INVESTIGADORES
CIANCIA Marina
congresos y reuniones científicas
Título:
Iota/kappa Carrageenans and Agarans from Gymnogongrus tenuis (Phyllophoraceae, Rhodophyta)
Autor/es:
MARINA CIANCIA; DILSIA CANELON; MERCEDES PEREZ RECALDE; ALIRICA SUAREZ; REINALDO COMPAGNONE; MARÍA CRISTINA MATULEWICZ; ALBERTO S. CEREZO
Lugar:
Florianopolis
Reunión:
Congreso; IV Congresso Latino-Americano de Biotecnologia de Algas; 2013
Institución organizadora:
Brazilian Network of Marine Algal Biotechnology
Resumen:
Iota/kappa Carrageenans and Agarans from Gymnogongrus tenuis (Phyllophoraceae, Rhodophyta)
1Ciancia
M, 2Canelón D, 1Perez Recalde M , 3Suarez
A, 4Compagnone R, 5Matulewicz MC, 5Cerezo AS.
[1] Cátedra de Química de Biomoléculas, Facultad de Agronomía, Universidad
de Buenos Aires, Buenos Aires, Argentina [2] Escuela de Bioanálisis, Facultad de Medicina, Universidad Central de
Venezuela, Caracas, Venezuela [3] Facultad
de Farmacia, Universidad Central de Venezuela,
Caracas, Venezuela. [4] Escuela de Química, Facultad de Ciencias, Universidad Central de
Venezuela [5] CIHIDECAR-CONICET-UBA, Buenos Aires, Argentina.
Correspondence
author: Marina Ciancia, ciancia@agro.uba.ar
Seaweeds from the genus Gymnogongrus
are know to produce kappa/iota-carrageenans with predominance of iota-structure1.
However, it was found that galactans from G.
tolulosus comprise also important quantities of agarans with an unusual
substitution pattern, including important quantities of a-L-galactose 3-sulfate units2,3. Vegetative thalli from Gymnogongrus tenuis (J. Agardh) J.
Agardh, collected in Puerto Maya, Estado Aragua, Venezuela, were extracted with
methanol and the residue was further extracted with water at room temperature
and at 90ºC giving extracts A1 and A2, and C1, respectively (yields, 0.6 and
0.3, and 47.7 % of the milled seaweed). Enantiomeric analyses showed that A1
and A2 are mostly agarans, while C1 is composed mainly by carrageenans, only
traces of agarans were detected. Structural analysis of the latter extract (molar
ratio carbohydrate:sulfate, 1.00:1.04), showed the presence of 1/3 of precursor
units, with predominance of iota/nu-carrageenan diads. Fractionation of C1 with
KCl gave nine fractions; the major fraction, F4 (43.3 % of C1,
carbohydrate:sulfate, 1.00:1.05) precipitated at 0.3-0.6 M, and another
important fraction, F9, remained soluble in 4.3 M KCl (14.7 %.
carbohydrate:sulfate, 1.00:1.18). All these fractions showed by chemical and
spectroscopic analyses, iota/kappa-structures; only minor quantities of agarans
were detected. On the other hand, extracts A1 and A2 (molar ratio
carbohydrates:sulfate 1.00:0.72 and 1.00:0.68, respectively) comprise only
small amounts of iota-carrageenans (~ 15 %).
The other structures present correspond to agarans, with 3-linked b-D-galactose units partially substituted on C-6 and 4-linked
3,6-anhydro-a-L-galactose and 3-substituted a-L-galactose residues, as found before in G. torulosus, being these substituents, sulfate ester groups and
single stubs of b-D-xylose in comparable quantities. These results show that Gymnogongrus tenuis biosynthesizes
important amounts of iota/kappa-carrageenans, being a potential source of
hydrocolloids, but also small quantities of interesting agaran structures that
seem to be independent polymer molecules.
1 Furneaux, R. H., & Miller, I. J. (1985) Botanica Marina, 28, 419?425. 2 Estevez, J. M., Ciancia,
M., & Cerezo, A. S. (2001) Carbohydrate Research, 331, 27?41. 3 Estevez, J. M., Ciancia, M.,
& Cerezo, A. S. (2008) Carbohydrate Polymers, 73, 594?605.