The isolation and structure elucidation of two cyanobacterial debromoaplysiatoxin (DAT) analogues, neo-debromoaplysiatoxin A (1) and neo-debromoaplysiatoxin B (2), were reported and found to possess 6/10/6 and 6/6/6 fused-ring systems, respectively, which are rarely seen among aplysiatoxins. Both compounds exhibited potent blocking activity against Kv1.5 with IC values of 6.94 ± 0.26 and 0.30 ± 0.05 μM, respectively. These findings suggest the potential of aplysiatoxin analogues in modulating ionic channels and also provide links between the DAT target, protein kinase C, and cell regulation.

New aplysiatoxin derivative (oscillatoxin E) exhibiting potent blocking activity against potassium channel Kv1.5 is consistent with molecular docking analysis.

Since the early 20th century, a number of active natural pigments have been identified from marine sources, especially algae and marine microorganisms. This review presents 81 marine pigments, covering over 90 % known natural marine pigments. The objective of this article is to provide an overview on the types of pigments, their structural characterization, origins and biological functions that make them unique. We divide the major categories of pigments by chemical structure, either as carotenoids, indole derivatives (quinones and violacein), alkaloids (prodiginines and tambjamines), polyenes, macrolides, peptides, or terpenoids. Many of these pigments have a variety of biological activities, including antitumor, antibacterial, antioxidant and anti‐inflammatory. In addition, we discuss the development of biotechnology, and the contribution and utilization of marine natural pigments and the potential applications in the field of pharmaceutical research.

Neo-debromoaplysiatoxin C (1), a new member of the aplysiatoxin family, was isolated from the marine cyanobacterium Lyngbya sp.. The structure of 1 was elucidated based on spectroscopic data, and its stereochemistry was determined from NOESY spectrum and biosynthetic considerations. This new compound presents an intriguing 10-membered lactone ring skeleton derived from debromoaplysiatoxin by structural rearrangement, which is the first example in the aplysiatoxin family. Its biological properties were evaluated for cytotoxicity, PKCδ activation and inhibitory effects on potassium channel.

A pair of stereoisomers possessing novel structures with 6/6/5 fused-ring systems, neo-debromoaplysiatoxin E (1) and neo-debromoaplysiatoxin F (2), were isolated from the marine cyanobacterium Lyngbya sp. Their structures were elucidated using various spectroscopic techniques including high resolution electrospray ionization mass spectroscopy (HRESIMS) and nuclear magnetic resonance (NMR). The absolute stereochemistry was determined by calculated electronic circular dichroism (ECD) and gauge-independent atomic orbital (GIAO) NMR shift calculation followed by DP4+ analysis. Significantly, this is the first report on aplysiatoxin derivatives with different absolute configurations at C9-C12 (1: 9S, 10R, 11S, 12S; 2: 9R, 10S, 11R, 12R). Compounds 1 and 2 exhibited potent blocking activities against Kv1.5 with IC 50 values of 1.22 ± 0.22 µM and 2.85 ± 0.29 µM, respectively.

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In the present work, a nanoscale piezoelectric beam is developed as an energy harvester. The proposed model can convert the flexural vibration energy to the electric energy. Based on the surface effect theory, the nano beam is considered to be a composite structure with a core and two surface layers. The analytical expressions of the model are given, and the numerical calculations are conducted. Results show that the surface effect has important influences on the performances of the energy harvester. The output power is sensitive to the surface elastic constant and surface piezoelectric constant. The coupling effects of the core and surface material constants are examined. The physical dimension of the piezoelectric beam can also affect the power density. This paper presents the possibility of applying the nanoscale piezoelectric beam to the energy harvester. POLYM. COMPOS., 39:936-941, 2018.

Since 1970s, aplysiatoxins (ATXs), a class of biologically active dermatoxins, were identified from the marine mollusk Stylocheilus longicauda, whilst further research indicated that ATXs were originally metabolized by cyanobacteria. So far, there have been 45 aplysiatoxin derivatives discovered from marine cyanobacteria with various geographies. Recently, we isolated two neo-debromoaplysiatoxins, neo-debromoaplysiatoxin G (1) and neo-debromoaplysiatoxin H (2) from the cyanobacterium Lyngbya sp. collected from the South China Sea. The freeze-dried cyanobacterium was extracted with liquid–liquid extraction of organic solvents, and then was subjected to multiple chromatographies to yield neo-debromoaplysiatoxin G (1) (3.6 mg) and neo-debromoaplysiatoxin H (2) (4.3 mg). They were elucidated with spectroscopic methods. Moreover, the brine shrimp toxicity of the aplysiatoxin derivatives representing differential structural classifications indicated that the debromoaplysiatoxin was the most toxic compound (half inhibitory concentration (IC50) value = 0.34 ± 0.036 µM). While neo-aplysiatoxins (neo-ATXs) did not exhibit apparent brine shrimp toxicity, but showed potent blocking action against potassium channel Kv1.5, likewise, compounds 1 and 2 with IC50 values of 1.79 ± 0.22 µM and 1.46 ± 0.14 µM, respectively. Therefore, much of the current knowledge suggests the ATXs with different structure modifications may modulate multiple cellular signaling processes in animal systems leading to the harmful effects on public health.