Brown Alga Bifurcaria Bifurcata Research Articles

Density Functional Theory (DFT)-Aided Structure Elucidation of Linear Diterpenes from the Irish Brown Seaweed Bifurcaria bifurcata.

Brown alga Bifurcaria bifurcata is an extraordinarily rich source of linear (acylic) diterpenes with enormous structural diversity. As part of our interest into secondary metabolites of the Irish seaweeds, here we report four new acyclic diterpenes (1–4) and seven known terpenoids (5–11) from the CHCl3 extract of B. bifurcata. The planar structures of the new metabolites were elucidated by means of 1D and 2D NMR, HRMS, and FT-IR spectroscopy. Since linear diterpenes are highly flexible compounds, the assignment of their stereochemistry by conventional methods, e.g., NOESY NMR, is difficult. Therefore, we employed extensive quantum-mechanical prediction of NMR chemical shifts and optical rotation analyses to identify the relative and absolute configurations of the new compounds 1–4. Several compounds moderately inhibited the human breast cancer cell line (MDA-MB-231) with IC50 values ranging from 10.0 to 33.5 μg/mL. This study not only demonstrates the vast capacity of the Irish B. bifurcata to produce highly oxygenated linear diterpenoids, but also highlights the potential of new methodologies for assignment of their stereogenic centers.

Extraction and characterization of phlorotannin-enriched fractions from the Atlantic seaweed Bifurcaria bifurcata and evaluation of their cytotoxic activity in murine cell line

Phlorotannins, a group of polymeric polyphenols composed of phloroglucinol monomers, were obtained from the brown alga Bifurcaria bifurcata by solvent extraction (acetone/water 70:30 v/v) and further semipreparative chromatography. Characterization of several polyphenolic fractions with different polymerization degrees was carried by HPLC-MS. Cytotoxic activity of phlorotannin fractions were tested in ATDC5 murine cell line and analyzed by MTT assay. A fraction eluted between 14 and 16 min showed the highest cytotoxicity against ATDC5 murine cells in a dose-responsive manner. Hydroxytetrafuhalol (tetrafuhalol B) was the main component of this fraction. Fractions with the highest molecular size, corresponding with oligomeric phlorotannins with a polymerization degree > 6, did not show the same cytotoxicity, likely due to their size. Cytotoxicity for the fraction containing the higher polarity and lower molecular size was not observed.

Bifurcatriol, a New Antiprotozoal Acyclic Diterpene from the Brown Alga Bifurcaria bifurcata.

Linear diterpenes that are commonly found in brown algae are of high chemotaxonomic and ecological importance. This study reports bifurcatriol (1), a new linear diterpene featuring two stereogenic centers isolated from the Irish brown alga Bifurcaria bifurcata. The gross structure of this new natural product was elucidated based on its spectroscopic data (IR, 1D and 2D-NMR, HRMS). Its absolute configuration was identified by experimental and computational vibrational circular dichroism (VCD) spectroscopy, combined with the calculation of 13C-NMR chemical shielding constants. Bifurcatriol (1) was tested for in vitro antiprotozoal activity towards a small panel of parasites (Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi, and Leishmania donovani) and cytotoxicity against mammalian primary cells. The highest activity was exerted against the malaria parasite P. falciparum (IC50 value 0.65 μg/mL) with low cytotoxicity (IC50 value 56.6 μg/mL). To our knowledge, this is the first successful application of VCD and DP4 probability analysis of the calculated 13C-NMR chemical shifts for the simultaneous assignment of the absolute configuration of multiple stereogenic centers in a long-chain acyclic natural product.

Assignment of absolute configurations of highly flexible linear diterpenes from the brown alga Bifurcaria bifurcata by VCD spectroscopy.

Correct assignment of the stereogenic centers of highly flexible linear diterpenes (LDs) is challenging. Herein we report the first application of VCD spectroscopy for the absolute configuration determination of LDs of algal origin and provide experimental and computational procedures, such as a fragmentation approach, which will facilitate the use of VCD spectroscopy for configuration assignments of LDs.

Linear diterpenes with anticancer activity from the irish brown alga Bifurcaria bifurcata

Linear diterpenes with anticancer activity from the irish brown alga Bifurcaria bifurcata

Linear diterpenes from the marine brown alga Bifurcaria bifurcata: a chemical perspective

This article will give a complete overview of linear diterpenes isolated from the brown alga Bifurcaria bifurcata. For this purpose all published acyclic diterpenoids are listed and gathered in three main biosynthetic families with respect to their structural similarities. These are the C-12 oxidized (e.g. eleganediol), the C-13 oxidized (e.g. eleganolone), and the direct geranylgeraniol derivatives. The origin and plausible biosynthesis of all compounds are discussed. Additionally, the issues concerning the configurational assignment such as the configuration of trisubstituted double bonds and the configuration of oxidized stereogenic centers are pointed out. Special emphasis is also given on synthesis, biological activities (cytotoxic, antimicrobial, and antifouling activities), chemotaxonomy, and ecology of the compounds.

