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Six new thiodiketopiperazine-class alkaloids lecanicilliums A-F were isolated from the mangrove sediment-derived fungus Lecanicillium kalimantanense SCSIO41702, together with thirteen known analogues. Their structures were determined by spectroscopic analysis. The absolute configurations were determined by quantum chemical calculations. Electronic circular dichroism (ECD) spectra and the structure of Lecanicillium C were further confirmed by a single-crystal X-ray diffraction analysis. Lecanicillium A contained an unprecedented 6/5/6/5/7/6 cyclic system with a spirocyclic center at C-2'. Biologically, lecanicillium E, emethacin B, and versicolor A displayed significant cytotoxicity against human lung adenocarcinoma cell line H1975, with IC 50 values of 7.2~16.9 μM, and lecanicillium E also showed antibacterial activity against four pathogens with MIC values of 10~40 μg/mL. Their structure-activity relationship is also discussed.

Fucoidan is a sulfated algal polyanionic polysaccharide that possesses many biological activities. In this paper, a fucoidan (SHF) polysaccharide was extracted from Sargassum hemiphyllum collected in the South China Sea. The SHF, with a molecular weight of 1166.48 kDa (44.06%, w / w ), consisted of glucose (32.68%, w / w ), galactose (24.81%, w / w ), fucose (20.75%, w / w ), xylose (6.98%, w / w ), mannose (2.76%, w / w ), other neutral monosaccharides, and three uronic acids, including glucuronic acid (5.39%, w / w ), mannuronic acid (1.76%, w / w ), and guronuronic acid (1.76%, w / w ). The SHF exhibited excellent immunostimulatory activity. An immunostimulating assay showed that SHF could significantly increase NO secretion in macrophage RAW 264.7 cells via upregulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) levels based on both gene expression and protein abundance. These results suggest that SHF isolated from Sargassum hemiphyllum has great potential to act as a health-boosting ingredient in the pharmaceutical and functional-food fields.

Puniceusines A-N ( 1 - 14 ), 14 new isoquinoline alkaloids, were isolated from the extracts of a deep-sea-derived fungus, Aspergillus puniceus SCSIO z021. Their structures were elucidated by spectroscopic analyses. The absolute configuration of 9 was determined by ECD calculations, and the structures of 6 and 12 were further confirmed by a single-crystal X-ray diffraction analysis. Compounds 3 - 5 and 8 - 13 unprecedentedly contained an isoquinolinyl, a polysubstituted benzyl or a pyronyl at position C-7 of isoquinoline nucleus. Compounds 3 and 4 showed selective inhibitory activity against protein tyrosine phosphatase CD45 with IC 50 values of 8.4 and 5.6 µM, respectively, 4 also had a moderate cytotoxicity towards human lung adenocarcinoma cell line H1975 with an IC 50 value of 11.0 µM, and 14 , which contained an active center, -C=N + , exhibited antibacterial activity. An analysis of the relationship between the structures, enzyme inhibitory activity and cytotoxicity of 1 - 14 revealed that the substituents at C-7 of the isoquinoline nucleus could greatly affect their bioactivity.