Analytical and pharmacological studies on a new antineoplastic tripeptide, PTT.119

The new synthetic tripeptide, p-fluoro-L-phenylalanyl-m-bis-(2-chloroethyl)-amino-L-phenylalanyl-methion ine ethylester hydrochloride, PTT.119, an alkylating agent, is currently undergoing preclinical trials as an antineoplastic agent. The molecular composition, C₂₉H₃₉N₄SCO₄Sl₂F, was confirmed by desorption chemical ionization mass spectrometry with accurate mass measurement. A high-performance liquid chromatographic technique was developed for the quantification of PTT.119 in cell culture medium and serum. Incubation of 5 x 10⁵ mammary tumor cells (MJY-α)/ml tissue culture medium with 25 μg PTT.119/ml for 60 min (37°C) removed 68% of the tripeptide from the medium. This corresponds to an uptake of 51 fmol PTT.119/tumor cell. Cell death, assessed 5 days after treatment, was directly proportional to the time-dependent removal of PTT.119 from the cell culture medium.