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Under the guidance of MS/MS-based molecular networking, four new cycloheptapeptides, namely, asperheptatides A-D ( 1 - 4 ), were isolated together with three known analogues, asperversiamide A-C ( 5 - 7 ), from the coral-derived fungus Aspergillus versicolor . The planar structures of the two major compounds, asperheptatides A and B ( 1 and 2 ), were determined by comprehensive spectroscopic data analysis. The absolute configurations of the amino acid residues were determined by advanced Marfey's method. The two structurally related trace metabolites, asperheptatides C and D ( 3 and 4 ), were characterized by ESI-MS/MS fragmentation methods. A series of new derivatives ( 8 - 26 ) of asperversiamide A ( 5 ) were semisynthesized. The antitubercular activities of 1 , 2 , and 5 - 26 against Mycobacterium tuberculosis H37Ra were also evaluated. Compounds 9 , 13 , 23 , and 24 showed moderate activities with MIC values of 12.5 μM, representing a potential new class of antitubercular agents.

A novel perylenequinone-related compound, alternatone A ( 1 ), with an unprecedented tricyclo[6.3.1.0 2,7 ] dodecane skeleton, together with three known perylenequinones, altertoxin I ( 2 ), stemphyperylenol ( 3 ), and alterperylenol ( 4 ), was isolated from the soft-coral-derived fungus Alternaria alternata L3111'. Their structures including absolute configurations were elucidated on the basis of comprehensive spectroscopic analysis, electronic circular dichroism calculations, and X-ray diffraction data. Compound 4 showed cytotoxicity against A-549, HCT-116, and HeLa cell lines with IC 50 values of 2.6, 2.4, and 3.1 μM, respectively. A possible biosynthetic pathway of 1 was proposed.

Three new diketopiperazine alkaloids, including two oxepine-containing diketopiperazines, chrysopiperazines A and B ( 1 and 2 ), and one quinazoline-containing diketopiperazine, chrysopiperazine C ( 5 ), together with three known analogues ( 3 , 4 , and 6 ), were isolated from the gorgonian-derived Penicillium chrysogenum fungus. The relative and absolute configurations of C-3 and C-15 in 1 and 2 , C-3 and C-14 in 5 were established by NOE modified Marfey's analysis and electronic circular dichroism (ECD) calculations. Particularly, the absolute configurations of C-19 in 1 and 3 , which was very challenging to be identified due to the flexible conformation in a short aliphatic chain, were successfully determined by the vibrational circular dichroism (VCD) method, supplying with a reliable and optional method to define the absolute configurations. Additionally, this is the first report on oxepine-containing diketopiperazines from the genus Penicillium ., Competing Interests: The authors declare no conflict of interest.

Coral-derived microorganisms are known for their inherent ability to produce novel products of pharmaceutical importance. Nearly 260 marine natural products (MNPs) have been isolated from coral-derived microorganisms till 2014. In the last three years, 118 MNPs have been isolated from coral-associated microorganisms including 46 new compounds, two with a novel skeleton, and four new natural products. Most of them exhibited in vitro or in vivo activities against tumor cell lines, parasites, pathogenic bacteria, fungi and virus. We reviewed the natural products reported from 2015 to 2017 that have a wide range of bioactivities against different biological targets., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Further chemical investigation of the secondary metabolites of the fungus Scopulariopsis sp. led to the discovery of a new alkaloid, scopuquinolone B (1). The structure of compound 1 was elucidated by extensive NMR spectroscopic data, CD spectrum and analysis of its Dess-Martin oxidation derivative. Compound 1 was evaluated for antilarval settlement activity of barnacle Balanus amphitrite and showed promising antifouling activity with an EC 50 value of 0.103 μM and a high therapeutic ratio of 222.

Vibrational circular dichroism (VCD) method has become robust and reliable alternative for the stereochemical characterization of natural products. In this paper, three new serrulatane-type diterpenoids, euplexaurenes A-C (1-3), and a known metabolite, anthogorgiene P (4), were obtained from the South China Sea gorgonian Euplexaura sp. GXWZ-05. The absolute configuration of C-11 in 1-4, which was difficult to be determined by common means due to the high conformational flexibility of the eight-carbon aliphatic chain attached at C-4, was determined by VCD method, suggesting a new horizon to define the absolute configurations of natural products possessing chains. Compounds 1-4 were found to show selective cytotoxic activities against human laryngeal carcinoma (Hep-2) cell line with the IC 50 values of 1.95, 7.80, 13.6 and 5.85 μM, respectively.

