Vibrational spectroscopic study of selected alkaloids with therapeutic effects

Abstract

Nowadays, scientists from various fields of chemistry, biochemistry or biology are interested in trace detection of different natural or synthetic substances such as alkaloids which can either positively or negatively affect human physical and mental health. Linked with that, growing interest in broad applications of advanced vibrational spectroscopic techniques encourage higher demands in this rapidly developing field. This study is focused on a detailed description of infrared and Raman spectra of two natural alkaloids (namely galantamine and buprenorphine) and study of their optical response in the vicinity of gold and silver nanostructured surface. The interpretation of individual bands was supported by DFT calculations. Both alkaloids were also studied using surface-enhanced Raman scattering technique aiming at a comparison with non-enhanced vibrational data construction of concentration-dependent series and determination of their limit of detection. From SERS spectral series the regression models were developed to predict alkaloids concentration in the range of 10^-3-10^-7 mol/l, in the case of buprenorphine adsorbed on Ag substrate we were able to broaden this range down to 10^-9 mol/l.

Keywords: Alkaloids; Buprenorphine; Galantamine; Infrared spectroscopy; Silver and gold substrates; Surface-enhanced Raman scattering.