article nonhuman unclassified drug drug isolation drug structure mass spectrometry nuclear magnetic resonance proton nuclear magnetic resonance priority journal Animals Molecular Structure carbon nuclear magnetic resonance controlled study Magnetic Resonance Spectroscopy echinoderm structure analysis Asterias antifungal activity chemical structure drug analysis drug identification drug synthesis glycoside sterol Argentina Asteroidea Fungi Glycosides Starfish Support, Non-U.S. Gov't