Structural elucidation of a pectin from flowers of Lonicera japonica and its antipancreatic cancer activity

•A new rhamnogalacturonan from flowers of Lonicera japonica is characterized.•Backbone is alternate 1,4-α-d-GalpA and 1,2-α-l-Rhap.•Branches contain T- and 1,4,6-linked β-d-Galp, T- and 1,5-linked α-l-Araf.•Rhamnogalacturonan might inhibit BxPC-3 and PANC-1 pancreatic cancer cells growth.

To investigate polysaccharide structure from Lonicera japonica, and study its effects on behavior of pancreatic cells, a homogenous polysaccharide, LJ-02-1, was extracted and purified from flowers of L. japonica by DEAE-cellulose and Sephacryl S-200HR column. The molecular weight was estimated to be 54 kDa. Monosaccharide composition was determined to be rhamnose, galacturonic acid, galactose and arabinose in the molar ratio of 10.77:7.88:15.45:65.89 by analyzing the PMP derivatives of the monosaccharides from 2 M trifluoracetic acid hydrolysis via HPLC. Based on methylation analysis, partial acid hydrolysis, and NMR spectra, the polysaccharide was elucidated to be a rhamnogalacturonan backbone and substituted partly at C-4 of rhamnose. The branches were determined to be T- and 1,4,6-linked β-d-Galp, T- and 1,5-linked α-l-Araf. The polysaccharide might inhibit BxPC-3 and PANC-1 pancreatic cancer cells growth at the concentration of 1 mg/mL with inhibitory ratio of 66.7% and 52.1%, respectively.

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