Two new diketopiperazines, namely samsoniellain A (1) and samsoniellain B (2), together with two known compounds (3, 4) were isolated from Cordyceps fungus Samsoniella sp. XY4. The planar structures of 1 and 2 were determined by HRESIMS, 1D and 2D NMR spectroscopy. The absolute configurations of 1 and 2 were determined by comparison of quantum chemical TDDFT calculated and experimental ECD spectra. Results of antimicrobial activity indicated that compound 2 showed weak bacteriostatic activities against S. typhimurium χ 8956, H. influenza ATCC 10211, MRSA 2024 with the MIC values of 128, 256, and 256 μg ml-1, respectively. This is the first report about secondary metabolites of Samsoniella sp.
© 2023. The Author(s), under exclusive licence to the Japan Antibiotics Research Association.