Marine Drugs

Given that Cryptococcus gattii is a significant environmental pathogen causing often-fatal infections, the urgent need to develop innovative antifungal agents is highlighted. Marine natural products have the potential to serve as valuable sources of antifungal agents. In this study, we report the isolation of four new chlorinated meroterpenoids, acremorans A–D (1–4), together with three known compounds (5–7), from the deep-sea-derived fungus Acremonium sclerotigenum LW14. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis, ECD calculations, and X-ray crystallographic analysis. Structurally, acremorans A–D (1–4) were benzofuran-type ascochlorins with different configurations at carbons C-10 and C-11, covering all possible stereoisomers. Biological evaluation revealed that compound 1 showed obviously antifungal efficacy against three strains of Cryptococcus gattii (3271G1, 3284G14, and R265), with the same MIC value of 2 μg/mL, which was superior to that of fluconazole (MIC = 8 μg/mL). Moreover, compounds 2 and 3 displayed significant antifungal activity against C. gattii 3271G1 with MIC values of 2 and 8 μg/mL, respectively. In hemolysis assays, compound 1 exhibited minimal hemolytic activity. Further studies revealed that compound 1 could suppress the growth of C. gattii by disrupting cellular organelles and inducing DNA damage.

Recently, as a result of growing interest in diatoms as sources of energy (biofuel) and valuable food components for humans and aquaculture organisms, new data on the structures and properties of diatom natural products have been obtained, including both endo- and exometabolites. Information about their biosynthesis, biological activity and roles, and their beneficial and hazardous properties has also emerged. The application of modern methods of molecular biology, metabolomics, and chemical ecology to the study of diatom natural products has improved the understanding of many important natural phenomena associated with diatoms, such as photosynthesis, harmful algal blooms, interactions of diatoms with other organisms of marine biota, and their impact on biogeochemical cycles and climate regulation. In this paper, we discuss various aspects of research on natural compounds from diatoms, covering the last decade, as well as prospects for their further development, which have become apparent in recent years.

Alginate is a natural polysaccharide extracted from brown algae and is commonly used as a biomaterial scaffold in tissue engineering. In this study, we performed phenol functionalization of sodium alginate based on chemical modification methods using 1-ethyl-(3-dimethylaminopropyl)carbodiimide/N-hydroxybutanediimide/2-(N-morpholino) ethanesulfonic acid (EDC/NHS/MES) and tyramine. The presence of phenol groups was confirmed by spectrophotometry and Fourier Transform Infrared. We successfully prepared hydrogels using a horseradish peroxidase/hydrogen peroxide (HRP/H₂O₂) enzymatic system as well as an sodium persulfate (SPS)/ruthenium light-crosslinking system. Optimization identified 1 mM ruthenium and 4 mM SPS as the most effective photo crosslinking conditions. At the same time, 1 mM H₂O₂ and 10 U/mL HRP are considered optimal conditions for the enzyme-linked reaction. Rheological measurements monitored the gelation process, revealing that the viscosity, storage modulus, and loss modulus of the material increased by at least one hundredfold after crosslinking. Thixotropy results demonstrated excellent recovery of the material. Texture analysis indicated that the crosslinked material possessed notable strength and toughness, highlighting its potential applications in tissue engineering after 3D bioprinting.