Antioxidant and anti-aging activities of Longan crude and purified polysaccharide (LP-A) in nematode Caenorhabditis elegans

Oxidative damage is an important cause of aging. The antioxidant and anti-aging activities of Longan polysaccharides, especially purified Longan polysaccharides, have not been thoroughly investigated. Therefore, this study aimed to investigate the antioxidant and anti-aging activities and mechanisms of crude polysaccharides and purified polysaccharides from Longan. A purified acidic Longan polysaccharide LP-A was separated from Longan crude polysaccharide LP. Subsequently, its structural characterization, anti-aging activity and mechanism were studied. The results showed that LP-A was an acidic heteropolysaccharide with an average molecular weight (Mw) of 4.606 × 104 Da which was composed of nine monosaccharides. The scavenging rate of ABTS free radical in vitro reached 99 %. In the nematode life experiment, 0.3 mg/mL LP group and LP-A group could prolong the average lifespan of nematodes by 9.31 % and 25.80 %, respectively. Under oxidative stress stimulation, LP-A group could prolong the survival time of nematodes by 69.57 %. In terms of mechanism, Longan polysaccharide can regulate insulin / insulin-like growth factor (IIS) signaling pathway, increase the activity of antioxidant enzymes, reduce lipid peroxidation, enhance the body's resistance to stress damage, and effectively prolong the lifespan of nematodes. In conclusion, LP-A has better anti-aging activity than crude polysaccharide LP, which has great potential for developing as an anti-aging drug.