Monoterpenoid indole alkaloids (MIAs) play an important
role in natural products due to their complicated
structures and biological activities.1 Additionally, bisindole
alkaloids are well known for their antitumor bioactivity, e.g.,
vincristine derivatives.2 Plants of the genus Tabernaemontana
are rich in MIAs, especial their dimeric forms.3,4 The genus
includes about 120 species and are distributed mainly in the
tropical and subtropical areas of Asia and Australia.