Antibacterial Polyketides Isolated from the Marine-Derived Fungus Fusarium solani 8388

Abstract

Seven new polyketides named fusarisolins F-K (1-6) and fusarin I (7) were isolated from the marine-derived fungus Fusarium solani 8388, together with the known anhydrojavanicin (8), 5-deoxybostry coidin (9), and scytalol A (10). Their structures were established by comprehensive spectroscopic data analyses, and by comparison of the ¹H and ¹³C NMR data with those reported in literature. Fusarisolin F (1) contained both a dichlorobenzene group and an ethylene oxide unit, which was rare in nature. In the bioassays, fusarisolin I (4), fusarisolin J (5), and 5-deoxybostry coidin (9) exhibited obvious antibacterial activities against methicillin-resistant Staphylococcus aureus n315 with MIC values of 3, 3, and 6 μg/mL, respectively. Fusarisolin H (3) and fusarisolin J (5) showed inhibitory effects against methicillin-resistant Staphylococcus aureus NCTC 10442 with the same MIC value of 6 μg/mL. With the exception of 5, all other compounds did not show or showed weak cytotoxicities against HeLa, A549, and KB cells; while fusarisolin J (5) demonstrated moderate cytotoxicities against the three human cancer cell lines with CC₅₀ values between 9.21 and 14.02 μM.

Keywords: Fusarium solani; antibacterial; cytotoxicity; fungus; marine microorganism; polyketide.

Figure 1

Chemical structures of 1–10 isolated from the Fusarium solani 8388.

Figure 2

Selected HMBC correlations of 1 and 2, and key NOE correlations of 2.

Figure 3

The ORTEP drawing of the crystal structure of compound 1.

Figure 4

Selected COSY and HMBC correlations of compounds 3–5.

Figure 5

(A) Comparison of the experimental and the calculated ECD spectra of 3; (B) the ECD spectrum of 4.

Figure 6

Comparison of the experimental and the calculated ECD spectra of 5.

Figure 7

Selected COSY and HMBC correlations of compounds 6 and 7, and NOESY correlations of compound 6.

Figure 8

Comparison of the experimental and calculated ECD spectra of 6 (A) and 7 (B).