Two New Sulfate-Modified Dibenzopyrones With Anti-foodborne Bacteria Activity From Sponge-Derived Fungus Alternaria sp. SCSIOS02F49

Abstract

At present, foodborne diseases (FBDs) caused by bacteria are gradually increasing every year, and the development of new antibiotics is an urgent necessity for human beings. To find novel antibacterial compounds, three sponge-derived fungal strains (SCSIOS02F40, F46, and F49) were investigated. As a result, Alternaria sp. SCSIOS02F49 was selected for investigation on its secondary metabolites because its ethyl acetate (EtOAc) extract of potato dextrose broth (PDB) culture showed rich metabolites and strong antibacterial activity. Two new dibenzopyrones with rare sulfate group (1–2), together with 10 known compounds (3–12), were isolated from the Alternaria sp. SCSIOS02F49. Their structures were confirmed by nuclear magnetic resonance (NMR), mass spectrometry (MS) data, and comparison with data from the relevant literature. Almost all compounds showed moderate inhibitory activity against eight foodborne bacteria (FBB) with minimum inhibitory concentration (MIC) values in the range of 15.6–250 μg/ml, and minimum bactericidal concentration (MBC) values in the range of 31.3–250 μg/ml. The antibacterial mechanism of compound 1 was preliminarily investigated using growth curves, scanning electron microscopy (SEM), and flow cytometry (FCM), which revealed that compound 1 altered the external structure of Staphylococcus aureus and caused the rupture or deformation of the cell membranes. This research provides lead compounds for the development of new antibiotics or microbial preservatives.

Marine natural products

“…121 Albifimbria verrucaria was the source of a modified γ-lactone 272 (ref. 122) and the genus Alternaria yielded a range of metabolites including the meroterpenoids tricycloalternarenes O–R, 273 – 276 , 123 dibenzo-α-pyrone derivatives 277 – 279 , 124 sulfated dibenzopyrones 280 and 281 , 125 phomalone derivatives 282 – 284 (ref. 126) and perylenequinone derivatives 285–287 .…”

The natural products discovered in marine sponge-associated microorganisms: structures, activities, and mining strategy

“…SCSIOS02F49 (Figure 1A, 50-51). Among them, alterlactone 5′-O-sulfate was shown to alter the external structure of S. aureus and caused the rupture or deformation of the cell membranes (Chen et al, 2022b). In addition, Ding et al found three new polyketides, nipyrones A-C (Figure 1A, 52-54), from a marine sponge-associated Aspergillus niger, but only nipyrone C inhibited S. aureus and B. subtilis with MIC values of 8 mg/mL and 16 mg/mL, respectively (Ding et al, 2019).…”

Polyketides with IDH1 R132h and PTP1B inhibitory activities from the desert-plant-derived fungus Alternaria sp. HM 134

“…The mycotoxins in Alternaria sp. had been widely studied, leading to the definition of a series of secondary metabolites, including polyketones ( Lu et al, 2021 ), dibenzopyrones ( Chen et al, 2022 ), anthraquinones ( Chen et al, 2014 ) and cephalochromin ( Song et al, 2021 ). These metabolites have cytotoxic, antiviral and enzyme inhibitory activities ( Xu et al, 2019 ; Tan et al, 2020 ; Saxena, 2021 ; Zhang et al, 2022 ).…”