José Darias

Uncommon tetrahydrofuran monoterpenes from Antarctic Pantoneura plocamioides

Abstract The participation of oxygen in the biogenesis of marine monoterpenes allowed us to isolate, from the Antarctic alga Pantoneura plocamioides, a variety of new monoterpenes that have a tetrahydrofuran ring. The structure and relative stereochemistry of these six compounds, pantofuranoids A-F (1–6), were established by spectroscopic methods. A biogenetic route for those compounds has also been proposed. The participation of oxygen in the biogenesis of marine monoterpenes allowed us to isolate from P. plocamioides a new structural type of monoterpenes, pantofuranoids A-F (1–6), containing a tetrahydrofuran ring. Download : Download full-size image

3-Keto-22-epi-28-nor-cathasterone, a brassinosteroid-related metabolite from Cystoseira myrica

Bioassay-guided purification of an ethanolic extract of Cystoseira myrica against HEPG-2 (liver) and HCT116 (colon) human cancer cell lines led to the isolation of 3-keto-22-epi-28-nor-cathasterone, 1 and cholest-4-ene-3,6-dione, 2. This finding allowed us to report for the first time that a brassinosteroid-related metabolite occurs in seaweed. These compounds showed activity in the range of 12.38-1.16 microM with selective activity of compound 2 to liver cancer cell lines.

Pronuciferine N-Oxide, a Proaporphine N-Oxide Alkaloid from Berberis coletioides

Pronuciferine N-oxide (1), a proaporphine N-methyl-N-oxide alkaloid, along with the parent alkaloid pronuciferine (2) were isolated from Berberis coletioides. The structure of the new compound was determined by spectroscopic evidence. Compound 1 is the first naturally occurring proaporphinoid alkaloid with an N-oxide functionality.

Validating an Endoperoxide as a Key Intermediate in the Biosynthesis of Elysiapyrones

Compounds 1-3 isolated from Elysia diomedea are described. Compound 1 is an endoperoxide derivative of elysiapyrone A. The biomimetic-type transformation of compound 1 to elysiapyrone A catalyzed by neutral base transformed the endoperoxide to a vicinal diepoxide, thus suggesting the endoperoxide as a key intermediate in the biosynthesis of elysiapyrone A. A biogenetic pathway for their formation involving a cycloaddition of singlet oxygen to a polypropionate alkenyl open chain is proposed.

Caminatal, an aldehyde sesterterpene with a novel carbon skeleton from the Antarctic sponge Suberites caminatus

A new sesterterpene, caminatal 1, containing a bicyclic terpenoid moiety with an aldehyde appendage in combination with an isolated isoprenic aromatic ring leading to a novel carbon skeleton has been obtained from the Antarctic sponge Suberites caminatus. Its structure and relative stereochemistry were established by spectroscopic evidence and biogenetic considerations.

Stypolactone, an interesting diterpenoid from the brown alga Stypopodium zonale

A new diterpenoid of mixed biogenesis, stypolactone 8, containing a tricyclic terpenoid moiety which in combination with its spirolactone ring, leads to a novel carbon skeleton, has been isolated from the brown alga Stypopodium zonale. Its structure and relative stereochemistry were established by spectroscopic evidence and biogenetic considerations.

SECONDARY METABOLITES FROM MARINE PENICILLIUM BREVICOMPACTUM

In a screening of Basidiomycete cultures isolated from marine invertebrates collected along the Chilean coastline for the production of antibiotics we identified a Penicillium brevicompactum strain as a producer of metabolites inhibiting the growth of bacteria and fungi. Bioactivity guided purification resulted in the isolation of four known metabolites. Their structures were elucidated by spectroscopic methods

A New C15 Acetogenin from the Marine Alga Laurencia claviformis

Abstract (3Z)-13-epipinnatifidenyne 1, a novel C15 acetogenin, has been isolated together with others five known compounds from the red alga Laurencia claviformis, a species endemic to Easter Island. The structure of 1 was elucidated based on spectral analysis, including 2D NMR spectroscopy.

Labdane diterpenes with a new oxidation pattern from the marine pulmonate Trimusculus peruvianus

Four new labdane diterpenes, 1-4, with an unusual oxidation pattern have been isolated from the marine pulmonate Trimusculus peruvianus. The structure and stereochemistry of these compounds were determined by spectroscopic data and chemical transformations. The absolute stereochemistry of 4 was assigned by application of the modified Mosher method. These compounds exhibit in vitro moderate cytotoxic activity against human colon carcinoma cell lines.

Bromocyclococanol, a halogenated sesquiterpene with a novel carbon skeleton from the red alga Laurencia obtusa

A bromo sesquiterpene, bromocyclococanol 1, containing fused cyclopropane–cyclopentane rings leading a novel carbon skeleton has been isolated from the red alga Laurencia obtusa. The structure and stereochemistry were established by spectroscopic evidence and biogenetic considerations. A biogenetic route for this compound has also been proposed