Fig. 2. Indole alkaloids with a in Monoterpene indole alkaloids from Vinca minor L. (Apocynaceae): Identification of new structural scaffold for treatment of Alzheimer's disease

Fig. 2. Indole alkaloids with a quebrachamine framework previously described in the literature employing at least 1H NMR analysis. The difference in the H-3 chemical shift of 3-epimers can be valuable for distinguishing between these diastereomers, which is highlighted. It must be mentioned that the C-3 configuration for all compounds shown was described to the contrary in Kutney's article (Kutney et al., 1975). However, the correct configuration of these alkaloids had already been identified by Kompisˇet al. (1968).