Cytotoxic Alkaloids and Antibiotic Nordammarane Triterpenoids from the Marine-Derived Fungus Aspergillus sydowi

Three new diketopiperazine alkaloids, 6-methoxyspirotryprostatin B (1), 18-oxotryprostatin A (2), and 14-hydroxyterezine D (3), with an oxaspiro[4.4]lactam moiety, 14-norpseurotin A (4), and the 29-nordammarane triterpenoid 6β,16β-diacetoxy-25-hydroxy-3,7-dioxy-29-nordammara-1,17(20)-dien-21-oic acid (5), as well as 12 known compounds (6−17), were isolated from the ethyl acetate extract of a marine-derived fungal strain, Aspergillus sydowi PFW1-13. The structures of compounds 1−5 were elucidated by comprehensive spectroscopic analysis. Compounds 1−3 exhibit weak cytotoxicity against A-549 cells, with IC50 values of 8.29, 1.28, and 7.31 µM, respectively. Compound 1 also shows slight cytotoxicity against HL-60 cells, with an IC50 value of 9.71 µM. Compounds 4 and 5 display significant antimicrobial activities against Escherichia coli, Bacillus subtilis, and Micrococcus lysoleikticus with MICs of 3.74, 14.97, and 7.49 µM and 10.65, 5.33, and 10.65 µM, respectively.