Structure–function relationships of the peptide Paulistine: A novel toxin from the venom of the social wasp Polybia paulista

AbstractBackgroundThe peptide Paulistine was isolated from the venom of wasp Polybia paulista. This peptide exists under a natural equilibrium between the forms: oxidised — with an intra-molecular disulphide bridge; and reduced — in which the thiol groups of the cysteine residues do not form the disulphide bridge. The biological activities of both forms of the peptide are unknown up to now.MethodsBoth forms of Paulistine were synthesised and the thiol groups of the reduced form were protected with the acetamidemethyl group [Acm-Paulistine] to prevent re-oxidation. The structure/activity relationships of the two forms were investigated, taking into account the importance of the disulphide bridge.ResultsPaulistine has a more compact structure, while Acm-Paulistine has a more expanded conformation. Bioassays reported that Paulistine caused hyperalgesia by interacting with the receptors of lipid mediators involved in the cyclooxygenase type II pathway, while Acm-Paullistine also caused hyperalgesia, but mediated by receptors involved in the participation of prostanoids in the cyclooxygenase type II pathway.ConclusionThe acetamidemethylation of the thiol groups of cysteine residues caused small structural changes, which in turn may have affected some physicochemical properties of the Paulistine. Thus, the dissociation of the hyperalgesy from the edematogenic effect when the actions of Paulistine and Acm-Paulistine are compared to each other may be resulting from the influence of the introduction of Acm-group in the structure of Paulistine.General significanceThe peptides Paulistine and Acm-Paulistine may be used as interesting tools to investigate the mechanisms of pain and inflammation in future studies

Estudos sobre atividade nociceptiva/antinociceptiva de peptídeos isolados do veneno bruto de abelha Apis mellifera

O veneno bruto de abelha Apis mellifera é composto por uma série de peptídeos, entre eles a melitina, adolapina, procamina A e B, apamina, tertiapina, secapina, peptídeos desgranuladores de mastócitos, entre outros. Estas substâncias apresentam diversos efeitos já estudadas, dentre elas, efeitos antitumorais, atividades hiperalgésicas ou analgésicas, inflamatórias ou anti-inflamatórias. O peptídeo secapina foi descrito há 35 anos atrás e, posteriormente nada mais foi relatado na literatura. Portanto, este é o primeiro trabalho que visa caracterizar o possível efeito hiperalgésico e/ou analgésico, inflamatório e/ou antiinflamatório, bem como analisar alguns dos mecanismos envolvidos nestes fenômenos. Para tanto, para caracterizar os possíveis efeitos hiperalgésicos/analgésicos da secapina, em diversas doses (0,005, 0,35, 1, 2, 10 e 30 μg / 50 μL), foi utilizado o teste de avaliação da sensibilidade dolorosa denominado teste do von Frey eletrônico. Para a caracterização do efeito inflamatório/anti-inflamatório da secapina foi utilizado o paquímetro digital determinando o volume da pata dos animais. Para investigar os possíveis mecanismos envolvidos nestes efeitos, foram realizados tratamentos farmacológicos utilizando indometacina, zileuton e zafirlikaste (inibidores da síntese da via da cicloxigenase, lipoxigenase e antagonista de receptor de leucotrieno, respectivamente). Os resultados mostraram que a secapina, em todas as doses testadas, induziu efeito hiperalgésico a partir dos primeiros 15 minutos após a administração deste peptídeo. Este efeito hiperalgésico persistiu por até 240 minutos nas doses de 0,005 e 0,35 μg/ 50μL e 480 minutos nas doses de 1 e 2 μg/ 50μL. O efeito edematogênico da secapina na dose de 0,35 μg/50 μL foi iniciado nos primeiros 15 minutos após a administração da secapina e persistiu por até 120 minutos, sendo... (Resumo completo, clicar acesso eletrônico abaixo

Neuroprotective Effects of Pomegranate Peel Extract after Chronic Infusion with Amyloid-β Peptide in Mice.

