Buthionine sulfoximine (BSO) is a sulfoximine derivative which reduces levels of glutathione and is being investigated as an adjunct with chemotherapy in the treatment of cancer.[1] The compound inhibits gamma-glutamylcysteine synthetase, the enzyme required in the first step of glutathione synthesis. Buthionine sulfoximine may also be used to increase the sensitivity of parasites to oxidative antiparasitic drugs.[2]