Acemannan

Acemannan is a D-isomer mucopolysaccharide in aloe vera leaves. This compound has been known to have immunostimulant, antiviral, antineoplastic and gastrointestinal properties.

Chemical structure and properties
Acemannan's monomer is mannoacetate linked by β-1,4-glycosidic bonds. This polymer is hydrophilic: It has 50 hydrogen bond acceptors, 19 hydrogen bond donors, and a partition coefficient of -3.27. Therefore, its permeability (and, hence, bioavailability) has been scored to be 1 according to Lipinsky's Rule of Five.

Immunostimulant properties
Acemannan has been demonstrated to induce macrophages to secrete interferon (INF), tumor necrosis factor-α (TNF-α) and interleukins (IL-1); therefore, it might help to prevent or abrogate viral infection. These three cytokines are known to cause inflammation, and interferon is released in response to viral infections. In vitro studies have shown acemannan to inhibit HIV replication; however, in vivo studies have been inconclusive.

Acemannan is currently being used for treatment and clinical management of fibrosarcoma in dogs and cats. Administration of acemannan has been shown to increase tumor necrosis and prolonged host survival; the animals have demonstrated lymphoid infiltration and encapsulation.

The compound has been found to have a LD50 of >80 mg/kg and LC50 >5,000 mg/Kg IV.