The Nitrogenous Hamigerans: Unusual Amino Acid-Derivatized Aromatic Diterpenoid Metabolites from the New Zealand Marine Sponge Hamigera tarangaensis

The NMR-directed isolation and structure elucidation of nine new nitrogenous hamigeran diterpenoids from the New Zealand marine sponge Hamigera tarangaensis are described. Featured in this set are the oxazole-containing hamigeran M (<b>4</b>) and eight compounds (<b>5a</b>–<b>6a</b> and <b>7a</b>–<b>8c</b>) related to the constitutional structure of hamigeran D (<b>1</b>). Moderate cytotoxicity in the low-micromolar range against the HL-60 promyeloid leukemic cell line is reported for seven of the new compounds. The structural nature of these compounds suggests that their adducts are derived from an amino acid source and has allowed for revision of the configuration about C-18 of the archetypal compound, hamigeran D, from <b>1a</b> to <b>1b</b>. The existence of three constitutionally identical forms of hamigeran Q (<b>8a</b>–<b>8c</b>) requires the involvement of an <i>allo</i>-isoleucine stereoisomer and suggests the intriguing possibility of partial prokaryotic biogenesis of these unusual secondary metabolites

Polyhalogenated Indoles from the Red Alga <i>Rhodophyllis membranacea</i>: The First Isolation of Bromo-Chloro-Iodo Secondary Metabolites

An unusual tetrahalogenated indole with the exceptionally rare inclusion of the three halogens bromine, chlorine, and iodine was found using mass spectrometry within a fraction of a semipurified extract obtained from the red alga <i>Rhodophyllis membranacea.</i> We report herein the isolation and structure elucidation, using a combination of NMR spectroscopy and mass spectrometry, of 11 new tetrahalogenated indoles (<b>1</b>–<b>11</b>), including four bromochloroiodoindoles (<b>5</b>–<b>7</b>, <b>10</b>). Several were evaluated for cytotoxic and antifungal activities against the HL-60 promyelocytic cell line and <i>Saccharomyces cerevisiae</i>, respectively