Investigation of bioactive metabolites produced by the endophytic fungus <i>Aspergillus iranicus</i> from <i>Houttuynia cordata</i> Thunb

The endophytic fungus <i>Aspergillus iranicus</i>, capable of producing bioactive substances, was isolated from the roots of <i>Houttuynia cordata</i> Thunb. Through chromatographic methods, five compounds were isolated in this study for the first time from the fermentation broth and mycelia of the endophytic fungus <i>Aspergillus iranicus</i> obtained from <i>Houttuynia cordata</i> Thunb. using ethyl acetate extracts. These compounds were identified as palmitic acid (<b>1</b>), protocatechuic acid (<b>2</b>), 4-hydroxybenzophenone (<b>3</b>), stigmasterol (<b>4</b>), and β-sitosterol (<b>5</b>). The IC₅₀ values for compound <b>2</b> was 1.32 mg/mL, which indicate strong DPPH radical scavenging activity. Compounds <b>2</b>, <b>3</b>, and <b>5</b> significantly inhibited the growth of <i>Escherichia coli</i>, demonstrating MIC values of 6.25, 3.13, and 3.13 mg/mL, respectively. Additionally, displaying a MIC value of 0.78 mg/mL, compound <b>3</b> demonstrated remarkable inhibition against <i>Candida albicans</i> growth. These findings suggest the presence of endophytic fungi in <i>H. cordata</i>, producing several valuable medicinal secondary metabolites.