Complete (1)H NMR spectral fingerprint of huperzine A.
Complete analysis of the (1)H NMR spectrum of huperzine A, 1-amino-13-ethylidene-11-methyl-6-aza-tricyclo[7.3.1.0(2, 7)]trideca-2(7),3,10-trien-5-one, a Lycopodium alkaloid and anti-Alzheimer drug lead containing an ABCD(E)(MN)(OP)X(3)Y(3)-type system of 15 nonexchangeable proton spins, is reported for the first time, and earlier assignments are corrected. The complete (1)H parameter set of 11 chemical shifts clarifies the diastereotopism of both methylene groups, and provides a total of 38 observed H,H-couplings including 31 long-range ((4-6)J) connectivities. The NMR data is consistent with the comparatively rigid alicyclic backbone predicted by molecular mechanics calculations, and forms the basis for (1)H NMR fingerprint analysis for the purpose of dereplication, purity analysis, and elucidation of structural analogs.
Niemitz
Matthias
M
Department of Biosciences, University of Kuopio, FIN-70211 Kuopio, Finland.
Laatikainen
Reino
R
Chen
Shao-Nong
SN
Kleps
Robert
R
Kozikowski
Alan P
AP
Pauli
Guido F
GF
D000470:Alkaloids; D002800:Cholinesterase Inhibitors / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D015394:Molecular Structure; D011522:Protons; D012717:Sesquiterpenes / Q000737:chemistry*; D013237:Stereoisomerism
D000470:Alkaloids; D002800:Cholinesterase Inhibitors; D011522:Protons; D012717:Sesquiterpenes; C050426:huperzine A