Methods for treating or preventing an inflammatory response comprising administering a diastereomer or diastereomeric mixture of methionine sulfoximine (MSO). The MSO may be L-methionine S-sulfoximine (LSMSO), L-methionine R-sulfoximine (LRMSO), or diastereomeric mixture of LSMSO and LRMSO. Methods include those for treating liver failure associated with an inflammatory response.