Na
ture is a well-recognized source of compounds of in
teres
t, bu
t access is of
ten an issue. One per
tinen
t example is
the cinchona alkaloids from
the bark of
Cinchona calisaya. In
this experimen
t, s
tuden
ts a
t the
third-year undergradua
te level under
take
the selec
tive isola
tion and charac
teriza
tion of
two of
the four main alkaloids presen
t in
the bark. Beginning wi
th powdered bark, acid鈥揵ase ex
trac
tion, followed by selec
tive crys
talliza
tion, serves
to yield cinchonine, na
ture鈥檚 chiral ca
talys
t, from
the complex mix
ture. Slow crys
talliza
tion provides sui
table quali
ty crys
tals for X-ray analysis. S
tuden
ts readily apprecia
te
the
three-dimensional na
ture of
this chiral ca
talys
t, which aids subsequen
t NMR spec
troscopic analysis. Manipula
tion of
the mo
ther liquor by
thin-layer and flash column chroma
tographic
techniques proves a simple bu
t elegan
t me
thod
to furnish quinine, na
ture鈥檚 an
ti-malarial agen
t. Bo
th alkaloids are
trea
ted
to an in
tensive s
truc
ture elucida
tion workshop comprising 1- and 2-dimensional NMR, infrared, and mass spec
trome
try. The me
thod is economical, polished, and robus
t, bringing
the s
tuden
t on a journey from crude plan
t ma
terial
to medicinally impor
tan
t na
tural produc
ts in
three, 2-h labora
tory sessions. Moreover, ques
tions in
the s
tuden
t handou
t and model answers in ins
truc
tor鈥檚 no
tes, respec
tively, require
tha
t s
tuden
ts engage fur
ther in
topics associa
ted wi
th
the con
tex
t of
this prac
tical.
Keywords:
thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Upper%5C-Division+Undergraduate&qsSearchArea=searchText">Upper-Division Undergraduate; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Laboratory+Instruction&qsSearchArea=searchText">Laboratory Instruction; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Organic+Chemistry&qsSearchArea=searchText">Organic Chemistry; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Hands%5C-On+Learning%2FManipulatives&qsSearchArea=searchText">Hands-On Learning/Manipulatives; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Biosynthesis&qsSearchArea=searchText">Biosynthesis; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Chromatography&qsSearchArea=searchText">Chromatography; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Drugs%2FPharmaceuticals&qsSearchArea=searchText">Drugs/Pharmaceuticals; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Natural+Products&qsSearchArea=searchText">Natural Products; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=NMR+Spectroscopy&qsSearchArea=searchText">NMR Spectroscopy; thors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=X%5C-ray+Crystallography&qsSearchArea=searchText">X-ray Crystallography