New oligosaccharides prepared by acid hydrolysis of the polysaccharides from Nerium indicum Mill and their anti-angiogenesis activities

To discover drug candidates with anti-angiogenesis activity for cancer therapeutics, three galactooligosaccharides (OJ1–OJ3) were prepared by acid hydrolysis of the polysaccharides from Nerium indicum Mill. Their structures were characterized using sugar analysis, methylation analysis, and both 1D and 2D NMR spectroscopy, complemented by mass spectrometry. They were hexasaccharide (OJ1), a pentasaccharide (OJ2), and an undecasaccharide (OJ3), which was a new linear galactan. Bioactivity testing in vitro showed that OJ2 and OJ3 significantly inhibited the HMEC-1 (human microvascular endothelial cell) cell tube formation.

Graphical abstractThree oligosaccharides (OJ1–OJ3) were obtained by acid degradation of crude polysaccharides from Nerium indicum Mill. The study of chemical and spectroscopic methods demonstrated that they were β-d-Galp-(1→[4)-β-d-Galp-(1→]44)-d-Galp (OJ1), β-d-Galp-(1→[4)-β-d-Galp-(1→]34)-d-Galp (OJ2) and another new oligosaccharide, β-d-Galp-(1→[4)-β-d-Galp-(1→]94)-d-Galp (OJ3). Angiogenesis test showed that OJ2 and OJ3 blocked cell tube formation of HMEC-1.