Taxol (or paclitaxel) is a natural diterpenoid.
It is isolated from the barks of the plants Taxus bravifolia , Taxus cuspidata, and Taxus canadensis
Family: Taxaceae
In this genus there are eight different species present in northern in northern hemisphere.
Generally, 1 Kg taxol will be isolated from seven tons of dried bark.
Taxol has the following characteristics:
1) It has a taxane ring system.
2) It has a 4-membered octane ring.
3) At C -13 of the taxane ring , an ester side chain is present, which is responsible for the cytotoxic activity of taxol.
4) At C-2 of the ester side chain, a hydroxyl moiety is present, which causes enhancement of the cytotoxic activity.
Industrial production of taxol involves the following steps:
1) The dried ground bark is extracted with methanol or ethanol, and alcohol is removed by concentrating the combined extract.
2) The obtained concentrate is re-extracted with dichloromethane and the solvent extract is concentrated to a powder.
3) This powder is stirred with a mixture of acetone and ligroin (1:1) and filtered to remove the insoluble matter.
4) The filtrate containing taxol is concentrated, dissolved in 30% acetone in ligroin, and applied to a column of Florisil.
5) The taxol fraction from the column is twice purified by crystallisation.
6) The crystalline taxol is subjected to chromatography on a silica column. The closely related analogue, cephalomannine, separates out from taxol.
7) The purified taxol obtained from the column is crystallised twice.
8) The unseparated mixtures and mother liquors are recycled through the silica column to obtain more pure taxol.
Production:
Put the dried powder of the leaves of plant in the rotary extractor.
Extract the leaves with ethanol with gentle agitation and rotation at 40-45°C.
Concentrate the extract and repeat the same process two more times so that the active constituents are completely extracted from the leaves.
Separate all the extract and leave the residue.
This extract is distributed with four time methanol and then treats with hexane to remove the pigment and fatty materials.
Extract this solvent with chloroform through liquid- liquid extraction.
Concentrate the chloroform extract and perform the column chromatography of this residue using chloroform and methanol as mobile phase and column of silica gel G to segregate different taxanes.
Last purification is done by HPLC using Hexane: ethyl acetate (1:1) as solvent system.
Taxol can be estimated by the following steps:
In a 250ml conical flask, 0.125gm of drug + 25ml water + 50ml of 0.83M KMnO4 + 100ml of H2SO4 are taken.
The solution is heated up to the boiling point, cooled, and transferred to a volumetric flask.
The solution is diluted with distilled water up to 250ml.
From the above solution, 50ml is treated with 1M Fe(NH4)2SO4, ferroin sulphate solution (an indicator) is added drop wise, and the blank is performed.
Each ml of 0.1M ferrous ammonium sulphate ≡ 0.000675gm of cellulose.
Estimation:
Weight around 0.125 gm of drug in conical flak and add 25 ml water add 50 ml of 0.83 M potassium permagnate and add 100 ml of sulphuric acid.
Boil the solution and then cool it and transfer in volumetric flask.
The solution is distilled with water to 250 ml.
From this solution separate out the 50 mi solution and add 1 M of ferrous ammonium sulphate.
Perform blank and make necessary correction.
Each ml of 0.1M Fe(NH4)2SO4 ≡ 0.000675Gm of drugs.
Thermospray ionization
HPLC-MS: The analysis was performed using triple stage quadrupole mass spectrometer with TSP2 interface Source blank temperature : 230°C Vaporizer temperature : 70°C Repeller Voltage : 30 V Discharge on mode : 1800 V Instrument scanned from m/z 300 to m/z1000.
The mobile phase use in HPLC is H2O:MeCN:MeOH (85:5:10) using flow rate 1ml/min. Dissolve the sample in methanol at concentration 1mg/ml.
Utilisation
Taxol inhibits the polymerization of tubulin similar to podophylotoxin and vincristine.
Taxol is in dicated in the treatment of bladder, prostate, melanoma, oesophageal, and other solid tumour cancers.
Taxol is a prescription medicine used against the following forms of cancer:
1) Advanced ovarian cancer.
2) Breast cancer; upon failure of combination chemother apy for metastatic disease or relapse within 6 months of adjuvant chemotherapy, taxol is the preferred choice.
3) Non-small cell lung cancer in patients who cannot undergo curative surgery and/or radiation therapy.
4) Kaposi’s sarcoma forms patches of abnormal tissue growth under the skin, in the nose, in the mouth lining, in the throat, or other organs
The toxicity produce by the treatment of taxol is neutropenia, peripheral neuropathy, cardiovascular problems, vomiting, alopecia, nausea, hypersensitivity etc.