active substances, for example diuretics, anti-arrhythmics, 3-blockers, tranquilisers, coronary dilating substances or hypolipidemics.

Owing to its positive inotropic activity, the compound of the invention is suitable for the treatment of myovascular insufficiency, collapse due to hemorrhage and in the state of shock.

The compound of the invention can be administered perorally or intravenously.

Depending on the severity of the disease and the weight of the patient, the daily dose may vary for example from 25 to 1000 mg. Preferably a pharmaceutical preparation is in dosage unit form.

For peroral administration tablets or dragees containing 25 to 1,000 mg of active compound and the usual auxiliaries and carrier materials, e.g. talcum, starch or lactose, are preferably used. For intravenous administration the active compound may be dissolved or suspended in a pharmaceutically tolerated plant oil, for example peanut oil or sesame oil, or dissolved in an alcohol e.g. ethanol, propanediol, or glycerol, or in a mixture thereof.

Tests with anaesthetised normotensive cats have shown the following results: after an intravenous injection of 0.50 mg of the active substance per kg of body weight in propylene glycol, a mean blood pressure of 120 mm Hg decreased to 60 mm Hg within 2 minutes; it was stabilised only after 10 minutes. Where 20 mg of the compound per kg of body weight was administered in propylene glycol intraduodenally to the cats, the mean blood pressure of 120 mm Hg decreased to 80 mm Hg within 5 minutes and was stabilised only after 90 minutes.

Experiments wtih normotensive dogs have shown that intravenous administration of 0.50 mg of the active substance per kg of body weight in propylene glycol decreased the blood pressure of 2()()/125 mm of Hg to 125/80 mm of Hg within 2 minutes. This effect lasted for about 15 minutes.

The active compound showed blood pressure lowering activity in spontaneous hyperten sivc rats. A daily dose of 1(1 mg of the active compound per kg of body weight when given orally for 5 days produced a decrease in systolic blood pressure from 207 mm of Hg to 159 mm of Hg on the third day of treatment; the pressure remained at this level for the remaining 2 days of the treatment.

The hind leg peripheral circulation experiment in dogs showed that 0.10 mg of the active compound per kg of body weight when administered intra-arterially decreased the hind leg perfusion pressure from 125 mm of Hg to 50 mm of Hg within 2 minutes.

The isolated guinea pig heart perfusion experiment showed that 30 llg of the active compound given through the aorta increased the force of contraction by about 120 percent.

The intraperitoneal toxicity (LD5") in mice amounted to 150 mg of active substance per kg of body weight.

The following Examples illustrate the invention.

Example 1 Dried and ground roots of Coleus forskohlii (12 kg) were extracted twice with 25 1 portions of petroleum ether (b.p. 60-80"). The roots were then repeatedly extracted with 25 1 portions of benzene at a temperature of 35-4() C to exhaustion. 100 1 of benzene were used. The combined benzene extracts were filtered and evaporated iii vacua. The residue (about 300 g) was dissolved in about 60 ml of benzene and about 1 1 of petroleum ether (b.p. 60 - 80") was added with stirring. A precipitate separated. The suspension was allowed to settle, the supernatant layer was removed and the residue was resubjected three times to the process of dissolution in benzene and precipitation with petroleum ether. After the third precipitation, the precipitate was filtered and dried.

To a stirred solution of the precipitate (7.0 g) in dry dioxan (140 ml) sodium methylate (1.0 g) was added and the solution was stirred at room temperature for one hour. A solution of acetic acid was added to the solution till the pH was adjusted to a value of about 5, the solvent was evaporated in vacuo. water was added. the mixture was chilled at 0.5"C for 1/2 hr., and the resulting precipitate was filtered off. The precipitate (about 6.0 g) was chromatographed on a column of silica gel. The appropriate chromatography fractions, as indicated by monitoring the eluted fractions by thin layer chromatography wherein visualisation was carried out with spray reagents specific for terpenoids, for example vanillin-sulphuric acid. were combined and evaporated to dryness in vacua. The residue was re-crystallised from ethyl acetatc-petroleum ether (b.p. 60-80") to give colourless crystals of Coleforsin.

Example 2 Dried, ground and defatted roots of Coleusforskohlii were extracted with benzene, the extract was concentrated and the residue was repeatedly precipitated from its solution in benzene with petroleum ether as described in Example 1.

Potassium carbonate (1.4 g) was added to a solution of the precipitate (6.0 g) in methanol (200 ml) and the solution was stirred for one hour at room temperature. The solution was concentrated to about 1/10 its volume and water was added to give a precipitate. The precipitate was filtered and recrystallised from chloroform-petroleum ether (b.p. 60-80"C) to give colourless crystals of Coleforsin.

