In Vitro Anti-tumor Effects of Chemically Modified Polysaccharides from Cherokee Rose Fruit

Abstract

Abstract Cherokee rose fruit (CRF) is a Chinese traditional herb which has been used in medicine for hundreds of years. The anti-tumor activity of CRF polysaccharides (CRFPs) has not yet been evaluated. To study the in vitro anti-tumor effects of CRFP and its derivatives, native CRFP was isolated from CRF by hot water extraction, and its molecular weight analyzed with gel filtration chromatography was 227,000 Da. Native CRFP was sulfated with ClSO3H-DMF and carboxymethylated with monochloroacetic acid in alkaline aqueous medium. The resulting derivatives were isolated and labeled as SF-CRFP and CM-CRFP, respectively. The in vitro inhibition rates of CRFP and its derivatives for tumor cells SKVO (human ovarian cancer cell), HepG2 (human hepatoma cell), and LoVo (human colon cancer cell) were evaluated, the result showed that native CRFP exhibited no significant inhibition effect on the three tumor cells even at a concentration of 50 μg/ml, but sulfation and carboxymethylation substantially enhanced the anti-tumor activities of CRFP in a dose-dependent way. SF-CRFP at the dose of 50 μg/ml displayed a significant inhibitory effect on SKVO, HepG2, and LoVo, with the viability rates of 33.6%, 44.8%, and 43.2%, respectively. It has a dosage-dependence inhibition on tumor growth in this model, with IC50 for SKVO, HepG 2, and LoVo being 21 μg/ml, 36 μg/ml, and 49 μg/ml, respectively. CM-CRFP showed a specific inhibition on HepG2 with a viability rate of 12.2%, with an IC50 of 17 μg/ml, while it had hardly any anti-tumor effect on SKVO cells. Thus, chemical modifications of CRFPs by sulfation and carboxymethylation effectively improved their anti-tumor properties.