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Profiling of the molecular weight and structural isomer abundance of macroalgae-derived phlorotannins.

Heffernan N, Brunton NP, FitzGerald RJ, Smyth TJ - Mar Drugs (2015)

Bottom Line: The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4-12 monomers of phloroglucinol.The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights.These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.

View Article: PubMed Central - PubMed

Affiliation: Food Biosciences Department, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland. dick.fitzgerald@ul.ie.

ABSTRACT
Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4-12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.

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UPLC-MS total percentage peak intensity for individual molecular ions corresponding to phlorotannins of between 3 and 16 phloroglucinol units (PGUs) enriched from four species of macroalgae. The number of phlorotannin isomers detected at each molecular weight correspond to phlorotannins detected fromin extracts from each brown algal species are highlighted with bold numbers. Fucus serratus (FS), Fucus vesiculosus (FV), Cystoseira nodicaulis (CN), Himanthalia elongata (HE).
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marinedrugs-13-00509-f005: UPLC-MS total percentage peak intensity for individual molecular ions corresponding to phlorotannins of between 3 and 16 phloroglucinol units (PGUs) enriched from four species of macroalgae. The number of phlorotannin isomers detected at each molecular weight correspond to phlorotannins detected fromin extracts from each brown algal species are highlighted with bold numbers. Fucus serratus (FS), Fucus vesiculosus (FV), Cystoseira nodicaulis (CN), Himanthalia elongata (HE).

Mentions: The peak intensities and also the number of isomers for each species can be viewed in Figure 5. F. serratus and C. nodicaulis show similar results, with 90% of the phlorotannins being observed between 3–12 and 3–10 PGUs, respectively. In the species F. vesiculosus, the percentage peak intensities observed highlight that a majority of the phlorotannins are of lower molecular weight and up to 90% of the phlorotannins are found to be between 3–8 PGUs. In H. elongata up to 80% of the phlorotannins found were between 7–11 PGUs. Previous research to date on the isolation and characterization of individual phlorotannin compounds from some of these species has been limited [31,32,34,37]. This study is the first to emphasize the complex nature of these compounds in relation to the number of isomers present even in these low molecular weight fractions. This outcome also draws attention to the considerable amount of research that would be required for complete characterization of some of the more complex species such as F. serratus and H. elongata.


Profiling of the molecular weight and structural isomer abundance of macroalgae-derived phlorotannins.

Heffernan N, Brunton NP, FitzGerald RJ, Smyth TJ - Mar Drugs (2015)

UPLC-MS total percentage peak intensity for individual molecular ions corresponding to phlorotannins of between 3 and 16 phloroglucinol units (PGUs) enriched from four species of macroalgae. The number of phlorotannin isomers detected at each molecular weight correspond to phlorotannins detected fromin extracts from each brown algal species are highlighted with bold numbers. Fucus serratus (FS), Fucus vesiculosus (FV), Cystoseira nodicaulis (CN), Himanthalia elongata (HE).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306949&req=5

marinedrugs-13-00509-f005: UPLC-MS total percentage peak intensity for individual molecular ions corresponding to phlorotannins of between 3 and 16 phloroglucinol units (PGUs) enriched from four species of macroalgae. The number of phlorotannin isomers detected at each molecular weight correspond to phlorotannins detected fromin extracts from each brown algal species are highlighted with bold numbers. Fucus serratus (FS), Fucus vesiculosus (FV), Cystoseira nodicaulis (CN), Himanthalia elongata (HE).
Mentions: The peak intensities and also the number of isomers for each species can be viewed in Figure 5. F. serratus and C. nodicaulis show similar results, with 90% of the phlorotannins being observed between 3–12 and 3–10 PGUs, respectively. In the species F. vesiculosus, the percentage peak intensities observed highlight that a majority of the phlorotannins are of lower molecular weight and up to 90% of the phlorotannins are found to be between 3–8 PGUs. In H. elongata up to 80% of the phlorotannins found were between 7–11 PGUs. Previous research to date on the isolation and characterization of individual phlorotannin compounds from some of these species has been limited [31,32,34,37]. This study is the first to emphasize the complex nature of these compounds in relation to the number of isomers present even in these low molecular weight fractions. This outcome also draws attention to the considerable amount of research that would be required for complete characterization of some of the more complex species such as F. serratus and H. elongata.

Bottom Line: The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4-12 monomers of phloroglucinol.The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights.These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.

View Article: PubMed Central - PubMed

Affiliation: Food Biosciences Department, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland. dick.fitzgerald@ul.ie.

ABSTRACT
Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4-12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.

Show MeSH
Related in: MedlinePlus