The majority of animals and plants are marine. The intensity of natural products research that has been spent on land forms is now extended significantly to the marine forms. Among the most active areas has been reseach on substances that are toxic to man or other land forms. Tetrodotoxin, saxitoxin, kainic acid and holotoxins are substances whose activity is elicited by the transfer from the sea to the land.
Hormones such as 1-methyladenine in the starfish gonad and pheromones such as bonellin are substances that are biologically active in the marine environment.
By using marine eggs as test materials, aphidicolin produced by a fungus was shown to be a direct and selective inhibitor of cellular DNA replication. Thus, aphidicolin was transferred from the land to the sea. In due course, the anti-cancer effect of aphidicolin has been shown. We should strive to detect the highest possible range of activity in all natural products...... including the activity toward a suitable marine organism.