Isolation and partial characterization of glabrin, a neurotoxin from Cnestis glabra (Connaraceae) root barks

A neurotoxic compound, inhibiting protein synthesis in cell culture, was isolated in a yield of about 0.4 per cent from Cnestis glabra root barks (Connaraceae) by a five-step fractionation procedure (filtration on activated charcoal, treatment by neutral lead acetate and fractionations on Dowex 50 X 8 in H+ and NH+4 forms). The purified toxin appeared homogeneous on thin-layer and in gas chromatography. The compound has a low molecular weight (less than 500). It is heat-stable, insoluble in usual organic solvents and gives a positive reaction with ninhydrin. Acidic hydrolysis does not change its behaviour on an amino acid analyzer. Its possible amino acid nature is discussed. It is temporarily named glabrin.