Opiate-like peptides. Part V. Aminoalkylamides of Met-enkephalin and [D-Ala]2-Met-enkephalin: synthesis and analgesic activity.

Four analogs of Met-enkephalin were synthetized using DPPA method. Their analgesic activity was estimated by the hot plate method, the neurotoxic effect being also determined. One of the analogs was 16 times as potent as Met-enkephalin, whereas with the three remaining the neurotoxic effect preceded the expected analgesic activity.