Studies on the Origin of (-)-α-Bisabolol and Chamazulene in Chamomile Preparations; Part I. Investigations by Isotope Ratio Mass Spectrometry (IRMS)

Abstract

IRMS was used to determine the δ¹³C-and δD-values of dried plant material and essential oil fractions of Chamomilla recutita and Vanillosmopsis erythropappa and of isolated components thereof. Both plants turned out to follow the same C₃ photosynthetic pathway. The carbon isotope ratios ( δ¹³C-values) of chamomile-derived bisabolol ranged from -32‰o to -30‰; the corresponding δD-values varied between -240‰ and -205‰. Vanillosmopsis bisabolol differed significantly, with δ¹³C-values of approximately -27‰, and a δD-value of about -175‰. In addition, chamazulene of chamomiie was characterized by a δ¹³C-value of -31‰, whereas in chamazulene from Achillea millefolium lower carbon discrimination was found (δ¹³C = -30‰). The δ¹³C-values allowed us to detect adulterations of chamomiie preparations. The isolation of bisabolol, a main ingredient of these preparations, and subsequent IRMS analysis is much more tedious than GC/IRMS, which makes it possible to determine the carbon isotope ratio of bisabolol without prior isolation. Only one commercial chamomiie preparation was completely free of non-chamomile admixtures. Our investigations clearly demonstrate that admixtures of natural compounds can be detected in chamomile oil and chamomile preparations even if there is no difference in the photosynthetic mechanism of the corresponding plants.

Key words

(-)-α-Bisabolol - chamazulene - Chamomilla recutita - Vanillosmopsis erythropappa - Achillea millefolium - adulteration of essential oils - isotope ratio mass spectrometry (IRMS)