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Two new antimicrobial cytochalasin derivatives, 6β,7β-epoxydeoxaphomin C (1) and 12-hydroxydeoxaphomin C (2), a new natural occurring product 24-nor-cytochalasin B (3), together with two related known analogs (4-5) were isolated and identified from an endozoic fungus Curvularia verruculosa CS-129, isolated from the deep-sea squat lobster Shinkaia crosnieri which was collected in cold seep region of south China sea. The structures of new compounds were elucidated on the basis of detailed spectroscopic analysis and ECD calculation. The spectroscopic data of 24-nor-cytochalasin B (3) were reported for the first time. All compounds were tested for their antibacterial activities against human and aquatic pathogenic bacteria.

Chevalinulins A (

An unusual sesquiterpene glycoside trichoacorside A (

Cyclopiumolides A (1) and B (2), first representatives of two novel biosynthetic related 13-membered macrolides featuring an uncommon verrucosidinol unit condensed with a spiculisporic acidic moiety, were identified from the fungus Penicillium cyclopium SD-413, which was obtained from the deep-sea sediments collected in the East China Sea. The structures of cyclopiumolides A (1) and B (2) were identified on the basis of extensive NMR spectroscopic and mass spectrometric data analysis. Their relative and absolute configurations were determined by quantum mechanical calculations of ECD spectra comparing with that of experimental curves and by DP4 + NMR data calculations. Compounds 1 and 2 exhibited significant cytotoxic potencies against the tumor cell lines SF126, FaDu, and TE-1 with IC

Four new 12-membered macrolides, thiocladospolides A-D (1-4), each possessing a sulfur substitution at C-2, along with the known congener pandangolide 3 (5) and the possible hydrolysis product seco-patulolide C (6), were isolated and identified from the culture extract of Cladosporium cladosporioides MA-299, an endophytic fungus obtained from the leaves of the mangrove plant Bruguiera gymnorrhiza. Their structures were established by interpretation of the NMR spectroscopic and mass spectrometric data. X-ray crystallographic analysis of compound 1, which represents the first crystal structure described for a sulfur-containing 12-membered macrolide, confirmed its structure and absolute configuration. The proposed sulfur side chain at C-3 in pandangolide 3 (5) was revised to be at C-2 by detailed analysis of the NMR data and by a comparison with data for thiocladospolide A (1). The structures for pandangolides 2 and 4 should also be considered for revisions. The isolated compounds were evaluated for the antimicrobial activities against aquatic bacteria and plant pathogens.

Nine secondary metabolites (1–9), including two new polyketide derivatives 9-dehydroxysargassopenilline A (4) and 1,2-didehydropeaurantiogriseol E (5), along with seven known related secondary metabolites (1–3 and 6–9), were isolated and identified from the deep sea-derived fungus Penicillium cyclopium SD-413. Their structures were elucidated on the basis of 1D/2D NMR spectroscopic and mass spectrometric analysis and the absolute configurations were determined by the combination of NOESY correlations and time-dependent density functional (TDDFT) ECD calculations. Compounds 1–9 inhibited some pathogenic bacteria including Escherichia coli, E. ictaluri, Edwardsiella tarda, Micrococcus luteus, Vibrio anguillarum, and V. harveyi, with MIC (minimum inhibitory concentration) values ranging from 4 to 32 μg/mL.

7β,8β-epoxy-(22

Secondary metabolites obtained from marine-derived fungi are rich sources of drug candidates. Three new sesquiterpenoids, chermesiterpenoids A–C (1–3), along with four known alkaloids (4–7), were isolated and identified from the marine red algal-derived fungus Penicillium chermesinum EN-480. The structures of these new sesquiterpenoids were elucidated using detailed analysis of the NMR data and their relative configurations were elucidated using nuclear overhauser effect spectroscopy (NOESY) spectra as well as gauge-independent atomic orbital (GIAO) NMR shift calculations and DP4+ probability analysis. Their absolute configurations were determined using electronic circular dichroism (ECD) calculations and modified Mosher’s method. Compounds 2 and 3 exhibited potent activities against human and aquatic pathogenic bacteria and plant pathogenic fungi.

A novel ureidobromophenol, rhodomelin A (1), was characterized from Rhodomela confervoides. Its structure was elucidated by spectroscopic analysis. Both enantiomers of 1 were synthesized using a convergent strategy starting from d/l-pyroglutamic acids, respectively, allowing assignment of the R-configuration for the naturally occurring isomer by chiral HPLC analysis. Rhodomelin A represents the first example of a naturally occurring ureidopyrrolidone alkaloid incorporating a γ-aminobutyric acid unit. The scavenging activity of 1 toward DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate)) radicals was assayed.

