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The following message was posted to: PharmPK
Hi everybody!
I have almost completed my doctoral work on
pharmacokinetic studies on piperine ( an alkaloid of
black peppers ( as I do not know how to post the
structure, it can be seen in Merck Index Mol wt
285.3). During this work, I have isolated a new
metabolite of this compound from rat urine. 13C and 1H
NMR studies showed that the unlike previously reported
metabolites, the new metab retains side chain with
modification only in piperidine ring as the DEPT gives
only one CH2 instead of 5 CH2 of piperidine ring (I
can send the spectras if somebody wants to have a
look). MS spectra gives mol. wt of 329. Some
scientists say that the metabolite is unstable and
gets degraded while doing NMR experiments and suggests
that proper characterisation can only be obtained by
LC-NMR-MS analysis. However, we do not have this
facility in India. I have developed HPLC for detection
of the metabolite in plasma as well as in urine. Can
somebody help me in the characterisation of this
metabolite. I cannot submit the thesis without
charaterisation.
sunil Bajad
Research Associate
Pharmacology Division
Regional Research Lab.
Jammu, India
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The following message was posted to: PharmPK
Certainly there's more information in the NMR than you're telling us. How
many carbons are seen? How many primary, secondary...etc. What are the
chemical shifts? The same would be true for the 1H. Was proton-proton
correlation done?
How was the MS done? If it was EI or LC/MS/MS were there fragment ions? Is
the compound more or less polar than parent? Has the UV spectrum changed?
The difference in molecular weight suggests a net addition of CO2, although
a direct addition of CO2 is unlikely. If degradation is a possibility
surely the simple experiment of HPLC before and after the NMR would tell you
if that's occurring. If degradation is occurring there might be unexplained
resonances although in something isolated from a biological matrix you
probably have plenty of those already.
Dale Sharp
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)