title: Immunostimulation by a partially modified retro-inverso-tuftsin analogue containing Thr1 psi[NHCO](R,S)Lys2 modification.
abstract: The tuftsin retro-inverso analogue H-Thr psi[NHCO](R,S)Lys-Pro-Arg-OH was synthesized through a novel procedure for the high-yield incorporation of isolated retro-inverso bonds into peptide chains and the use of the new Meldrum's acid derivative (CH3)2C(OCO)2CH(CH2)4NHCOCF3 followed by its efficient coupling in solution to trimethylsilylated H-D-Thr(t-Bu)NH2. Closely related peptide impurities were eliminated both from the crude final peptide and the fully protected tetrapeptide amide precursor via ion-exchange and reversed-phase displacement chromatography, respectively. The tuftsin retro-inverso analogue proved to be completely resistant to enzymatic degradation in vitro, either against isolated aminopeptidases or human plasma proteolytic enzymes. When administered either orally or intravenously, it was significantly more active than normal tuftsin in increasing the number of specific antibody secreting cells in spleen of mice immunized with sheep erythrocytes. Furthermore, the analogue exerted an enhanced stimulatory effect on the cytotoxic activity of splenocytes against YAC-1 tumor cells. Finally, retro-inverso-tuftsin was about 10-fold more potent than the native peptide in reducing rat adjuvant arthritis. The resistance of the retro-inverso analogue to peptidases might explain the increased in vivo activities and allows its further immunopharmacological characterization.
authors.affiliation: Sclavo Research Centre, Siena, Italy.
authors.forename: A S
authors.initials: AS
authors.lastname: Verdini
authors.forename: S
authors.initials: S
authors.lastname: Silvestri
authors.forename: C
authors.initials: C
authors.lastname: Becherucci
authors.forename: M G
authors.initials: MG
authors.lastname: Longobardi
authors.forename: L
authors.initials: L
authors.lastname: Parente
authors.forename: S
authors.initials: S
authors.lastname: Peppoloni
authors.forename: M
authors.initials: M
authors.lastname: Perretti
authors.forename: P
authors.initials: P
authors.lastname: Pileri
authors.forename: M
authors.initials: M
authors.lastname: Pinori
authors.forename: G C
authors.initials: GC
authors.lastname: Viscomi
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D001169:Arthritis, Experimental / Q000628:therapy; D004355:Drug Stability; D004912:Erythrocytes / Q000276:immunology; D005260:Female; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D012756:Sheep; D014405:Tuftsin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000276:Adjuvants, Immunologic; C072234:H-Thr-(psi)(NHCO)Lys-Pro-Arg-OH; D010447:Peptide Hydrolases; D014405:Tuftsin