Metabolites, Biotransformation, and Plant-Growth Dual Regulatory Activity from <i>Aspergillus nishimurae</i> Uncovered by the Fermentation Interaction with a Host

One new azaphilone derivative (<b>1</b>) from <i>Aspergillus nishimurae</i> in ordinary medium, one new phthalide derivative (<b>8</b>), a microbial transformation product of <i>Angelica sinensis</i> ingredients by <i>A. nishimurae</i>, a pair of new austdiol enantiomers (+)-<b>9</b> and (-)-<b>9</b>, one new epsilon-caprolactone derivative (<b>10</b>), and one new ophiobolin-type sesterterpenoid (<b>13</b>) from the <i>A. nishimurae</i> in host medium were reported. The structures were determined by spectroscopic analysis and single-crystal X-ray diffraction. Compounds <b>1</b>-<b>3</b> could completely inhibit the germination of rice seeds at 50 μg/mL, which is higher than that of the positive control. The mixture of compounds <b>8</b>+<b>2</b> represented an approximately 84% increase in root length at 20 μg/mL compared with that of phytotoxic compound <b>2</b>. Compounds <b>8</b> and <b>16</b> led to approximately 39 and 7% increases in root length at 5 μg/mL compared with those of untreated rice seeds. Fermentation interactions between endophytes and host constituents induced cryptic metabolite, plant growth inhibiting, and plant growth promoting activities.