Secondary metabolites from the Aspergillus sp. in the rhizosphere soil of Phoenix dactylifera (Palm tree)

Abstract The soil-derived fungus Aspergillus sp. isolated from the rhizospheric soil of Phoenix dactylifera (Date palm tree) and cultured on the large scale solid rice medium yielded a novel compound 1-(4-hydroxy-2,6-dimethoxy-3,5-dimethylphenyl)-2-methyl-1-butanone (1) and four known compounds; citricin (2), dihydrocitrinone (3), 2, 3, 4-trimethyl-5, 7-dihydroxy-2, 3-dihydrobenzofuran (4) and oricinol (5). The structures of the isolated compounds were elucidated by MS, 1H, 13C and 2D NMR spectra. Compound (1) exhibited potent antimicrobial activities against Staphylococcus aureus with MIC values of 2.3 μg mL−1 and significant growth inhibitions of 82.3 ± 3.3 against Candida albicans and of 79.2 ± 2.6 against Candida parapsilosis. This is the first report to isolate metabolites from the fungus Aspergillus found in temperate region date plant rhizospheres.