The protective effect of polysaccharide extracted from Portulaca oleracea L. against Pb-induced learning and memory impairments in rats.

This paper studied the extraction of polysaccharide from Portulaca oleracea L. (POP) by hot water extraction and ethanol precipitation. Structural properties of the extracted polymers were determined. POP was composed of rhamnose, arabinose and galactose in ratios of 1: 2.34: 3.07 with a molecular weight of 1.55 × 107 Da. The neuroprotective effect of POP on Pb-induced neuronal toxicity was then evaluated in vitro and in vivo test. Treatment with POP markedly increased the survival of PC12 cells and repressed the generation of reactive oxygen species following Pb exposure. In Morris water maze analysis, Pb exposure led to an increase in escape latency and a decrease in platform crossing times of rats in the probe test, which could be attenuated by POP treatment. Additionally, the Pb-induced loss of dendritic spine was recovered after feeding rats with POP at 600 mg/kg/day. These results indicated that Pb-induced cognitive impairments could be inhibited by POP.