As the naphthoquinones and a derivative relating to the already reported catalpalactone (1), the following seven substances have been isolated from Catalpa ovata wood : α-lapachone (3), α-dihydrocaryopterone (=9-hydroxy-α-lapachone) (4), 9-methoxy-α-lapachone (5), 4-hydroxy-α-lapachone (6), 4, 9-dihydroxy-α-lapachone (7), 4-oxo-α-lapachone (8) and catalponol (9). Their sturctures, except catalponol (9) have been clarified.
