Assignment of agar or carrageenan structures to red algal polysaccharides

Whyte, J. N. C.; Hosford, S. P. C.; Englar, J. R.

doi:10.1016/0008-6215(85)85135-1

Cited by 74 publications

(21 citation statements)

References 11 publications

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“…Whyte et al (1985) found the combination of IR analysis with high performance liquid chromatography of methanolysates from algal galactans helpful for their classification into agar or carrageenan structures.…”

Section: Methods In the Chemical Analysis Of Agar And Agarosementioning

confidence: 99%

Chemical structure and physico-chemical properties of agar

Lahaye¹,

1991

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Advances in the chemistry and physico-chemical properties of agar since the review of Araki at the Fifth International Sqweed Symposium in 1965 are discussed. These advances are essentially the result of better separation techniques of the heterogeneous family of polysaccharides known as agar, the use of nuclear magnetic resonance spectroscopy, the use of agarases and, particularly, the use of combinations of the three approaches. Although physico-chemical methods have evolved, particularly molecular-weight determinations, X-ray diffraction data and molecular modelling of agar, correlations between chemical and functional properties of agar and agarose and their gelation mechanisms remain to be studied.

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Section: Methods In the Chemical Analysis Of Agar And Agarosementioning

confidence: 99%

Chemical structure and physico-chemical properties of agar

Lahaye¹,

1991

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“…This is an excellent, non-destructive and easily accessible technique, which provides important structural information, in particular about the location of the sulphate groups (Lloyd et al, 1961;Whyte et aL, 1985;Rochas et al. 1986;Armisen & Galatas, 1987).…”

Section: Infrared Spectroscopymentioning

confidence: 98%

Chemical structure and quality of agars from Gracilaria

Murano

1995

J Appl Phycol

110

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Agar polymers synthesized by species of the genus Gracilaria constitute a complex mixture of molecules, containing several extremes in structure. Sulphate hemi-esters, methyl ethers and pyruvic ketals can alter in a number of ways the structural regularity of agar based on strictly 3-O-linked /I-L-galactopyranose and 4-O-linked a-L-galactopyranose residues. In comparison with agars from Gelidium and Pterocladia, agars from Gracilaria can have higher degrees of sulphation, methoxylation and pyruvylation. The gelling ability of agars from most of Gracilaria species is considerably improved by adopting, before extraction, an alkali pretreatment which converts a-L-galactose 6 sulphate into 3,6-anhydro-a-L-galactose. Native agars obtained from Gracilaria cannot be classified, with few exceptions, as bacteriological grade agar as they have a high content of methoxyls and consequently high gelling temperatures. On the contrary, the genus Gracilaria is considered the most important source of food and sugar-reactive grade agars.Among techniques which can be used to study algal polysaccharides, combined H and 3 C nuclear magnetic resonance spectroscopy represent the most effective and powerful method for the investigation of the chemical structure of agarocolloids.

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“…cm" 1 ) of the IR spectra of the polysaccharides resembled that of i-carfafgeenan (Standoff and Stanley 1969) (Whyte et al 1985). Compared with the IR spectra of the native polysaccharides, those of the alkali-modified polysaccharides displayed an enhanced valley at 820-830 cm" 1 , the region associated with equatorial sulphate esters at C(O)6 and C(O)2 of the precursor residues (Stancioff and Stanley 1969).…”

Section: Ir Spectroscopic Analysismentioning

confidence: 99%

Cell Wall Polysaccharides from Australian Red Algae of the Family Solieriaceae (Gigartinales, Rhodophyta): Highly Methylated Carrageenans from the Genus Rhabdonia

Chiovitti¹,

Liao²,

Kraft³

et al. 1996

Botanica Marina

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The hot water-soluble polysaccharides from RJiabdonia coccinea and R. verticillata were characterised by a combination of constituent sugar analysis, sulphate and pyruvate content assays, infrared (IR) spectroscopy, linkage analysis, and 13 C-nuclear magnetic resonance (NMR) spectroscopy. These revealed unique polysaccharides belonging to the red algal galactan family. The polysaccharides had IR spectra resembling that of icarrageenan, but were rich in 6-0-methylgalactose (ca. 31 mol% and 17mol% for R. coccinea and R. verticillata, respectively). Data from 13 C-NMR spectroscopy provided evidence that the polysaccharides were carrageenans rather than agarocolloids. The preparations contained mainly ι-carrageenan, partially methylated at C(O)6 of the 3-linked galactose residue. The polysaccharide from R. verticillata also contained significant quantities of 3-0-methylgalactose and pyruvate. The unusual sugar 3-0-methylgalactose occurred primarily as main-chain 4-linked residues, with a small proportion in the form of terminal residues. Other structural variations occurred in the polysaccharides of both species. IntroductionThe phycocolloids from red algae are variously substituted galactans which form the dominant components of the matrix phase of algal cell walls (see Craigie 1990 for a review). The gelling and thickening properties and protein-reactivity of these phycocolloids have led to their widespread commercial use in industry (Glicksman 1987, Stanley 1990, Selby and Whistler 1993, Therkelsen 1993. The chemistry of red algal galactans has also been used to supplement classical criteria, such as morphology, anatomy, and life history studies, in the formulation of taxonomic hypotheses (e. g. Gabrielson and Garbary 1986, Doty 1989, Liao et al 1993, Chiovitti et al 1995.The galactans from red algae consist of repeating disaccharide units of alternating β-1,3-and a-1,4-linked galactopyranosyl residues. The disaccharide units are variously substituted with sulphate ester, methyl ether, pyruvate acetal, or single glycosyl side branches and the 4-linked galactose residue may be converted into 3,6-anhydrogalactose. There are two main classes of these galactans, the agars and the carrageenans. In ag rs, the 44inked residue is in the Lconfiguration, whereas in carrageenans, it is in the Dconfiguration. The 3-linked residue is in the D-configuration in both classes of galactan. Carrageenans are typically more sulphated than agars, and idealised carrageenan types (e. g. κ-, ι-, °1-) have traditionally been defined according to their sulphate substitution pattern and their 3,6-anhydrogalactose content. By contrast, agars typically contain significant amounts of methyl ether or pyruvate acetal substitution (Craigie 1990). The type and amount of substitution modify solution properties of red algal polysaccharides , Arnott et al 1974, Guiseley 1987.The Australian coastline is rich in both its abundance and diversity of red algae, but their phycocolloids have not been extensively studied. We are currently undertaking a progr...

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Assignment of agar or carrageenan structures to red algal polysaccharides

Cited by 74 publications

References 11 publications

Chemical structure and physico-chemical properties of agar

Chemical structure and physico-chemical properties of agar

Chemical structure and quality of agars from Gracilaria

Cell Wall Polysaccharides from Australian Red Algae of the Family Solieriaceae (Gigartinales, Rhodophyta): Highly Methylated Carrageenans from the Genus Rhabdonia

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