RESUMO
Increasing resistance in antibiotic and chemotherapeutic treatments has been pushing studies of design and evaluation of bioactive peptides. Designing relies on different approaches from minimalist sequences and endogenous peptides modifications to computational libraries. Evaluation relies on microbiological tests. Aiming a deeper understanding, we chose the octapeptide Jelleine-I (JI) for its selective and low toxicity profile, designed small modifications combining the substitutions of Phe by Trp and Lys/His by Arg and tested the antimicrobial and anticancer activity on melanoma cells. Biophysical methods identified environment-dependent modulation of aggregation, but critical aggregation concentrations of JI and analogs in buffer show that peptides start membrane interactions as monomers. The presence of model membranes increases or reduces the partial aggregation of peptides. Compared to JI, analog JIF2WR shows the lowest tendency to aggregation on bacterial model membranes. JI and analogs are lytic to model membranes. Their composition-dependent performance indicates preference for the higher charged anionic bilayers in line with their superior performance toward Staphylococcus aureus and Streptococcus pneumoniae. JIF2WR presented the higher partitioning, higher lytic activity and lower aggregated contents. Despite these increased membranolytic activities, JIF2WR exhibited comparable antimicrobial activity in relation to JI at the expenses of some loss in selectivity. We found that the substitution Phe/Trp (JIF2W) tends to decrease antimicrobial but to increase anticancer activity and aggregation on model membranes and the toxicity toward human cells. However, the concomitant substitution Lys/His by Arg (JIF2WR) modulates some of these tendencies, increasing both the antimicrobial and the anticancer activity while decreasing the aggregation tendency.
Assuntos
Anti-Infecciosos/farmacologia , Peptídeos Catiônicos Antimicrobianos/toxicidade , Antineoplásicos/farmacologia , Membrana Celular/metabolismo , Hemólise/efeitos dos fármacos , Melanoma/patologia , Oligopeptídeos/toxicidade , Animais , Anti-Infecciosos/química , Peptídeos Catiônicos Antimicrobianos/química , Antineoplásicos/química , Arginina/química , Candida/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Humanos , Melanoma/tratamento farmacológico , Camundongos , Oligopeptídeos/química , Staphylococcus aureus/efeitos dos fármacos , Streptococcus pneumoniae/efeitos dos fármacos , Triptofano/químicaRESUMO
In the present study we evaluated the cardiovascular effects produced by microinjection of the new component of the renin-angiotensin system, alamandine, into caudal ventrolateral medulla of urethane-anesthetized normotensive and hypertensive 2K1C rats. The participation of different angiotensin receptors in the effects of alamandine was also evaluated. Microinjection of angiotensin-(1-7) was used for comparison. The microinjection of 4, 40 and 140pmol of alamandine or angiotensin-(1-7) into caudal ventrolateral medulla induced similar hypotensive effects in Sham-operated rats. However, contrasting with angiotensin-(1-7), in 2K1C rats the MAP response to the highest dose of alamandine was similar to that observed with saline. The microinjection of A-779, a selective Mas receptor antagonist, blunted the angiotensin-(1-7) effects but did not block the hypotensive effect of alamandine in Sham or in 2K1C rats. However, microinjection of D-Pro7-angiotensin-(1-7), a Mas/MrgD receptor antagonist, blocked the hypotensive effect induced by both peptides. Furthermore, microinjection of PD123319, a putative AT2 receptor antagonist blocked the hypotensive effect of alamandine, but not of angiotensin-(1-7), in Sham and 2K1C rats. Microinjection of the AT1 receptor antagonist, losartan, did not alter the hypotensive effect of angiotensin-(1-7) or alamandine in both groups. These results provide new insights about the differential mechanisms participating in the central cardiovascular effects of alamandine and angiotensin-(1-7) in normotensive and 2K1C hypertensive rats.
Assuntos
Bloqueadores do Receptor Tipo 2 de Angiotensina II/farmacologia , Angiotensina I/toxicidade , Hipertensão/induzido quimicamente , Oligopeptídeos/toxicidade , Fragmentos de Peptídeos/toxicidade , Animais , Imidazóis/farmacologia , Masculino , Piridinas/farmacologia , Ratos , Receptor Tipo 2 de Angiotensina/metabolismo , Sistema Renina-Angiotensina/efeitos dos fármacosRESUMO
High resolution mass spectrometry investigation of an extract of the toxic cyanobacterium Sphaerospermopsis torques-reginae ITEP-024 led to the discovery of four new spumigin congeners. The structures for these peptides were postulated on the basis of accurate mass data and isotopic pattern information of both full scan and product ion spectra. This is the first reported evidence of spumigins on Sphaerospermopsis species.
