Astragalus glycyphyllos and Astragalus glycyphylloides Derived Polysaccharides Possessing in vitro Antioxidant Properties

Aim: To evaluate and compare the effects of polysaccharides, isolated from n-butanol extracts of Astragalus glycyphyllos (PS1) and Astragalus glycyphylloides (PS2) in model of non-enzyme- and enzyme-induced lipid peroxidation (LPO) in isolated rat liver microsomes.

Place and Duration of Study: Department of Pharmacognosy and Laboratory of Drug Metabolism and Drug Toxicity, Department of Pharmacology, Pharmacotherapy and Toxicology, between August 2014 and December 2015.

Methods: In non enzyme-induced LPO, the microsomes were incubated with a solution of iron sulphate and ascorbinic acid (Fe2+/AA). The enzyme-induced lipid peroxidation was performed by incubating rat liver microsomes with carbon tetrachloride (CCl4) in the presence of NADPH. The effects of PS1 and PS2 were evaluated after 20 min of incubation at the following concentrations: 60 µg/mL; 6 µg/mL; 0.6 µg/mL. The production of malondialdehyde (MDA), a biomarker of lipid peroxidation was measured. Silymarin (60-0.6 µg/mL) was used as a positive control.

Results: The results of our study showed that in non-enzyme induced LPO model, both PS1 and PS2 exerted comparable, concentration-dependent antioxidant activity. At the highest concentration, which was the most potent as well, the formation of MDA was significantly decreased by 45% (P<0.05) by PS1 and by 40% (P<0.05) by PS2. In enzyme-induced LPO model, the PS1 showed slightly more potent antioxidant activity at the highest tested concentration, discerned by MDA decrease by 35% (P<0.05), in comparison to a decrease of 29% (P<0.05) by PS2 at the same concentration level. The antioxidant activity of both polysaccharides, in the both LPO models, however, was lower in comparison to silymarin which at 60 µg/mL decreased the MDA production by 53-55% (P<0.05) in both models.

Conclusion: On the basis of our results we conclude that the investigated two polysaccharide mixtures, PS1 and PS2 possess antioxidant properties in in vitro models of Fe2+/AA and CCl4/NADPH lipid peroxidation, induced in isolated liver microsomes.