Four new Myrioneuron alkaloids from Mycetia effusa (Myrioneuron effusum)

Four new Myrioneuron alkaloids, named mysumamines A-D (1-4), together with six known compounds (5-10), were isolated from the aerial parts of Mycetia effusa (syn. Myrioneuron effusum (Rubiaceae)). Among these natural products, compounds 1-3 are undescribed tricyclic Myrioneuron alkaloids and compound 4 is a new hexacyclic Myrioneuron alkaloid. The structures of these new compounds were elucidated by MS, 1D- and 2D NMR spectral analysis.