Formyleleganolone and bibifuran, two metabolites from the brown alga Bifurcaria bifurcata

Two new diterpenoids formyleleganolone (1) and bibifuran (2) were isolated from a sample of the brown alga Bifurcaria bifurcata collected near Roscoff (Brittany, France). The structures of the new compounds were established on the basis of 1D and 2D NMR spectroscopic and mass spectrometric (ESI and EI) analyses. Formyleleganolone (1) is derived from eleganolone (4) by formylation of the hydroxy group. Bibifuran (2) has been identified as a new furan derivative of 4. Additionally, the diterpenoid 16-hydroxygeranylgeraniol (3) is reported for the first time from this species.

Benthic assemblages of rock pools in northern Portugal: seasonal and between-pool variability

We investigated the seasonal (winter vs summer and within season) and spatial (between-pool) variability of benthic assemblages of rock pools at mid-intertidal level along the shore of Viana do Castelo (North Portugal). Physical traits of rock pools, including size, depth and position along the shore, were also compared between pools. While pools did not differ for any of the examined physical traits, results indicated a clear seasonal difference in the structure of assemblages, including a total of 49 macroalgal and 13 animal taxa. This finding was driven by six taxa that are more abundant in winter (the reef-forming polychaete Sabellaria alveolata , the articulated coralline algae Corallina spp., the brown alga Bifurcaria bifurcata , the encrusting coralline alga Lithophyllum incrustans , the red alga Chondracanthus acicularis and the grazing snails Gibbula spp.) and four algal taxa that are more abundant in summer (the invasive brown Sargassum muticum , the green Ulva spp., the kelp Laminaria ochroleuca and the filamentous red Ceramium spp.). These data provide a new contribution to the knowledge of rock pool systems and have potential implications for monitoring programmes aimed at assessing ecological modifications related to natural and anthropogenic disturbances and for identifying processes responsible for the variability of rock pool assemblages.

Further eleganolone-derived diterpenes from the brown alga Bifurcaria bifurcata

Four new diterpenes (1–4) together with six known members of this family were isolated from the brown alga Bifurcaria bifurcata collected off the coast near Roscoff, France. The structures of the new compounds were established in a comprehensive study on the basis of 1D and 2D NMR spectroscopic and mass spectrometric (ESI-MS) analyses. Our assignment is supported by a comparison of the 13C NMR chemical shifts to known compounds and predicted values. The new diterpenes are derivatives of the diterpene eleganolone (5). The structural relation and hypothetical metabolic pathway of the new diterpenes (1–4) with the co-isolated known diterpenes are discussed.

CORROSION INHIBITION OF CARBON STEEL IN ACIDIC MEDIA BY BIFURCARIA BIFURCATA EXTRACT

The effect of extract of brown alga Bifurcaria bifurcata (Bb) on the corrosion of steel in 1 M HCl solution was studied using weight loss, potentiodynamic, and polarization resistance measurements. Experimental data revealed that Bb extract acted as an inhibitor in the acid environment. The extract was a mixed-type inhibitor, predominating as an anodic inhibitor at higher concentration. It was found that the inhibition efficiency increased with an increase in Bb extract concentration. The corrosion inhibition of Bb extract on carbon steel in 1 M HCl solution was also investigated by infrared and UV-visible spectrophotometry to obtain information on bonding mechanism between the metallic surface and the inhibitor. The process of inhibition is attributed to the adsorption of the extract molecules, the precipitation of Fe-chelates, and/or formation of complex at the electrode surface.

An extract from the brown alga Bifurcaria bifurcata induces irreversible arrest of cell proliferation in a non-small-cell bronchopulmonary carcinoma line

In this study, the antiproliferative activity of a crude extract isolated from Bifurcaria bifurcata (Velley) Ross, a common marine brown alga of the Atlantic shores of Europe, was investigated. Its antiproliferative effect on asynchronous cells of a human non-small-cell bronchopulmonary carcinoma line (NSCLC-N6), particularly chemo-resistant, was expected in vitro. Cell growth appeared to be inhibited in the G1 phase of the cell cycle, and kinetic studies in pretreated cells showed that this growth arrest was irreversible. These events are related to a terminal differentiation induction.

Polar acyclic diterpenoids from Bifurcaria bifurcata (Fucales, Phaeophyta)

From the lipophilic extract of the brown alga Bifurcaria bifurcata collected off the Atlantic coast of Southern Brittany (Quiberon, France), five polar linear diterpenoids have been isolated. These metabolites have been identified as hydroxylated derivatives of 13-oxo- and 13-hydroxygeranylgeraniol. Their structures were characterized on the basis of chemical and spectral evidence including two-dimensional NMR experiments and mass spectrometric techniques. The absolute configuration of the 13-position has been determined, for the 13-hydroxygeranylgeraniol derivatives, to be R by means of a modified Mosher’s method and therefore that of 13-hydroxygeranylgeraniol (eleganediol) has been revised. Along with these compounds, three related known geranylgeraniol derivatives were also identified, and these data were used for chemotaxonomical purposes.

