Abstract: The invention relates to derivatives and metabolites of ambrisentan, including compounds of general Formula (I) or salts, hydrates, solvates, racemates, or optical isomers thereof, wherein R1 is —OH or —OCH3; R2 is —H, lower alkyl (e.g. C1-C4 alkyl) or glycosidyl; and R3 and R4 are independently —CH3, —C(O)H or —CH2OR6, wherein R6 is —H or a hydrocarbyl group having 1 to 20 carbon atoms.

Abstract: The present invention provides antineoplastic peptides of formula I, R1R2N-CHX-CO-A-B-D-E-(G)S-K?I wherein R1, R2, X, A, B, D, G, K and s have the meanings stated in the description. The compounds have antineoplastic activity.

Abstract: The invention relates to derivatives and metabolites of ambrisentan, including compounds of general Formula (I) or salts, hydrates, solvates, racemates, or optical isomers thereof, wherein R1 is —H or —OCH3; R2 is —H, lower alkyl (e.g. C1-C4 alkyl) or glycosidyl; and R3 and R4 are independently —CH3, —C(O)H or —CH2OR6, wherein R6 is —H or a hydrocarbyl group having 1 to 20 carbon atoms. In some embodiments, compounds of Formula (I) exhibit selective affinity for ETA receptors and serve as endothelin receptor antagonists. In some embodiments, the compounds correspond to metabolites of ambrisentan produced by the enzymatic action of cytochrome P450 or uridine diphosphate glucuronosyl transferase enzymes, for example as elucidated in pre-clinical or clinical studies.