Investigation of bioactive metabolites produced by the endophytic fungus Aspergillus iranicus from Houttuynia cordata Thunb

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The endophytic fungus Aspergillus iranicus, capable of producing bioactive substances, was isolated from the roots of Houttuynia cordata 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 Aspergillus iranicus obtained from Houttuynia cordata Thunb. using ethyl acetate extracts. These compounds were identified as palmitic acid (1), protocatechuic acid (2), 4-hydroxybenzophenone (3), stigmasterol (4), and β-sitosterol (5). The IC50 values for compound 2 was 1.32 mg/mL, which indicate strong DPPH radical scavenging activity. Compounds 2, 3, and 5 significantly inhibited the growth of Escherichia coli, 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 3 demonstrated remarkable inhibition against Candida albicans growth. These findings suggest the presence of endophytic fungi in H. cordata, producing several valuable medicinal secondary metabolites.