In vitro comparison of enzymatic effects among Brazilian Bothrops spp. venoms

Comparative compositional and functional analyses of Bothrops moojeni specimens reveal several individual variations

Snake venoms are complex protein mixtures with different biological activities that can act in both their preys and human victims. Many of these proteins play a role in prey capture and in the digestive process of these animals. It is known that some snakes are resistant to the toxicity of their own venom by mechanisms not yet fully elucidated. However, it was observed in the Laboratory of Herpetology of Instituto Butantan that some Bothrops moojeni individuals injured by the same snake species showed mortalities caused by envenoming effects. This study analyzed the biochemical composition of 13 venom and plasma samples from Bothrops moojeni specimens to assess differences in their protein composition. Application of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed distinct venom protein profiles, but very homogeneous plasma profiles. Western Blotting (WB) was performed with plasma samples, which were submitted to incubation with the respective venom. Some individuals showed an immunorecognized band zone around 25 kDa, indicating interaction between the same individual plasma and venom proteins. Crossed-WB assay using non-self-plasma and venom showed that this variability is due to venom protein composition instead of plasma composition. These venoms presented higher caseinolytic, collagenolytic and coagulant activities than the venoms without these regions recognized by WB. Mass spectrometry analyses performed on two individuals revealed that these individuals present, in addition to higher protein concentrations, other exclusive proteins in their composition. When these same two samples were tested in vivo, the results also showed higher lethality in these venoms, but lower hemorrhagic activity than in the venoms without these regions recognized by WB. In conclusion, some Bothrops moojeni specimens differ in venom composition, which may have implications in envenomation. Moreover, the high individual venom variability found in this species demonstrates the importance to work with individual analyses in studies involving intraspecific venom variability and venom evolution.

Tabebuia aurea decreases hyperalgesia and neuronal injury induced by snake venom

ETHNOPHARMACOLOGICAL RELEVANCE

Tabebuia aurea (Silva Manso) Benth. & Hook. f. ex S. Moore is used as anti-inflammatory, analgesic and antiophidic in traditional medicine, though its pharmacological proprieties are still underexplored. In the bothropic envenoming, pain is a key symptom drove by an intense local inflammatory and neurotoxic event. The antivenom serum therapy is still the main treatment despite its poor local effects against pain and tissue injury. Furthermore, it is limited to ambulatorial niches, giving space for the search of new and more inclusive pharmacological approaches.

AIM OF THE STUDY

evaluation of Tabebuia aurea hydroethanolic extract (HEETa) in hyperalgesia and neuronal injury induced by Bothrops mattogrossensis venom (VBm).

MATERIALS AND METHODS

Stem barks from Tabebuia aurea were extracted with ethanol and water (7:3, v/v) to yield the extract HEETa. Then, HEETa was analyzed by LC-DAD-MS and its constituents were identified. Snake venoms were extracted from adult specimens of Bothrops mattogrossensis, lyophilized and kept at -20 °C until use. Male Swiss mice, weighting 20-25 g, were used to hyperalgesia (electronic von Frey), motor impairment (Rotarod test) and tissue injury evaluation (histopatology and ATF-3 immunohistochemistry). Therefore, three experimental groups were formed: VBm (1 pg, 1 ng, 0.3 μg, 1 μg, 3 and 6 μg/paw), HEETa orally (180, 540, 720, 810 or 1080 mg/kg; 10 mL/kg, 30 min prior VBm inoculation) and VBm neutralized (VBm: HEETa, 1:100 parts, respectively). In all set of experiments a control (saline group) was used. First, we made a dose-time-response course curve of VBm's induced hyperalgesia. Next, VBm maximum hyperalgesic dose was employed to perform HEETa orally dose-time-response course curve and analyses of VBm neutralized. Paw tissues for histopathology and DRGs were collected from animals inoculated with VBm maximum dose and treated with HEETa antihyperalgesic effective dose or neutralized VBm. Paws were extract two or 72 h after VBm inoculation and DRGs, in the maximum expected time expression of ATF-3 (72 h).

