Isolation, characterisation and sulphation of soluble polysaccharides isolated from Cucurbita maxima

Summary Using hot water extraction, a large number of polysaccharides were obtained from Cucurbita maxima . A DEAE ‐Sepharose CL ‐6B chromatography column was used to isolate the major polysaccharides from C. maxima . Two fractions were obtained ( LP 2‐1 and LP 2‐2). LP 2‐1 and LP 2‐2 consisted of neutral polysaccharides ( MW : 1.02 × 10 4 and 4.32 × 10 8 g mol −1 , respectively) comprised mainly of galactose units. Analyses by FT ‐ IR spectrometry, partial acid hydrolysis, periodate oxidation, Smith degradation and GC ‐ MS indicated that LP 2‐1 consisted of 85.3% (1→4) glycosidic linkages and 1.7% (1→3) or (1→6) glycosidic linkages. The LP 2‐1 backbone consisted of (1→4)‐linked galactose units, which occasionally branched at O6 or O3. The branches were composed of (1→4)‐linked galactose and terminated with galactose (13%). Two sulphated derivatives ( SLP 2‐1 and SLP 2‐2) with variable degrees of sulphation ( DS ) were obtained by the sulphur trioxide–pyridine method, without degradation of the polysaccharide. DS of PL 2‐1 and PL 2‐2 was 0.19 and 0.20, respectively.