Pharmacotherapy using natural substances can be currently regarded as a very promising future alternative to
conventional therapy. With the rapid development of biotechnologies and analytical techniques, a great number of methods
have been developed for the identification and quantification of the material, extracts, and products of natural ingredients.
The advances available today. The need for safer drugs without side effects has led to the use of natural ingredients
with proven safety. In recent years, some bioactive polysaccharides isolated from natural sources have attracted much attention
in the field of biochemistry and pharmacology. As an example, polysaccharides or their glycoconjugates were
shown to exhibit multiple biological activities including anticarcinogenic, anticoagulant, immunostimulating, antioxidant,
etc. During the last several years, we have witnessed a steady expansion in the number of publications that focus in antioxidant
polysaccharides. This review presents current findings on the latest advancements and trends in antioxidant polysaccharides
isolated from the following: plants, fungi, bacteria, animal sources, and algae. Some interesting studies focus
on investigation of the relationship between their structure and antioxidant activity, elucidation of their antioxidant
mechanism at the molecular level, and improvement of their various biological activities by chemical modifications. Although
the mechanism of their antioxidant action is still not completely clear, these polysaccharides are suggested to enhance
cell-mediated immune responses in vivo and in vitro and act as biological response modifiers.