A new alkaloid, myrioneurinol (1), was isolated from the leaves of Myrioneuron nutans and its structure determined from spectral analysis, including mass spectrometry and 2D NMR. Myrioneurinol (1) presented an unprecedented fused tetracyclic skeleton. The absolute configuration was established by the modified Mosher's method, using (R)- and (S)-9-anthrylmethoxyacetic acid (9-AMAA). A plausible biosynthetic pathway starting from L-lysine via D-piperideine was proposed for 1 in comparison with nitraramine biosynthesis and related alkaloids.