Antioxidant and antiproliferative activities of intracellular polysaccharides extracted from plasmodia of Physarum polycephalum and Physarella oblonga

This study aimed to evaluate antioxidant and antiproliferative properties of intracellular polysaccharides (IPSs) isolated from plasmodia of two myxomycele species - Physarum polycephalum and Physarella oblonga. Unbound proteins and impurities were eliminated from the crude IPSs by trichloroacetic acid treatment followed by dialysis. The data suggested that these partially purification steps significantly reduced the contents of protein and sulfate groups, but did not necessarily enhance the bioactivities of all the IPS samples. Monomer analysis by HPLC found that glucose (55.91 %) was the main monosaccharide in the R polycephalum IPS composition, whereas that of Ph. oblonga IPS was galactose (56.17 %). Gel permeation chromatography data showed that the molecular weight of the partially purified IPSs from R polycephalum and Ph. oblonga were 2,875 kDa and 943 kDa, respectively. Significant differences in bioactivities of these IPSs were also recorded. The Ph. oblonga IPSs exhibited higher antioxidant activities than those of P polycephalum. However, P. poleephalum IPSs displayed higher antiproliferative activities toward the tested cancer cells. Specifically, after being treated with 1.0 mg/ml of the partially purified IPS of P polycephalum, only 33.24 % of the cervical cancer cells remained viable. Notably, the sample displayed low toxicity toward the non-transformed bovine aortic endothelial cells.