Monoterpene indole alkaloids with acetylcholinesterase inhibitory activity from the leaves of Rauvolfia vomitoria

Cytotoxic Yohimbine‐Type Alkaloids from the Leaves of Rauvolfia vomitoria

“…Hence, the planar structure of 2 can be determined as shown in Figure 2 and belongs to yohimbine‐type alkaloid with a β ‐carbolinium group. The similar 13 C‐NMR data of ring D between 2 and other yohimbine‐type alkaloids featuring the β ‐carbolinium group together with the molecular formula of 2 (C 20 H 21 N 2 O 4 ) established by the experimental HR‐ESI‐MS data can further confirm the elucidation [18–20] …”

“…The UV absorption bands at 205, 250, 305, and 365 nm implied the presence of a β ‐carbolinium chromophore [15] . The 1 H‐ and 13 C‐NMR data of 2 ( Table 1) exhibited typical β ‐carbolinium moiety signals [18,19] . The 1 H, 1 H‐COSY spectrum established the existence of −CH(15)−CH(16)−CH(17)−CH(18)−CH 2 (19)−CH(20)−CH 2 (21)− and −CH(15)−CH(20)− structural subfragments ( Figure 2).…”

“…The correlations observed in the NOESY spectrum from H‐18 to H‐16 and H‐20 also supported the α ‐orientation of H‐18, H‐16, and H‐20. Considering the shared biogenic sources, [10,12,19] the absolute configuration of the metabolite was proposed as depicted for compound 2 .…”

“…Some MIAs, obtained from the stems and leaves of R. vomitoria , had been reported to have the significant acetylcholinesterase (AChE) inhibition activities [10,19] . Therefore, the new MIAs were screened for their AChE inhibitory activities.…”

“…The dry leaves of R. vomitoria (18 kg) were extracted with 80 % MeOH (50 L×2 h×4 times) under reflux. Using the method of pH gradient extraction, the CHCl 3 and BuOH extract at pH 9 were obtained as previously described [19] . The BuOH fraction (158 g) was subjected to a silica gel CC with CH 2 Cl 2 /MeOH (a gradient from 12 : 1 to 1 : 1) to obtain eight fractions (Frs.…”