3-Decalinoyltetramic acids from kiwi-associated fungus Zopfiella sp. and their antibacterial activity against Pseudomonas syringae

Four rare 3-decalinoyltetramic acid derivatives, zofielliamides A–D (1–4), were obtained from cultures of kiwi-associated fungus Zopfiella sp. Their structures with absolute configurations were established by extensive spectroscopic methods and single crystal X-ray diffraction. The compounds possessed rare pentacyclic systems that might derive from a polyene precursor via [4 + 2] intramolecular Diels–Alder reactions. Compounds 1, 2, and 4 showed antibacterial activity against plant pathogen Pseudomonas syringae with MIC values of 64, 32, and 64 μg mL−1, respectively.