Eva Zubía

New Rubrolides from the Ascidian Synoicum blochmanni

Abstract The ascidian Synoicum blochmanni has been investigated as a part of our ongoing project directed towards the search for pharmacologically active marine natural products. The chemical study of S. blochmanni has afforded, in addition to four known compounds, six new members of the rubrolide family. Their structures were defined by spectroscopic methods with special emphasis in 1D and 2D NMR and MS. The cytotoxicities exhibited by the compounds of S. blochmanni against several cancer cell lines are presented.

Phallusides, new glucosphingolipids from the ascidian Phallusia fumigata

Abstract The ascidian Phallusia fumigata contains a series of new glucosphingolipids named phallusides 1–4 ( 1–4 ). The structures were elucidated by spectroscopic methods and chemical degradations. Phallusides 1–3 ( 1–3 ) contain the uncommon sphingoid base 2-amino-9-methyl-D- erythro -(4 E ,8 E ,10 E )-octadeca-4,8,10-triene-1,3-diol. This is the first report of glucosphingolipids isolated from ascidians.

NEW DITERPENOIDS FROM THE ALGA DICTYOTA DICHOTOMA

Abstract The marine alga Dictyota dichotoma from Cortadura (Cadiz, Spain) contains, in addition to nineteen known diterpenes (8–26), the new dolabellanes, (1R,2E,4S,5R,6S,7E,10S,11S,12R)-5,6,18-triacetoxy-10-hydroxy-2,7-dolabelladiene (1), (1R,2E,4R,7E,10S,11S,12R)-18-acetoxy-10-hydroxy-2,7-dolabelladiene (2), (1R,2E,4S,5R,7E,10S,11S,12R)-5-acetoxy-10,18-dihydroxy-2,7-dolabelladiene (3), (1R ∗ ,3E,7S ∗ ,8S ∗ ,11S ∗ ,12R ∗ )-7,8- epoxy-3,18-dolabelladiene (4), and (1R ∗ ,2E,4R ∗ ,7E,11S ∗ ,12R ∗ )-18- acetoxy-2,7-dolabelladiene (5) together with two new hydroazulene diterpenes, isopachydictyol A (6) and dictyotatriol A (7). The structures of the new compounds were elucidated by interpretation of spectroscopic data and the absolute configurations of compounds 3, 7 and 10 were established using the Moshers method and of compounds 1, 2, and 11 by chemical interconversions. The new diterpenes isolated from D. dichotoma showed mild cytotoxicity against four tumor cell lines excepting compounds 1 and 7 that were inactive. Dolabellane 2 exhibited the greatest activity.

Novel alkaloids from the red ascidian botryllus leachi

The red ascidian Botryllus leachi contains two novel pyrazine alkaloids, botryllazine A (1) and botryllazine B (2) together with the new imidazole alkaloid 2-(p-hydroxybenzoyl)-4-(p-hydroxyphenyl)imidazole (3). The structures of compounds 1–3 were elucidated by interpretation of spectral data, with special emphasis on the analyses of 1H-13C couplings. Botryllazine A (1) represents the first example of a marine alkaloid containing a pyrazine nucleus derived from three tyrosine precursors. It is proposed that the biogenetic pathway leading from two tyrosine precursors to botryllazine B (2) involves amide formation and, subsequently, cyclization via imine formation. The cytotoxicity assay results of the new compounds 1–3 against four tumor cell lines are presented.

Obscuraminols, new unsaturated amino alcohols from the tunicate Pseudodistoma obscurum: structure and absolute configuration

Abstract The study of the ascidian Pseudodistoma obscurum from Tarifa Island (Cadiz, Spain) has led to the characterization of six new unsaturated 2-amino-3-ol compounds, the obscuraminols A-F. Five of them, the obscuraminols B–F, were isolated as their corresponding diacetyl derivatives. Their structures were established by spectroscopic analysis, their relative configurations by NOEDS study of oxazolidinone derivatives, and their absolute configurations by application of Moshers method to N-acetyl derivatives.

Structure and cytotoxicity of new polyhydroxylated sterols from the Caribbean gorgonian Plexaurella grisea

The gorgonian Plexaurella grisea contains the new steroids 9-hydroxygorgosterol (1), 9,11 alpha,14-trihydroxygorgosterol (2), 5 beta,6 beta-epoxyergost-24(28)-ene-3 beta,7 beta-diol (3), ergost-24(28)-ene-3 beta,5 alpha,6 beta,7 beta-tetrol (4), an unseparable 1:1 mixture of the epimers (25R) and (25S)-26-acetoxy-3 beta,5 alpha-dihydroxyergost-24(28)-en-6-one (5/6), and seven related, known compounds (7-13). The structures of these new compounds were defined by spectroscopic analysis. All the compounds (1-13) isolated from P. grisea were tested against P 388, A 549, and HT 29 tumor cell lines. Compounds 3, 5/6, and 12 exhibited selective activity against the HT 29 cell line (ED(50) = 0.1 microg/ml).

An efficient synthesis of furanocoumarins

Abstract An efficient synthesis of linear and angular furanocoumarins has been carried out starting from iodoumbelliferone derivatives. First synthesis of 6-iodoumbelliferone is described. The average yields are higher than those reported before.

Diasteroisomeric ichthyotoxic acylglycerols from the dorsum of two geographically distinct populations ofArchidoris nudibranchs

Two marine opisthobranchs,Archidoris tuberculata from Asturias (N. Spain) andArchidoris carvi from Patagonia (S. Argentina), contain in their dorsum diasteroisomeric ichthyotoxic acylglycerols esterified in position 1-sn by antipodal diterpenoid acids.

Isolation and structure elucidation of new cytotoxic steroids from the gorgonian Leptogorgia sarmentosa.

The gorgonian Leptogorgia sarmentosa contains three new steroids, (20S)-20-hydroxycholestane-3,16-dione (1), (16S, 20S)-16,20-dihydroxycholestan-3-one (2), and (20S)-20-hydroxycholest-1-ene-3,16-dione (3) together with a known related compound (4). Their structures were defined by spectroscopic analysis. The new steroids exhibited significant cytotoxicity against four tumor cell lines (ED50 = 1 microg/ml).

Enantioselective synthesis of arylmethoxyacetic acid derivatives

Abstract The preparation of several arylmethoxyacetic acids by a sequence of asymmetric dihydroxylation and further oxidation of the resulting glycol with TEMPO/NaClO/NaClO2 is described. The scope and limitations of the reaction are discussed.