NOVEL ANTIINFLAMMATORY UNDECAPEPTIDES THAT CONTAIN ANISOLYLATED GLUTAMIC-ACID DERIVATIVES

In various animal models of tissue injury, corticotropin-releasing fac tor (CRF) and related peptides inhibit swelling, edema and loss of pro tein from the vascular compartment. To search for smaller peptide segm ents of CRF that might retain anti-inflammatory activity, the authors tested peptides similar to the carboxy terminals of ovine (o) and huma n/rat (h/r) CRF. Also, because h/rCRF(35-39), -Arg-Lys-Leu-Met-Glu-, r esembles -Arg-Lys-Leu-Leu-Glu-, a sequence found in many intermediate filament proteins, analogous peptides were evaluated. Ovine CRF(21-41) , n-Ala-His-Ser-Asn-Arg-Lys-Leu-Leu-Asp-Ile-Ala-NH2, its carboxy termi nal carboxyl derivative, oCRF(21-41 )-OH, and the fragments, oCRF(26-4 1) and oCRF(30-41), were inactive when assayed at 5 mg/kg i.v. on edem a induced in the pentobarbital-anesthetized rat's hindpaw after immers ion in 58-degrees-C water for 1 min. Crude peptides, eu-Ala-Thr-D-Tyr- Arg-Lys-Leu-Leu-Glu-Ile-D-Leu-NH2 and a-His-Ser-D-Asn-Arg-Lys-Leu-Leu- Glu-Ile-D-Leu-NH2, were found to have activity in this bioassay. Chara cterization of the structures within the crude mixture revealed that s ubstitution of the glutamic acid residue with an anisolylated glutamic acid (2-amino-5-(methoxyphenyl)-5-oxopentanoic acid) derivative, desi gnated as (A), increased the overall potency. The glutamyl-anisole de rivative was a by-product of the temperature-dependent Friedel-Crafts acylation reaction that occurs during hydrogen fluoride cleavage of gl utamyl-containing peptides. Several undecapeptides that contained D-am ino acids and the anisolylated glutamic acid derivative were synthesiz ed and characterized by high-performance liquid chromatography, amino acid analysis, mass spectroscopy and nuclear magnetic resonance spectr oscopy. The more potent peptides, u-Ala-Thr-D-Tyr-Arg-Lys-Leu-Leu-(A) -Ile-D-Leu-NH2 and a-His-Ser-D-Asn-Arg-Lys-Leu-Leu-(A)-Ile-D-Leu-NH2 reduced epinephrine-induced pulmonary edema and heat-induced edema wit h ED50 values of 0.04 and 0.05 mg/kg i.v., respectively.