Example 3 Dried, ground and defatted roots of Coleus forskohlii were extracted with benzene, the extract was concentrated and the residue was repeatedly precipitated from its solution in benzene with petroleum ether as described in Example 1.

90 g of alumina were added to a solution of the precipitate (6.0 g) in benzene (150 ml) and the suspension was stirred at room temperature. The benzene layer was filtered and the alumina was repeatedly extracted by trituration with ethyl acetate-methanol (95:5). The combined ethyl acetate-methanol (95:5) extracts were evaporated to dryness in vacua. The residue was recrystallised from benzene-petroleum ether (b.p. 60-80 ) (1:5) to give colourless crystals of Coleforsin.

Example 4 Dried and ground roots (12 kg) of Coleus forskohlii were exhaustively extracted with 25 1 portions of chloroform 75 1 of chloroform were used. The combined chloroform extracts were filtered and evaporated in vacua. The residue (about 300 g) was stirred three times with 1.5 1 portions of methanol and filtered. The filtrate was evaporated to dryness to give a gummy residue (about 200 g). The residue was processed further as described in Examples 1, 2 and 3 for the residue from the benzene extract of the plant.

Example 5 Dried and ground whole plant material of Coleus forskohlii (12 kg) was repeatedly extracted with 25 1 portions of methanol to exhaustion. 100 1 of methanol were used. The combined methanol extracts were filtered and evaporated in vacua. The residue (about 650 g) was partitioned between 2 1 chloroform and 1.5 1 water. The chloroform layer was separated. The aqueous layer, together with the interphase between the aqueous and chloroform layers, was extracted repeatedly with 1.5 1. portions of chloroform and the chloroform layer was separated. The combined chloroform extracts were filtered, dried over anhydrous sodium sulphate and evaporated in vacuo to give a gummy residue (about 300 g). The residue was processed further according to the procedure described in Examples 1, 2 and 3 for the residue obtained from the benzene extract of the plant.

WHAT WE CLAIM IS: 1. A compound of the structural formula

2. A process for obtaining Coleforsin which comprises (a) extracting a plant of the Labiatae family with a solvent which will dissolve the desired substance to obtain a solution and obtaining a concentrate or residue therefrom by evaporation, (b) subjecting the concentrate or residue from step (a) to a solvent treatment to effect preliminary purification on the basis of differing solubilities of the desired and undesired material, (c) treating the crude product obtained from step (b) with a base to obtain a crude terpenoid mixture, and (d) purifying the crude terpenoid mixture from step (c) to obtain Coleforsin.

3. A process as claimed in claim 2, wherein step (b) comprises (i) dissolving the concentrate or residue from the previous step and precipitating out the crude product therefrom, by means of a non-solvent for the crude product, or precipitating out by means of a non-solvent therefor, the crude product from the concentrate from the previous step, and, if desired, re-dissolving and re-precipitating one or more times; or (ii) extracting the residue or concentrate obtained from step (a) with an alkanol, obtaining a residue or concentrate from the alkanol solution and treating this as defined in (i); or (iii) partitioning the residue or concentrate obtained from step (a) between two solvents immiscible with each other and obtaining a residue or concentrate from one solvent and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (43)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   Example 3 Dried, ground and defatted roots of Coleus forskohlii were extracted with benzene, the extract was concentrated and the residue was repeatedly precipitated from its solution in benzene with petroleum ether as described in Example 1.

   90 g of alumina were added to a solution of the precipitate (6.0 g) in benzene (150 ml) and the suspension was stirred at room temperature. The benzene layer was filtered and the alumina was repeatedly extracted by trituration with ethyl acetate-methanol (95:5). The combined ethyl acetate-methanol (95:5) extracts were evaporated to dryness in vacua. The residue was recrystallised from benzene-petroleum ether (b.p. 60-80 ) (1:5) to give colourless crystals of Coleforsin.

   Example 4 Dried and ground roots (12 kg) of Coleus forskohlii were exhaustively extracted with 25 1 portions of chloroform 75 1 of chloroform were used. The combined chloroform extracts were filtered and evaporated in vacua. The residue (about 300 g) was stirred three times with 1.5 1 portions of methanol and filtered. The filtrate was evaporated to dryness to give a gummy residue (about 200 g). The residue was processed further as described in Examples 1, 2 and 3 for the residue from the benzene extract of the plant.

