Chemical composition and anti-inflammatory activity of a pectic polysaccharide isolated from sweet pepper using a simulated gastric medium

A pectic polysaccharide named capsicuman (CA) was isolated from fresh sweet pepper by extraction with a saline solution containing hydrochloric acid (pH 1.5) and pepsin at 37 °C for 4 h. Capsicuman was shown to consist of d-galacturonic acid (GalA, 74.0%), rhamnose (Rha, 1.6%), arabinose (Ara, 2.6%) and galactose (Gal, 2.4%) residues. This polysaccharide was digestible with 1,4-alpha-d-galacturonase to yield d-GalA, thus confirming capsicuman as a pectic polysaccharide. Partial acid hydrolysis of capsicuman revealed galacturonan to be the core of the macromolecule. Purified capsicuman (CA-2) was obtained from CA by ion-exchange chromatography on DEAE-cellulose. Nuclear magnetic resonance (NMR) spectra indicated that the backbone of capsicuman contained 1,4-alpha-d-galacturonan partially substituted with methyl and O-acetyl ester groups. After oral administration to mice, capsicuman CA, CA-2 and the galacturonanic fragment of CA (CA-H) were found to decrease tumour necrosis factor-alpha TNF-alpha release and to increase production of interleukin-10 (IL-10) in lipopolysaccharide (LPS)-stimulated whole blood. This pectin was also shown to improve the survival of mice that were subjected to a lethal dose of LPS.The present study demonstrates that the pectin capsicuman CA, which possesses anti-inflammatory properties, can be isolated from fresh sweet peppers using extraction with simulated gastric media.