Toxicity of scorpion venom in chick embryo and mealworm assay depending on the use of the soluble fraction versus the whole venom

Innovative Microemulsion Loaded with Unusual Dimeric Flavonoids from Fridericia platyphylla (Cham.) L.G. Lohmann Roots

Fridericia platyphylla (Cham.) L.G. Lohmann is a species native to the Brazilian cerrado, with promising bioactivity. The organic fraction of the roots is rich in unusual dimeric flavonoids, reported as potential candidates for cancer treatment. The exploration of these flavonoids is very important, considering their diverse biological activities and the need for innovative therapeutic options. This work aimed to develop and characterize a microemulsion loaded with a non-polar fraction (DCM). The constituents were chosen, and the pseudo-ternary diagram was constructed to determine the region of microemulsion formation. The microemulsions blank (ME), with 3% (ME3) and 5% (ME5) of fraction DCM, were characterized in terms of droplet size, zeta potential, and polydispersity index. Both MEs showed particle sizes <100 nm; only ME3 exhibited better values for polydispersity index and zeta potential and was therefore selected for further study. The organoleptic and physicochemical characteristics were evaluated, revealing limpidity and transparency typical of these microstructures, physiologically acceptable pH, refractive index of 1.42±0.01, and density of 1.017 g/cm3±0.01. The stability tests showed good stability profiles even after exposure to extreme thermal conditions, with minimal changes in pH and the content of the incorporated fraction. The in vitro release study demonstrated that ME3 enabled the controlled release of the fraction, with a cumulative amount released over 60% within 6 h. Furthermore, fraction DCM and ME3 exhibited no toxicity in Tenebrio molitor larvae. The developed microemulsion exhibited excellent properties, so this study represents the first successful attempt to develop a formulation that incorporates the dimeric flavonoid fraction.

Antileishmanial activity of 2-amino-thiophene derivative SB-200

Leishmaniasis, presenting the highest number of cases worldwide is one of the most serious Neglected Tropical Diseases (NTDs). Clinical manifestations are intrinsically related to the host's immune response making immunomodulatory substances the target of numerous studies on antileishmanial activity. The currently available drugs used for treatment present various problems including high toxicity, low efficacy, and associated drug resistance. The search for therapeutic alternatives is urgent, and in this context, thiophene derivatives appear to be a promising therapeutic alternative (many have shown promising anti-leishmanial activity). The objective of this study was to investigate the antileishmanial activity of the 2-amino-thiophenic derivative SB-200. The thiophenic derivative was effective in inhibiting the growth of Leishmania braziliensis, Leishmania major, and Leishmania infantum promastigotes, obtaining respective IC50 values of 4.25 μM, 4.65 μM, and 3.96 μM. For L. infantum, it was demonstrated that the antipromastigote effect of SB-200 is associated with cell membrane integrity losses, and with morphological changes observed during scanning and transmission electron microscopy. Cytotoxicity was performed for J774.A1 macrophages and VERO cells, to obtain a CC50 of 42.52 μM and a SI of 10.74 for macrophages and a CC50 of 39.2 μM and an SI of 9.89 for VERO cells. The anti-amastigote activity of SB-200 revealed an IC50 of 2.85 μM and an SI of 14.97 against macrophages and SI of 13.8 for VERO cells. The anti-amastigote activity of SB-200 is associated with in vitro immunomodulation. For acute toxicity, SB-200 against Zophobas morio larvae permitted 100% survival. We conclude that the 2-amino-thiophenic derivative SB-200 is a promising candidate for in vivo anti-leishmania drug tests to evaluate its activity, efficacy, and safety.

Antileishmania and immunomodulatory potential of cashew nut shell liquid and cardanol

Conventional treatments for leishmaniasis have caused serious adverse effects, poor tolerance, development of resistant strains. Natural products have been investigated as potential therapeutic alternatives. The cashew nut shell liquid (CNSL) is a natural source of phenolic compounds with several biological activities, where cardanol (CN) is considered one of the most important and promising compounds. This study aimed to evaluate antileishmanial, cytotoxic and immunomodulatory activities of CNSL and CN. Both showed antileishmanial potential, with IC₅₀ for CNSL and CN against Leishmania infantum: 148.12 and 56.74 μg/mL; against Leishmania braziliensis: 85.71 and 64.28 μg/mL; against Leishmania major: 153.56 and 122.31 μg/mL, respectively. The mean cytotoxic concentrations (CC₅₀) of CNSL and CN were 37.51 and 31.44 μg/mL, respectively. CNSL and CN significantly reduced the percentage of infected macrophages, with a selectivity index (SI) >20 for CN. CNSL and cardanol caused an increase in phagocytic capacity and lysosomal volume. Survival rates of Zophobas morio larvae at doses of 3; 30 and 300 mg/kg were: 85%, 75% and 60% in contact with CNSL and 85%, 60% and 40% in contact with CN, respectively. There was a significant difference between the survival curves of larvae when treated with CN, demonstrating a significant acute toxicity for this substance. Additional investigations are needed to evaluate these substances in the in vivo experimental infection model.