RESULTS

From HEETa extract, glycosylated iridoids were identified, such as catalpol, minecoside, verminoside and specioside. VBm induced a time and dose dependent hyperalgesia with its highest effect seen with 3 µg/paw, 2 h after venom inoculation. HEETa effective dose (720 mg/kg) decreased significantly VBm induced hyperalgesia (3 µg/paw) with no motor impairment and signs of acute toxicity. HEETa antihyperalgesic action starts 1.5 h after VBm inoculation and lasted up until 2 h after VBm. Hyperalgesia wasn't reduced by VBm: HEETa neutralization. Histopathology revealed a large hemorragic field 2 h after VBm inoculation and an intense inflammatory infiltrate of polymorphonuclear cells at 72 h. Both HEETa orally and VBm: HEETa groups had a reduced inflammation at 72 h after VBm. Also, the venom significantly induced ATF-3 expression (35.37 ± 3.25%) compared with saline group (4.18 ± 0.68%) which was reduced in HEETa orally (25.87 ± 2.57%) and VBm: HEETa (19.84 ± 2.15%) groups.

CONCLUSION

HEETa reduced the hyperalgesia and neuronal injury induced by VBm. These effects could be related to iridoid glycosides detected in HEETa and their intrinsic reported mechanism.

Bradykinin-potentiating PEPTIDE-10C, an argininosuccinate synthetase activator, protects against H2O2-induced oxidative stress in SH-SY5Y neuroblastoma cells

Bradykinin-potentiating peptides (BPPs - 5a, 7a, 9a, 10c, 11e, and 12b) of Bothrops jararaca (Bj) were described as argininosuccinate synthase (AsS) activators, improving l-arginine availability. Agmatine and polyamines, which are l-arginine metabolism products, have neuroprotective properties. Here, we investigated the neuroprotective effects of low molecular mass fraction from Bj venom (LMMF) and two synthetic BPPs (BPP-10c, <ENWPHPQIPP; BPP-12b, <EWGRPPGPPIPP) in the SH-SY5Y cell line against H₂O₂-induced oxidative stress. The neuroprotective effects against H₂O₂-induced were analyzed by reactive oxygen species (ROS - DCFH) production; lipid peroxidation (TBARS); intracellular GSH; AsS, iNOS, and NF-kB expressions; nitrite levels (Griess); mitochondrial membrane potential (TMRM); and antioxidant activity (DPPH). Analysis of variance followed by Tukey's post hoc test were calculated for statistical comparisons. Pre-treatment with both BPPs significantly reduced cell death induced by H₂O₂, but BPP-10c showed higher protective capacity than BPP-12b. LMMF pretreatment was unable to prevent the reduction of cell viability caused by H₂O₂. The neuroprotective mechanism of BPP-10c against oxidative stress was investigated. BPP-10c reduced ROS generation and lipid peroxidation in relation to cells treated only with H₂O₂. BBP-10c increased AsS expression and was not neuroprotective in the presence of MDLA, a specific inhibitor of AsS. BPP-10c reduced iNOS expression and nitrate levels but decreased NF-kB expression. Furthermore, BPP-10c protected the mitochondrial membrane against oxidation. Overall, we demonstrated for the first time neuroprotective mechanisms of BPPs against oxidative stress, opening new perspectives to the study and application of these peptides for the treatment of neurodegenerative diseases.

Prospection of Effects of Guava Leaves Infusion: Antigenotoxic Action and Enzymatic Inhibition

Several forms of Psidium guajava L. (guava) leaf preparations have been widely used for prevention and treatment of illnesses. However, researches about the protective action of guava's natural products on the genetic material of animal cells is scarce. Accordingly, the aim of this study was to evaluate the antigenotoxic potential of infusions of guava leaves from three cultivars (Pedro Sato, Paluma and Roxa) against DNA damage induced by Doxorubicin (DXR) in human leukocytes, and their effects on enzymatic inhibition. To assess the antigenotoxic potential of these infusions, a comet assay (single cell electrophoresis) was conducted. In addition, their inhibitory potential on phospholipase and hemolytic activities was assessed. The evaluated infusion volumes (25, 50 and 300μL) presented inhibitions around 75% of the DXR-induced damage frequencies. Their protective effect was demonstrated by arbitrary unit calculations, with values between 52.51 and 66.60 for all treatments, 250.51 for positive control (DXR), and 45.49 for phosphate buffered saline (negative control). The infusions significantly inhibited phospholipase and hemolytic activities induced by Bothrops alternatus and B. moojeni venoms, with inhibitions ≥ 50% for both activities induced by B. alternatus. The infusions of P. guajava from the cultivars analyzed present antigenotoxic potential, but also demonstrate potential of enzymatic inhibition on A2phospholipases and proteases.

