The marine environment has been, and continues to be, a fruitful source of novel chemical compounds that are not found in terrestrial and freshwater organisms. Many of these substances show potential biomedical applications, which could lead to development of new pharmaceutical products. Research on the utilization of natural products from marine organisms is growing by leaps and bounds; one important reason why being that, investigators, through new diving technologies, are becoming able to explore at greater depths. Studies of these marine natural products include investigations of neuronal membrane-active toxins, ion channel blockers, antitumor and antiviral agents, and anti-inflammatory molecules. This volume is the sixth in the ongoing series.