Raquel S.B. Oliveira

Proteins from latex of Calotropis procera prevent septic shock due to lethal infection by Salmonella enterica serovar Typhimurium

AIM OF THE STUDY The latex of Calotropis procera has been used in traditional medicine to treat different inflammatory diseases. The anti-inflammatory activity of latex proteins (LP) has been well documented using different inflammatory models. In this work the anti-inflammatory protein fraction was evaluated in a true inflammatory process by inducing a lethal experimental infection in the murine model caused by Salmonella enterica Subsp. enterica serovar Typhimurium. MATERIALS AND METHODS Experimental Swiss mice were given 0.2 ml of LP (30 or 60 mg/kg) by the intraperitoneal route 24 h before or after lethal challenge (0.2 ml) containing 10(6) CFU/ml of Salmonella Typhimurium using the same route of administration. RESULTS All the control animals succumbed to infection within 6 days. When given before bacterial inoculums LP prevented the death of mice, which remained in observation until day 28. Even, LP-treated animals exhibited only discrete signs of infection which disappeared latter. LP fraction was also protective when given orally or by subcutaneous route. Histopathological examination revealed that necrosis and inflammatory infiltrates were similar in both the experimental and control groups on days 1 and 5 after infection. LP activity did not clear Salmonella Typhimurium, which was still present in the spleen at approximately 10(4) cells/g of organ 28 days after challenge. However, no bacteria were detected in the liver at this stage. LP did not inhibit bacterial growth in culture medium at all. In the early stages of infection bacteria population was similar in organs and in the peritoneal fluid but drastically reduced in blood. Titration of TNF-alpha in serum revealed no differences between experimental and control groups on days 1 and 5 days after infection while IL-12 was only discretely diminished in serum of experimental animals on day 5. Moreover, cultured macrophages treated with LP and stimulated by LPS released significantly less IL-1beta. CONCLUSIONS LP-treated mice did not succumb to septic shock when submitted to a lethal infection. LP did not exhibit in vitro bactericidal activity. It is thought that protection of LP-treated mice against Salmonella Typhimurium possibly involves down-regulation of pro-inflammatory cytokines (other than TNF-alpha). LP inhibited IL-1beta release in cultured macrophages and discretely reduced IL-12 in serum of animals given LP. Results reported here support the folk use of latex to treat skin infections by topic application.

Osmotin from Calotropis procera latex: new insights into structure and antifungal properties.

This study aimed at investigating the structural properties and mechanisms of the antifungal action of CpOsm, a purified osmotin from Calotropis procera latex. Fluorescence and CD assays revealed that the CpOsm structure is highly stable, regardless of pH levels. Accordingly, CpOsm inhibited the spore germination of Fusarium solani in all pH ranges tested. The content of the secondary structure of CpOsm was estimated as follows: α-helix (20%), β-sheet (33%), turned (19%) and unordered (28%), RMSD 1%. CpOsm was stable at up to 75°C, and thermal denaturation (T(m)) was calculated to be 77.8°C. This osmotin interacted with the negatively charged large unilamellar vesicles (LUVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-1-glycerol (POPG), inducing vesicle permeabilization by the leakage of calcein. CpOsm induced the membrane permeabilization of spores and hyphae from Fusarium solani, allowing for propidium iodide uptake. These results show that CpOsm is a stable protein, and its antifungal activity involves membrane permeabilization, as property reported earlier for other osmotins and thaumatin-like proteins.

Involvement of NO in the inhibitory effect of Calotropis procera latex protein fractions on leukocyte rolling, adhesion and infiltration in rat peritonitis model

AIM OF THE STUDY The latex of Calotropis procera has been used in the traditional medicinal system for the treatment of leprosy, ulcers, tumors, piles and diseases of liver, spleen, abdomen and toothache. It comprises of a non-dialyzable protein fraction (LP) that exhibits anti-inflammatory properties and a dialyzable fraction (DF) exhibiting pro-inflammatory properties. The present study was carried out to evaluate the effect of LP sub-fractions on neutrophil functions and nociception in rodent models and to elucidate the mediatory role of nitric oxide (NO). MATERIAL AND METHODS The LP was subjected to ion exchange chromatography and the effect of its three sub-fractions (LP(PI), LP(PII) and LP(PIII)) thus obtained was evaluated on leukocyte functions in the rat peritonitis model and on nociception in the mouse model. RESULTS LP sub-fractions exhibit distinct protein profile and produce a significant decrease in the carrageenan and DF induced neutrophil influx and exhibit anti-nociceptive property. The LP and its sub-fractions produced a marked reduction in the number of rolling and adherent leukocytes in the mesenteric microvasculature as revealed by intravital microscopy. The anti-inflammatory effect of LP(PI), the most potent anti-inflammatory fraction of LP, was accompanied by an increase in the serum levels of NO. Further, our study shows that NO is also involved in the inhibitory effect of LP(PI) on neutrophil influx. CONCLUSIONS Our study shows that LP fraction of Calotropis procera comprises of three distinct sets of proteins exhibiting anti-inflammatory and anti-nociceptive properties of which LP(PI) was most potent in inhibiting neutrophil functions and its effects are mediated through NO production.