Functional Elucidation of Nemopilema nomurai and Cyanea nozakii Nematocyst Venoms' Lytic Activity Using Mass Spectrometry and Zymography

Background: Medusozoans utilize explosively discharging penetrant nematocysts to inject venom into prey. These venoms are composed of highly complex proteins and peptides with extensive bioactivities, as observed in vitro. Diverse enzymatic toxins have been putatively identified in the venom of jellyfish, Nemopilema nomurai and Cyanea nozakii, through examination of their proteomes and transcriptomes. However, functional examination of putative enzymatic components identified in proteomic approaches to elucidate potential bioactivities is critically needed. Methods: In this study, enzymatic toxins were functionally identified using a combined approach consisting of in gel zymography and liquid chromatography tandem mass spectrometry (LC-MS/MS). The potential roles of metalloproteinases and lipases in hemolytic activity were explored using specific inhibitors. Results: Zymography indicated that nematocyst venom possessed protease-, lipase- and hyaluronidase-class activities. Further, proteomic approaches using LC-MS/MS indicated sequence homology of proteolytic bands observed in zymography to extant zinc metalloproteinase-disintegrins and astacin metalloproteinases. Moreover, pre-incubation of the metalloproteinase inhibitor batimastat with N. nomurai nematocyst venom resulted in an approximate 62% reduction of hemolysis compared to venom exposed sheep erythrocytes, suggesting that metalloproteinases contribute to hemolytic activity. Additionally, species within the molecular mass range of 14–18 kDa exhibited both egg yolk and erythrocyte lytic activities in gel overlay assays. Conclusion: For the first time, our findings demonstrate the contribution of jellyfish venom metalloproteinase and suggest the involvement of lipase species to hemolytic activity. Investigations of this relationship will facilitate a better understanding of the constituents and toxicity of jellyfish venom.

l-amino acid oxidase from Bothrops marajoensis causes nephrotoxicity in isolated perfused kidney and cytotoxicity in MDCK renal cells

Renal alterations caused by Bothrops venom and its compounds are studied to understand these effects and provide the best treatment. Previously, we studied the renal effect of the whole venom of Bothrops marajoensis and its phospholipase A2 (PLA2), but these effects could not to be attributed to PLA2. To continue the study, we report in this short communication the effects of l-amino acid oxidase from B. marajoensis venom (LAAOBm) on renal function parameter alterations observed in the same model of isolated perfused kidney, as well as the cytotoxic effect on renal cells. LAAOBm caused a decrease in PP, RVR, UF, GFR, %TNa(+) and %TCl(-), very similar to the effects of whole venom using the same model. We also demonstrated its cytotoxicity in MDCK cells with IC50 of 2.5 μg/mL and late apoptotic involvement demonstrated by flow cytometry assays. In conclusion, we suggested that LAAOBm is a nephrotoxic compound of B. marajoensis venom.

L-Aminoacid Oxidase from Bothrops leucurus Venom Induces Nephrotoxicity via Apoptosis and Necrosis

Acute renal failure is a common complication caused by Bothrops viper envenomation. In this study, the nefrotoxicity of a main component of B. leucurus venom called L-aminoacid oxidase (LAAO-Bl) was evaluated by using tubular epithelial cell lines MDCK and HK-2 and perfused kidney from rats. LAAO-Bl exhibited cytotoxicity, inducing apoptosis and necrosis in MDCK and HK-2 cell lines in a concentration-dependent manner. MDCK apoptosis induction was accompanied by Ca2+ release from the endoplasmic reticulum, reactive oxygen species (ROS) generation and mitochondrial dysfunction with enhanced expression of Bax protein levels. LAAO-Bl induced caspase-3 and caspase-7 activation in both cell lines. LAAO-Bl (10 μg/mL) exerts significant effects on the isolated kidney perfusion increasing perfusion pressure and urinary flow and decreasing the glomerular filtration rate and sodium, potassium and chloride tubular transport. Taken together our results suggest that LAAO-Bl is responsible for the nephrotoxicity observed in the envenomation by snakebites. Moreover, the cytotoxic of LAAO-Bl to renal epithelial cells might be responsible, at least in part, for the nephrotoxicity observed in isolated kidney.