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Snake envenomation results in a range of clinical sequelae, and widely used animal-based conventional antivenoms exhibit several limitations including the adverse immunological effects in human snake bite victims. Therefore, human monoclonal anti-snake venom antibodies or fragments can be an alternate therapy for overcoming the existing limitations. We developed venom-neutralizing humanized scFv antibodies and analyzed biochemical mechanisms associated with the inhibition of toxicity. Tomlinson I and J human scFv antibody libraries were screened against Naja naja and Echis carinatus venoms, and seven unique scFv antibodies were obtained. Further, specific toxins of snake venom interacting with each of these scFvs were identified, and phospholipase A2 (PLA2) was found to be prominently captured by the phage-anchored scFv antibodies. Our study indicated PLA2 to be one of the abundant toxins in Naja naja and Echis carinatus venom samples. The scFvs binding to PLA2 were used to perform in vivo survival assay using the mouse model and in vitro toxin inhibition assays. scFv N194, which binds to acidic PLA2, protected 50% of mice treated with Naja naja venom. Significant prolongation of survival time and 16% survival were observed in Echis carinatus venom-challenged mice treated with scFv E113 and scFv E10, respectively. However, a combination comprised of an equal amount of two scFvs, E113 and E10, both interacting with basic PLA2, exhibited synergistically enhanced survival of 33% in Echis carinatus venom-challenged mice. No such synergistically enhanced survival was observed in the case of combinatorial treatment with anti- Naja naja scFvs, N194, and N248. These scFvs demonstrated partial inhibition of venom-induced myotoxicity, and E113 also inhibited hemolysis by 50%, which corroborates the enhanced survival during combinatorial treatment in Echis carinatus venom-challenged mice. • Conventional antivenoms exhibit adverse effects in snakebite victims. • Seven human scFvs antibody fragments against two prominent Indian snake venoms were isolated. • Majority of antibodies were specific to phospholipase A2, which is an abundant toxin in both venoms. • These antibodies partially inhibited venom-induced myotoxicity, and one of them also exhibited partial hemolysis inhibition. • Antibodies developed against PLA2 exhibited partial in vivo venom neutralization. [ABSTRACT FROM AUTHOR]

African cobras (Naja species) represent one of the most encountered medically important snakes in Africa. They are classified as African spitting (Afronaja subgenus) and non-spitting cobras (Uraeus and Boulengerina subgenera) with similar and different characteristics. Snake venom toxins including three-finger toxin (3FTx), phospholipase A2 (PLA 2), and snake venom metalloproteinase (SVMP) cause snakebite envenomation leading to morbidity and mortality. The profile of the proteome of African cobra venoms will help to develop safer and more effective antivenoms. The approval of Captopril by the US Food and Drug Administration (FDA) for the treatment of cardiovascular diseases, has led to intensified research towards possible use of venom toxins as therapeutics. In this review, we compare the venom proteome profile of 3 African Naja subgenera. In both Afronaja and Boulengerina subgenera, 3FTx (Afronaja –69.79%; Boulengerina –60.56%) followed by PLA 2 (Afronaja –21.15%; Boulengerina –20.21%) dominated the venoms compared to the Uraeus subgenus dominated by 3FTx (84.55%) with little to no PLA 2 abundance (0.8%). The venom of subgenus Uraeus was distinct from the other two subgenera by the almost total absence of PLA 2 , thus indicating little or no contribution of PLA 2 in the envenomation caused by Uraeus compared to Afronaja and Boulengerina. Furthermore, we report studies on the experimental testing of African cobra venoms and toxins against diseases including anti-cancer properties. [Display omitted] • African spitting and non-spitting cobra venoms cause severe envenomation. • 3FTxs are the most dominant toxin of spitting and non-spitting cobras venoms. • African non-spiting cobra venom of the Uraeus genus constitutes little or no PLA 2. • African cobras have potential therapeutic applications against diseases including cancer. [ABSTRACT FROM AUTHOR]

