Phenylethylamine and piperidine alkaloids in aloe species.
Of the approximately 300 species of ALOE (Liliaceae) native to Africa and Arabia, leaf extracts of 224 species have been examined chromatographically for alkaloids using ninhydrin, Dragendorff's reagent, nitroprusside, and iodoplatinate as revealing agents. From these, 48 (21%) species contained compounds giving a strong colorimetric reaction with at least one of these reagents. Tyramine derivatives were identified in 18 species and piperidine derivatives in a further 6 species. The other coloured zones remain unidentified but often appeared to represent common amino acids. Some taxonomic correlations are suggested. The presence of the toxic hemlock alkaloids in aloes readily available for potential medicinal use by local inhabitants sounds a note of caution against the unthinking use of these otherwise useful plants.