Evaluation of Anti-Venom Potential of Areca catechu Seed Extract on Bungarus caeruleus Venom

Areca catechu seeds and their extract/s are currently used to treat various ailments and infections including snakebites. The purpose of this investigation was to assess the inhibiting/neutralizing effect of ethyl acetate and aqueous ethanolic seed extracts of A. catechu on Bungarus caeruleus (krait) venom. The enzyme activities and their inhibition were evaluated using standard procedures (in vitro). In vivo studies were conducted using chick embryos and murine models. The extracts inhibited hyaluronidase and phospholipase A2 activities. Protease activity was neutralized by the aqueous ethanolic extract only. The IC50 value of aqueous ethanolic extract for hyaluronidase was 0.001 g/mL, while that for the ethyl acetate extract for phospholipase A2 was 0.006 g/mL. In addition, both the extracts neutralized the indirect hemolysis and fibrinogenolytic activity induced by B. caeruleus venom. The LD50 for the chick embryos was 4.9 µg/egg. The 50 and 100 µg aqueous ethanolic extracts neutralized the LD50 and the challenging dose (3LD50) of venom effectively in the chick embryo model. The LD50 of B. caeruleus venom in mice was 0.1927 µg/kg; the extract extended the survival time of the mice from 25 min to 30 and 35 min in 1:10 and 1:20 ((w/w) venom:extract) ratios, respectively. The extract also neutralized myotoxic activity. The A. catechu seed extract showed promising inhibitory properties against B. caeruleus venom. In this regard, academia and industries should work collaboratively to develop and formulate a cost-effective first-aid drug.

Evaluation of recombinant toxin JFTX-23, an oral-effective anti-insect peptide from the spider Selenocosmia jiafu venom gland proteome

Excessive utilization of chemical pesticides for pest control can lead to adverse consequences for the health of humans and other organisms and may also cause irreversible ecological changes; therefore, the use of biologically derived insecticides can be a safe alternate strategy. Transcriptomic studies have shown JFTX- 23,a small peptide from the spider Selenocosmia jiafuis highly similar to U1-TRTX-Sp1, a well-characterized oral-effective insecticide toxin from the Australian tarantula Selenotypus plumipes. First, we evaluated the JFTX-23 peptide sequence using bioinformatics tools and modeling studies. Preliminary results showed a high similarity of JFTX-23 to JZTX-58 (91.67%) and U1-TRTX-Sp1 (86.11%). Superimposition of the α-carbons of the modeled JFTX-23 and U1-TRTX-Sp1 demonstrated a very high similarity of the 3-D structure of the two peptides (RMSD of 0.02 Å).The injection assay of JFTX-23 in Helicoverpa armigera indicated an LD50 of 0.077 and 0.423 nmol/insect after 24 and 120 h, respectively. JFTX-23 was toxic to H. armigera via oral administration with an LC50 of 1.16 nmol/g food after 5 days, which was comparable to the toxicity of the oral-effective toxin U1-TRTX-Sp1. Our studies have shown that JFTX-23 is a potent oral-effective toxin that can be considered an attractive candidate for the biological control of insect pests.

Scorpion Species with Smaller Body Sizes and Narrower Chelae Have the Highest Venom Potency

Scorpionism is a global health concern, with an estimation of over one million annual envenomation cases. Despite this, little is known regarding the drivers of scorpion venom potency. One widely held view is that smaller scorpions with less-developed chelae possess the most potent venoms. While this perception is often used as a guide for medical intervention, it has yet to be tested in a formal comparative framework. Here, we use a phylogenetic comparative analysis of 36 scorpion species to test whether scorpion venom potency, as measured using LD50, is related to scorpion body size and morphology. We found a positive relationship between LD50 and scorpion total length, supporting the perception that smaller scorpions possess more potent venoms. We also found that, independent of body size, scorpion species with long narrow chelae have higher venom potencies compared to species with more robust chelae. These results not only support the general perception of scorpion morphology and potency, but also the presence of an ecology trade-off with scorpions either selected for well-developed chelae or more potent venoms. Testing the patterns of venom variations in scorpions aids both our ecological understanding and our ability to address the global health burden of scorpionism.

