Polysaccharides from the peels of Citrus aurantifolia induce apoptosis in transplanted H22 cells in mice

In this study, an acidic polysaccharide (CAs) was extracted and purified from the peels of Citrus aurantifolia by Sephadex G-150. HPGPC showed the molecular weight of CAs was about 7.94 × 106 Da. Ion chromatography (IC) analysis showed CAs was mainly composed of rhamnose (Rha), arabinose (Ara), galactose (Gal), glucose (Glu), mannose (Man) and galacturonic acid (GalA), with the molar ratio of 0.67: 7.67: 10.83: 3.83: 4.00: 1.00. 1H and 13C NMR spectra of CAs also identified the presence of five kinds of monosaccharides and galacturonic acid. Moreover, the antitumor activity of CAs was evaluated in mice transplanted H22 hepatoma cells. It was shown that CAs dose-dependently suppressed tumor cells growth with few toxic effects on host. Further investigations revealed that CAs increased the levels of tumor infiltrating CD8+ T lymphocytes, blocked tumor cell cycle in S phase, down-regulated anti-apoptotic protein Bcl-xL and Mcl-1 expression, and led to the activation of caspase 3. These results suggested that CAs had capacity of inducing tumor cells apoptosis in vivo, and it supported considering CAs as an adjuvant reagent in hepatocellular carcinoma treatment.