AUTHOR=Zhong Weimao , Wang Junfeng , Wei Xiaoyi , Fu Tingdan , Chen Yuchan , Zeng Qi , Huang Zhonghui , Huang Xinan , Zhang Weimin , Zhang Si , Long Lijuan , Wang Fazuo 

TITLE=Three Pairs of New Spirocyclic Alkaloid Enantiomers From the Marine-Derived Fungus Eurotium sp. SCSIO F452

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00350

DOI=10.3389/fchem.2019.00350

ISSN=2296-2646

ABSTRACT=<p>Three pairs of new spirocyclic alkaloid enantiomers eurotinoids A–C (<bold>1</bold>–<bold>3</bold>), as well as a known biogenetically related racemate dihydrocryptoechinulin D (<bold>4</bold>) were isolated from a marine-derived fungus <italic>Eurotium</italic> sp. SCSIO F452. Their structures were determined by spectroscopic analyses and electronic circular dichroism (ECD) calculations. Compounds <bold>1</bold> and <bold>2</bold> represent the first two “<italic>meta</italic>” products from a non-stereoselective [4 + 2] Diels-Alder cycloaddition presumably between an enone group of a diketopiperazine alkaloid and a diene group of a benzaldehyde derivative via a new head-to-tail coupling mode biosynthetically, while <bold>3</bold> and <bold>4</bold> were “<italic>ortho</italic>” products. Their enantiomers exhibited different antioxidative and cytotoxic activities. The modes of action were investigated by a preliminary molecular docking study.</p>