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Pan-histone deacetylase (HDAC) inhibitors often have some toxic side effects. In this study, three series of novel polysubstituted N -alkyl acridone analogous were designed and synthesised as HDAC isoform-selective inhibitors. Among them, 11b and 11c exhibited selective inhibition of HDAC1, HDAC3, and HDAC10, with IC 50 values ranging from 87 nM to 418 nM. However, these compounds showed no inhibitory effect against HDAC6 and HDAC8. Moreover, 11b and 11c displayed potent antiproliferative activity against leukaemia HL-60 cells and colon cancer HCT-116 cells, with IC 50 values ranging from 0.56 μM to 4.21 μM. Molecular docking and energy scoring functions further analysed the differences in the binding modes of 11c with HDAC1/6. In vitro anticancer studies revealed that the hit compounds 11b and 11c effectively induced histone H3 acetylation, S-phase cell cycle arrest, and apoptosis in HL-60 cells in a concentration-dependent manner.

Under the guidance of MS/MS-based molecular networking, eight odoriferous sesquiterpenes including two undescribed geosmin-type sesquiterpenoid degradations, odoripenoid A (1) and odoripenoid B (2), and two undescribed germacrane-type sesquiterpenoids, odoripenoid C (3) and odoripenoid (4), together with four known related compounds (5-8) were isolated from the EtOAc extract of the marine mesophotic zone sponge-associated Streptomyces sp. NBU3428. All chemical structures including absolute configurations of these compounds were elucidated by means of HRESIMS, NMR, ECD calculations and single-crystal X-ray diffraction experiments. Compounds 1 and 2 represent the rarely geosmin-related metabolites directly as natural products from actinomycetes. The isolated compounds (1-8) were assayed in a range of biological activities. Compounds 1 and 2 showed anti-Candida albicans activity with MIC values of 16 and 32 μg/mL, respectively, representing potential antifungal agents., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A facultative anaerobic, Gram-strain-negative, rod-shaped bacterium (strain NBU2970 T ) was isolated by using modified ichip in situ cultivation from a marine sediment sample collected from Meishan Island in the East China Sea. Strain NBU2970 T grew optimally at 37 °C, with a NaCl concentration of 2.0 % (w/v) and at pH 7.0. The 16S rRNA gene sequence analyses revealed that strain NBU2970 T represents a novel species with the genus Muricauda , sharing highest sequence identities with Muricauda beolgyonensis BB-My12 T (96.1 %), Muricauda alvinocaridis SCR12 T (96.0 %), Muricauda taeanensis 105 T (96.0 %) and Muricauda ruestringensis B1 T (95.6 %). Phylogenetic analyses also indicated that strain NBU2970 T clustered with the genus Muricauda and was closely related to M. beolgyonensis BB-My12 T and M. ruestringensis B1 T . The draft genome sequence of strain NBU2970 T was composed of six contigs with a size of 3.2 Mbp, containing 3045 protein-coding genes and 38 RNA genes. The DNA G+C content was 43.8 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain NBU2970 T and related species of the genus Muricauda were well below the threshold limit for prokaryotic species delineation. The major cellular fatty acids were iso-C 15 : 0 , iso-C 15 : 1 G and iso-C 17 : 0 3-OH. The only respiratory quinone was MK-6. The major polar lipid was phosphatidylethanolamine. Based on its phenotypic, chemotaxonomic and genotypic data, strain NBU2970 T is considered to be a representative of a novel species in the genus Muricauda , for which the name Muricauda meishanensis sp. nov. is proposed. The type strain is NBU2970 T (=KCTC 82915 T =MCCC 1K06394 T ).

