Swainsonine is an indolizidine alkaloid. It is a potent inhibitor of Golgi alpha-mannosidase II, an immunomodulator, and a potential chemotherapy drug. As a toxin in locoweed (likely its primary toxin) it also is a significant cause of economic losses in livestock industries, particularly in North America. Swainsonine inhibits glycoside hydrolases, specifically N-linked glycosylation. Disruption of Golgi alpha-mannosidase II with swainsonine induces hybrid-type glycans. These glycans have a Man5GlcNAc2 core with processing on the 3-arm that resembles so-called complex-type glycans. Swainsonine is an anti-cancer drug with potential for treating glioma and gastric carcinoma. However, a phase II clinical trial of GD0039 (a hydrochloride salt of swainsonine) in 17 patients with renal carcinoma was discouraging. Swainsonine's activity against tumors is attributed to its stimulation of macrophages.
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