Tracking pereirine and flavopereirine in pau-pereira using Raman and SERS spectroscopies

Pau-pereira (Geissospermum vellosii) is a native tree of Brazil from which a mixture of alkaloids named pereirine and the compound flavopereirine has been isolated. Preventive and curative properties have been recorded by ethnopharmacological studies performed with Geissospermum species. Pereirine has been prescribed as a herbal drug since the early 1830's and flavopereirine has shown anticancer properties. In this work, the alkaloid content produced by G. vellosii has been investigated from 20 commercial samples collected from different localities. The identification of compounds has been performed by Raman and surface-enhanced Raman scattering (SERS) spectroscopies, with the assignment of Raman bands supported by theoretical calculations. The obtained results have demonstrated that Raman and SERS techniques are suitable to detect both pereirine and flavopereirine from raw materials, infusions prepared as teas and ethanolic extracts, which is the extraction procedure to prepare tinctures. Chemometric analysis was able to discriminate the alkaloid content present in each sample type according to the extraction methodology.