New Antibacterial Secondary Metabolites from a Marine-Derived Talaromyces sp. Strain BTBU20213036.

New polyketide-derived oligophenalenone dimers, bacillisporins K and L (1 and 2) and xanthoradone dimer rugulosin D (3), together with four known compounds, bacillisporin B (4), macrosporusone D (5), rugulosin A and penicillide (6 and 7), were isolated from the marine-derived fungus Talaromyces sp. BTBU20213036. Their structures were determined by detailed analysis of HRESIMS, 1D and 2D NMR data, and the absolute configurations were determined on the basis of calculated and experimental electronic circular dichroism (ECD). The antibacterial and antifungal activities of these compounds were tested against Gram-positive-Staphylococcus aureus, Gram-negative-Escherichia coli, and fungal strain-Candida albicans. These compounds showed potential inhibitory effects against S. aureus with minimum inhibitory concentrations ranging from 0.195 to 100 µg/mL.

Dimeric hexylitaconic acids from the marine-derived fungus Aspergillus welwitschiae CUGBMF180262.

In the course of our efforts to search new secondary metabolites from marine-derived fungi, one new hexylitaconic acid derivative, 3-(5-methoxycarbonylpentyl)-4-methylfuran-2,5-dione (1), and two dimeric analogues asperwelwinates A and B (2 and 3), together with ten known compounds, asperitaconic acid C (4), kotanin (5) and orlandin (6), desertorin B (7), fonsecinone A (8), aurasperone A (9), asperpyrones B and C (10 and 11), aspernigrin B (12), and pyrophen (13), were isolated from a strain of Aspergillus welwitschiae CUGBMF180262. The structures of compounds 1-3 were determined by detailed analysis of HRMS, and 1D/2D NMR experiments, while the absolute configurations of 2 and 3 were determined by comparison of experimental and calculated electronic circular dichroism spectra. 2 and 3 were first reported dimeric hexylitaconic acid derivatives. Compounds 8, 9 and 11 showed moderate antibacterial activities against Helicobacter pylori with minimum inhibitory concentration (MIC) values of 16 µg/mL.

New Isocoumarin Analogues from the Marine-Derived Fungus Paraphoma sp. CUGBMF180003.

Nine new secondary metabolites, including six isocoumarin analogues, 7-hydroxyoospolactone (1), 7-methoxyoospolactone (2), 7-methoxy-9-hydroxyoospolactone (3), 10-acetoxy-9-hydroxyoospolactone (4), 6-dehydroxysescandelin (5), parapholactone (6), and three compounds with a rare skeleton of isocoumarin coupled with phenylethylamine, namely paraphamide A (12), paraphamide B (13), and paraphamide C (14), together with five known compounds, oospolactone (7), 8-O-methyloospolactone (8), 10-hydroxyoospolactone (9), 9,10-dihydroxyoospolactone (10), and oospoglycol (11), were isolated and identified from the marine-derived fungus Paraphoma sp. CUGBMF180003. Their chemical structures were determined using spectroscopic data, including HRESIMS and 1D and 2D NMR techniques. Furthermore, the stereogenic carbons in 5 and 14 were determined by comparing the experimental and calculated electronic circular dichroism (ECD) spectra. The carbon skeleton of 12-14 was identified as the first example of isocoumarin coupled with phenylethylamine derivatives. All of these compounds were examined for antimicrobial activities against Candida albicans and Staphylococcus aureus. Both 1 and 6 showed antibacterial activity against S. aureus with MIC values of 12.5 µg/mL.

Antibacterial Secondary Metabolites from Marine-Derived Fungus Aspergillus sp. IMCASMF180035.

Four new secondary metabolites, including one spiro[anthracenone-xanthene] derivative aspergiloxathene A (1), one penicillide analogue, Δ2'-1'-dehydropenicillide (2), and two new phthalide derivatives, 5-methyl-3-methoxyepicoccone (3) and 7-carboxy-4-hydroxy-6-methoxy-5-methylphthalide (4), together with four known compounds, yicathin C (5), dehydropenicillide (6), 3-methoxyepicoccone (7), 4-hydroxy-6-methoxy-5-methylphthalide (8), were identified from the marine-derived fungus Aspergillus sp. IMCASMF180035. Their structures were determined by spectroscopic data, including high-resolution electrospray ionization mass spectrometry (HRESIMS), 1D and 2D nuclear magnetic resonance (NMR) techniques. Compound 1 was identified as the first jointed molecule by xanthene and anthracenone moieties possessing an unprecedented carbon skeleton with spiro-ring system. All compounds were evaluated activities against Staphylococcus aureus, methicillin resistant S. aureus (MRSA), Escherichia coli, Escherichia faecium, Pseudomonas aeruginosa, and Helicobacter pylori. Compound 1 showed significant inhibitory effects against S. aureus and MRSA, with minimum inhibitory concentration (MIC) values of 5.60 and 22.40 µM. Compounds 2 and 6 exhibited potent antibacterial activities against H. pylori, with MIC values of 21.73 and 21.61 µM, respectively.

Four new species of Talaromyces section Talaromyces discovered in China.

Four new Talaromyces species without any close relatives are reported here, namely, T. aureolinus (ex-type AS3.15865 T), T. bannicus (ex-type AS3.15862 T), T. penicillioides (ex-type AS3.15822 T), and T. sparsus (ex-type AS3.16003 T). Morphologically, T. aureolinus is unique in producing orange-yellow mycelium and gymnothecia, singly borne asci, and ellipsoidal, spiny ascospores. Talaromyces bannicus is characterized by the slow growth rate, polymorphic conidiophores, inconsistent stipe lengths, and pyriform to ellipsoidal, echinulate conidia. Talaromyces penicillioides is distinguished by good growth and sporulation on malt extract agar (MEA) and yeast extract sucrose agar (YES) media, resembling the colony appearances of certain Penicillium species, and appressed biverticillate and occasionally monoverticillate penicilli bearing globose to ellipsoidal, echinulate conidia. Talaromyces sparsus has wide, submerged colony margins with sparse aerial mycelium, and conidial areas overlaid with yellow-green, sterile hyphae on MEA medium. These four new species are well supported by individual phylogenetic trees based on ß-tubulin (BENA), calmodulin (CALM), DNA-dependent RNA polymerase II second largest subunit (RPB2), and internal transcribed spacer region (ITS) gene sequences and the tree of the concatenated BENA-CALM-RPB2 sequence.

Two New Spiro-Heterocyclic γ-Lactams from A Marine-Derived Aspergillus fumigatus Strain CUGBMF170049.

Two new spiro-heterocyclic γ-lactam derivatives, cephalimysins M (1) and N (2), were isolated from the fermentation cultures of the marine-derived fungus Aspergillus fumigatus CUGBMF17018. Two known analogues, pseurotin A (3) and FD-838 (4), as well as four previously reported helvolic acid derivatives, 16-O-propionyl-16-O-deacetylhelvolic acid (5), 6-O-propionyl-6-O-deacetylhelvolic acid (6), helvolic acid (7), and 1,2-dihydrohelvolic acid (8) were also identified. One-dimensional (1D), two-dimensional (2D) NMR, HRMS, and circular dichroism spectral analysis characterized the structures of the isolated compounds.