Galactans of Gracilaria pudumadamensis (Gracilariales, Rhodophyta) of Indian Waters

Abstract

Galactans from the Indian agarophyte Gracilaria pudumadamensis were extracted and characterized. The isolated native (GPNative) and alkali treated (GPAlkali) galactans were characterized by IR, 13C NMR, GC-MS and GPC. It was found that GPNative and GPAlkali were composed mainly of 3,6-anhydro L-galactose, 6- O-methylated D-galactose and galactose in various mole proportions (15.6:69.9:17.5 mole% for GPNative and 20.2:69.8:10.0 mole% for GPAlkali). The GPNative and GPAlkali exhibited low gel strengths (<100 g/cm2) and high melting points (~76 °C), which may be due to the presence of high 6- O-Me-galactose contents. The latter, having low sulfate (2.1%), was by far the greatest 6- O-Me-galactose containing polysaccharide in a Gracilaria spp. reported in the literature. This methylated agar contained very low heavy metal ions estimated by inductively coupled plasma spectrophotometry (ICP). The results of this investigation would be useful in bioprospecting of agarophytes, especially those occurring in Indian waters and would be potentially useful in food, personal care and related domains.