Bioactive Secondary Metabolites from the Culture of the Mangrove-Derived Fungus Daldinia eschscholtzii HJ004

Abstract

Two new polyketides, 8-O-methylnodulisporin F (1) and nodulisporin H (2), two new naphthoquinones, 5-hydroxy-2-methoxy-6,7-dimethyl-1,4-naphthoquinone (3) and 5-hydroxy-2-methoxynaphtho[9–c]furan-1,4-dione (4), and a new naphthofuran 1,3,8-trimethoxynaphtho[9–c]furan (5), along with five known compounds 4-O-methyl eleutherol (6), 2-acetyl-7-methoxybenzofuran (7), (-)-orthosporin (8), diaporthin (9), and 6-hydroxymellein (10), were obtained from the EtOAc extract of the mangrove-derived fungus Daldinia eschscholtzii HJ004. The structures of the isolated compounds were elucidated by extensive NMR and MS analyses, while the absolute configurations of the stereogenic carbons were established based on experimental and calculated electronic circular dichroism spectra. Compounds 4 and 7 displayed a potent inhibitory activity against α-glucosidase with the IC50 values of 5.7 and 1.1 μg/mL, respectively. Compounds 1 and 2 showed a moderate antibacterial activity against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA) and Bacillus cereus, with minimum inhibitory concentration (MIC) values ranging from 6.25 to 12.5 μg/mL. Compound 3 exhibited antibacterial activity against B. cereus with the MIC value of 12.5 μg/mL.

<p class="Author"> <p class="Title" style="text-indent:0mm;"> Natural Products from the genus <i>Daldinia</i> and Their Bioactivities

“…Wang et al [6] also found three new polyketides from mantis-associated fungus D.eschscholzii, named daldinone F (8), nodulisporin G (9), and dalmanol C (10). And then, Zhang et al [7] found a novel polyketide natural product named galewone (11)(12).…”

“…From the mangrove endophytic fungus D.eschscholtzii HJ001, Yang et al [10] obtained a new cytochalasin (15). And then, the group [11] isolated two new polyketides 8-O-methylnodulisporin F (16) and nodulisporin H (17), two new naphthoquinones, 5-hydroxy-2methoxy-6,7-dimethyl-1,4-naphthoquinone (18), and 5-hydroxy-2-methoxynaphtho [9-c] furan-1,4-dione (19), and a new naphthofuran 1,3,8-trimethoxynaphtho [9-c] furan (20). After that, this group [12] found five new tetralones, daldiniones…”

“…5-Hydroxy-2-methoxy-6,7-dimethyl-1,4-naphthoquinone (18) exhibited antibacterial activity against B. cereus with the MIC value of 12.5 µg/mL. [11] Dalesindoloid A (31) displayed moderate inhibition on the growth of S. aureus with its MIC value disclosed to be 9.1 μM, the MIC value of co-assayed streptomycin, 0.5 μM. [13] Daldispones B (56) showed moderate antimicrobial activity against Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus with MIC of 32, 16, 32 μg/mL, respectively.…”

“…[21] α-Glucosidase inhibitory activity 5-Hydroxy-2-methoxynaphtho[9-c]furan-1,4-dione (19) displayed potent inhibitory activity against α-glucosidase with the IC50 values of 5.7 µg/mL. [11] Compounds (26) showed inhibitory activities against α-glucosidase with IC50 values of 13 μM. Acarbose was used as a positive control with IC50 values of 3 μM.…”

New Diterpenoids and Isocoumarin Derivatives from the Mangrove-Derived Fungus Hypoxylon sp.

“…Fungi especially from unique ecological niches are capable of producing a variety of bioactive compounds [ 3 , 4 , 5 ]. Mangrove-derived endophytic fungi, as plant mutualists that occur in the tropical and subtropical intertidal estuarine zones, have attracted more attention of natural product chemists due to their production of structurally diverse and biologically active secondary metabolites [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Hypoxylon species are widespread in terrestrial and marine environments, and chemical investigations of some Hypoxylon spp.…”