Three new prenylated phenol derivatives, terreprenphenols A–C (1–3), along with four known related compounds (4–7), were isolated from Aspergillus terreus EN-539, an endophytic fungus obtained from the marine red alga Laurencia okamurai. The structures of these compounds were established by extensive analysis of 1D/2D NMR data, mass spectrometric data, and optical rotation (OR). The corresponding relationship between absolute configuration and optical rotation for known compounds anodendroic acid (4) and asperterreusine C (5) was ambiguous in literature, and their absolute configurations were therefore discussed and confirmed for the first time by time-dependent density functional (TDDFT) ECD and OR calculations. Compounds 1–7 inhibited some common aquatic bacteria with MIC values ranging from 2 to 64 μg/mL.

Thirteen alkaloids, which include three new diketopiperazines, namely, 3-hydroxyprotuboxepin K (4), 3,15-dehydroprotuboxepin K (5), and versiamide A (6), together with ten known alkaloid derivatives (1–3 and 7–13), were isolated from the marine red algal-derived fungus Aspergillus creber EN-602. Versiamide A (6) represents the first example of a naturally occurring quinazolinone alkaloid with a diketopiperazine ring that is derived from phenylalanine (Phe) and leucine (Leu). The structures of these compounds were elucidated by detailed interpretation of their 1D/2D NMR spectroscopic and mass spectrometric data, while the absolute configurations of compounds 1–6 were established on the basis of X-ray crystallographic analysis and time-dependent density functional (TDDFT) calculations of the ECD spectra. Compounds 1, 2, and 4 exhibited inhibitory activity against the angiotensin converting enzyme (ACE) with IC50 values of 11.2, 16.0, and 22.4 μM, respectively, and compounds 5 and 6 inhibited various aquatic bacteria with MIC values that ranged from 8 to 64 μg/mL. The intermolecular interactions and potential binding sites between compounds 1–6 and ACE were investigated via molecular docking simulations.

Eight phenalenone derivatives, including four new compounds, aceneoherqueinones A and B (1 and 2), (+)-aceatrovenetinone A (3a), and (+)-aceatrovenetinone B (3d), along with four known congeners, (–)-aceatrovenetinone A (3b), (–)-aceatrovenetinone B (3c), (–)-scleroderolide (4a), and (+)-scleroderolide (4b), were characterized from the marine mangrove-derived fungus Penicillium herquei MA-370. Among them, compounds 1 and 2 are rare phenalenone derivatives featuring cyclic ether unit between C-5 and C-2′. All of these compounds were subjected to chiral HPLC analysis, and the unstable stereoisomers 3a–3d, containing configurationally labile chirality centers, were characterized by online HPLC-ECD measurements supported with TDDFT-ECD calculations. The structures of these compounds were elucidated by detailed analysis of their NMR and mass spectroscopic data, and the absolute configuration of compound 1 was confirmed by X-ray diffraction analysis, while those of compounds 2 and 3a–3d were determined by TDDFT-ECD calculations of their ECD spectra. All of the isolated compounds were tested for the inhibitory activity against angiotensin-I-converting enzyme (ACE), and compounds 1 and 2 displayed activity with IC50 values 3.10 and 11.28 μM, respectively. The intermolecular interaction and potential binding sites of 1 and 2 with ACE were elaborated by molecular docking, showing that compound 1 bound well with ACE via hydrogen interactions with residues Ala261, Gln618, Trp621, and Asn624, while compound 2 interacted with residues Asp358 and Tyr360.

Chemical investigation of the marine algal-derived endophytic fungus Aspergillus alabamensis EN-547 resulted in the isolation of 4-epi-seco-shornephine A methyl ester (1) and 4-epi-seco-shornephine A carboxylic acid (2), two new secondary metabolites having a rare diketomorpholine motif, and 28-acetoxy-12β,15α,25-trihydroxyergosta-4,6,8(14),22-tetraen-3-one (3), a new highly conjugated ergostane-type steroid, together with four known metabolites (4–7). Their chemical structures were elucidated by detailed analysis of their NMR spectra, ECDs, HRESIMS, optical rotation, and X-ray crystallographic data, and by comparison with literature data as well. The antimicrobial activities of compounds 1–7 were evaluated.

Three new indolediterpenoids, namely, 22-hydroxylshearinine F (1), 6-hydroxylpaspalinine (2), and 7-O-acetylemindole SB (3), along with eight related known analogs (4–11), were isolated from the sea-anemone-derived fungus Penicillium sp. AS-79. The structures and relative configurations of these compounds were determined by a detailed interpretation of the spectroscopic data, and their absolute configurations were determined by ECD calculations (1 and 2) and single-crystal X-ray diffraction (3). Some of these compounds exhibited prominent activity against aquatic and human pathogenic microbes.

Two new terpenoid glucosides, namely 2-O-beta-D-glucopyranoside-vicodiol (1) and 10-O-beta-D-glucopyranoside-oplopanone (2), along with seven known compounds, were isolated from the aerial part of Aster flaccidus (composite), a traditional Chinese herb medicine. The structures of 1 and 2 were established by spectroscopic methods, especially 2D NMR experiments.