1. New proctolin analogues and their myotropic effects on heart of yellow mealworm Tenebrio molitor L. and foregut of locust-Schistocerca gregaria L
M Kuczer, G Rosiński, J Issberner, R Osborne, D Konopińska Pol J Pharmacol. 1998 Mar-Apr;50(2):143-50.
We have extended our work on structure/activity relationship of neuropeptide proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH) by evaluating the effects of the following proctolin analogues: H-X1-Tyr-Leu-Pro-Thr-OH, where X1 = D-Arg (1), N-Me-Arg (2), Can (3), D-Tyr2, D-Leu3, D-Thr5]-proctolin (12). In analogues 1-9, the N-terminal Arg-residue was replaced by basic amino acid derivatives with peptides containing amino acid residues with an isosteric system on the back side chain relative to Arg (compounds 3, 5 and 6) or homo-Arg (compound 7). Analogues 1-12 were evaluated for myotropic action on in vitro heart preparation of Tenebrio molitor, whereas peptides 2, 5 and 7-12 were tested for contractile action on isolated foregut of Schistocerca gregaria. Peptides 2 and 3 retained full cardiotropic activity in Tenebrio molitor while peptides 5 and 7 preserved 40% and 15%, respectively, locust-gut contracting activity of proctolin. Peptides 11 and 12 showed antagonistic activity in Schistocerca gregaria foregut.
2. Myotropic effects of new proctolin analogues modified in the position 5 of peptide chain in insects
W Szeszel-Fedorowicz, G Rosiński, J Issberner, R Osborne, J Sliwowska, D Konopińska Pol J Pharmacol. 2001 Jan-Feb;53(1):31-8.
To explain the role of the Thr5 residue of proctolin (Arg-Tyr-Leu-Pro-Thr) in the myotropic activity of this insect neuropeptide, we synthesized two groups of its analogues: 1) Arg-Tyr-Leu-Pro-X-OH with X = Val (1), D-Val (2), Ile (3), D-Ile (4), Ala (5), D-Ala (6), Asn (7), Gln (8), Ser (9), Pro (10), Phe (11), Asp (12), Glu (13), Arg (14), D-Arg (15), Lys (16) and Gly (17) and 2) Arg-Tyr-Leu-Pro-R', where R' = isobutylamine (18), S-1-methyl-1-phenylmethylamine (19), R-1-methyl-1-phenylmethylamine (20), R-2-amino-1-propanol (21), S-2-amino-1-propanol (22), R-1-amino-2-propanol (23), S-2-amino-1-propanol (24), 3-amino-1-propanol (25). Decapeptide proctolylproctolin (H-Arg-Tyr-Leu-Pro-Thr-Arg-Tyr-Leu-Pro-Thr-OH) (26) was synthesized. Syntheses of these peptides were carried out by solid-phase method. All peptides were bioassayed in vitro on the semi-isolated hearts of Tenebrio molitor using a cardioexcitatory test and on the foregut of locust (Schistocerca gregaria). Peptides 1, 3, 5, 9, 13, 14, 16, 22, and 23 retained about 30-50% of the cardioexcitatory activity in T. molitor. Analogues 1 and 3 preserved about 50% and analogue 8 about 80% of the myotropic activity, whereas compound 4 and 9 showed a very weak contractile activity in S. gregaria.
3. Synthesis and biological evaluation of selected insect neuropeptide analogs modified by D- or L-phenylglycine derivatives
W Szeszel-Fedorowicz, G Rosiński, J Issberner, R Osborne, I Janssen, A De Loof, D Konopińska Acta Pol Pharm. 2000 Nov;57 Suppl:88-9.
Novel analogs, modified by L- or D- phenylglycine and p-substituted derivatives, of the neuromodulator proctolin (Arg-Tyr-Leu-Pro-Thr) and of the Trypsin Modulating Oostatic Factor from the gray flesh fly Neobellieria bullata (Neb-TMOF-Asn-Pro-Thr-Asn-Leu-His) were synthesized and checked for activity. Proctolin analogs were modified at position 2: Arg-Phg-Leu-Pro-Thr (I), Arg-D-Phg-Leu-Pro-Thr (II), Arg-Phg(p-OH)-Leu-Pro-Thr (III), Arg-D-Phg(p-OH)-Leu-Pro-Thr (IV), Arg-Phg(p-NO2)-Leu-Pro-Thr (V) Arg-D-Phg(p-NO2)-Leu-Pro-Thr (VI), Arg-Phg(p-NH2)-Leu-Pro-Thr (VII), Arg-D-Phg(p-NH2)-Leu-Pro-Thr (VIII), Arg-Phg(p-N,N-di-Me)-Leu-Pro-Thr (IX), Arg-D-Phg(pp-N,N-di-Me)-Leu-Pro-Thr (X) while analogs of Neb-TMOF underwent modifications at position 6: Asn-Pro-Thr-Asn-Leu-Phg(p-NO2) (XI), Asn-Pro-Thr-Asn-Leu-D-Phg(p-NO2) (XII), Asn-Pro-Thr-Asn-Leu-Phg(p-NH2) (XIII), Asn-Pro-Thr-Asn-Leu-D-Phg(p-NH2) (XIV), Asn-Pro-Thr-Asn-Leu-Phg(p-N,N-di-Me) (XV), Asn-Pro-Thr-Asn-Leu-D-Phg(p-N,N-di-Me) (XVI). Earlier studies on proctolin demonstrated that the presence of the -CH2- group between C-alpha and the phenyl ring at position 2 of the peptide chain is important for the myotropic activity. Based on these results, we replaced Tyr at position 2 by different phenylglycine derivatives, lacking the methylene group at the side chain. Myotropic activity of the proctolin analogs was assayed in vitro on the semi-isolated heart of the mealworm Tenebrio molitor and on the foregut of the locust Schistocerca gregaria. All analogs (I-X) were practically inactive. For Neb-TMOF, it was previously demonstrated that the exchange of His-6 by p-substituted Phe-derivatives, especially by Phe(p-NH2), an amino acid containing a basic function, results into analogs which inhibit trypsin biosynthesis in the gray fleshfly. For this reason these new Neb-TMOF analogs with L- or D-phenylglycine p-substituted derivatives at position 6, were developed and tested (in vivo) in the trypsin biosynthesis assay of the gray fleshfly N. bullata. Only analogs XV and XVI slightly inhibited trypsin biosynthesis in the midgut. Because more than 50% of the injected animals died and none of the surviving animals ate much of the liver meal, the lower trypsin level in the gut might be a indirect effect. Other peptides (XI-XIV) had no effect on the level of trypsin biosynthesis in the midgut.