OdTx12/GNA, a chimeric variant of a β excitatory toxin from Odontobuthus doriae, reveals oral toxicity towards Locusta migratoria and Tenebrio molitor

OdTx12, a beta excitatory toxin from Odontobothus doriae had previously been identified and characterized. It had been shown that OdTx12 causes significant lethal effects on insects by injection but does not show any toxicity on mice. Due to the natural ineffectiveness of scorpion toxins to act as oral toxins, OdTx12 was fused to Galanthus nivalis agglutinin (GNA), a protein with the potential to cross the insect gut. The sequence of OdTx12/GNA gene was chemically synthesized, cloned in Escherichia coli, and expressed. The effect of the purified fusion protein (OdTx12/GNA) was assessed on the insect and mammalian cell lines, insect larvae and mice. Toxicity assay on insect cell culture (SF9 cell line) showed comparable toxicity between OdTx12 and OdTx12/GNA (LD50 of 0.0030 and 0.0048 μM, respectively). Also very similar mortality rates were observed by injecting OdTx12 and OdTx12/GNA to Locusta migratoria and Tenebrio molitor. Oral administration of OdTx12/GNA, after five days of feeding, resulted in 96.6% and 98.3% mortality of L. migratoria and T. molitor larvae with an LC50 of 0.69 and 0.43 nmol/g of insect food, respectively, while OdTx12 alone did not cause any toxic effects on the larvae orally, suggesting the role of GNA in delivering the toxin to the insect's haemolymph. No toxicity or mortality was observed after toxicity testing of OdTx12/GNA on a mammalian cell line (HEP-2) or any mortality in vivo, by testing the protein in the laboratory mouse. Herein, we demonstrated that the fusion protein OdTx12/GNA could be considered an effective toxin for the biological control of insects.

Armed stem to stinger: a review of the ecological roles of scorpion weapons

Scorpions possess two systems of weapons: the pincers (chelae) and the stinger (telson). These are placed on anatomically and developmentally well separated parts of the body, that is, the oral appendages and at the end of the body axis. The otherwise conserved body plan of scorpions varies most in the shape and relative dimensions of these two weapon systems, both across species and in some cases between the sexes. We review the literature on the ecological function of these two weapon systems in each of three contexts of usage: (i) predation, (ii) defense and (iii) sexual contests. In the latter context, we will also discuss their usage in mating. We first provide a comparative background for each of these contexts of usage by giving examples of other weapon systems from across the animal kingdom. Then, we discuss the pertinent aspects of the anatomy of the weapon systems, particularly those aspects relevant to their functioning in their ecological roles. The literature on the functioning and ecological role of both the chelae and the telson is discussed in detail, again organized by context of usage. Particular emphasis is given on the differences in morphology or usage between species or higher taxonomic groups, or between genders, as such cases are most insightful to understand the roles of each of the two distinct weapon systems of the scorpions and their evolutionary interactions. We aimed to synthesize the literature while minimizing conjecture, but also to point out gaps in the literature and potential future research opportunities.

Target-Specificity in Scorpions; Comparing Lethality of Scorpion Venoms across Arthropods and Vertebrates

Scorpions use their venom in defensive situations as well as for subduing prey. Since some species of scorpion use their venom more in defensive situations than others, this may have led to selection for differences in effectiveness in defensive situations. Here, we compared the LD₅₀ of the venom of 10 species of scorpions on five different species of target organisms; two insects and three vertebrates. We found little correlation between the target species in the efficacy of the different scorpion venoms. Only the two insects showed a positive correlation, indicating that they responded similarly to the panel of scorpion venoms. We discuss the lack of positive correlation between the vertebrate target species in the light of their evolution and development. When comparing the responses of the target systems to individual scorpion venoms pairwise, we found that closely related scorpion species tend to elicit a similar response pattern across the target species. This was further reflected in a significant phylogenetic signal across the scorpion phylogeny for the LD₅₀ in mice and in zebrafish. We also provide the first mouse LD₅₀ value for Grosphus grandidieri.