Conformational and biological properties of Bauhinia bauhinioides kallikrein inhibitor fragments with bradykinin-like activities

Abstract

Proteinase inhibitors extracted form medicinal plants are an interesting source of new drugs. Modifications in the structure of some of this kind of macromolecules could also lead to compounds of interesting biological properties. In this work, we synthesized and tested one fragment containing the reactive site of the Bauhinia bauhinioides kallikrein inhibitor (BbKI), denoted BbKI51-62 , and a related analog (P2 ) in which a proline residue was inserted in order to mimic the N-terminal region of the bradykinin molecule. The related retro-inverso counterparts Ri-BbKI51-62 and Ri-P2 were also included. The ability of these peptides to induce contraction of stomach fundus isolated from mouse was evaluated as well as their capability to induce calcium release from a cell culture of smooth muscle from guinea pig ileum. The conformational properties of the peptides were evaluated by circular dichroism and their resistance to enzymatic degradation by exposure to human blood plasma. Our results show that neither the parent BbKI51-62 nor its Ri-BbKI51-62 analog exhibit bradykinin-like activity, although the retro-inverso isomer was resistant to blood plasma degradation. On the other hand, the peptides P2 and Ri-P2 presented contractile activities on gastric smooth muscle from stomach fundus possibly by acting via B-2 receptor. Both compounds also induce calcium release from guinea pig ileum muscle cells in a manner similar to bradykinin. Moreover, both compounds also inhibited porcine pancreatic kallikrein. However, conformational analysis did not reveal any direct correlation between structure and biological effects.

Bauhinia Bauhinioides Kallikrein Inhibitor Fragments with Bradykinin-Like Activities

“…Conformational studies by Circular Dichroism in different environments were performed (data not shown). The full results of this study is presented elsewhere [5]. Neither BbKI51-62 nor Ri-BbKI51-62 presented bradykinin-like activity, but as expected, the retro-inverso compound was resistant to the enzymes presented in the blood plasma.…”

Sarconesin II, a New Antimicrobial Peptide Isolated from Sarconesiopsis magellanica Excretions and Secretions

“…The peptide was analyzed in pure water and 30, 70 and 100% v/v solutions of 2,2,2 trifluoroethanol (TFE) in water. Fast Fourier Transform (FTF) was used to minimize background effects [141].…”

Angiotensin II analogues with N‐terminal lactam bridge cyclization: an overview on AT1 receptor activation and tachyphylaxis

“…Experiments were carried out with C57BL/6J mice from the Centro de Desenvolvimento de Modelos Experimentais da Universidade Federal de São Paulo (CEDEME‐UNIFESP) according to Alves et al . Briefly, the stomach fundus was isolated from the mouse, stripped into two longitudinal muscle strips and mounted into 5‐mL organ baths (Panlab, Cornella, CA, Spain) containing modified Krebs‐Ringer solution: 144 m m NaCl, 5 m m KCl, 1.1 m m MgSO 4 , 25 m m NaHCO 3 , 1.1 m m NaH 2 PO 4 , 1.25 m m CaCl 2 and 5.5 m m glucose at 37 °C (pH 7.4) continuously carboxygenated (95% O 2 /5% CO 2 ).…”