Naja naja snake bite causes thousands of deaths worldwide in a year. N. naja envenomed victims exhibit both local and systemic reactions that potentially lead to death. In clinical practice, pulmonary complications in N. naja envenomation are commonly encountered. However, the molecular mechanisms underlying N. naja venom-induced lung toxicity remain unknown. Here, we reasoned that N. naja venom-induced lung toxicity is prompted by NLRP3 inflammasome and MAPKs activation in mice. Treatment with dimethyl ester of bilirubin (BD1), significantly inhibited the N. naja venom-induced activation of NLRP3 inflammasome and MAPKs both in vivo and in vitro (p < 0.05). Further, BD1 reduced N. naja venom-induced recruitment of inflammatory cells, and hemorrhage in the lung toxicity examined by histopathology. BD1 also diminished N. naja venom-induced local toxicities in paw edema and myotoxicity in mice. Furthermore, BD1 was able to enhance the survival time against N. naja venom-induced mortality in mice. In conclusion, the present data showed that BD1 alleviated N. naja venom-induced lung toxicity by inhibiting NLRP3 inflammasome and MAPKs activation. Small molecule inhibitors that intervene in venom-induced toxicities may have therapeutic applications complementing anti-snake venom. [Display omitted] • Dimethyl ester of bilirubin reversed Naja naja venom induced NLRP3 inflammasome and MAPKs activation. • Dimethyl ester of bilirubin ameliorated Naja naja venom-induced local and systemic toxicities in mice. • Dimethyl ester of bilirubin improved the survival time of Naja naja venom-induced mortality in mice. [ABSTRACT FROM AUTHOR]

Catuneragam nilotica has been used in ethnomedicine to treat snakebite, inflammation, and diarrhea among others. The aim of this research is to isolate, and characterize potential potential phospholipase A 2 (PLA 2) inhibitors from the roots of C. nilotica. The plant material was collected, authenticated, and sequentially extracted using solvents of increasing polarity starting from n-hexane, ethyl acetate, and methanol. The extracts as reported in our previous work, were screened in vitro for their inhibitory activity against PLA 2 enzyme from N. nigricollis venom using acidimetric assay. In line with the bio-activity guided isolation, methanol extract (being the most active) was subjected to chromatographic separation using silica gel and sephadex LH-20 which resulted in the isolation and characterization of scopoletin, and scopolin; the compounds were able to inhibit the hydrolytic actions of PLA2 enzyme with percentage inhibition ranging from 67.82 to 100.00 % and 65.76–93.15 %, respectively while the standard Antisnake Venom (ASV) had 74.96–85.04 % after 10 min incubation at 37 °C. The molecular docking of the compounds against PLA 2 enzyme was performed using Auto Dock Vina while ADME-Tox analysis was evaluated using swissADME and ProTox-II online servers; The findings indicated that both compounds were able to bind to the active site of PLA 2 enzyme with high affinity (−6.5 to −6.2 kcal/mol) and they exhibited favorable drug-likeness and pharmacokinetic properties, and according to toxicity predictions, scopolin was found to be non-toxic (LD 50 of 5000 mg/kg) while scopoletin has a slight chance of being toxic (LD 50 of 3800 mg/kg). In conclusion, the findings of the research revealed that the roots of C. nilotica contains phytoconstituents with anti-PLA 2 enzyme activity and thus, validates the ethnomedicinal claim of the use of the plant as herbal therapy against N. nigricollis envenomation. [Display omitted] • Scopoletin and Scopolin were identified from the roots of Catuneragam nilotica. • Both compounds were able to inhibit the hydrolytic actions of PLA 2 enzyme from Naja nigricollis venom. • The compounds interacted with key amino acid residues such as HIS47 and ASP48 at the active site of PLA 2 with high affinity. • Scopoletin and Scopolin also exhibited favorable drug-like and pharmacokinetics properties. • The roots of C. nilotica contain active phytoconstituents with proven antisnake properties. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma and bacterial resistance are major health burdens nowadays. Thus, providing new therapies that overcome that resistance is of great interest, particularly those derived from nature rather than chemotherapeutics to avoid cytotoxicity on normal cells. Venomous animals are among the natural sources that assisted in the discovery of novel therapeutic regimens. L-amino acid oxidase Nh-LAAO (140 kDa), purified from Egyptian Naja haje venom by a successive two-step chromatography protocol, has an optimal pH and temperature of 8 and 37 °C. Under standard assay conditions, Nh-LAAO exhibited the highest specificity toward L-Arg, L-Met and L-Leu, with K m and V max values of 3.5 mM and 10.4 μmol/min/ml, respectively. Among the metal ions, Ca+2, Na+, and K+ ions are activators, whereas Fe+2 inhibited LAAO activity. PMSF and EDTA slightly inhibited the Nh-LAAO activity. In addition, Nh-LAAO showed antibacterial and antifungal activities, particularly against Gentamicin-resistant P. aeruginosa and E. coli strains with MIC of 18 ± 2 μg/ml, as well as F. proliferatum and A. parasiticus among the selected human pathogenic strains. Furthermore, Nh-LAAO exhibited anti-proliferative activity against cancer HepG2 and Huh7 cells with IC50 of 79.37 and 60.11 μg/ml, respectively, with no detectable effect on normal WI-38 cells. Consequently, the apoptosis % of the HepG2 and Huh7 cells were 12 ± 1 and 34.5 ± 2.5 %, respectively, upon Nh-LAAO treatment. Further, the Nh-LAAO arrested the HepG2 and Huh7 cell cycles in the G0/G1 phase. Thus, the powerful selective cytotoxicity of L-amino acid oxidase opens up the possibility as a good candidate for clinical cancer therapy. [Display omitted] • A novel homodimeric L-amino acid oxidase with two subunits of 70 kDa was purified from Egyptian Cobra (Naja haje) venom. • The purified L-amino acid oxidase is optimally active at pH 8 and 37 °C with L-Leucine as a substrate. • Naja haje - L-amino acid oxidase displays anti-bacterial effect against several bacterial strains. • The purified L-amino acid oxidase induces apoptotic activity against hepatic cancer cell lines. • This study offers insight into L-amino acid oxidase purified from Naja haje venom as a promising cancer drug candidate. [ABSTRACT FROM AUTHOR]

