Tetrahedron Letters
An optimized method for the synthesis of amino-functionalized
phosphatidylcholine
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Fanzhi Kong , Goreti Ribeiro Morais, Robert A. Falconer, Chris W. Sutton
Institute of Cancer Therapeutics, School of Life Sciences, University of Bradford, Bradford BD7 1DP, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Phosphatidylcholine analogues were synthesised as affinity ligands for the capture of membrane pro-
teins. Several protecting group strategies were investigated to synthesize the amino-functionalized phos-
phatidylcholine: 11-aminoundecyl 2-(trimethylammonio)ethyl phosphate (4). The acid-mediated
deprotection of the Boc group generated a mixture of the target products which could only be purified
by HPLC. However, an alternative strategy, using the hydrazine-labile phthalimide group route, followed
by a gel filtration step proved straightforward to afford the desired amino-functionalized phosphatidyl-
choline product in high yield and purity.
Received 28 September 2011
Revised 31 October 2011
Accepted 18 November 2011
Available online 26 November 2011
Keywords:
Phosphatidylcholine (PC)
Boc deprotection
Ó 2011 Elsevier Ltd. All rights reserved.
Phthalimide deprotection
Phospholipid purification
Cytochrome P450s (CYPs) are a superfamily of mixed-function
oxidases, members of which are present in virtually all living
organisms. CYPs are characterized into families and sub-families
by their sequence similarities. There are 103 isoforms identified
in mouse and 57 in humans, predominantly expressed in the liver,
but also specific forms occurring in other tissues, including
tumours. Each member can also be characterized by their substrate
(endogenous and foreign metabolites) specificity. CYPs are thought
to have evolved, in part, as a protective adaptive response against
the toxic effects of environmental chemicals.1 They are the most
important drug metabolizing enzymes in mammals, and, in
humans, are responsible for the phase I metabolism of 70–80% of
all clinically used drugs.2 Essentially, by monitoring the changes
in the protein expression profile of CYPs, the effect of drugs on tar-
get tissues can be determined, and hypotheses proposed as to the
likely mechanisms of drug action. In addition to their detoxifica-
tion role, CYPs are also responsible for the conversion of chemical
toxins and procarcinogens into their toxic or carcinogenic forms.3
The ability of CYPs to activate chemical toxins has been exploited
in cancer chemotherapy where several anticancer drugs, including
cyclophosphamide, tamoxifen and banoxantrone, are known to
require metabolic CYP activation in order to exert their cytotoxic
effects.4 Because of their ability to metabolize drugs, CYPs have
huge significance in pharmaceutical research.5 The action of CYPs
is one of the major causes of adverse drug reactions to many
marketed drugs and drug-combination therapies, and many fail-
ures of novel drugs during their development have been attributed
to their interactions with this class of enzyme. For example, drugs
may be metabolized too rapidly by CYPs before they have had time
to be effective, or they may be metabolized into smaller molecules
which are toxic beyond their site of proposed action. Certain drugs
may also inhibit the activity of a CYP enzyme which is involved in
the metabolism of another drug that, given at the same time, can
become elevated in the patient to levels which can cause side ef-
fects or become dangerous. There is now the potential to use the
CYP profile of a subject to develop personalized medicines. A sub-
ject’s genotype may impact on the pharmacodynamics (drug con-
centration vs time vs pharmacological effect), pharmacokinetics
(absorption, distribution, metabolism and excretion) and/or the
incidence of adverse events. The use of pharmacogenetic tests to
determine this genetic variation can facilitate correct drug selec-
tion for treatment efficacy and minimize adverse side effects.
In the course of our research into the affinity purification of
membrane proteins such as the CYP450s, we required a route to
synthesize the amino-functionalized phosphatidylcholine: 11-
aminoundecyl 2-(trimethylammonio)ethyl phosphate (4), which
would be immobilized onto epoxy-activated softgel agarose to
facilitate affinity enrichment-based proteomics experiments. There
have been many papers and patents published outlining the
synthesis of phosphatidylcholine derivatives,6 but each of these
methods has drawbacks. Some processes are lengthy and overly
complex,7 others use expensive and toxic reagents,8 some require
heavy metals during purification, or result in poor yields.9 To
address these issues, we report two new and simple methods for
the synthesis and purification of phosphatidylcholine derivatives
in excellent yields, utilizing relatively cheap, commercially avail-
able starting materials.
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Corresponding authors. Tel.: +44 (0) 1274 235894.
(C.W. Sutton).
0040-4039/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.