Oryzamutaic acid K and oryzadiamine C, alkaloids from an Oryza sativa mutant with yellow endosperm

[Display omitted] •The rare rice (Oryza sativa) cultivar Hatsuyamabuki has yellow endosperm.•Oryzamutaic acid K and oryzadiamine C were isolated from the endosperm.•Oryzamutaic acid K is a new C23N4-type alkaloid.•Oryzadiamine C is a new C19N3-type alkaloid.•Oryzadiamine C may play a significant role in the yellow color of the endosperm. Two new alkaloids, oryzamutaic acid K and oryzadiamine C, were isolated from the yellow endosperm of an Oryza sativa mutant. The structures of oryzamutaic acid K and oryzadiamine C were elucidated with spectroscopic analyses. Oryzamutaic acid K and oryzadiamine C are new C23N4- and C19N3-type alkaloids, respectively, that possess nitrogen-containing heterocyclic ring systems. Oryzadiamine C may play a significant role in the yellow color of the endosperm.