Amira Rudi

Three new sesquiterpene hydroquinones from marine origin

Abstract Three new sesquiterpene hydroquinones peyssonol A and B (5 and 6 and hyatellaquinone (7) have been isolated from the alga Peyssonnelia sp. and the sponge Hyatella intestinalis. The structure of the three compounds was determined mainly by NMR measurements. Peyssonol A (5) is the first reported bromo sesquiterpene hydroquinone. Several of the new compounds were found in a preliminary test to inhibit the reverse transcriptase of human immunodeficiency virus (HIV).

Eilatin, a novel alkaloid from the marine tunicate

Abstract Eilatin ( 4 ), dibenzotetraazaperylene, is a novel highly symmetric heptacyclic aromatic compound isolated from the marine tunicate Eudistoma sp .

Phorbazoles AD, novel chlorinated phenylpyrrolyloxazoles from the marine sponge phorbas aff. clathrata

Abstract Four new chlorinated phenylpyrrolyloxazoles, phorbazoles AD (1a-4) have been isolated from the sponge Phorbas aff clathrata. The structure of phorbazole A was unambiguously determined by X-ray diffraction studies of its dimethyl derivative (1b). The structures of compounds 2–4 were determined by extensive use of 1D and 2D NMR techniques. Phorbazoles AD represent a new class of marine alkaloids embodying the previously unprecedented, chlorinated pyrrole moiety, from marine sources.

The biomimetic synthesis of marine alkaloid related pyrido- and pyrrolo[2,3,4-kl]acridines

Abstract A biomimetic reaction between β,β′-diamenoketones (e.g. kynuramine, kynurenine or o,o′-diaminobenzophenone) and a variety cyclohexanediones and quinones leading to pyrido[2,3,4-kl) acridines is described. The synthesis of several di- and tetrahydro-pyrido[2,3,4-kl)acridine derivatives (7, 10. 12 and 15) as well as benzoderivatives of the marine alkaloids eilatin (1) and ascididemin (2), compounds 28 and 30, has been accomplished. Additionally, the new heterocycles isoeilatin (24), and diazapentacene 19 have also been synthesized. All newly prepared heterocycles have been fully characterized by IR, MS and mainly by NMR spectroscopy. An analogous synthesis has been developed for pyrrolo[2,3,4-kl)acridines, the heterocyclic core of the bioactive marine alkaloids the plakinidines (31 A-C).

Niphatoxin A and B; two new ichthyo- and cytotoxic tripyridine alkaloids from a marine sponge

Abstract Two novel cytotoxic tripyridine alkaloids, niphatoxin A & B, have been isolated from the Red Sea sponge Niphates sp. and the structures elucidated on the basis of spectroscopic data.

Alkaloid metabolites of the marine tunicate .: Segoline a, isosegoline a and nor-segoline.

Three alkaloid constituents of the marine tunicate . havebeen shown to be segoline A(), isosegoline A() and norsegoline ().

Four new cytotoxic cyclic hexa- and heptapeptides from the marine ascidian Didemnum molle

Abstract Two novel cyclic hexapeptides, comoramides A and B and two new cyclic heptapeptides, mayotamides A and B were isolated, separately, from two collections of the compound ascidian Didemnum molle collected at two spots of the lagoon of Mayotte. The structure of all four peptides, including the absolute configuration of all amino acids, was elucidated by spectroscopic analysis, mainly NMR data, and degradation experiments. All four compounds exhibit mild cytotoxicity against several tumor cells. Obtaining four new cyclic peptides from two D. molle collections, which add to the two earlier reported cyclic peptides from an Australian and Philippine D. molle , supports the notion that these compounds originate from prokaryotic algal symbionts.

The 13C-NMR spectrum and stereochemistry of heteronemin

Abstract The 13C-NMR spectrum of heteronemin (1), a new sesterterpene from marine origin is reported. Assignment of most of the signals was accomplished by a combination of off-resonance decoupling, PRFT measurement, comparison with suitable known model compounds and LIS measurements. An all trand-anti-trans configuration is suggested from 1 according to the 13C-NMR data.

Taumycins A and B, Two Bioactive Lipodepsipeptides from the Madagascar Sponge Fascaplysinopsis sp.

Two closely related lipodepsipeptides, taumycins A and B (1 and 2) have been isolated from the Madagascar sponge Fascaplysinopsis sp. The two compounds have the same 12-membered oxodepsipeptide ring system in common. Both were toxic to brine shrimp larvae, and taumycin A (1 microM), but not taumycin B, inhibited growth of the human UT-7 leukemic cell line. The structure of the two compounds, likely to be derived from microorganisms, was established by MS and 1D and 2D NMR data.

Asmarines A-C; Three novel cytotoxic metabolites from the marine sponge Raspailia sp.

Abstract Three novel nitrogen-containing metabolites, asmarines A-C (1 – 3) together with two known diterpenes, zaatirin and chelodane were isolated from the Red Sea sponge Raspailia sp. collected in the Dahlak archipelago, Eritrea. The structure of the three new compounds and the known zaatirin and chelodane were established by spectroscopic analysis including X-ray diffraction analysis for asmarine A. Asmarines A-C are cytotoxic to a few human cancer cells.