A New Type of Monoterpenoid Indole Alkaloid Precursor from Alstonia rostrata

Currently, all monoterpenoid indole alkaloids (MIAs) have been derived from strictosidine, which originates from the condensation of tryptophan with secologanin in a 1:1 ratio. However, our phytochemical research on Alstonia rostrata revealed a potential new precursor for these compounds. We isolated the alstrostines A and B, and it was determined that they were derived from tryptophan and secologanin in a 1:2 ratio, which supported the presence of a new type of MIA precursor.