Research on Secondary Metabolites From the Soft Coral-Associated Fungus Aspergillus sydowii SCSIO41203 and Their Bioactivities

Objective: As part of our ongoing search for bioactive secondary metabolites, the Beibu Gulf soft coral-derived fungus Aspergillus sydowii SCSIO41203 was investigated, which led to the isolation of 15 compounds. Methods: These compounds were purified by chromatographic methods, including normal phase silica gel column chromatography, octadecylsilyl column chromatography, Sephadex LH-20, and high-performance liquid chromatography. Their structures were elucidated by nuclear magnetic resonance, and mass spectrometry and compared their data with those related metabolites in the literature. Results: The structures of 1 to 15 were identified as expansol F (1), expansol C (2), expansol D (3), ( Z)-5-(hydroxymethyl)-2-(6′-methylhept-2′-en-2′-yl)phenol (4), ( E)-5-(hydroxymethyl)-2-(6′-methylhept-2′-en-2′-yl)phenol (5), sydonol (6), (-)-(7 R,10 S)-10-hydroxysydowic acid (7), (-)-(7 R,10 R)- iso-10-hydroxysydowic acid (8), sydowic acid (9), 1-hydroxyboivinianin A (10), (+)-sydonic acid (11), 3-hydroxydiorcinol (12), cordyol C (13), ( R)-mevalonolactone (14), and 4-methyl-5,6-dihydropyren-2-one (15). These isolated compounds were evaluated for antibacterial, cytotoxic, and enzyme-inhibitory activities. Among them, compounds 1 to 3 and 13 showed moderate acetylcholinesterase inhibitory activity, with IC 50 values of 3.9, 33.8, 11.5, and 19.8 μM, respectively, with the positive control (tacrine) of 0.5 μM.