Red Seaweed Laurencia Microcladia Research Articles

Diterpene Biosynthesis in Catenulispora acidiphila: On the Mechanism of Catenul-14-en-6-ol Synthase.

A new diterpene synthase from the actinomycete Catenulispora acidiphila was identified and the structures of its products were elucidated, including the absolute configurations by an enantioselective deuteration approach. The mechanism of the cationic terpene cyclisation cascade was deeply studied through the use of isotopically labelled substrates and of substrate analogues with partially blocked reactivity, resulting in derailment products that gave further insights into the intermediates along the cascade. Their chemistry was studied, leading to the biomimetic synthesis of a diterpenoid analogue of a brominated sesquiterpene known from the red seaweed Laurencia microcladia.

Calenzanane sesquiterpenes from the red seaweed Laurencia microcladia from the Bay of Calenzana, Elba Island: acid-catalyzed stereospecific conversion of calenzanol into indene- and guaiazulene-type sesquiterpenes.

It is shown here that calenzanane sesquiterpenes (1 and 6) can be isolated from organic extracts from the red seaweed Laurencia microcladia Kützing from the Bay of Calenzana, Elba Island, provided contact with acidic media is minimized. Such contact induces rearrangements of 1 in dry solvents to indene-type 5 and the blue-colored guaiazulenium-type ion 17, via spectrometrically (NMR) characterized indene-type transient intermediates 10, 14, and 12. Addition of NEt(3) to the reaction mixture at appropriate stages allowed the isolation of 12 (and 8 on workup on SiO(2)), and guaiazulene (18). Prolonged contact with silica gel led to complete degradation of 1, giving calenzanane-type epimeric enones 20 a/20 b as well as indene-type epimeric carbinols 22 a/22 b and fulvene 7. The latter was also formed during silica-gel flash chromatography of the algal extracts. A unifying mechanistic view of these branching and cascade transformations may have both heuristic value, suggesting possible artefact origin of azulenoids, and synthetic applications.

The First 6,8-Cycloeudesmane Sesquiterpene from a Marine Organism: The Red Seaweed Laurencia microcladia from the Baia di Calenzana, Elba Island

Reported here is the isolation and structural elucidation of a new 6,8-cycloeudesmane sesquiterpene, 5-bromo-1-isopropyl-2,5a-dimethyl-decahydro-cyclopropa[a]inden-2-ol (5), alongside the known sesquiterpenes (-)-δ-cadinene (7) and (+)-α-cadinol (8), from the red seaweed Laurencia microcladia Kützing of the Baia di Calenzana, Elba Island. Other than belonging to a rare sesquiterpene class, 5 is the first 6,8-cycloeudesmane sesquiterpene of marine origin.

ChemInform Abstract: Calenzanol, the First Member of a New Class of Sesquiterpene with a Novel Skeleton Isolated from the Red Seaweed Laurencia microcladia from the Bay of Calenzana, Elba Island.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Calenzanol, the first member of a new class of sesquiterpene with a novel skeleton isolated from the red seaweed Laurencia microcladia from the Bay of Calenzana, Elba Island

The sesquiterpene calenzanol 1 , the major metabolite of the red seaweed Laurencia microcladia Kützing from the Bay of Calenzana in Elba Island, possesses a previously unreported ring system, thus establishing a new class of sesquiterpene with a novel skeleton, calenzanane 2 . Because of the special array of functionalities, 1 exhibits marked instability, readily rearranging to give the novel indene 3 .

A New-Skeleton Diterpenoid, New Prenylbisabolanes, and Their Putative Biogenetic Precursor, from the Red SeaweedLaurencia microcladia from Il Rogiolo: Assigning the Absolute Configuration when Two Chiral Halves are Connected By Single Bonds

We report here a new-skeleton tricyclic diterpenoid, neorogioldiol (8), along with new prenylbisabolanes, rogioldiol D (6) and O11,15-cyclo-14-bromo-14,15-dihydrorogiol-3,11-diol (5), and their putative biogenetic precursor, (−)-geranyllinalool (7), isolated from the red seaweed Laurencia microcladia, which has colonized a small tract of the Tuscany coast called Il Rogiolo. In a case study of the assignment of the absolute configuration for molecules composed of chiral halves that are connected by single bonds, the absolute configuration of neorogioldiol (8) was based on a) the assumption of the identity of the cyclohexane moiety with co-occurring (2S,3R,6S)-rogiolal (4) and b) NMR-derived relative configurations for the bicyclic moiety, and c) the combination of these two pieces of information by molecular-mechanics-aided conformational analysis, in agreement with NOE data.

