Bioorg Chem 2021 Mar 12;110:104822. Epub 2021 Mar 12.
CAS and Shandong Province Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Nanhai Road 7, Qingdao 266071, People's Republic of China; Laboratory of Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Wenhai Road 1, Qingdao 266237, People's Republic of China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Nanhai Road 7, Qingdao 266071, People's Republic of China. Electronic address:
Thirteen alkaloids, which include three new diketopiperazines, namely, 3-hydroxyprotuboxepin K (4), 3,15-dehydroprotuboxepin K (5), and versiamide A (6), together with ten known alkaloid derivatives (1-3 and 7-13), were isolated from the marine red algal-derived fungus Aspergillus creber EN-602. Versiamide A (6) represents the first example of a naturally occurring quinazolinone alkaloid with a diketopiperazine ring that is derived from phenylalanine (Phe) and leucine (Leu). The structures of these compounds were elucidated by detailed interpretation of their 1D/2D NMR spectroscopic and mass spectrometric data, while the absolute configurations of compounds 1-6 were established on the basis of X-ray crystallographic analysis and time-dependent density functional (TDDFT) calculations of the ECD spectra. Read More