AUTHOR=Pang Xiaoyan , Chen Weihao , Wang Xin , Zhou Xuefeng , Yang Bin , Tian Xinpeng , Wang Junfeng , Xu Shihai , Liu Yonghong TITLE=New Tetramic Acid Derivatives From the Deep-Sea-Derived Fungus Penicillium sp. SCSIO06868 With SARS-CoV-2 Mpro Inhibitory Activity Evaluation JOURNAL=Frontiers in Microbiology VOLUME=Volume 12 - 2021 YEAR=2021 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.730807 DOI=10.3389/fmicb.2021.730807 ISSN=1664-302X ABSTRACT=Three new tetramic acid derivatives (1–3) and a new polyketide (4) along with eight known compounds (5–12) were isolated from cultures of the deep-sea-derived fungus Penicillium sp. SCSIO06868. Four new structures were elucidated by analysis of 1D/2D NMR data and HRESIMS. Their absolute configurations were established by X-ray crystallography analysis and comparison of the experimental and reported ECD values or specific optical rotation. Compound 3 exhibited potent selective inhibitory activities against Staphylococcus aureus and methicillin-resistant S. aureus with MIC values of both 2.5 μg/mL. Also, compound 3 showed weak antiviral activity against SARS-CoV-2 main protease, which was responsible for the COVID-19 pandemic.