Separation, structural identification and antibacterial activity of pectin oligosaccharides derived from seed melon.

In this study, the pectin of waste seed melon peel in Xinjiang was used as raw material to prepare seed melon pectin oligosaccharide (Sm-POS). The separation and purification of Sm-POS were carried out by HPD-750 macroporous resin chromatography column and gel chromatography to further study the molecular structure of its active component with antibacterial effect by FT-IR, NMR, and LC/MS. The antibacterial activity and mechanism of the Sm-POS active component were investigated by inhibition zone experiment, minimum inhibitory concentration determination, cell growth curve determination, scanning electron microscopy, and flow cytometry analysis. Results showed that Sm-POS-2 was an oligosaccharide composed of two galacturonic acids, one glucose, one arabinose, and one xylose. It showed good antibacterial activity and suppressed the growth of E. coli and S. aureus at minimum inhibitory concentrations (MIC) of 25.0 and 50.0 g/L, respectively. The inhibitory effect of Sm-POS on E. coli and S. aureus was mainly due to cell membrane contraction or rupture, leading to the apoptosis or necrosis of bacterial cells. [ABSTRACT FROM AUTHOR]