Comparison of latrepirdine 1D NMR proton spectra in DMSO from two sources. Latrepirdine was custom synthesized by either Nanosyn Inc or SinoChemexper and purity was determined to be ~97.3% or >99.0%, respectively. 1D NMR proton spectra are compared here for latrepirdine synthesized by SinoChemexper (top) or Nanosyn (bottom, reprinted with permission from Wu et al, 2008 ). Aliquots of latrepirdine from both sources were tested in each protocol. Identical effects were observed regardless of source of compound, and data were pooled for overall analysis.