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Two new ansamycin derivatives, damavaricin H (1) and protostreptovaricin VI (2) were isolated from the Streptomyces spectabilis CCTCC M2017417 derived mutants of ΔstvP5 and ΔstvA2, respectively. The structures of 1 and 2 were established by analysis of the HRESIMS as well as 1D and 2D NMR datasets. The minimum inhibitory concentration (MIC) results showed that compounds 1 and 2 possessed the corresponding anti-MRSA bioactivities of 4 ∼ 8 μg/ml and 8 ∼ 16 μg/ml, which confirmed the structure-activity relationships of streptovaricins reported previously and also revealed that addition of the hydroxyl group at C-8 increased the anti-MRSA activity.

Mycophenolic acid (MPA) is a group of metabolite derived from several species of Penicillium, which shows potent bioactivity. In this study, a new derivative of MPA compound named penicacid D (1), was isolated from the marine derived fungus Penicillium sp. SCSIO sof101, along with seven known compounds (2-8). Their structures were elucidated based on the HR-ESI-MS and NMR data. Moreover, the 1H and 13C NMR data of compound 2 and the 13C NMR data of compound 3 are reported. Compounds 1, 4 and 6 exhibited weak activities against Escherichia coli (clinical isolation number 100385570) and Acinetobacter baumannii (clinical isolation number 100069).