A review of the antibacterial activity and mechanisms of plant polysaccharides

Various plant polysaccharides have been studied for their medically significant bioactivities in the past few decades. Some plant polysaccharides have been shown to have strong antibacterial activity against various Gram-negative and Gram-positive bacteria. However, the relationships between plant sources, polysaccharide properties, and the antibacterial activity of plant polysaccharides have not been thoroughly reviewed. Here, the relationships between the sources of plant polysaccharides, and the structural properties and antibacterial activity of several plant polysaccharides were reviewed. The polysaccharides, extracted from roots, leaves, branches, seeds or other parts of herbal, woody, shrub plants, or extracted from algae, exhibit different antibacterial activities. The structural features of plant polysaccharides, such as molecular weight, monosaccharide composition, degree of polysaccharide branching, chemical modifications, and extraction methods, are closely tied to their antibacterial activity. Plant polysaccharides interact with bacteria through hydrophilic and hydrophobic action, electrostatic adsorption, or the presence of sugar receptors. The antibacterial activity of plant polysaccharides can be exerted by increasing the permeability of the cell membrane, inhibiting the adsorption of pathogenic bacteria to host cells, or blocking the transmembrane transport of nutrients or energy substances. Overall, this review will aid future applications of plant polysaccharides.