Alginic acid is a structural polysaccharide present naturally in the cell walls of brown algae; functionally equivalent to that of cellulose in terrestrial plants.

It is found in brown algae of the Phaeophycean family, but only some of them contain an interesting amount of algin; these are the genera Ascopyllum, Macrocystis, Laminaria, Fucus and

Cystoseira with an amount of alginic acid that can reach 40% of its dry extract.

Its biomolecular structure gives it important properties. Although most salts are insoluble in water (not even the di and polyvalent metal salts except for the magnesium salt)not necessary , the alginates in the form of alkaline salts are soluble and they provide colloidal solutions.

The use of marine algae as biostimulants has also become increasingly important, based largely on its alginic content, given its applications in:

• Seed germination
• Improved crop development in all growth stages.
• High resistance to abiotic and biotic stress.
• Higher Shelf life

The recognized stimulation that alginate carries out in response to certain pathogens, should be highlighted , since it induces the coding of such response genes. In fact, the polysaccharides present in seaweed extracts are effective inducers of the plant’s defense against diseases.

In the soil, alginic acid salts combine with metal ions to form high molecular weight complexes that absorb moisture, retain moisture and improve structure; stimulating the growth of the root system as well as the soil’s microbial activity.