Fusarium solani H915 (MCCC3A00957), a fungus originating
from mangrove sediment, showed potent inhibitory activity against
tea pathogenic fungus Pestalotiopsis theae. Successive
chromatographic separation on an ethyl acetate (EtOAc) extract of F. solani H915 resulted in the isolation of five new alkenoic
diacid derivatives: fusarilactones A–C (1–3), and fusaridioic acids B (4) and C (5), in addition to seven known compounds (6–12). The chemical structures of these metabolites were elucidated
on the basis of UV, IR, HR-ESI-MS, and NMR spectroscopic data. The
antifungal activity of the isolated compounds was evaluated. Compounds
with a β-lactone ring (1, 2, and 7) exhibited potent inhibitory activities, while none of the
other compounds show activity. The ED50 values of the compounds 1, 2, and 7 were 38.14 ± 1.67,
42.26 ± 1.96, and 18.35 ± 1.27 μg/mL, respectively.
In addition, inhibitory activity of these compounds against 3-hydroxy-3-methylglutaryl-CoA
(HMG-CoA) synthase gene expression was also detected using real-time
RT-PCR. Results indicated that compounds 1, 2, and 7 may inhibit the growth of P. theae by interfering with the biosynthesis of ergosterol by down-regulating
the expression of HMG-CoA synthase.