Biological evaluation of analogues of an insect neuropeptide proctolin.

Continuing our studies on proctolin (Arg-Tyr-Leu-Pro-Thr) we performed the synthesis and biological evaluation of 52 analogues substituted in position 2, 3, 4, and 5 of the peptide chain. The peptides were bioassayed for cardiotropic activity in vitro on Tenebrio molitor and myotropic activity on foregut of Schistocerca gregaria. Twenty analogues retained 20-80% of proctolin activity

Semantic and Perceptual Representations of Color: Evidence of a Shared Color-Naming Function

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New proctolin analogues modified by the novel D-or L-phenylglycine derivatives. Synthesis and biological studies

New analogues of insect neuromodulator proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH), modified in position 2 of the peptide chain by L-or D-phenylglycine and its 4-substituted derivatives were synthesized. For modification of proctolin a series of novel L-or D-phenylglycine derivatives H-Phg(4-NO2)-OH (1), Boc-Phg(4-NO2)-OH (2), Boc-Phg(4-Me2N)-OH (3), H-Phg(4-OBzl)-OH (4), Boc-Phg(4-OBzl)-OH (5), H-D-Phg(4-NO2)-OH (6), Boc-D-Phg(4-NO2,)-OH (7), Boc-D-Phg(4-Me2N)-OH (8), were used. The following proctolin analogues were synthesized: H-Arg-Phg-Leu-Pro-Thr-OH (9), H-Arg-D-Phg-Leu-Pro-Thr-OH (10), H-Arg-Phg(4-OH)-Leu-Pro-Thr-OH (11), H-Arg-D-Phg(4-OH)-Leu-Pro-Thr-OH (12), H-Arg-Phg(4-NO2)-Leu-Pro-Thr-OH (13), H-Arg-D-Phg(4-NO2)-Leu-Pro-Thr-OH (14), H-Arg-Phg(4-NH2)-Leu-Pro-Thr-OH (15), H-Arg-D-Phg(4-NH2)-Leu-Pro-Thr-OH (16), H-Arg-Phg(4-NMe2)-Leu-Pro-Thr-OH (17), H-Arg-D-Phg(4-NMe2)-Leu-Pro-Thr-OH (18). Myotropic activity of proctolin analogues 9-18 was assayed in vitro on the semi-isolated heart of the mealworm Tenebrio molitor and on the foregut of the locust Schistocerca gregaria. All analogues showed a weak or none activity.</p

Myotropic effects of new proctolin analogues modified in the position 5 of peptide chain in insects

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-l-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.</p

New proctolin analogues modified by the novel D-or L-phenylglycine derivatives. Synthesis and biological studies

New analogues of insect neuromodulator proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH), modified in position 2 of the peptide chain by L-or D-phenylglycine and its 4-substituted derivatives were synthesized. For modification of proctolin a series of novel L-or D-phenylglycine derivatives H-Phg(4-NO2)-OH (1), Boc-Phg(4-NO2)-OH (2), Boc-Phg(4-Me2N)-OH (3), H-Phg(4-OBzl)-OH (4), Boc-Phg(4-OBzl)-OH (5), H-D-Phg(4-NO2)-OH (6), Boc-D-Phg(4-NO2,)-OH (7), Boc-D-Phg(4-Me2N)-OH (8), were used. The following proctolin analogues were synthesized: H-Arg-Phg-Leu-Pro-Thr-OH (9), H-Arg-D-Phg-Leu-Pro-Thr-OH (10), H-Arg-Phg(4-OH)-Leu-Pro-Thr-OH (11), H-Arg-D-Phg(4-OH)-Leu-Pro-Thr-OH (12), H-Arg-Phg(4-NO2)-Leu-Pro-Thr-OH (13), H-Arg-D-Phg(4-NO2)-Leu-Pro-Thr-OH (14), H-Arg-Phg(4-NH2)-Leu-Pro-Thr-OH (15), H-Arg-D-Phg(4-NH2)-Leu-Pro-Thr-OH (16), H-Arg-Phg(4-NMe2)-Leu-Pro-Thr-OH (17), H-Arg-D-Phg(4-NMe2)-Leu-Pro-Thr-OH (18). Myotropic activity of proctolin analogues 9-18 was assayed in vitro on the semi-isolated heart of the mealworm Tenebrio molitor and on the foregut of the locust Schistocerca gregaria. All analogues showed a weak or none activity.</p