FIELD OF THE INVNETION
This invention relates to the process for purification of
paclitaxel.
BACKGROUND OF THE INVENTION
Paclitaxel is an approved anticancer drug and is a natural
product isolated from the bark of Yew tree. Since, it is available in very small quantities from natural sources, semisynthetic methods have been developed to increase the yield and to meet the demands. Further, isolation of paclitaxel of pharmaceutical grade from both plants as well as from semisynthetic crude paclitaxel is a great problem.
In case of natural extracts, low concentration of paclitaxel along with high amount of structurally similar compounds requires tedious HPLC and/or chemical purifications. The semisynthetic crude paclitaxel also contains lots of degradation products of taxanoid structure. These are mainly formed during deprotection of coupled product, because the taxane nucleus is a fragile structure. Therefore, purification of crude paclitaxel also requires HPLC purification. The HPLC equipment are expensive to intall and run, and have limitation in scale up.
The object of the present invention is to propose a process for the isolation of pharmaceutical grade pure paclitaxel from the semisynthetic crude paclitaxel and natural crude paclitaxel. Yet another object of this invention is to propose a simple process for purification using solvents. Still another object of this invention is to propose a process
for purification which does not require any sophisticated instruments.
BRIEF DESCRIPTION OF THE INVENTION
Paclitaxel is composed of two distinct units. One is baccatin, a taxane (3), and other N-benzoyl-3—pheny1isoserine, the side chain connected to baccatin through ester linkage at C-13. The 13-hydro:99.5% and total impurity NMT 0.5%).
WE CLAIM:
1. A process for the purification of paclitaxel comprising:
a) mixing crude paclitaxel of 40-50% w/w purity with a mixture of solvents selected from the group consisting of alkane and chlorinated alkane;
b) filtering the solid of step(a) followed by drying to obtain paclitaxel of 55-65% w/w purity;
c) repeating steps (a) and (b) one or more times to obtain paclitaxel of 60-70% w/w purity,
d) dissolving the solid obtained from step (c ) in alkyl ketone followed by adding alkane thereto, filtering and drying the solid thus formed to obtain paclitaxel of 80-85% w/w purity;
e) repeating step (d) one or more times to obtain paclitaxel of 85-90% w/w purity;
f) dissolving the paclitaxel of 85-90% w/w purity obtained from step (e) in alkanol and then adding water, filtering and drying the solid thus formed, to obtain paclitaxel the purity of 97-98% w/w; and
g) dissolving the solid obtained from step (f) in alkyl ketone, filtering, followed by adding alkane to the filtrate, filtering and drying the solid thus formed to obtain pure paclitaxel of 98-100% w/w purity.
2. The process as claimed in claim 1, wherein the alkane solvents used are preferable selected from pentane and hexane.

3. The process as claimed in claim 1, wherein the chlorinated alkane is preferably selected from dichloromethane, chloroform.
4. The process as claimed in claim 1, wherein the alkyl ketone is preferably selected from acetone, ethyl methyl ketone.
5. The process as claimed in claim 1, wherein the alkanol is preferably selected from methanol, ethanol.
6. The process as claimed in claim 1, wherein said crude paclitaxel is obtained from semisynthetic or natural sources.
7. The process for the purification of paclitaxel substantially as herein described.
A process for the purification of paclitaxel comprising: (a) mixing crude paclitaxel of 40-50% w/w purity with a mixture of solvents selected from the group consisting of alkane and chlorinated alkane; (b) filtering the solid of step (a) followed by drying to obtain paclitaxel of 55-65% w/w purity; (c) repeating steps (a) and (b) one or more times to obtain paclitaxel of 60-70% w/w purity, (d) dissolving the solid obtained from step (c) in alkyl ketone followed by adding alkane thereto, filtering and drying the solid thus formed to obtain paclitaxel of 80-85% w/w purity; (e) repeating step (d) one or more times to obtain paclitaxel of 85-90% w/w purity; (f) dissolving the paclitaxel of 85-90% w/w purity obtained from step (e) in alkanol and then adding water, filtering and drying the solid thus formed, to obtain paclitaxel the purity of 97-98% w/w; and (g) dissolving the solid obtained from step (f) in alkyl ketone, filtering, followed by adding alkane to the filtrate, filtering and drying the solid thus formed to obtain pure paclitaxel of 98-100% w/w purity.