Antagonist G (trifluoroacetate salt) (Synonyms: Arg-D-Trp-NmePhe-D-Trp-Leu-Met-NH2, Arg6,D-Trp7,9,NmePhe8-substance P (6-11))

Antagonist G is a neuropeptide antagonist.^1,2,3 It inhibits the binding of vasopressin to rat liver or Swiss 3T3 membranes (IC₅₀s = 3.5 and 2.2 µM, respectively) and vasopressin-induced production of inositol phosphate in Swiss 3T3 fibroblasts (IC₅₀ = 1 µM).¹ Antagonist G (50 µM) induces apoptosis and the production of reactive oxygen species (ROS) in NCI H69 small cell lung cancer (SCLC) cells.² It reduces tumor growth in an NCI H69 mouse xenograft model when administered at a dose of 45 µg/g.³

1.Seckl, M.J., Newman, R.H., Freemont, P.S., et al.Substance P-related antagonists inhibit vasopressin and bombesin but not 5’-3-O-(thio)triphosphate-stimulated inositol phosphate production in swiss 3T3 cellsJ. Cell Physiol.163(1)87-95(1995) 2.MacKinnon, A.C., Waters, C., Rahman, I., et al.[Arg6, D-Trp7,9, NmePhe8]-substance P (6-11) (antagonist G) induces AP-1 transcription and sensitizes cells to chemotherapyBr. J. Cancer.83(7)941-948(2000) 3.Langdon, S., Sethi, T., Ritchie, A., et al.Broad spectrum neuropeptide antagonists inhibit the growth of small cell lung cancer in vivoCancer Res.52(16)4554-4557(1992)