A Highly Methylated Agar from Red Seaweed, Gracilaria arcuata

Abstract

A highly methylated agar was isolated from Gracilaria arcuata which was harvested from Ishigaki Island, Okinawa, Japan. The yield of the agar was 33.2% (w/w dry algae). Gelation occurred at a concentration of 0.35% (w/v) at room temperature. The total carbohydrate, sulphate, ash and methoxyl content were 85.0, 0.8, 3.8 and 13.4% (w/w), respectively. The methylated sugar was identified as 6-O-methyl-D-galactose and 2-O-methyl-anhydro-L-galactose residues, respectively, by 13 C- and 1 H-NMR spectroscopy. The methylated agar was composed of D-galactose, 6-O-methyl-D-galactose, 3,6-anhydro-L-galactose, and 2-O-methyl-3,6-anhydro-L-galactose.