Fusarisolins A⁻E, Polyketides from the Marine-Derived Fungus Fusarium solani H918

Abstract

Five new (fusarisolins A⁻E, 1 to 5) and three known (6 to 8) polyketides were isolated from the marine-derived fungus Fusarium solani H918, along with six known phenolics (9 to 14). Their structures were established by comprehensive spectroscopic data analyses, methoxyphenylacetic acid (MPA) method, chemical conversion, and by comparison with data reported in the literature. Compounds 1 and 2 are the first two naturally occurring 21 carbons polyketides featuring a rare β- and γ-lactone unit, respectively. All isolates (1 to 14) were evaluated for their inhibitory effects against tea pathogenic fungus Pestalotiopsis theae and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase gene expression. Compound 8 showed potent antifungal activity with an ED₅₀ value of 55 μM, while 1, 8, 13, and 14 significantly inhibited HMG-CoA synthase gene expression.

Keywords: HMG-CoA synthase; bioactivity; microorganisms; ocean; β-lactones.

Figure 1

Chemical structures of 1 to 14 isolated from the Fusarium solani H918.

Figure 2

Selected COSY (), HMBC (), and NOESY () correlations of 1.

Figure 3

Key COSY, HMBC, and NOESY correlations of 2.

Figure 4

Alkaline hydrolysis of 8 to yield 7.

Figure 5

Inhibitory effects of 1 to 14 on the mRNA expression of HMG-CoA synthase. The gene expression level was determined by real-time polymerase chain reaction (RT-PCR). Dimethyl sulfoxide (DMSO) and abscisic acid were used as blank and positive controls, respectively. G lyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as reference gene. Values represent the mean ± SD of three independent experiments. * p < 0.05, ** p < 0.01, and *** p < 0.001.