s m i t h s o n i a n c o n t r i b u t i o n s t o b o t a n y • n u m b e r 1 0 5 Smithsonian Institution Scholarly Press Smithsonian Institution Scholarly PressThe Mesophotic, Coral Reef-Associated, Marine Algal Flora of Puerto Rico, Caribbean Sea David L. Ballantine, Hector Ruiz Torres, and Nilda E. Aponte SERIES PUBLICATIONS OF THE SMITHSONIAN INSTITUTIONEmphasis upon publication as a means of "diffusing knowledge" was expressed by the first Secretary of the Smithsonian. In his formal plan for the Institution, Joseph Henry outlined a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge." This theme of basic research has been adhered to through the years by thousands of titles issued in series publications under the Smithsonian imprint, commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: s m i t h s o n i a n c o n t r i b u t i o n s t o b o t a n y • n u m b e r 1 0 5The Cover images, from left to right: Edge of insular shelf, offshore from La Parguera; technical divers' descent to the mesophotic; bottom habit, edge of insular shelf, "Weinberg," offshore from La Parguera. Published by SMITHSONIAN INSTITUTION SCHOLARLY PRESS

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Lophocladines A (1) and B (2), two 2,7-naphthyridine alkaloids, were isolated from the marine red alga Lophocladiasp. collected in the Fijian Islands. Their structures were deduced on the basis of high-resolution mass spectra and one- and two-dimensional NMR spectroscopy. Lophocladine A (1) displayed affinity for NMDA receptors and was found to be a delta-opioid receptor antagonist, whereas lophocladine B (2) exhibited cytotoxicity to NCI-H460 human lung tumor and MDA-MB-435 breast cancer cell lines. Immunofluorescence studies indicated that the cytotoxicity of lophocladine B (2) was correlated with microtubule inhibition. This is the first reported occurrence of alkaloids based on a 2,7-naphthyridine skeleton from red algae.