Proteins derived from latex of C. procera maintain coagulation homeostasis in septic mice and exhibit thrombin- and plasmin-like activities

The proteins derived from the latex (LP) of Calotropis procera are well known for their anti-inflammatory property. In view of their protective effect reported in the sepsis model, they were evaluated for their efficacy in maintaining coagulation homeostasis in sepsis. Intraperitoneal injection of LP markedly reduced the procoagulation and thrombocytopenia observed in mice infected with Salmonella; while in normal mice, LP produced a procoagulant effect. In order to understand its mechanism of action, the LP was subjected to ion-exchange chromatography, and the three subfractions (LPPI, LPPII, and LPPIII) thus obtained were tested for their proteolytic effect and thrombin- and plasmin-like activities in vitro. Of the three subfractions tested, LPPII and LPPIII exhibited proteolytic effect on azocasein and exhibited procoagulant effect on human plasma in a concentration-dependent manner. Like trypsin and plasmin, these subfractions produced both fibrinogenolytic and fibrinolytic effects that were mediated through the hydrolysis of the Aα, Bβ, and γ chains of fibrinogen and α-polymer and γ-dimer of fibrin clot, respectively. This study shows that the cysteine proteases present in the latex of C. procera exhibit thrombin- and plasmin-like activities and suggests that these proteins have therapeutic potential in various conditions associated with coagulation abnormalities.

Crystal structure of an antifungal osmotin-like protein from Calotropis procera and its effects on Fusarium solani spores, as revealed by atomic force microscopy: Insights into the mechanism of action.

CpOsm is an antifungal osmotin/thaumatin-like protein purified from the latex of Calotropis procera. The protein is relatively thermostable and retains its antifungal activity over a wide pH range; therefore, it may be useful in the development of new antifungal drugs or transgenic crops with enhanced resistance to phytopathogenic fungi. To gain further insight into the mechanism of action of CpOsm, its three-dimensional structure was determined, and the effects of the protein on Fusarium solani spores were investigated by atomic force microscopy (AFM). The atomic structure of CpOsm was solved at a resolution of 1.61Å, and it contained 205 amino acid residues and 192 water molecules, with a final R-factor of 18.12% and an Rfree of 21.59%. The CpOsm structure belongs to the thaumatin superfamily fold and is characterized by three domains stabilized by eight disulfide bonds and a prominent charged cleft, which runs the length of the front side of the molecule. Similarly to other antifungal thaumatin-like proteins, the cleft of CpOsm is predominantly acidic. AFM images of F. solani spores treated with CpOsm resulted in striking morphological changes being induced by the protein. Spores treated with CpOsm were wrinkled, and the volume of these cells was reduced by approximately 80%. Treated cells were covered by a shell of CpOsm molecules, and the leakage of cytoplasmic content from these cells was also observed. Based on the structural features of CpOsm and the effects that the protein produces on F. solani spores, a possible mechanism of action is suggested and discussed.

Latex fluids are endowed with insect repellent activity not specifically related to their proteins or volatile substances

Latex is an endogenous milky fluid synthesized and accumulated under pressure in a network of laticifer cells. In this study, latices from five plant species were examined for deterrent effect on oviposition of two Coleoptera (Bruchidae) pests. The latex from Euphorbia tirucalli, Calotropis procera and Plumeria rubrae exhibited deterrent activity on oviposition of both Callosobruchus maculatusand Zabrotis subfasciatus beetles. The latex from Cryptostegia grandiflora and Himathantus drasticus were less effective to C. maculatus and Z. subfasciatus oviposition, respectively. Eggs laid on latex-treated seeds were not affected.The emergence and the mean time of development and weight of larvae grown in treated seeds were similar to the controls. The deterrent activity of C. procera and P. rubra was dose and time-dependent for Z. subfasciatus rather than to C. maculatus. The deterrent effect was completely eliminated if the whole latices were fractionated in protein fractions, rubber and small metabolites. Exposing insects to crude latices did not alter ovipostion on untreated seeds. These RESULTSsuggest that latices possess deterrent activity on insect oviposition mediated by a repellent effect, but that proteins and volatile substances are probably not involved. The repellent-like activity can be considered as a defensive role played by these fluids that relies on the combined action of their components.

Crystallization and X‐ray diffraction analysis of an antifungal laticifer protein

An osmotin (CpOsm) from the latex of Calotropis procera has been crystallized in both tetragonal and trigonal forms suitable for structure determination. Crystallographic studies of CpOsm are of great interest because limited information is available concerning the structure of latex proteins and CpOsm has previously been shown to interact with the spore membranes of some plant pathogenic fungi, thus impairing spore germination and hyphal growth. CpOsm crystals were grown using 0.1 M HEPES buffer pH 7.5, 26% PEG 4000, 0.2 M ammonium sulfate (space group P4(3)) or using 0.1 M HEPES buffer pH 7.5, 35% MPD, 0.7 M ammonium sulfate (space group P3(1)12). X-ray diffraction data were collected to 2.17 Å (P4(3)) and 1.80 Å (P3(1)12) resolution and molecular-replacement analyses produced initial phases for both crystal forms.

First Clinical Consensus and National Recommendations on Tracheostomized Children of the Brazilian Academy of Pediatric Otorhinolaryngology (ABOPe) and Brazilian Society of Pediatrics (SBP)

INTRODUCTION Tracheostomy is a procedure that can be performed in any age group, including children under 1year of age. Unfortunately health professionals in Brazil have great difficulty dealing with this condition due to the lack of standard care orientation. OBJECTIVE This clinical consensus by Academia Brasileira de Otorrinolaringologia Pediátrica (ABOPe) and Sociedade Brasileira de Pediatria (SBP) aims to generate national recommendations on the care concerning tracheostomized children. METHODS A group of experts experienced in pediatric tracheostomy (otorhinolaryngologists, intensive care pediatricians, endoscopists, and pediatric pulmonologists) were selected, taking into account the different regions of Brazil and following inclusion and exclusion criteria. RESULTS The results generated from this document were based on the agreement of the majority of participants regarding the indications, type of cannula, surgical techniques, care, and general guidelines and decannulation. CONCLUSION These guidelines can be used as directives for a wide range of health professionals across the country that deal with tracheostomized children.