Further phytochemical investigations on Veratrum album L. have led to the isolation of a new steroidal compound, 1-hydroxy-5,6-dihydrojervine (1). We now describe here the isolation of 1 and antihypertensive actions of jervinone, O-acetyljervine, and 1-hydroxy-5,6-dihydrojervine (1). 1-Hydroxy-5,6-dihydrojervine (1), C27H43NO4, was obtained as a white amorphous powder. Its structure was elucidated by spectral data (UV, IR, MS, 1H-NMR, 13C-NMR). In anaesthetized rats, jervinone caused a dose-dependent fall in blood pressure, which was abolished by atropine. O-acetyljervine and 1-hydroxy-5,6-dihydrojervine also produced falls in blood pressure but their effects were not modified by atropine, suggesting different mechanisms. The roots of Melochia tomentosa were extracted to isolate melosatin D [5-hydroxy-6,7-dimethoxy-4-(5'-phenylpentyl)isatin], whose structure was determined by comparison with melosatin A and spectral data. Melochia tomentosa is the only known plant producing isatin alkaloids, which are not artifacts.