Psammaplysins: Insights from Natural Sources, Structural Variations, and Pharmacological Properties

Ceratinadin G, a new psammaplysin derivative possessing a cyano group from a sponge of the genus Pseudoceratina

A new psammaplysin derivative, ceratinadin G (1), was obtained from the Okinawan marine sponge Pseudoceratina sp., and the gross structure was clarified through spectroscopic and spectrometric analyses. The absolute configuration of compound 1 was established by comparing its NMR and ECD data with those of the known psammaplysin derivative, psammaplysin F (2). Ceratinadin G (1) is a rare nitrile containing a cyano group as aminoacetonitrile, and is the first psammaplysin derivative possessing a cyano group. In vitro assays indicated that compound 1 displayed moderate cytotoxicity against L1210 murine leukemia cells and KB epidermoid carcinoma cells.

Irciniaplysins A-D: New Psammaplysin Derivatives from Philippine Marine Sponge Ircinia sp

Four new psammaplysin derivatives (1-4) with fatty acyl substituents, designated irciniaplysins A-D, and three known psammaplysins (5-7) were isolated from a marine sponge Ircinia sp. Their structures were elucidated using extensive spectroscopic analyses. The positions of the double bonds and the branch points of the fatty acyl side chains were determined by GC-MS analysis of their fatty acid methyl ester (FAME) derivatives. Irciniaplysins A (1) and B (2) contained an unusual long-chain fatty acyl substituent with a 5,9-diene unit. The isolated compounds were evaluated for their cytotoxic activity against the human colorectal carcinoma (HCT 116) cells, however, none of these compounds showed significant activity.

Total Synthesis of Psammaplysins A, M, O, and Q and Ceratinamide A

The psammaplysins are a unique class of brominated marine alkaloids bearing a signature 5/7-spiroisoxazoline-oxepine core linked to a variable tyramine-derived unit. Here, we report the total synthesis of several members of this family via a dipolar cycloaddition between an in situ generated nitrile oxide and an unusual seven-membered enediol diether dipolarophile. Carefully orchestrated oxidative transformation toward the fully functionalized spirocycle and direct coupling with tyramine-derived amines provides access to five representative family members, psammaplysins A, M, O, and Q and ceratinamide A, the latter four for the first time. Additionally, kinetic resolution of a late-stage intermediate enables the first asymmetric synthesis of (-)-psammaplysin A, thereby confirming its absolute configuration.