Abstract:

Objective: To optimize the extraction of polysaccharides from Gracilaria chouae (GLP) and to investigate their
inhibitory effects on tumor cells. Methods: Response surface methodology was used to optimize the extraction process for GLP.
Methyl thiazolyl tetrazolium (MTT) method was used to determine the effects of GLP on the proliferation of HeLa, EC-109,
HepG-2 and MCF-7 cells. Results: The optimal extraction conditions were determined as follows: temperature, 93.1 ℃;
material-to-liquid ratio, 1:61.5 (g/mL); and ultrasonification time, 35 min. Under these conditions, the maximum yield of
polysaccharides of 16.75% was obtained. GLP revealed anti-proliferation effect on HeLa, EC-109, HepG-2 and MCF-7 cells
in a dose-dependent manner in the range of 200–1 000 μg/mL. When the concentration was up to 1 000 μg/mL, the percentage
growth inhibition of the above four cells were 49.11%, 41.18%, 34.98% and 31.33% respectively. With increasing GLP dose
over a certain range, the numbers of apoptotic and necrotic cells increased, as revealed by cell morphology observation and
Annexin V-FITC/PI fluorescence double staining detection. Conclusions: GLP could induce apoptosis of cancer cells.

Key words: Gracilaria chouae polysaccharides (GLP), extraction, HeLa cell, apoptosis