Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan
A homogeneous iota/nu-hybrid cairageenan (71% iota- and 21% nu-) isolated from Eucheuma denticulatum was used as a model compound to study the cyclization reaction of α-D-galactose 2,6-disulfate units to 3,6-anhydro-α-D- galactose 2-sulfate. The rate of cyclization, at 70°C, of this carrageenan is a...
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| Autores principales: | , |
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| Publicado: |
2004
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01448617_v58_n4_p455_Viana http://hdl.handle.net/20.500.12110/paper_01448617_v58_n4_p455_Viana |
| Aporte de: |
| Sumario: | A homogeneous iota/nu-hybrid cairageenan (71% iota- and 21% nu-) isolated from Eucheuma denticulatum was used as a model compound to study the cyclization reaction of α-D-galactose 2,6-disulfate units to 3,6-anhydro-α-D- galactose 2-sulfate. The rate of cyclization, at 70°C, of this carrageenan is about 50 times faster than that of a porphyran (non-sulfated β-D-galactose linked to α-L-galactose 6-sulfate) and 210 times faster when compared with a lambda-carrageenan (2-sulfated β-D-units linked to α-D-galactose 2,6-disulfate). The use of this model compound confirms the previous hypothesis of the accelerating effect of the β-o-4-sulfate group as well as suggests the influence of the 2-sulfate of the α-D-galactose units on the 4C1 → 1C4 chair forms interchange. The easy of cyclization indicates that to produce commercial iota-carrageenans milder alkaline treatments could be used, avoiding degradation and increasing the gel strength. © 2004 Elsevier Ltd. All rights reserved. |
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