Purification and neuroprotective effects of polysaccharides from Opuntia Milpa Alta in cultured cortical neurons

Opuntia is a traditional plant from China with medicinal applications. In this experiment, polysaccharides from Opuntia Milpa Alta (MAPs) were analyzed using gas chromatograph-mass spectrometer (GC-MS) method and result showed that MAPs contained mannose (6.37%), rhamnose (14.94%), xylose (1.99%), arabinose (24.07%), galactose (38.25%), ribose (2.63%) and glucose (11.48%). The neuroprotective effects of MAPs were evaluated at the mechanistic level in vitro models of cerebral ischemic injury. In vitro oxygen/glucose deprivation (OGD) model, MAPs (0.5 μg/ml, 5 μg/ml, 50 μg/ml) effectively increased cell viability by methyl thiazolyl tetrazolium (MTT) assay, inhibited cell cytotoxicity by lactate dehydrogenase (LDH) assay, reduced neuronal cell death, suppressed the production of intracellular reactive oxygen species (ROS), decreased of intracellular free Ca²⁺ concentrations (Ca²⁺]_i), and reduced extracellular glutamate level. Therefore, MAPs might prevent intracellular calcium overload and decreased glutamate excitotoxicity, both of which can cause neuronal injury and death in vitro models of cerebral ischemic injury.