A new alkaloid (I), C15H23O2N has been isolated from Nuphar japonicum DC. and named nuphamine. The compound (III) obtained by the catalytic reduction after the chlorination of I with thionyl chloride is completely in accordance with (')-desoxy-nupharamine, derived from nupharamine (IX). By the catalytic reduction of I with palladium-carbon, dihydronuphamine (V), (')-deoxynupharidine (VI-A) and allodeoxynupharidine (VI-B) were prepared. VI-A and VI-B were also prepared from V. Judging from these reactions and the nuclear magnetic resonance spectra, the structure of I has been determined to be presented by the formula VIII. The steric chemical correlations among the alkaloids, (')-desoxy-nupharidine (VI-A), (')-nuphamine (VIII) and (')-nupharamine (IX) isolated from Nuphar japonicum have been also achieved. © 1965, The Pharmaceutical Society of Japan. All rights reserved.