Two new flavones, aspergivones A (1) and B (2), were isolated from the fungus Aspergillus candidus cultured from the gorgonian coral Anthogorgia ochracea collected from the South China Sea. The structures of 1 and 2 were elucidated by NMR and MS methods and comparison with relatively known compounds. Only 2 showed slight inhibitory activity against alpha-glucosidase with an IC 50 value of 244 μg/mL. Compounds 1 and 2 were also evaluated for their cytotoxic and antibacterial activities.

Three new azaphilone derivatives, pinophilins D-F (1-3), and one new diphenyl ether derivative, hydroxypenicillide (10), together with nine known compounds (4-9, 11-13), were isolated from the gorgonian-derived fungus Penicillium pinophilum XS-20090E18. Their structures including absolute configurations were determined by spectroscopic data, chemical conversions, the ECD exciton chirality method, and ECD calculations. Compounds 10-13 exhibited inhibitory activity against the larval settlement of the barnacle Balanus amphitrite at nontoxic concentrations. Compounds 10 and 11 showed cytotoxicity against Hep-2, RD, and HeLa cell lines.

One new merosesquiterpenoid, craterellin D (1), along with one known analog, craterellin A (2), and five known ten-membered macrolides, 3-7, were isolated from a soft coral-derived Lophiostoma sp. fungus. The absolute configuration of 1 was established based on biogenetic consideration with the co-isolated analog 2, whose configuration was determined by modified Mosher's method and single-crystal X-ray diffraction analysis using CuKα radiation. The absolute configuration of 3 was determined by X-ray diffraction analysis using CuKα radiation. Compounds 2 and 3 showed antibacterial activities against Bacillus cereus with a MIC value of 3.12 μM., (Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.)

Marine biofouling has a major economic impact, especially when it occurs on ship hulls or aquaculture facilities. Since the International Maritime Organization (IMO) treaty to ban the application of organotin-based paints to ships went into effect in 2008, there is an urgent demand for the development of efficient and environmentally friendly antifouling agents. Marine microorganisms have proved to be a potential source of antifouling natural compounds. In this study, six dihydroquinolin-2-one-containing alkaloids, three monoterpenoids combined with a 4-phenyl-3,4-dihydroquinolin-2(1H)-one (1-3) and three 4-phenyl-3,4-dihydroquinolin-2(1H)-one alkaloids (4-6), were isolated from the gorgonian coral-derived fungus Scopulariopsis sp. collected in the South China Sea. These dihydroquinolin-2-one-containing alkaloids were evaluated against the larval settlement of barnacle Balanus amphitrite, and antifouling activity was detected for the first time for this class of metabolites. All of them except 6 showed strong antifouling activity. Compounds 1 and 2 were discovered to be the most promising non-toxic antilarval settlement candidates. Especially, compound 1 is the strongest antifouling compound in nature until now which showed highly potent activity with picomolar level (EC50 17.5 pM) and a very safety and high therapeutic ratio (LC50/EC50 1200). This represents an effective non-toxic, anti-larval settlement structural class of promising antifouling lead compound.

Three new Δ(1) -3-ketosteroids characterized with a 9-OH, subergosterones A-C (1-3), together with five known analogs 4-8, were obtained from the gorgonian coral Subergorgia rubra collected from the South China Sea. The structures of 1-3, including their absolute configurations, were determined by comprehensive spectroscopic methods and electronic circular dichroism (ECD) experiments. Compounds 2 and 3 exhibited inhibitory antibacterial activities against Bacillus cereus with MIC values of 1.56 μM., (Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.)