Snakebite envenomation often leads to severe visceral injuries, including acute liver injury (ALI). However, the toxicity mechanism remains unclear. Moreover, varespladib can directly inhibit phospholipase A 2 (PLA 2) in snake venom, but its protective effect on snakebite-induced ALI and the mechanism have not been clarified. Previous studies have shown that snake venom PLA 2 leads to neuron cell death via reactive oxygen species (ROS), one of the initial factors related to the mitophagy pathway. The present study group also found that ROS accumulation occurred after Naja atra envenoming. Hematoxylin and eosin (H/E) staining and immunohistochemistry (IHC) were performed to identify the expression of inflammatory factors in the liver tissue, and flow cytometry and immunofluorescence were used to detect ROS levels and mitochondrial function. Immunofluorescence and western blotting were also used for detecting mitophagy pathway-related proteins. The results showed that N. atra bite induced ALI by activating mitophagy and inducing inflammation and that varespladib had a protective effect. Collectively, these results showed the pathological mechanism of ALI caused by N. atra bite and revealed the protective effect of varespladib. [Display omitted] • N.atra venom causes acute liver injury(ALI), which accompanies with ROS generation. • Excess ROS could induce mitophagy. • Varespladib could effectively allevitate ALI caused by N.atra venom. [ABSTRACT FROM AUTHOR]

Three-finger toxins (3FTxs) have traditionally been obtained via venom fractionation of whole venoms from snakes. This method often yields functional toxins, but it can be difficult to obtain pure isoforms, as it is challenging to separate the many different toxins with similar physicochemical properties that generally exist in many venoms. This issue can be circumvented via the use of recombinant expression. However, achieving the correct disulfide bond formation in recombinant toxins is challenging and requires extensive optimization of expression and purification methods to enhance stability and functionality. In this study, we investigated the expression of α-cobratoxin, a well-characterized 3FTx from the monocled cobra (Naja kaouthia), in three different expression systems, namely Escherichia coli BL21 (DE3) cells with the csCyDisCo plasmid, Escherichia coli SHuffle cells, and Komagataella phaffii (formerly known as Pichia pastoris). While none of the tested systems yielded α-cobratoxin identical to the variant isolated from whole venom, the His 6 -tagged α-cobratoxin expressed in K. phaffii exhibited a comparable secondary structure according to circular dichroism spectra and similar binding properties to the α7 subunit of the nicotinic acetylcholine receptor. The findings presented here illustrate the advantages and limitations of the different expression systems and can help guide researchers who wish to express 3FTxs. [Display omitted] • α-cobratoxin produced in bacteria or yeast is not completely identical to the native toxin structure • α-cobratoxin produced in yeast has a similar circular dichroism spectrum as the native toxin and binds the target receptor • Solubilization tags aid in enhancing the expression of soluble protein, but removal negatively affects net yield • E. coli and K. phaffii -expressed α-cobratoxin retains functional binding to its target receptor. • Recombinant toxins can be used to advance antivenom research and the development of toxin-derived therapeutics. [ABSTRACT FROM AUTHOR]

