Structures and Absolute Configurations of Diketopiperazine Alkaloids Chrysopiperazines A–C from the Gorgonian-Derived <i>Penicillium chrysogenum</i> Fungus
Wei-Feng Xu,
Ning Mao,
Xiao-Jia Xue,
Yue-Xuan Qi,
Mei-Yan Wei,
Chang-Yun Wang,
Chang-Lun Shao
Affiliations
Wei-Feng Xu
Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
Ning Mao
Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
Xiao-Jia Xue
Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
Yue-Xuan Qi
Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
Mei-Yan Wei
Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
Chang-Yun Wang
Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
Chang-Lun Shao
Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
Three new diketopiperazine alkaloids, including two oxepine-containing diketopiperazines, chrysopiperazines A and B (1 and 2), and one quinazoline-containing diketopiperazine, chrysopiperazine C (5), together with three known analogues (3, 4, and 6), were isolated from the gorgonian-derived Penicillium chrysogenum fungus. The relative and absolute configurations of C-3 and C-15 in 1 and 2, C-3 and C-14 in 5 were established by NOE modified Marfey’s analysis and electronic circular dichroism (ECD) calculations. Particularly, the absolute configurations of C-19 in 1 and 3, which was very challenging to be identified due to the flexible conformation in a short aliphatic chain, were successfully determined by the vibrational circular dichroism (VCD) method, supplying with a reliable and optional method to define the absolute configurations. Additionally, this is the first report on oxepine-containing diketopiperazines from the genus Penicillium.
