Lentinan is a polysaccharide isolated from the fruit body of shiitake mushroom (Lentinula edodes).

It has a molecular weight of 500,000 Da and specific rotation of +14-22° (NaOH).

[1] Lentinan is thought to be inactive in humans when given orally and is therefore administered intravenously.

The authors of an in vivo study of lentinan suggested that the compound may be active when administered orally in mice.

[2] Lentinan has been the subject of a limited number of clinical studies in cancer patients in Japan;[3][4][5][6][7][8][9][10] however, evidence of efficacy is lacking.