4-Hydroxykigelin and 6-demethylkigelin, root growth promoters, produced by Aspergillus terreus.

Root growth promoters, 4-hydroxykigelin (1) and 6-demethylkigelin (2), together with 6-hydroxymellein (3) were isolated from cultures of the fungus Aspergillus terreus and their structures were identified by spectroscopic analysis. The biological activities of the three dihydroisocoumarins, 1, 2, and 3, have been examined using a bioassay method with lettuce seedlings. Furthermore, interactions between the dihydroisocoumarins and indole-3-acetic acid against the root growth have been examined.