Concerning the requirements of effective drug candidates to combat against high rising multidrug resistant pathogens, we isolated three new linear lipopeptides, gageostatins A–C (1–3), consisting of hepta-peptides and new 3-β-hydroxy fatty acids from the fermentation broth of a marine-derived bacterium Bacillus subtilis. Their structures were elucidated by analyzing a combination of extensive 1D, 2D NMR spectroscopic data and high resolution ESIMS data. Fatty acids, namely 3-β-hydroxy-11-methyltridecanoic and 3-β-hydroxy-9,11-dimethyltridecanoic acids were characterized in lipopeptides 1 and 2, respectively, whereas an unsaturated fatty acid (E)-7,9-dimethylundec-2-enoic acid was assigned in 3. The 3R configuration of the stereocenter of 3-β-hydroxy fatty acids in 1 and 2 was established by Mosher’s MTPA method. The absolute stereochemistry of amino acid residues in 1–3 was ascertained by acid hydrolysis followed by Marfey’s derivatization studies. Gageostatins 1–3 exhibited good antifungal activities with MICs values of 4–32 µg/mL when tested against pathogenic fungi (R. solani, B. cinerea and C. acutatum) and moderate antibacterial activity against bacteria (B. subtilis, S. aeureus, S. typhi and P. aeruginosa) with MICs values of 8–64 µg/mL. Futhermore, gageostatins 1–3 displayed cytotoxicity against six human cancer cell lines with GI₅₀ values of 4.6–19.6 µg/mL. It is also noteworthy that mixed compounds 1+2 displayed better antifungal and cytotoxic activities than individuals.

Chemical investigation of a marine-derived fungus, Penicillium steckii 108YD142, resulted in the discovery of a new tanzawaic acid derivative, tanzawaic acid Q (1), together with four known analogues, tanzawaic acids A (2), C (3), D (4), and K (5). The structures of tanzawaic acid derivatives 1–5 were determined by the detailed analysis of 1D, 2D NMR and LC-MS data, along with chemical methods and literature data analysis. These compounds significantly inhibited nitric oxide (NO) production and the new tanzawaic acid Q (1) inhibited the lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins and mRNA expressions in RAW 264.7 macrophages. Additionally, compound 1 reduced the mRNA levels of inflammatory cytokines. Taken together, the results of this study demonstrated that the new tanzawaic acid derivative inhibits LPS-induced inflammation. This is the first report on the anti-inflammatory activity of tanzawaic acid Q (1).

Two new α-pyrone derivatives, violapyrones H (1) and I (2), along with known violapyrones B (3) and C (4) were isolated from the fermentation broth of a marine actinomycete Streptomyces sp. The strain was derived from a crown-of-thorns starfish, Acanthaster planci, collected from Chuuk, Federated States of Micronesia. The structures of violapyrones were elucidated by the analysis of 1D and 2D NMR and HR-ESIMS data. Violapyrones (1–4) exhibited cytotoxicity against 10 human cancer cell lines with GI₅₀ values of 1.10–26.12 μg/mL when tested using sulforhodamine B (SRB) assay. This is the first report on the cytotoxicity of violapyrones against cancer cell lines and the absolute configuration of violapyrone C.

A new α-pyrone merosesquiterpenoid possessing an angular tetracyclic carbon skeleton, ochraceopone F (1), and four known secondary metabolites, aspertetranone D (2), cycloechinulin (3), wasabidienone E (4), and mactanamide (5), were isolated from the marine fungus Aspergillus flocculosus derived from a sponge Stylissa sp. collected in Vietnam. The structures of Compounds 1–5 were elucidated by analysis of 1D and 2D NMR spectra and MS data. All the isolated compounds were evaluated for anti-proliferation activity and their suppression effects on receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation using tartate-resisant acid phosphatase (TRAP). Compounds 1–5 had no anti-proliferative effect on human cancer cell lines up to 30 μg/mL. Among these compounds, aspertetranone D (2) and wasabidienone E (4) exhibited weak osteoclast differentiation inhibitory activity at 10 μg/mL. However, mactanamide (5) showed a potent suppression effect of osteoclast differentiation without any evidence of cytotoxicity.

The new polyketides lopouzanones A and B, as well as the new 1-O-acetyl and 2-O-acetyl derivatives of dendrodochol B, were isolated from the sponge-derived marine fungus Lopadostoma pouzarii strain 168CLC-57.3. Moreover, six known polyketides, gliorosein, balticolid, dendrodolide G, dihydroisocoumarine, (–)-5-methylmellein, and dendrodochol B, were identified. The structures of the isolated compounds were determined by a combination of NMR and ESIMS techniques. The absolute configurations of the lopouzanones A and B were determined using the Mosher’s method. The cytotoxicity of the isolated compounds against human prostate cancer cells PC-3 and normal rat cardiomyocytes H9c2 was investigated. Gliorosein showed weak DPPH radical-scavenging activity and in vitro cardioprotective effects toward rotenone toxicity and CoCl₂-mimic hypoxia.