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Three new cyclohexapeptides, petrosamides A-C (1-3), were isolated from the sponge-derived fungus Aspergillus sp. 151304. Their structures were elucidated by detailed 1D and 2D spectroscopic analyses, and the absolute configurations of the amino acid residues were determined by the advanced Marfey's method. These peptides displayed significant and dose-dependent pancreatic lipase (PL) inhibitory activities, with IC50 values of 7.6 ± 1.5, 1.8 ± 0.3, and 0.5 ± 0.1 μM, respectively. Further inhibition kinetics analyses showed that compound 3 inhibited PL in a noncompetitive manner, while molecular dynamics simulation revealed that it could bind to PL at the entrance of the catalytic pocket.

A novel actinobacterium, designated LHW52908T, was isolated from a marine sponge, Leucettachagosensis, collected in the South China Sea. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain LHW52908T was member of the family Geodermatophilaceae , with highest similarities to Geodermatophilus obscurus DSM 43160T (97.7 %), Geodermatophilus siccatus CF6T (97.6 %) and Geodermatophilus chilensis B12T (97.5 %). Multilocus sequence analysis confirmed that the strain should be a member of genus Geodermatophilus . Chemotaxonomic characteristics confirmed the genus-level affiliation of strain LHW52908T. Based on phylogenetic data, average nucleotide identity and digital DNA–DNA hybridization results, strain LHW52908T could be distinguished from its closest neighbours, representing a novel species of the genus Geodermatophilus , for which the name Geodermatophilus marinus sp. nov. is proposed, with the type strain LHW52908T (=DSM 106570T=CCTCC AA 2018014T).

LC-DAD/MS-based dereplication of organic extract of a calcareous sponge Leucetta chagosensis afforded one new chiral aminoimidazole-containing alkaloid, (-)-calcaridine B (1), along with on...

Two new quinoline alkaloids, aaptolines A and B, were isolated from the marine sponge Aaptos aaptos. Their structures were determined by HR-ESI-MS data, NMR analysis, and X-ray crystallography. Structurally, aaptoline A is characterized as having a quinoline skeleton fused with a 1,4-dioxane motif at the C(7)-C(8) position, whereas aaptoline B possessed an intriguing 1H-pyrrolo[2,3-g]quinoline moiety. The cytotoxic assay of these compounds showed no cytotoxicity towards HepG2, A549, and PC9 cancer cell lines and had IC50 values greater than 20 μm.

Five new imidazole derivatives (1–5), together with eight related known alkaloids, were isolated from a calcareous marine sponge, Leucetta chagosensis, collected from the South China Sea. Their structures were fully characterized by spectroscopic methods. Structurally, 1 possesses an unusual skeleton featuring imidazole and oxazolone rings linked via a nitrogen atom, whereas 2 bears an intriguing guanylurea-substituted imidazole ring. Compounds 4 and 5 were identified as zinc complexes; they represent the metal complex analogues of naamidine J (6) and pyronaamidine (7), respectively. Among the isolated compounds, 2 and 5 showed significant inhibitory activities toward the LPS-induced production of IL-6 in the human acute monocytic leukemia cell line THP-1, and 7 displayed cytotoxicity against MCF-7, PC9, A549, and breast cancer stem cells (MCF-7-Oct4-GFP) with IC50 values of 5.2, 5.6, 7.8, and 10 μM, respectively.

Two new norterpenes dicarperoxides M and N and one new polyketide diacarnustin C were isolated from the marine sponge Diacarnus megaspinorhabdosa. Detailed spectroscopic analysis guided the elucidation of their structure. Structurally, dicarperoxides M and N incorporate a typical norterpene cyclic peroxide core, while diacarnustin C is noteworthy in that it contains an α, β-unsaturated ester unit linked to a furan ring. Dicarperoxides M and N displayed moderate cytotoxicity against THP-1 (IC50 values of 15.3 and 20.6 μM, respectively) and u937 cells (IC50 values of 13.4 and 25.7 μM, respectively).

Chemical investigation on CH2Cl2 extract of the marine sponge Leucetta chagosensis, collected from the South China Sea, afforded two new 5,6-epoxysterols, 5α,6α-epoxycholesta-8(14),22(E)-diene-3β,7α-diol (1) and (24R)-24-ethyl-5α,6α-epoxycholesta-8(14),22(E)-diene-3β,7α-diol (2) along with ten known related steroid analogs (3–12). Their structures were elucidated on the basis of NMR spectroscopic analyses, and comparison with the literature. All isolates were tested for cytotoxicity against three tumor cell lines only known compounds 11 and 12 exhibited notable cytotoxic activity against A549 (IC50: 3.0 and 5.6 μM), PC9 (2.0 and 15.6 μM), and MCF-7 (9.4 and 11.8 μM) cell lines, respectively.

Chemical investigation on CH2Cl2 extract of the marine sponge Diacarnus megaspinorhabdosa resulted in the isolation of two new farnesylacetone derivatives 1-2, a new γ-lactone 3, a known dinorditerpenone 4 and four known norsesterterpene peroxides 5-8. Their structures were elucidated by using one and two dimensional (1D and 2D)-NMR, high resolution-electrospray ionization (HR-ESI)-MS, and comparison with the literature. Compounds 1 and 2 were cis/trans-olefinic isomers and determined through nuclear Overhauser effect spectroscopy (NOESY) experiment. The absolute configuration of 3 was established by comparison of circular dichroism (CD) data with known lactones. The cytotoxic activities of the compounds were evaluated against five cancer cell lines, and compound 3 showed moderate cytotoxicity activities against cancer cell lines HeLa, H446, NCI-H460, SGC-7901 and MCF-7, with IC50 values in the range of 18.5 to 47.1 µM.

Chemical investigation on CH2Cl2 extract of the marine sponge Leucandra sp. afforded two new compounds named leucanone A (1) and naamine J (2), together with eight known compounds (3–10). Their structures were elucidated on the basis of NMR spectroscopic analyses, and comparing with the literature. The cytotoxic activities of the compounds were evaluated against four cancer cell lines, and compound 2 showed mild cytotoxic activities against MCF-7, A549, HeLa, and PC9 cancer cell lines with IC50 values in the range of 20.1–45.3 μM.