Trihydroxylated linear diterpenes from the brown alga Bifurcaria bifurcata

Two novel polar diterpenes were isolated from the brown alga Bifurcaria bifurcata collected off the Atlantic coast of Morocco, and their structures established by spectral methods. Both compounds are trihydroxylated acyclic diterpenes derived from 12-hydroxygeranylgeraniol. They were tested in vitro for their cytotoxicity and proved to be active against the NSCLC-N6 cell line. Their absolute configuration at the C-12 position has been determined with a modified Mosher's method [J. Am. Chem. Soc. 113 (1991) 4092] and that of the 12-hydroxygeranylgeraniol (bifurcadiol) has been revised.

( S)-12-Hydroxygeranylgeraniol-derived diterpenes from the brown alga Bifurcaria bifurcata

Four novel diterpenes were isolated from the brown alga Bifurcaria bifurcata collected off the Atlantic coast from Morocco, and their structures established by spectral and chemical methods. These compounds are acyclic diterpenes derived from ( S)-12-hydroxygeranylgeraniol. One of them is its dehydration product at C-12, while the others are its oxidation derivatives : the methyl ester of the acid at C-1 and two stereoisomers ( Z and E) of the aldehyde at C-1. These results are discussed from a chemotaxonomic point of view.

Geranylgeraniol-derived diterpenoids from the brown alga Bifurcaria bifurcata

Three novel diterpenes were isolated from the brown alga Bifurcaria bifurcata collected off the Atlantic coast from Brittany, and their structures established by spectroscopic methods. Two of them are acyclic diterpenoids derived from 13-ketogeranylgeraniol, while the third is a β,γ-epoxy-γ-butyrolactone derived from ( S)-hydroxygeranylgeraniol. Some assignments of 13 C - and 1 H -NMR signals in 13-ketogeranylgeraniol and related diterpenoids were revised to take account of the results obtained in 2D NMR long-range C–H correlation experiments. These results are discussed from a chemotaxonomic point of view.

( S)-13-hydroxygeranylgeraniol-derived furanoditerpenes from Bifurcaria bifurcata

Two new diterpenes were isolated from a sample of the brown alga Bifurcaria bifurcata collected from Brittany on the Atlantic coast and their structures established by spectroscopic methods. The new diterpenes are derived from ( S)-13-hydroxygeranylgeraniol by terminal cyclization and oxidation leading to a furan-3-yl ring or a β, γ-epoxy-γ-lactone. One of them showed a cytotoxic effect to fertilized sea urchin eggs. The chemical shifts of the methyl groups and quaternary carbons in ( S)-13-hydroxygeranylgeraniol have been revised to take account of the results obtained in a 2D NMR long-range C H correlation experiment and the absolute configuration at C-13 determined for the first time. The geographical variation in the diterpenoid composition of B. bifurcata was also studied.

Variation de la composition en diterpènes deBifurcaria bifurcatasur les côtes atlantiques françaises

Summary Geographical variations in the diterpene composition of the diethyl ether extract from the brown alga Bifurcaria bifurcata are described in algae collected on the French Atlantic coasts. They are then compared with those in same algae from the coasts of Morocco. Several types of extracts have been found, and they vary according to where they are collected, thus delimiting more or less extensive geographical zones. Altogether, five diterpenes (1 to 5) have been isolated, identified and analysed in the different extracts. Two of them had not, so far, been recorded in this alga (4 and 5).

Linear diterpene with antimitotic activity from the brown alga Bifurcaria bifurcata

A new linear diterpene, isolated from the brown alga Bifurcaria bifurcata collected on the Atlantic coasts from Morocco, has been characterized by spectral methods and chemical reactions. This compound revealed a potent cytotoxicity to fertilized sea urchin eggs which was compared to that of previously described acyclic diterpenes. The seasonal and geographical variations in the diterpenoid composition of this species are also studied and the results discussed.

Two new diterpenoid dihydroxy-γ-butyrolactones from Bifurcaria bifurcata (Cystoseiraceae)

Two new stereoisomeric eleganolone derived diterpenes (I and II) were isolated from the brown alga Bifurcaria bifurcata and the structures were assigned by 1H- and 13C-NMR experiments.

Eleganolone derived diterpenes from Bifurcaria bifurcata

Three new diterpenes were isolated from the brown alga Bifurcaria bifurcata together with elegandiol and eleganolone. The new compounds are all formally derived from eleganolone. This is the first report on cyclic diterpenoids from Bifurcaria. The structures were established by spectroscopic methods.