Two pink-pigmented bacterial strains, designated NBU2971 T and NBU2972 T , were isolated from the pit mud of a Chinese liquor. Phylogenetic analyses based on 16S rRNA gene sequences suggested that strains NBU2971 T and NBU2972 T formed a distinct lineage within the family Hymenobacteraceae and were closely related to members of the genus Pontibacter . 16S rRNA gene sequences revealed that strain NBU2971 T showed highest similarity of 97.9 % to Pontibacter arcticus 2b14 T , and strain NBU2972 T showed the highest similarity of 96.9 % to Pontibacter deserti JC215 T . The 16S rRNA gene sequence similarity, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two novel strains were 95.2, 73.8 and 19.6 %, respectively, suggesting that they represent different species. The ANI and dDDH values between two novel strains and related species of genus Pontibacter were well below the threshold limit for prokaryotic species delineation. The genomic DNA G+C contents of strains NBU2971 T and NBU2972 T were 51.3 and 44.5 mol%, respectively. The major cellular fatty acids of the two novel strains were iso-C 15 : 0 and summed feature 4 (iso-C 17 : 1 I and/or anteiso-C 17 : 1 B). The major polar lipid of both novel strains was phosphatidylethanolamine. The only respiratory quinone was MK-7. Combining results of phenotypic, chemotaxonomic and genotypic data, strains NBU2971 T and NBU2972 T are considered to be two representatives in the genus Pontibacter , which the name Pontibacter liquoris sp. nov. and Pontibacter vulgaris sp. nov. are proposed. The type strains of the new species are NBU2971 T (=KCTC 82916 T =MCCC 1K06395 T ) and NBU2972 T (=KCTC 82917 T =MCCC 1K06396 T ), respectively.

Biofilm is a complex microbial consortium that are embedded in a membrane structure of the extracellular polymeric substances (EPS). As a major form of microorganisms in nature, biofilm has evolved complex and diverse resistance mechanisms to numerous known antibiotics, posing a major threat to human health. The biofilm formation of pathogens including Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans, etc. has become the most commonly reasons for clinically chronic and incurable infectious diseases, which urges the development of effective antibiofilm agents. The adaptation of marine organisms and microorganisms to their unique habitats has led to the formation of natural products with charming chemical diversity and biological activity, providing a rich reservoir for the development of antibiofilm agents. According to chemical classification, 129 marine-derived natural products and their synthetic analogs with antibiofilm activity were systematically reviewed, and the related mechanisms and efficacy were discussed as well, aiming to find and develop new and effective antibiofilm agents., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Guignardones Y-Z (1-2), two new meroterpenoids, and six known metabolites involving guignardones A-H (3-4), gyorgy-isoflavone (5), daidzein (6), blumenol A (7) and guignardianone A (8) were isolated from the fungus Penicillium sp. NBUF154, which was obtained from a 60 m deep Crella sponge. Their structures including absolute configurations were unambiguously elucidated by exhaustive spectroscopic analysis and ECD calculations. A putative biosynthetic pathway toward guignardones (1-4) is here proposed. Biological evaluation of compounds 1-8 showed that 1 and 7 exert potent inhibitory effects towards human enterovirus 71 (EV71)., (© 2022 Wiley-VHCA AG, Zurich, Switzerland.)

A modified in situ cultivation technique was developed and applied to resource mining of uncultured microbes from marine sediments of Meishan Island in the East China Sea. Two novel strains NBU2968 T and NBU2984 T were isolated by this method but not standard Petri dish, which indicated the modified technique was more effective compared to conventional approaches for isolating uncultured microbes and could be popularized and applied to other aquatic environments. The two novel strains were identified by the polyphasic taxonomic approach. Cells of both strains were observed to be Gram-staining-negative, rod-shaped, nonmotile, aerobic, and yellow-pigmented. Catalase and oxidase activities and hydrolysis of Tweens 40, 60, and 80 of two novel strains were positive. Methyl red reaction, H 2 S production, and hydrolysis of Tween 20 were negative. According to 16S rRNA gene sequence analysis, two novel strains shared the highest similarities (96.4-97.7%) to the species with a validated name in the genus Hanstruepera , while shared lower sequence similarities (<95.6%) to all other genera. Phylogenetic analysis revealed that strains NBU2968 T and NBU2984 T were affiliated with the genus Hanstruepera . ANI and dDDH values between the two novel strains and Hanstruepera species were 77.4-78.3% and 20.4-20.9%, respectively, which were below the thresholds for species delineation. The 16S rRNA gene sequence similarity, ANI, and dDDH values between the two novel strains were 99.3, 88.9, and 36.3%, respectively, indicating that the two strains represent different species. The genomes of NBU2968 T and NBU2984 T were 3.28 Mbp with a G+C content of 34.2% and 3.09 Mbp with a G+C content of 34.4%, respectively. The only respiratory quinone was menaquinone-6 (MK-6). The major cellular fatty acids were iso-C 15:0 , iso-C 15:1 G, and iso-C 17:0 3-OH. The major polar lipids of the two strains were phosphatidylethanolamine, unidentified amino lipids, and unidentified lipids. Based on the above polyphasic characteristics, strains NBU2968 T and NBU2984 T represent two novel species within the genus Hanstruepera , for which the names Hanstruepera marina sp. nov. and Hanstruepera flava sp. nov. are proposed. The type strains are NBU2968 T (= MCCC 1K06392 T = KCTC 82913 T ) and NBU2984 T (= MCCC 1K07472 T = KCTC 92511 T ), respectively., (Copyright © 2022 Ding, Liu, Yang, Guo, Ding, Jung and Zhang.)

