Thebaine-Synonym Paramorphine-Papaver bracteatum

C. Thebaine

Synonym Paramorphine;

Biological Sources It is obtained from the fresh capsule latex (0.125%), dried 0.25 to 0.26% of Papaver bracteatum Lindl. (Papaveraceae) (Great Scarlet Poppy, Thebaine Poppy); and the airdried milky exudation obtained from excised unripe fruits of Papaver somniferium L. (Papaveraceae)

(Opium Poppy, Poppyseed Poppy Keshi).

Chemical Structure

(5α)-6, 7, 8, 14-Tetrahydro-4, 5-epoxy-3, 6-dimethoxy-17-methylmorphinan; (C₁₉H₂₁NO₃).

Isolation Thebaine may be isolated from opium by means of the following steps, namely:

Step-1: Opium (dried latex) is treated with calcium chloride solution and then extracted with warm water. Allow it to remain as such for 24 hours.

Step-2: Filter the resulting product and collect the residue and filtrate separately.

Residue—contains the salts of calcium as lactate, sulphate, resinate and meconate (To be discarded).

Filtrate— contains the hydrochloride of various alkaloids present in opium.

Step-3: Add dilute NaOH solution (2N) carefully to the resulting filtrate and allow it to stand for 4- 6 hours. Filter the contents of the flask:

Filtrate—contains morphine, codeine and narceine

Residue—contains thebaine, papaverine and narcotine

Step-4: Dissolve the residue or precipilate in dilute ethanol (50% v/v), make slightly acidic with the addition of dilute glacial acetic acid and finally add to it approximately three volumes of boiling distilled water.

Step-5: Filter the above reaction product:

Filtrate—contains thebaine

Residue—contains papaverine and narcotine

Step-6: Concentrate the filtrate obtained in Step-5 under reduced pressure and add to it dilute NH₄OH solution to make it alkaline; and extract the liberated alkaloid thebaine successively with chloroform. Thebaine is obtained after evaportion of chloroform under vaccuo.

Characteristic Features

1. It is obtained as orthorhombic, rectangular plates by sublimation at 170-180°C under atmospheric pressure and a 1 mm distance mp 193°C (rapid heating).

2. Its physical parameters are: [α]_D¹⁵ -219⁰(p = 2 in ethanol); [α]_D²³ (p = 5 in chloroform); pK at 15°C = 6.05; and pH of a saturated solution is 7.6.

3. Solubility Profile: 1 g dissolves in 1460 ml water at 15°C, in about 15 ml hot ethanol, 13 ml chloroform, 200 ml ether, 25 ml benzene, 12 ml pyridine; and not very soluble in petroleum ether.

Identification Tests Thebaine forms a number of salt derivatives which have specific characteristic features, such as:

1. Thebaine Salicylate (C₁₉H₂₁NO₃.C₇H₆O₃): It is obtained as crystals which are soluble in 750 parts of water. Thus, thebaine may be separated from other major alkaloids of opium by forming its salicylate derivative which is sparingly soluble in water.

2. Thebaine Hydrochloride Monohydrate (C₁₉H₂₁NO₃.HCl.H2O): It is obtained as orthorhombic prisms from alcohol having [α]_D²³  -164⁰(p = 2). It is found to be soluble in about 12 parts of water and in ethanol. The pH of a 0.05 molar solution is 4.95.

3. Thebaine Oxalate Hexahydrate (2 C₁₉H₂₁NO₃.C₂H₂O₄.6 H₂O): It is obtained as prisms. It is soluble in 10 parts of water and also in ethanol; and is almost insoluble in ether.

4. Thebaine Binoxalate Monohydrate (C₁₉H₂₁NO₃.C₂H₂O₄.H₂O): It is obtained as prisms and found to be soluble in 45 parts of water.

5. Thebaine Bitartrate Monohydrate (C₁₉H₂₁NO₃.C₄H₆O₆.H₂O): It is obtained as prisms, soluble in 130 parts of water, quite soluble in both hot water and hot ethanol.

6. It gives a red colour on the addition of a few drops of cold sulphuric acid which ultimately changes to orange yellow.

Uses It is an opiate analgesic.
Source:Pharmacognosy And Pharmacobiotechnology By Ashutosh Kar