ChemInform Abstract: Rogioldiol A, a New Obtusane Diterpene, and Regiolal, a Degraded Derivative of the Red Seaweed Laurencia microcladia from Il Rogiolo Along the Coast of Tuscany: A Synergism in Structural Elucidation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Rogioldiol A, a new obtusane diterpene, and rogiolal, a degraded derivative, of the red seaweed Laurencia microcladia from II rogiolo along the coast of tuscany: A Synergism in Structural Elucidation

AbstractThe structure of rogioldiol A ((−)‐1), isolated from the red seaweed Laurencia microcladia, was determined. Employing the exciton‐coupling technique for rogioldiol A p‐bromobenzoate (2), the absolute configuration at C(9) of (−)‐1 was assigned, and, together with extensive NMR experiments, the absolute configuration at C(10) and preferred conformations of (−)‐1 were determined. The absolute configuration of the hetero‐substituted cyclohexane ring was deduced in analogy from the X‐ray structure of 4, a derivative of the aldehyde 3, which was isolated from the same seaweed and is believed to be a degradation product of (−)‐1.

C15 acetogenins and terpenes of the dictyoceratid sponge Spongia zimocca of Il Rogiolo: A case of seaweed-metabolite transfer to, and elaboration within, a sponge?

Abstract 1. 1. In the narrow Mediterranean area of Il Rogiolo, the acetates of the secondary alcohols of β-chamigrene (−)-1b, branched lauroxepane (−)-2b, and isopimarane (+)-3b are found in the dictyoceratid sponge Spongia zimocca , whereas the corresponding free alcohols (+)-1a, (−)-2a, and probably also (+)-3a, are found in the red seaweed Laurencia microcladia . 2. 2. No one of these acetylated metabolites could be detected either in this seaweed or in the global algal mass of Il Rogiolo. 3. 3. Terpenes bearing tertiary alcoholic functionalities of either L. microcladia (−)-4E, (−)-4Z or another red seaweed of the same area, Sphaerococcus coronopifolius [(+)-5, (−)-6], are found unaltered also in S. zimocca . 4. 4. These findings imply transfer of the hydroxyl-bearing metabolites from the seaweeds to the sponge and it is tempting to speculate that the secondary alcoholic function is acetylated in the sponge while tertiary alcohols and the secondary alcohol (+)-7 escape acetylation, the first ones as sterically-hindered alcohols and the latter one as a sponge metabolite residing in a special cell compartment.

On the unusual propensity by the red seaweed Laurencia microcladia of II Rogiolo to form C15 oxepanes: Isolation of rogioloxepane A, B, C, and their likely biogenetic acyclic precursor, prerogioloxepane

AbstractIt is shown here that the red seaweed Laurencia microcladia KÜTZNING, collected in the Mediterranean off the torrent Il rogiolo, contains the C15 acetogenin rogioloxepane A ( = (+)‐(2R,7R)‐2‐(1‐bromopropyl)‐7‐[(Z)‐1‐chlorohex‐3‐en‐5‐ynyl]‐2,3,6,7‐tetrahydrooxepin; (+)‐3) besides its epoxy derivative rogioloxepane B ((+)‐4) and the rogioloxepane C ((+)‐5) derived from (+)‐4 by epoxide opening. Co‐occurring is an acyclic C15 acetogenin, perrogioloxepane ( = (7R,4Z,9Z,12Z)‐6‐chloropentadeca‐3,9,12‐trien‐1‐yn‐7‐ol; 9), which exists preferentially in a folded conformation as required to give, by intramolecular cyclization, rogioloxepane A (3TC) in its favored twist‐chair form. Molecular‐mechanics calculations support this view and help also to assign the relative configurations at the side chains, whereas the configurations at the seven‐membered ring are established via NMR spectroscopy and chemical correlations. The absolute configuration is established by Mosher's NMR method applied to the MTPA esters of (+)‐5 or 9.