Marine biological resources are rich of new physiologically active substances including polysaccharides of various chemical structure and lectins. Lectins are carbohydrate-binding proteins specifically recognizing and reversibly binding to certain carbohydrate glycoconjugate structures without change in covalent structure of the recognized glycosyl ligands. This distinguishes lectins from other carbohydrate binding proteins and enzymes, and makes them invaluable tools in biomedical and glycoconjugate research. Lectins are involved in various biological processes, such as fertilization, cell adhesion, cell signaling, cell growth and differentiation. It is usually assumed that the lectins perform a protective function in the system of innate immunity. Marine invertebrates lectins exhibit various biological activities such as antifungal, mytogenic, antiproliferative and antiviral. They can be used as diagnostic tools for the investigation of the early cell-membrane alterations and carbohydrate changes that accompany tumor and immune processes. 

 
Marine polysaccharide recently attracted attention because they are not toxic and reveal interesting biological properties (immunomodulatory, anti-inflammatory, radio-protective, antiviral, antimicrobial, anti-tumor, wound-healing and etc.). They can find application in medical practice, food and cosmetic industries. 

Both microorganisms and macrophitic algae are the important component of marine ecosystems and possess a wide spectrum of physiological adaptable mechanisms. 

The chemical structure of the carbohydrate moiety of the marine gram-negative bacteria lipopolysachharides is highly diverse and includes an ever-extending number of rare and unusual monosaccharides and non-carbohydrate substituents. A comparative study of lipopolysachharides primary structure is important for understanding the chemical modifications of the cell envelope to reinforce the external membrane and to ensure their survival.