The invention belongs to the technical field of medicine, and relates to alkaloid compounds and their preparation methods and medical applications, in particular to morphinanes and bisbenzylisoquinoline alkaloids and their preparation methods and their preparation for the prevention or treatment of neurodegenerative diseases, Application in antitumor drugs, the structure of the compound is as follows: wherein, R 1 , R 2 is hydroxyl, C1‑C4 acyl; R 3 is C1‑C4 aldehyde group, R 4 , R 9 is C1‑C4 alkoxy, R 5 for hydrogen, R 6 and R 7 form methylenedioxy, R 8 is C1‑C4 alkyl; R 1 'is C1‑C4 alkyl, R 2 ', R 3 ', R 5 ', R 7 'is C1‑C4 alkoxy, R 4 ' is hydrogen, R 6 ' is a C1-C4 aldehyde group.