Biological properties

Antibacterial activity

Solutions of chitosan (1% or less) and acetic acid (1% or less) show inhibition of the growth of the bacterias Pseudomonas aeruginosa and Staphylococcus aureus, and the fungus Candida tropicalis. This was shown not to be a viscosity phenomenon or an effect of the acetate. The solutions showed little or no effect on Streptococcus pyogenes and Echerichia coli. The inhibitory effect did not depend on molecular weight [2]. When ingested, chitosan has an inhibitory effect on bacterial growth in burn injuries [19].

Antifungal activity

In agriculture chitosan can be used as an antifungi and to enhance host resistance response [26]. The activity of chitosan is both from the polymer inducing synthesis of phenolic acids, including the precursors to lignin, and from having an antifungal activity itself, being incorporated into the plant [26].

Antiviral activity

Inhibitor/Concentration (μg/mL) 100
Adsorption HSV-1 in Vero cells [23] 100
Adsorption HSV-2 in Vero cells [23] 80
Adsorption and replication HSV-1 in Vero cells [23] 100
Adsorption and replication HSV-2 in Vero cells [23] 75
Inhibition of virus multiplication in cells.

Cell line Concentration
Vero cells [23] 100
Maximal non-cytotoxic concentration (μg/ml).

Gastrointestinal effect

Chitosan has been shown to reduce cholestrol levels significantly in blood [6,10]. The reduction is related to the molecular weight. High molecular weight chitosans (>700 kDa) were found to be less effective than a 70 kDa preparation [10]. There is however a toxicological effect. Chitosan and chitin has been shown to increase the fecal excreation of Fe and lower the hemoglobin levels in rats at high dietary levels [2]. Chitosan significantly reduces the growth rate of rats or even kills them. This is believed to be because of the viscous nature of chitosan, causing a morphological and physiological insult to the intestinal system. Indications show, that at chitin and chitosan cause no damage to the intestinal system, at dietary levels below 10% [2].

Molecular biology

When in contact with blood, chitosan promotes plasma protein adsorption, platelet adhesion and thrombosis [5,11]. It is of special interest, that chitosan can induce clot formation in the absence of coagulation factors and/or platelets [11].

Chitosan has a moderate effect on the activation of cytotoxic macrophages [2]. The activation of macrophages is a stimulation of NO-production and chemotaxi [4].

Chitosan has an immunostimulating activity. The mechanism is unknown but it is believed, that the activation of macrophages is important. The ability to induce TNF-α is dependent on the molecular weight, neutral solubility and degree of deacetylation [12]. The immunopotentiating effect of chitosan is only in the presence of antigen activated immune cells, and is not present in resting cells [22].

Wound healing

The chitosan gel has a cooling and soothing effect on burn injuries. Also it has a positive effect on the healing process in burn treatment. This is dependent on the molecular weight, low molecular chitosan is better than high molecular. The addition of silver sulfadiazine further enhances the healing effect [2]. In the early stages of wound healing, chitosan attract fibroblastic cells to the wound site [12].

Chitosan with 1-2% acetic acid has shown a positive effect on dermatitis on monkeys and humans [2].


Addition of chitosan to a soy bean suspension resulted in increased leakage of electrolytes, UV-absorbing material and peptiders. The leaking can be enhanced by EGTA [17].