Assuntos
Cianobactérias/metabolismo , Toxinas Marinhas/química , Oligopeptídeos/química , Fracionamento Químico , Cromatografia Líquida , Cianobactérias/química , Toxinas Marinhas/isolamento & purificação , Toxinas Marinhas/metabolismo , Espectrometria de Massas , Oligopeptídeos/isolamento & purificação , Oligopeptídeos/toxicidadeRESUMO
BACKGROUND: The snakes from the Bitis genus are some of the most medically important venomous snakes in sub Saharan Africa, however little is known about the composition and effects of these snake venom peptides. Considering that the victims with Bitis genus snakes have exacerbate hypotension and cardiovascular disorders, we investigated here the presence of angiotensin-converting enzyme modulators on four different species of venoms. METHODS: The peptide fractions from Bitis gabonica gabonica, Bitis nasicornis, Bitis gabonica rhinoceros and Bitis arietans which showed inhibitory activity on angiotensin-converting enzyme were subjected to mass spectrometry analysis. Eight proline-rich peptides were synthetized and their potencies were evaluated in vitro and in vivo. RESULTS: The MS analysis resulted in over 150 sequences, out of which 32 are new proline-rich oligopeptides, and eight were selected for syntheses. For some peptides, inhibition assays showed inhibitory potentials of cleavage of angiotensin I ten times greater when compared to bradykinin. In vivo tests showed that all peptides decreased mean arterial pressure, followed by tachycardia in 6 out of 8 of the tests. CONCLUSION: We describe here some new and already known proline-rich peptides, also known as bradykinin-potentiating peptides. Four synthetic peptides indicated a preferential inhibition of angiotensin-converting enzyme C-domain. In vivo studies show that the proline-rich oligopeptides are hypotensive molecules. GENERAL SIGNIFICANCE: Although proline-rich oligopeptides are known molecules, we present here 32 new sequences that are inhibitors of the angiotensin-converting enzyme and consistent with the symptoms of the victims of Bitis spp, who display severe hypotension.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/toxicidade , Pressão Arterial/efeitos dos fármacos , Hipotensão/induzido quimicamente , Oligopeptídeos/toxicidade , Venenos de Víboras/toxicidade , Inibidores da Enzima Conversora de Angiotensina/síntese química , Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Animais , Cromatografia Líquida de Alta Pressão , Transferência Ressonante de Energia de Fluorescência , Frequência Cardíaca/efeitos dos fármacos , Hipotensão/fisiopatologia , Masculino , Oligopeptídeos/síntese química , Oligopeptídeos/isolamento & purificação , Prolina , Ratos Wistar , Sistema Renina-Angiotensina/efeitos dos fármacos , Taquicardia/induzido quimicamente , Taquicardia/fisiopatologia , Espectrometria de Massas em Tandem , Venenos de Víboras/químicaRESUMO
Cyanobacteria produce a high variety of bioactive oligopeptides, which function, ecological, physiological roles and responses to environmental changes are still unclear. The influence of light intensity on the cell quota and the diversity of oligopeptides of two strains of the cyanobacterium Radiocystis fernandoii were experimentally tested. The peptides were quantified by HPLC and identified by a MALDI-TOF-TOF. Microcystins (MC) were generally more abundant in the treatment with low light. A compensatory mechanism was observed for the different variants of microcystin, whereby MC-RR responses were contrary to those observed for the other three variants and showed higher concentration in the treatment with intermediate light. Two microviridins were also produced at higher amounts at intermediate irradiance. For cyanopeptolins and a third microviridin no significant difference among treatments was found. The absence of a similar response for all peptides suggests that these compounds may have unique cellular functions, which better understanding could help explaining changes in toxicity. Finally, we observed that each chemical profile reflected in physiological differences between strains, strengthening the idea that chemotypes may act as distinct ecotypes in nature.
Assuntos
Cianobactérias/metabolismo , Cianobactérias/efeitos da radiação , Oligopeptídeos/biossíntese , Cianobactérias/química , Cianobactérias/genética , Luz , Espectrometria de Massas , Oligopeptídeos/química , Oligopeptídeos/toxicidadeRESUMO
BACKGROUND AND OBJECTIVE: Integrins are the main mediators of the interaction between fibroblasts and extracellular matrix (ECM) during scar formation. The adhesion motive RGD (Arg-Gly-Asp) is contained in the ECM and is recognized by the integrin receptor. Soluble peptides containing the RGD sequence can compete with -RGD- contained in the ECM for binding to the integrin receptor and thus prevent cell adhesion and scar formation. MATERIALS AND METHODS: The peptides RGD (p602), GRGDSP (p603), GRGDSPCA (p604), and GGRGDSPCA (p605) were used in 25 glaucoma filtering surgeries in rabbits (five eyes per peptide and five with saline). RESULTS: Postoperative subconjunctival injections of peptides were given at days 0, 4, 8, 12, and 16. Bleb size, bleb survival, and signs of toxicity were examined. The GRGDSPCA and GGRGDSPCA showed an increase in bleb formation, size, and survival with no clinical signs of toxicity compared with controls (P < .008). Histopathologic evaluation confirmed inhibitory effects in scar formation with bleb formation, and transmission electron microscopy demonstrated that there was no toxicity to the ciliary body. CONCLUSION: These peptides were effective in controlling scar formation in glaucoma filtering surgery.