Twelve new 9,10-secosteroids designated as subergorgiaols A-L (1-12), along with four known analogues (13-16), were isolated from the gorgonian Subergorgia rubra collected from the South China Sea. Their planar structures and the relative configurations were elucidated by comprehensive spectroscopic methods including NOESY spectra. The absolute configuration of 1 was established by a dimolybdenum tetraacetate [Mo2(AcO)4] induced circular dichroism (ICD) procedure and the modified Mosher's method. Compounds 1-12 represent the first series of 9,10-secosteroids characterized with a hydroxy group at C-8, which are 8-OH derivatives of astrogorgiadiols/calicoferols. Compound 4 exhibited cytotoxicity against the cervical carcinoma cell line (CaSki) with an IC50 value of 2.4 μM, and 6 showed toxicity toward brine shrimp Artemia salina with an LC50 value of 2.0 μM., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Investigation on diversity of culturable fungi mainly focused on sponges and corals, yet little attention had been paid to the fungal communities associated with zoanthid corals. In this study, a total of 193 culturable fungal strains were isolated from the zoanthid Palythoa haddoni collected in the South China Sea, of which 49 independent isolates were identified using both morphological characteristics and internal transcribed spacer (ITS) sequence analyses. Thirty-five strains were selected for phylogenetic analysis based on fungal ITS sequences. The results indicated that 18 genera within eight taxonomic orders of two phyla (seven orders of the phylum Ascomycota and one order of the phylum Basidiomycota) together with one unidentified fungal strain have been achieved, and Cladosporium sp. represented the dominant culturable genus. Particularly, 14 genera were isolated from a zoanthid for the first time. The antibacterial activities of organic extracts of mycelia and fermentation broth of 49 identified fungi were evaluated, and 29 (59.2 %) of the isolates displayed broad-spectrum or selective antibacterial activity. More interestingly, more than 60 % of the active fungal strains showed strong activity against two aquatic pathogenic bacteria Nocardia brasiliensis and Vibrio parahaemolyticus, compared with other pathogenic bacteria, indicating that zoanthid-derived fungi may protect its host against pathogens. This is the first report of systematically phylogenetic diversity and extensively antibacterial activity of zoanthid-derived fungi.

Coral-derived microorganisms have been a major focus of many research efforts on marine ecology in recent decades. Importantly, research on bioactive compounds from these diverse microorganisms, which include fungi and bacteria, has experienced an explosive growth during the past five years. This has unveiled the ecological roles of these microorganisms, which prevent antifouling, inhibit pathogenic bacteria, and deter predators in ocean ecosystems. Moreover, the structural diversity and pharmacological activity of the compounds produced by these microorganisms have also been studied extensively, leading not only to an understanding their roles within ecosystems, but also the potential value of their use in human health. In this review, 258 marine natural products, including polyketides, terpenoids, meroterpenoids, alkaloids, peptides, shikimates and lipids, all discovered in the past 24 years, are presented. 146 references are cited.

Three new lumazine peptides, penilumamides B-D (2-4), and one known analogue, penilumamide (1), together with a new cyclic pentapeptide, asperpeptide A (5), were isolated from the gorgonian-derived fungus Aspergillus sp. XS-20090B15. Among them, 2 was obtained from the feeding culture with l-methionine of this strain. All structures were elucidated by spectroscopic methods and chemical derivatization. Compounds 1-4 are rare lumazine peptides, of which 1 and 3 are formed from 2 by oxidation of the l-methionine residue.

Five new 9,11-secosteroids 1, 2, and 4-6, and seven known analogs, 3 and 7-12, with the same steroid skeleton, (5αH)-3β,6α,11-trihydroxy-9,11-secocholest-7-en-9-one, were isolated from the South China Sea gorgonian Subergorgia suberosa. Among them, 2/3 and 4/5 are C(24)-epimeric mixtures, and 6/7 is an (E)/(Z) mixture of (C(24)C(28)). Their structures and relative configurations were elucidated by using comprehensive spectroscopic methods including NOESY spectra. The absolute configuration of the steroidal nucleus was established by the modified Mosher method applied to 10 and on the basis of a common biogenesis for all of these compounds. All isolated compounds, 1-12, and five synthetic acetylated derivatives, 12a-12e, were evaluated for their cytotoxicities in vitro. Compounds 4/5, 11, 12, and 12b-12d showed cytotoxic activities against K562 cell line with the IC50 values ranging from 1.09 to 8.12 μM., (Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.)

Four new steroids with an acetoxy linked at the end of the side chain, echrebsteroids A-D (1-4) were obtained from the South China Sea gorgonian Echinogorgia rebekka. The absolute configurations of 1-3 were determined using the modified Mosher's method on the hydrolysis products. The isolation of the pair of epimers (2 and 3) represents the first reported separation of C-25 epimers of 26-acetoxy steroids. The (25R)-epimer (3) exhibited promising antiviral activity against respiratory syncytial virus with an IC50 value of 0.19 μM and a comparatively higher therapeutic ratio (TC50/IC50 = 128).

Two new guaiazulene-based analogues, ochracenoids A (1) and B (2), along with four known analogues (3-6), were isolated from the gorgonian Anthogorgia ochracea collected from the South China Sea. The planar structures of the new compounds were elucidated by comprehensive spectroscopic data. The absolute configuration of 1 was determined as 3R by the comparison of TDDFT calculated electronic circular dichroism with its experimental spectrum. Compound 1 is a rare guaiazulene-based analogue possessing a unique C₁₆ skeleton. The possible generation process of 1 through an intermolecular one-carbon-transfer reaction was also discussed. Compound 2 was previously described as a presumed intermediate involved in the biogenesis of anthogorgienes A and I. Compound 3 exhibited antiproliferative effects on the embryo development of zebrafish Danio rerio.