Snake bite envenomation causes tissue damage resulting in acute and chronic inflammatory responses. Inflammasome activation is one of the factors involved in tissue damage in a mouse model of snake envenomation. The present study examines the potency of Indian Big Four snake venoms in the activation of inflammasome and its role in local and systemic tissue toxicity. Among Indian Big Four snake venoms, Naja naja venom activated NLRP3 inflammasome in mouse macrophages. Activation of NLRP3 inflammasome was also observed in mouse foot paw and thigh muscle upon administration of N. naja venom. Intraperitoneal administration of N. naja venom cause systemic lung damage showed activation of NLRP3 inflammasome. Treatment with MCC950, a selective NLRP3 inflammasome inhibitor effectively inhibited N. naja venom-induced activation of caspase-1 and liberation of IL-1β in macrophages. In mice, MCC950 partially inhibited the activation of NLRP3 inflammasome in N. naja venom administered foot paw and thigh muscle. In conclusion, the present data showed that inflammasome is one of the host responses involved in N. naja snake venom-induced toxicities. The inhibition of inflammasome activation will provide new insight into better management of snake bite-induced local tissue damage. Proposed mechanism of NLRP3 inflammasome activation by N. naja venom. LPS priming as a first signal triggers the activation of NLRP3, which leads to the expression of the pro-IL-1β gene and the production of the pro-IL-1β protein. N. naja venom and DAMPs released from muscle tissue due to N. naja venom-induced edema and myotoxicity serve as the second signal for inflammasome activation. These two signals trigger the assembly and activation of the NLRP3 inflammasome complex and the liberate IL-1β cytokine. MCC950 inhibits N. naja venom-induced NLRP3 inflammasome activation by blocking pro-Caspase-1 cleavage into active Caspase-1. [Display omitted] • Naja naja snake venom activates NLRP3 inflammasome complex in macrophages. • Inflammasome pathway is activated in vivo in Naja naja venom-induced edema and myotoxicity in mice. • MCC950 an inhibitor of NLRP3 inflammasome pathway neutralizes Naja naja venom-induced inflammasome activation. [ABSTRACT FROM AUTHOR]

Snake venoms consist of highly biologically active proteins and peptides that are responsible for the lethal physiological effects of snakebite envenomation. In order to guide the development of targeted antivenom strategies, comprehensive understanding of venom compositions and in-depth characterisation of various proteoforms, often not captured by traditional bottom-up proteomic workflows, is necessary. Here, we employ an integrated 'omics' and intact mass spectrometry (MS)-based approach to profile the heterogeneity within the venom of the forest cobra (Naja melanoleuca), adopting different analytical strategies to accommodate for the dynamic molecular mass range of venom proteins present. The venom proteome of N. melanoleuca was catalogued using a venom gland transcriptome-guided bottom-up proteomics approach, revealing a venom consisting of six toxin superfamilies. The subtle diversity present in the venom components was further explored using reversed phase-ultra performance liquid chromatography (RP-UPLC) coupled to intact MS. This approach showed a significant increase in the number of venom proteoforms within various toxin families that were not captured in previous studies. Furthermore, we probed at the higher-order structures of the larger venom proteins using a combination of native MS and mass photometry and revealed significant structural heterogeneity along with extensive post-translational modifications in the form of glycosylation in these larger toxins. Here, we show the diverse structural heterogeneity of snake venom proteins in the venom of N. melanoleuca using an integrated workflow that incorporates analytical strategies that profile snake venom at the proteoform level, complementing traditional venom characterisation approaches. • Forest cobra venom was found to consist of six toxin families, using a transcriptome-guided bottom-up proteomics approach. • Venom proteoform diversity was revealed within various toxin families using RP-UPLC coupled to intact mass spectrometry. • Higher-order structures of larger toxins were profiled using native mass spectrometry and mass photometry. [ABSTRACT FROM AUTHOR]