Physicochemical properties, antioxidant and antiproliferative activities of polysaccharides from Morinda citrifolia L. (Noni) based on different extraction methods

The influences of different extraction methods on the yields, physicochemical properties, antioxidant activities and antiproliferative abilities of polysaccharides from Morinda citrifolia L. (Noni) were investigated and compared. Three extraction methods were applied to extract Noni polysaccharides (NP), which include hot water extraction (HWE), pulsed electric field-assisted extraction (PEFAE) and ultrasonic-assisted extraction (UAE). The extraction yields, sugar contents, uronic acid contents, molecular weights, monosaccharide proportions, antioxidant activities and antiproliferative abilities of three NP samples were significantly different. However, their preliminary structural characteristics and monosaccharide types were similar. More specifically, UAE-NP had the highest extraction yield, the smallest molecular weight and the best antioxidant activities. Especially, UAE-NP showed excellent antiproliferative abilities. Compared with HWE-NP and PEFAE-NP, the IC50 value of UAE-NP on HepG2 cells reduced by 45.45% and 33.14%, respectively. The highest antioxidant activities of the UAE-NP might be attributed to its smaller molecular weight, lower Gal content and higher Fuc content. The strongest antiproliferative effects of the UAE-NP might be related to the low molecular weight. Overall, UAE could be a potential technique for the extraction of high-quality NP due to its high yield, high efficiency and notable bioactivities.