   Example 5 Dried and ground whole plant material of Coleus forskohlii (12 kg) was repeatedly extracted with 25 1 portions of methanol to exhaustion. 100 1 of methanol were used. The combined methanol extracts were filtered and evaporated in vacua. The residue (about 650 g) was partitioned between 2 1 chloroform and 1.5 1 water. The chloroform layer was separated. The aqueous layer, together with the interphase between the aqueous and chloroform layers, was extracted repeatedly with 1.5 1. portions of chloroform and the chloroform layer was separated. The combined chloroform extracts were filtered, dried over anhydrous sodium sulphate and evaporated in vacuo to give a gummy residue (about 300 g). The residue was processed further according to the procedure described in Examples 1, 2 and 3 for the residue obtained from the benzene extract of the plant.

   WHAT WE CLAIM IS: 1. A compound of the structural formula
2. 2. A process for obtaining Coleforsin which comprises (a) extracting a plant of the Labiatae family with a solvent which will dissolve the desired substance to obtain a solution and obtaining a concentrate or residue therefrom by evaporation, (b) subjecting the concentrate or residue from step (a) to a solvent treatment to effect preliminary purification on the basis of differing solubilities of the desired and undesired material, (c) treating the crude product obtained from step (b) with a base to obtain a crude terpenoid mixture, and (d) purifying the crude terpenoid mixture from step (c) to obtain Coleforsin.
3. 3. A process as claimed in claim 2, wherein step (b) comprises (i) dissolving the concentrate or residue from the previous step and precipitating out the crude product therefrom, by means of a non-solvent for the crude product, or precipitating out by means of a non-solvent therefor, the crude product from the concentrate from the previous step, and, if desired, re-dissolving and re-precipitating one or more times; or (ii) extracting the residue or concentrate obtained from step (a) with an alkanol, obtaining a residue or concentrate from the alkanol solution and treating this as defined in (i); or (iii) partitioning the residue or concentrate obtained from step (a) between two solvents immiscible with each other and obtaining a residue or concentrate from one solvent and

