Optimization of microwave assisted extraction, chemical characterization and antitumor activities of polysaccharides from porphyra haitanensis

Microwave assisted extraction (MAE) technology was used to extract polysaccharides from Porphyra Haitanensis (PHP) with water. Polysaccharide yield was used as index to evaluate the extraction process. Effects of ratio of water to raw material (X1), microwave power (X2) and extraction time (X3) on polysaccharide yield were investigated. Based on single factor experiment, MAE process of PHP was optimized using response surface methodology. Chemical characterization of PHP was investigated based on analysis of chemical compositions, monosaccharide and thermal gravimetric. The antitumor activities of PHP in vivo and in vitro were evaluated. The results indicated that the optimal conditions for MAE of PHP were ratio of water to raw material 28.98(mL/g), microwave power 77.84 W and extraction time 14.14 min. MAE was a suitable and efficient technique for PHP extraction compared with traditional hot water extraction. Analysis of chemical characterization showed that PHP contained 75.36 ± 1.48% of total carbohydrates, 24.63 ± 1.69% of uronic acid residue and no proteins with monosaccharides such as rhamnose, arabinose, xylose, mannose, glucose, and galactose in a molar ratio of 10.25:9.38:1:12.45:9.9:11.55. Thermal gravimetric analysis suggested that PHP was relatively stable below 170℃. PHP had obvious effect on inhibiting proliferation, inducing apoptosis of SGC-7901 tumor cells in vitro and antitumor effect on SGC-7901 tumor-bearing mice in vivo. The results suggested that PHP had the potential for clinical use in cancer prevention and treatment.