Two new briarane-type diterpenoids, dollfusilin A (1) and dollfusilin B (2), along with five known briarane-type diterpenoids (3-7), were isolated from the gorgonian Ellisella dollfusi collected from the South China Sea. The structures of the two new compounds (1 and 2) were elucidated through a comprehensive analysis of spectroscopic data, especially 2D NMR. The bioactivities of the isolated compounds were evaluated using the zebrafish toxicity model.

Biofouling results in tremendous economic losses to maritime industries around the world. A recent global ban on the use of organotin compounds as antifouling agents has further raised demand for safe and effective antifouling compounds. In this study, 49 secondary metabolites, including diterpenoids, steroids, and polyketides, were isolated from soft corals, gorgonians, brown algae, and fungi collected along the coast of China, and their antifouling activity was tested against cyprids of the barnacle Balanus (Amphibalanus) amphitrite. Twenty of the compounds were found to inhibit larval settlement significantly at a concentration of 25 μg ml(-1). Two briarane diterpenoids, juncin O (2) and juncenolide H (3), were the most promising non-toxic antilarval settlement candidates, with EC50 values less than 0.13 μg ml(-1) and a safety ratio (LC50/EC50) higher than 400. A preliminary structure-activity relationships study indicated that both furanon and furan moieties are important for antifouling activity. Intriguingly, the presence of hydroxyls enhanced their antisettlement activity.

One new phenylalanine derivative 4'-OMe-asperphenamate (1), along with one known phenylalanine derivative (2) and two new cytochalasins, aspochalasin A1 (3) and cytochalasin Z24 (4), as well as eight known cytochalasin analogues (5-12) were isolated from the fermentation broth of Aspergillus elegans ZJ-2008010, a fungus obtained from a soft coral Sarcophyton sp. collected from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods. The absolute configuration of 1 was determined by chemical synthesis and Marfey's method. All isolated metabolites (1-12) were evaluated for their antifouling and antibacterial activities. Cytochalasins 5, 6, 8 and 9 showed strong antifouling activity against the larval settlement of the barnacle Balanus amphitrite, with the EC50 values ranging from 6.2 to 37 μM. This is the first report of antifouling activity for this class of metabolites. Additionally, 8 exhibited a broad spectrum of antibacterial activity, especially against four pathogenic bacteria Staphylococcus albus, S. aureus, Escherichia coli and Bacillus cereus.

Fumiquinazoline L (1), an alkaloid with a heptacyclic skeleton formed via a bridging hemiaminal linkage, was isolated from a gorgonian-derived Scopulariopsis sp. fungus. The structure and absolute configuration of the new compound were identified by comprehensive spectroscopic data and X-ray diffraction analysis. During acid hydrolysis of 1, the isomerization of the valine residue was observed and also studied in different conditions. Fumiquinazoline L (1) showed no cytotoxic or antibacterial activities.

A new pregnane steroid, 1, and three known analogues 2-4, have been isolated from a gorgonian Carijoa sp. collected from the South China Sea. The planar structure and relative configuration of 1 were elucidated from comprehensive spectroscopic data. Its absolute configuration was determined by application of the modified Mosher method. Compounds 1, 3 and 4 exhibited cytotoxicity against the human hepatoma cell line Bel-7402, with IC50 values of 9.33, 11.02 and 18.68 µM, respectively. Additionally, compound 1 exhibited promising antibacterial activity against Pseudomona puido, with a MIC value of 31 nM, which is approximately 5-fold more potent than ciprofloxacin (MIC = 156 nM).

One new polyhydroxylated steroid, caerulsteroid A (1), along with nine known analogues (2-10), was isolated from the gorgonian coral Anthogorgia caerulea collected from the South China Sea. The structure of the new compound was elucidated by 1-D and 2-D NMR, and mass spectrometry. The absolute configuration of 1 was assigned on the basis of the absolute configurations of the related congeners 2 and 3, which were determined by application of the modified Mosher's method. The isolated compounds were assayed for their cytotoxicity, antimicrobial activity and lethality towards brine shrimp Artemia salina.

