Sulfation on polysaccharides from Zizania latifolia extracted using ultrasound: Characterization, antioxidant and anti-non-small cell lung cancer activities

Zizania latifolia is a highly nutritious vegetable being praised as “Ginseng in Water”. Polysaccharides are the main bioactive ingredients in Z. latifolia, but there have been no reports on the yield- and activity-guided ultrasonic-assisted extraction (UAE), sulfation and anti-non-small cell lung cancer (NSCLC) activity. In this study, Z. latifolia polysaccharides (ZLP) were extracted using UAE under an optimized power, followed by sulfation to give three derivatives (SZLP-1 ∼ 3). After characterization, the antioxidant and anti-NSCLC activities were evaluated. The optimal ultrasonic power for ZLP extraction was screened out to be 300 W, under which the yield was 16.9 ± 2.10 %, and the scavenging rate against 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical was 63.3 ± 5.71 %, significantly higher than those of other powers and hot-water extraction. A series of characterizations fully confirmed the sulfated modification of ZLP. Sulfation improved the antioxidation of ZLP and was positively proportional to the degree of substitution (DS), of which SZLP-2 with a DS of 15.1 ± 2.50 elicited strong hydroxyl and DPPH radicals-scavenging capacities. Meanwhile, SZLP-2 also exerted promising anti-NSCLC potency via inhibiting A549 cell proliferation, with a median inhibition concentration (IC50) of 0.57 ± 0.01 mg/mL at 72 h, markedly smaller than that of unmodified ZLP (0.78 ± 0.04 mg/mL). In summary, the yield- and activity-guided UAE led to the ZLP with high yield and strong antioxidation. Further sulfation enhanced the bioactivities and produced the promising SZLP-2, which showed great potential in the development of novel antioxidant and anti-NSCLC drug.