trichosanthin

Trichosanthin is a ribosome-inactivating protein (RIP) isolated from the root tuber of Trichosanthes kirilowii, a plant in the Cucurbitaceae family commonly known as Chinese snake gourd. It is categorized as a type I RIP, consisting of a single polypeptide chain with an approximate molecular weight of 27 kDa. Its biochemical activity is an RNA N-glycosidase that depurinates an adenine in the 28S rRNA (A4324), thereby inactivating eukaryotic ribosomes and inhibiting protein synthesis.

Cellular uptake is via endocytosis, and the protein can reach the cytosol to exert its enzymatic effect, though it lacks the binding chain seen in type II RIPs, which means cell-entry efficiency can vary across cell types. Trichosanthin has been studied for antiviral, immunomodulatory, and anticancer effects in preclinical systems.

It has shown activity against several viruses in vitro, including HIV, and has been explored in experimental immunotoxins and as a potential anticancer agent. Despite these findings, clinical use has not been established due to toxicity and safety concerns. Reported adverse effects include fever, gastrointestinal symptoms, systemic toxicity, and reproductive toxicity, with abortifacient effects documented in some contexts. Consequently, trichosanthin-containing preparations are not approved as medical therapies in most jurisdictions and any use is strictly controlled in traditional medicine settings.

Research continues on safer formulations and delivery methods to reduce systemic toxicity, and to harness its ribosome-inactivating properties for targeted therapies. The compound remains primarily a subject of biochemical and pharmacological study rather than a standard therapeutic agent.