Antimicrobial Depsides Produced by Cladosporium uredinicola, an Endophytic Fungus Isolated from Psidium guajava']java Fruits

Four depsides, all of them new as natural products, were isolated from Cladosporium uredinicola solid-media culture and identified as 3-hydroxy-2,5-dimethylphenyl 2,4-dihydroxy-3,6-dimethylbenzoate (1), 3-hydroxy-2,4,5-trimethylphenyl 2,4-dihydroxy-3,6-dimethylbenzoate (2), 3-hydroxy-2,5-dimethylphenyl 3-[(2,4-dihydroxy-3,6-dimethylbenzoyl)oxy]-6-hydroxy-2,4-dimethylbenzoate (3), and 3-hydroxy-2,4,5-trimethylphenyl 3-[(2,4-dihydroxy-3,6-dimethylbenzoyl)oxy]-6-hydroxy-2,4-dimethylbenzoate (4). The endophytic fungus was isolated from Psidium guajava fruits and cultivated over sterilized rice. The compounds 1-4 were purified by classical chromatographic procedures, and the chemical structures were identified by spectroscopic studies, mainly 1D- and 2D-NMR and LC/ESI-MS/MS. Three of the isolated depsides exhibited moderate bacteriostatic and/or bactericide effects on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtillis.