A New Polyketide Derivative from the Nicotiana tabacum Symbiotic Fungus Aspergillus japonicus TE-739D

Filamentous fungi are very well known for producing a wide variety of secondary metabolites with important biological effects.In our study chemical exploration of the Nicotiana tabacum symbiotic fungus Aspergillus japonicus TE-739D led to the discovery of a new polyketide derivative, namely (3S,4E,6E,9S)-9hydroxy-3,7-dimethyldeca-4,6-dienoic acid (1), along with three previously reported compounds 2-4.The structures of these compounds were elucidated by using HRESIMS, NMR spectroscopic analyses, and quantum chemical calculations.Compounds 3 and 4 showed strong antibacterial activity against four representative bacterial strains including two Gram-negative species (Agrobacterium tumefaciens and Xanthomonas oryzae) and two Gram-positive Bacillus species (B.cereus and B. subtilis), with MIC values range from 1 to 16 g/mL, respectively.