   treating this as defined in (i).
4. 4. A process as claimed in claim 3, wherein the crude product is precipitated in step (b) with an aliphatic hydrocarbon having from 5 to 7 carbon atoms.
5. 5. A process as claimed in claim 3 or claim 4, wherein the solvent used for dissolution in step (b) is an aromatic hydrocarbon, a halohydrocarbon or an ester.
6. 6. A process as claimed in claim 5, wherein the solvent is benzene, toluene, chloroform or ethyl acetate.
7. 7. A process as claimed in any one of claims 3 to 5, wherein the dissolution is carried out at a temperature in the range of from 30 to 40 C.
8. 8. A process as claimed in any one of claims 3 to 7, wherein the alkanol used for the procedure (bii) has from l to 6 carbon atoms.
9. 9. A process as claimed in claim 8. wherein the alkanol is methanol or ethanol.
10. 10. A process as claimed in any one of claims 3 to 9, wherein the alkanol in procedure (bii) is used in an amount of from 1() to 40 parts by weight per part by weight of residue.
11. 11. A process as claimed in any one of claims 3 to 10, wherein the alkanol treatment is carried out at a temperature in the range of from 30 to 40 C.
12. 12. A process as claimed in any one of claims 3 to 7, wherein the two solvents used in procedure (bii) are water and an aromatic hydrocarbon or water and an aliphatic or aromatic halohydrocarbon.
13. 13. A process as claimed in claim 12, wherein the solvents are benzene and water or chloroform and water.
14. 14. A process as claimed in claim 12 or claim 13, wherein the solvents are used in a ratio of substantially 1 1 by volume.
15. 15. A process as claimed in any one of claims 2 to 14, wherein the extraction step (a) is carried out with an aromatic hydrocarbon, an aliphatic or aromatic halohydrocarbon, dialkyl ether, dialkyl ketone, an alkanol, a carboxylic acid or an ester thereof, dimethylformamide, dioxan, tetrahydrofuran or dimethyl sulphoxide.
16. 16. A process as claimed in claim 15. wherein the extraction is carried out with an aromatic hydrocarbon or an aliphatic halohydrocarbon having from 1 to 3 carbon atoms and up to 3 chlorine atoms or with an alkanol having from 1 to 6 carbon atoms.
17. 17. A process as claimed in claim 16, wherein the extraction is carried out with benzene, toluene, xylenc, methylene chloride, chloroform, methanol or ethanol.
18. 18. A process as claimed in any one of claims 15 to 17, wherein procedure (bi) is carried out when an aromatic hydrocarbon or an aliphatic halohydrocarbon is used for step (a), or procedure (bii) is carried out when an aromatic hydrocarbon or a halohydrocarbon is used for step (a) or procedure (biii) is carried out when an alkanol is used for step (a).
19. 19. A process as claimed in any one of claims 2 to 18, wherein the extraction step (a) is carried out with a weight ratio of plant material to extracting agent of from 1: 2 to 1:10.
20. 20. A process as claimed in any one of claims 2 to 19, wherein step (a) is carried out at a temperature in the range of from 30 to 40"C.
21. 21. A process as claimed in any one of claims 2 to 20, wherein before step (a) the plant is treated with an aliphatic hydrocarbon in which it is insoluble, to remove plant fats and waxes.
22. 22. A process as claimed in claim 21, wherein the hydrocarbon is petroleum ether, pentane or hexane.
23. 23. A process as claimed in claim 21 or claim 22. wherein the hydrocarbon is used in a weight ratio of plant material to solvent of from 1 . 2 to 1 . 10.
24. 24. A process as claimed in any one of claims 2 to 23, wherein step (c) is carried out by treatment (i) with an alkali metal alkoxide in a solvent. and the pH is then adjusted to a value in the range of from 5 to 7, and the solution is then concentrated, diluted with water and the mixture of crude terpcnoids filtered off, or (ii) with an alkali metal carbonate or bicarbonate in a solvent and the solution is then concentrated, diluted with water and the mixture of crude terpenoids filtered off, or (iii) with a basic metal oxide in a solvent and the suspension is then filtered, the metal oxide treated with an organic solvent and the crude terpenoid obtained from the organic extract by evaporation to dryness.
25. 25. A process as claimed in claim 24, wherein step (c) is carried out (i) with sodium methoxide or ethoxide in dioxan, tetrahydrofuran or diethyl ether, (ii) with sodium or potassium carbonate or potassium bicarbonate in methanol or ethanol, or (iii) with basic alumina in benzene. toluene, dioxan. tetrahydrofuran or diethyl ether and the subsequent treatment with organic solvent is carried out with ethyl acetate, acetone. chloroform. methanol or ethanol.
26. 26. A process as claimed in claim 25, wherein the treatment is carried out at a temperature in the range of from 30 to 40"C.
27. 27. A process as claimed in any one of claims 2 to 26, wherein step (d) comprises recrystallisation or chromatographic separation and recrystallisation.
28. 28. A process as claimed in claim 27, wherein the recrystallisation is carried out with ethyl acetate, chloroform or benzene in admixture with petroleum ether, hexane or pentane.
29. 29. A process as claimed in any one of claims 2 to 28, which is carried out on a plant or plant parts which have been ground.
30. 30. A process as claimed in any one of claims 2 to 29, wherein the plant is a plant of the Coleus species.
31. 31. A process as claimed in claim 30, wherein the plant is Coleus forskohlii.
32. 32. A process as claimed in claim 31, which is carried out on the roots of Coleus forskohlii.
33. 33. A process as claimed in claim 1, carried out substantially as described in any one of Examples 1 to 5 herein.
34. 34. Coleforsin whenever obtained by a process as claimed in any one of claims 2 to 33.
35. 35. The pharmacologically active substance Coleforsin having the empirical formula C22Hl407, a molecular weight, as determined by mass spectroscopy, of 410, a melting point of from 208 to 211"C, an ultra-violet spectrum having absorption maxima at 208 - 210 nm and 305 - 310 nm, and an IR and NMR spectrum as shown in the accompanying drawings.
36. 36. A pharmacologically active substance obtainable from a plant of the Labiatae family and having a melting point of from 208 to 2110C, the molecular formula C22H3407, and the structural formula
37. 37. A salt of a compound claimed in any one of claims 1 and 34 to 36.
38. 38. A physiologically tolerable salt of a compound claimed in any one of claims 1 and 34 to 36.
39. 39. A pharmaceutical preparation which comprises a compound as claimed in any one of claims 1, 34 to 36 and 38, in admixture or conjunction with a pharmaceutically suitable carrier.
40. 40. A pharmaceutical preparation as claimed in claim 39, which is in dosage unit form.
41. 41. A pharmaceutical preparation as claimed in claims 39 or claim 40, which is in a form suitable for oral administration.
42. 42. A pharmaceutical preparation as claimed in claim 41, which contains from 25 to 1000 mg of active compound per dosage unit.
43. 43. A pharmaceutical preparation as claimed in claim 39 or claim 40, which is in a form suitable for intravenous administration.