Chemical investigation of the ethanol extract of soft coral Sinularia sp. collected from the South China Sea led to the isolation of three new polyoxygenated sterols, (3S,23R,24S)-ergost-5-ene-3β,23α,25-triol (1), (24S)-ergostane-6-acetate-3β,5α,6β,25-tetraol (2), (24S)-ergostane-6-acetate-3β,6β,12β,25-tetraol (3) together with three known ones (4-6). The structures, including relative configurations of the new compounds (1-3), were elucidated by detailed analysis of spectroscopic data (IR, UV, NMR, MS) and by comparison with related reported compounds. The absolute configuration of 1 was further determined by modified Mosher's method. Compound 5 exhibited moderate cytotoxicity against K562 cell line with an IC(50) value of 3.18 μM, but also displayed strong lethality toward the brine shrimp Artemia salina with a LC(50) value of 0.96 μM.

Two new steroidal glycosides, fragilioside A (1) and fragilioside B (2), along with five known compounds (3-7) were isolated from the gorgonian Dichotella fragilis (Ridleg) collected from the South China Sea. The structures of the new compounds (1 and 2) were elucidated by comprehensive analysis of spectral data, especially 2D NMR. The brine shrimp lethality and antifouling activity of the isolated compounds were also evaluated.

Two novel benzylazaphilone derivatives with an unprecedented carbon skeleton, aspergilone A (1), and its symmetrical dimer with a unique methylene bridge, aspergilone B (2), have been isolated from the culture broth of a marine-derived fungus Aspergillus sp. from a gorgonian Dichotella gemmacea. Their structures and relative stereochemistries of 1 and 2 were elucidated using a combination of NMR spectroscopy and X-ray crystallography. Compound 1 not only exhibited in vitro selective cytotoxicity but also showed potent antifouling activity., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The diversity of symbiotic fungi associated with the gorgonian coral Echinogorgia rebekka from the Weizhou coral reef in the South China Sea was investigated. Combined with morphologic traits, ITS-rDNA sequences revealed 18 fungal strains from this gorgonian. All of the 18 fungi belonged to the phylum Ascomycota and were distributed among seven genera in five orders: Eurotiales (Aspergillus and Penicillium), Pleosporales (Alternaria), Capnodiales (Cladosporium), Trichosphaeriales (Nigrospora) and Hypocreales (Hypocrea and Nectria). Antibacterial activities of these fungal strains were investigated with five pathogenic bacteria. All of the 18 fungal strains displayed different levels of antibacterial activities, most of which exhibited moderate to high antibacterial activities to the Gram-positive pathogens Staphylococcus aureus and Micrococcus tetragenus, and showed relatively low bioactivities to other three pathogenic bacteria. Several fungal strains in the genera Penicillium and Cladosporium with strong antibacterial activities provide potential for further research on isolation of bioactive secondary metabolites.

Two new eicosanoids with a unique isovalerianic acid ester group at C-12, named dichotellates A (1) and B (2), were isolated from the gorgonian Dichotella gemmacea collected from the South China Sea using bioassay-guided fractionation. Their structures were established on the basis of extensive spectroscopic analysis including one-dimensional (1D) and two-dimensional (2D) NMR as well as high-resolution ESI-MS experiments. These two compounds were evaluated for their lethal activity toward brine shrimp Artemia salina and both showed weak activity.

One new cembrane diterpenoid, named sarcolactone A (1), along with five known compounds (2-6) were isolated from the soft coral Sarcophyton infundibuliforme collected from the South China Sea. The structure of sarcolactone A (1) was elucidated by comprehensive analysis of spectral data, especially 2D-NMR spectra (1H-1H COSY, HMBC and NOESY). All the compounds were evaluated for their brine shrimp lethality and antifouling activities.

Three new phenolic bisabolane-type sesquiterpenoids: (+)-methyl sydowate (1), 7-deoxy-7,14-didehydrosydonic acid (2), and 7-deoxy-7,8-didehydrosydonic acid (3), together with two known fungal metabolites were isolated from the fermentation broth of a marine-derived fungus Aspergillus sp., which was isolated in turn from a gorgonian Dichotella gemmacea collected from the South China Sea. Their structures were elucidated by combined spectroscopic methods, and the structure of 1 was further confirmed by single-crystal X-ray data.

Two new metabolites, sarcophytonone (1) and sarcophytonamine (2), have been isolated from the Hainan soft coral Sarcophyton crassocaule. Their structures were elucidated on the basis of a detailed analysis of spectroscopic data, and by comparison of their NMR spectral data with those of the related model compounds.