Plant growth inhibitory activity of azo- and azoxyformamides from Calvatia craniiformis and Lycoperdon hiemale

4-Methoxybenzene-1-ONN-azoxyformamide (1), 4-methoxybenzene-1-azoformamide (2), 4-hydroxyben-zene-1-azoformamide (3) and 4-hydroxybenzene-1-ONN-azoxyformamide (4) were isolated from the fruiting bodies of Calvatia craniiformis and Lycoperdon hiemale, respectively. Compounds 1 and 4 showed radicle growth inhibitory activities against the lettuce seedlings by more than 50% at 5.0 x 10(-1) mM, suggesting that the azoxy moiety contributes to the inhibitory activity. The plant growth inhibitory activities of 1, 2 and 4 against the barnyard millet seedlings were also measured.