A New Monoterpene Alkaloid From the Stems of Rauvolfia vomitoria

: One new monoterpene alkaloid ( 1 ) and eight known compounds ( 2 – 9 ), belonging to two monoterpene alkaloids ( 1 – 2 ), one pyridine alkaloid ( 3 ), four phenylpropanoid derivatives ( 4 – 7 ), and two matrine-type alkaloids ( 8 – 9 ), were isolated from Rauvolfia vomitoria Afzel. The structure of new compound 1 was determined by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculation. Notably, this is the first reported monoterpene alkaloids from R. vomitoria . Besides, compounds 3 , 5 , and 7 – 9 were first discovered in the Apocynaceae family and compounds 4 and 6 were first reported in the Rauvolfia genus. This is also the first example of matrine-type alkaloids reported in the Apocynaceae family, indicating that matrine-type alkaloids are not unique to the Leguminosae/Fabaceae family. All isolated compounds were evaluated for their anti-acetylcholinesterase, anti-α-glucosidase, and antioxidant activities. Compound 6 showed significant α-glucosidase inhibitory activity and remarkable DPPH radical scavenging capacity, both of which are superior to the positive controls. Molecular docking of compound 6 with α-glucosidase was further performed, suggesting that compound 6 could form hydrogen bonds with residues ALA-292, ASN-259, and ARG-263.