Alzheimer's disease is a chronic and degenerative condition that had no treatment until recently. The current therapeutic strategies reduce progression of the disease but are expensive and commonly cause side effects that are uncomfortable for treated patients. Functional foods to prevent and/or treat many conditions, including neurodegenerative diseases, represent a promising field of study currently gaining attention. To this end, here we demonstrate the effects of pomegranate (Punica granatum) peel extract (PPE) regarding spatial memory, biomarkers of neuroplasticity, oxidative stress and inflammation in a mouse model of neurodegeneration. Male C57Bl/6 mice were chronically infused for 35 days with amyloid-β peptide 1-42 (Aβ) or vehicle (control) using mini-osmotic pumps. Another group, also infused with Aβ, was treated with PPE (p.o.- βA+PPE, 800 mg/kg/day). Spatial memory was evaluated in the Barnes maze. Animals treated with PPE and in the control group exhibited a reduction in failure to find the escape box, a finding that was not observed in the Aβ group. The consumption of PPE reduced amyloid plaque density, increased the expression of neurotrophin BDNF and reduced the activity of acetylcholinesterase enzyme. A reduction in lipid peroxidation and in the concentration of the pro-inflammatory cytokine TNF-α was also observed in the PPE group. No hepatic lesions were observed in animals treated with PPE. In conclusion, administration of pomegranate peel extract has neuroprotective effects involving multiple mechanisms to prevent establishment and progression of the neurodegenerative process induced by infusion with amyloid-β peptide in mice

Neuroprotective Effects of Pomegranate Peel Extract after Chronic Infusion with Amyloid-β Peptide in Mice - Fig 4

<p><b>Representative figures of thioflavine-S staining in brain of Ctrl (A), Aβ (B) and Aβ + PPE (C) groups.</b> The coronal sections showed are at approximately the same anatomical level (-1.58 mm from Bregma) and correspond to hippocampal areas. Representative figures are from samples run in the same batch during staining procedure. White arrows indicate the senile plaques. Scale bar is 140 μm.</p

Intracerebroventricular infusion with amyloid-β peptide or consuption of pomegranate peel extract did not affect the hepatic function.

<p>Serum was tested to OGT and GPT by ELISA. There was no diference in the biomarkers levels in the serum of Control (n = 6), Aβ (n = 6) and Aβ + PPE (n = 6). Histograms and vertical bars are means ± S.E.M.</p

Treatment with pomegranate peel extract maintained spatial memory.

<p>In the “acquisition session”, all animals (Ctrl, n = 12; Aβ, n = 12 and Aβ + PPE, n = 12) learned the task as demonstrated by the significant decrease in number of errors to find the escape box on the 4^th day of exposition of all groups [F_(3,81) = 9.55, P < 0.0001, panel A].</p

Infusion with amyloi-β increased the level of TNF-α in the brain and the treatment with pomegranate peel extract significantly decreased the inflammatory process.

<p>Brain homogenates and serum were tested to TNF-α by ELISA. There was no diference in TNF-α levels in the serum of Control (n = 5), Aβ (n = 6) and Aβ + PPE (n = 6) groups. In the cortex, the infusion of Aβ increased the TNF-α level. The treatment with Aβ + PPE (n = 6) decreased the TNF-α level when compared to the Control (n = 6) and Aβ (n = 5) groups. Histograms and vertical bars are means ± S.E.M. *: P < 0.05; **: P < 0.001.</p

Infusion with amyloid-β peptide and treatment with pomegranate peel did not interfere with motor activity of the animals.

<p>There was no difference in the locomotor activity or the rearing between groups before or after the infusion period and treatment (Ctrl, n = 12; Aβ, n = 12 and Aβ + PPE, n = 12). Data are plotted as the mean ± S.E.M. of units of motor activity.</p

Treatment with pomegranate peel extract significantly decreased the number of plaques.

<p>Chronic infusion with Aβ peptide promoted the formation of senile plaques in the brain of mice, as described previously in rats [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166123#pone.0166123.ref018" target="_blank">18</a>]. The Aβ + PPE group (n = 6) presented a significant reduction in the number of plaques, when compared to the Aβ group (n = 6). Histograms and vertical bars are the means ± SEM. *: P < 0.01.</p

Treatment with pomegranate peel extract significantly decreased AChE levels.

<p>There was no significant difference in the activity of the AChE between the control and the Aβ groups. However, treatment with pomegranate promoted a significant reduction in the activity of this enzyme in both the cortex (Ctrl, n = 7; Aβ, n = 7 and Aβ + PPE, n = 8) and hippocampus (Ctrl, n = 6; Aβ, n = 7 and Aβ + PPE, n = 6). Data are the means ± S.E.M. *: P < 0.05; **: P < 0.01.</p