Ten siderophore-related compounds were isolated by MS/MS-based molecular networking from a mesophotic sponge-associated Streptomyces diastaticus NBU2966. Among them, there were three kinds of siderophores including three undescribed phenol/thiazoline-type compounds, thiazostatin C, methyl thiazostatin B, and pulicatin J, one undescribed phenol/oxazoline-type compound, spoxazomicin E, and one undescribed phenol/oxazoline/thiazoline-type compound, streptochelin A, as well as five known compounds. Pulicatin J and spoxazomicin E were both isolated as a pair of inseparable epimers. The planar structures of all these compounds were determined based on the detailed NMR and HRESIMS spectroscopic analysis, and the absolute configurations of them were assigned by ECD and NMR quantum chemical calculations. Additionally, in vitro antibacterial activities, inhibition of MRSA biofilm formation, and neuroprotective activity for these compounds were tested., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Marine sponge-associated fungi are promising sources of structurally interesting and bioactive secondary metabolites. Great plenty of natural products have been discovered from spongeassociated fungi in recent years. Here reviewed are 571 new compounds isolated from marine fungi associated with sponges in 2010-2018. These molecules comprised eight different structural classes, including alkaloids, polyketides, terpenoids, meroterpenoids, etc. Moreover, most of these compounds demonstrated profoundly biological activities, such as antimicrobial, antiviral, cytotoxic, etc. This review systematically summarized the structural diversity, biological function, and future potential of these novel bioactive natural products for drug discovery., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Three new itaconic acid derivatives, asperitaconic acids A-C (1-3), were isolated from the ethyl acetate extracts of the rice fermentation of a marine-derived fungus Aspergillus niger, and asperitaconic acids A-C were characterized by an itaconic acid unit and an alkyl chain moiety. Their structures were established by interpretation of their spectroscopic data including NMR and HRESIMS. Asperitaconic acids A-C exhibited antibacterial effect against Staphylococcus aureus with MIC values of 16-32 μg/mL, whereas these compounds showed no cytotoxicity against HepG2 and HeLa cancer cell lines.

Marine-derived fungi Trichoderma genus are serving as a valuable resource for structurally novel natural products encompassing a variety of chemical substances and diverse pharmacological applications. So far, about 78 metabolites have been structurally documented from the species of marine Trichoderma genus and a large proportion of these metabolites exhibited therapeutic properties with potential application in drug discovery. This mini-review focuses on the structures and bioactivities of these secondary metabolites from marine-derived Trichoderma species., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Abstract : A new cyclopentenone, 5-hydroxycyclopeni cillone ( 1 ), was isolated together with three known compounds, ar -turmerone ( 2 ), citreoisocoumarin ( 3 ), and 6-O-methyl-citreoisocoumarin ( 4 ), from a culture of the sponge-derived fungus Trichoderma sp . HPQJ-34. The structures of 1 - 4 were characterized using comprehensive spectroscopic analyses. The absolute configuration of 1 was determined by comparison of electronic circular dichroism (ECD) spectra with literature values used for the reported analogue, cyclopenicillone ( 5 ), which was not isolated in this research. Compound 1 was shown to scavenge 2,2-diphenyl-1-picrylhydrazyl free radicals, and decrease β-amyloid (Aβ) fibrillization in vitro. Moreover, 1 significantly reduced H₂O₂-induced neurotoxicity in SH-SY5Y cells. These findings suggested that compound 1, a newly discovered cyclopentenone, has moderate anti-oxidative, anti-Aβ fibrillization properties and neuroprotective effects, and might be a good free radical scavenger., Competing Interests: The authors declare no conflict of interest.