Plant DNases are potent therapeutic agents against Echis carinatus venom‐induced tissue necrosis in mice

A comparative cross-reactivity and paraspecific neutralization study on Hypnale hypnale, Echis carinatus, and Daboia russelii monovalent and therapeutic polyvalent anti-venoms

Envenoming by the hump-nosed pit viper (Hypnale hypnale) raises concern as it inflicts significant debilitation and death in the Western Ghats of India and in the adjacent island nation of Sri Lanka. In India, its medical significance was realized only during 2007 due to its misidentification as Echis carinatus and sometimes as Daboia russelii. Of late, several case reports have underlined the ineptness of the existing polyvalent anti-venom therapy against H. hypnale envenoming. Currently, H. hypnale bite has remained dreadful in India due to the lack of neutralizing anti-venom therapy. Hence, this study was undertaken to establish a systematic comparative, biochemical, pathological, and immunological properties of Sri Lankan H. hypnale venom alongside Indian E. carinatus, and D. russelii venoms. All three venoms differed markedly in the extent of biochemical activities including proteolytic, deoxyribonuclease, L-amino acid oxidase, 5'-nucleotidase, hyaluronidase, and indirect hemolytic activities. The venoms also differed markedly in their pathological properties such as edema, hemorrhage, myotoxic, cardiotoxic, and coagulant activities. The venoms showed stark differences in their protein banding pattern. Strikingly, the affinity-purified rabbit monovalent anti-venoms prepared against H. hypnale, E. carinatus, and D. russelii venoms readily reacted and neutralized the biochemical and pathological properties of their respective venoms, but they insignificantly cross-reacted with, and thus failed to show paraspecific neutralization of any of the effects of the other two venoms, demonstrating the large degree of variations between these venoms. Further, the Indian therapeutic polyvalent anti-venoms from VINS Bioproducts, and Bharath Serums and Vaccines failed to protect H. hypnale venom-induced lethal effects in mice.

Botanical treatments for snakebite in rural Ghana: A narrative review

ETHNOPHARMACOLOGICAL RELEVANCE

In the countryside, there are some limitations with the use of venom antisera to manage snake bites. Due to poor access to healthcare and as a result of the difficulty in receiving treatment for cases of snake bites, most rural people in Ghana, a West African country, rely on plant medicine as a first aid to manage cases of venomous snakebite. This calls for more research into the species of plants used to medically manage snakebite envenomation.

AIM OF THE STUDY

This review sought to present plants that are used in managing snakebite cases and also gather data supporting their use.

METHODOLOGY

This is a systematic search and review of information obtained from textbooks and databases such as PubMed and ScienceDirect between January 1975 and August 2020.

RESULTS

A search done identified 43 plant species and these were found to belong to 25 taxonomic families with the most frequent ones being, Fabaceae, Euphorbiaceae, Apocynaceae, and Solanaceae. Experimental data gathered indicate that among the many plants identified to be used to manage snakebites, only 5 were found with anti-venom in vitro and in vivo evidence-based data.

CONCLUSION

Data collated hint that a few plant species identified namely Anacardium occidentale, Euphorbia hirta, Mimosa pudica, Musa paradisiaca and Mangifera indica, work by targeting diverse physiopathological and biochemical processes involved in the clinical manifestations of snakebites. This review has also unearthed knowledge gaps that can form the basis for broad investigations and development of these and other medicinal plants into useful anti-venom medications.

Echis carinatus snake venom metalloprotease-induced toxicities in mice: Therapeutic intervention by a repurposed drug, Tetraethyl thiuram disulfide (Disulfiram)

Echis carinatus (EC) is known as saw-scaled viper and it is endemic to the Indian subcontinent. Envenoming by EC represents a major cause of snakebite mortality and morbidity in the Indian subcontinent. Zinc (Zn++) dependent snake venom metalloproteases (SVMPs) present in Echis carinatus venom (ECV) is well known to cause systemic hemorrhage and coagulopathy in experimental animals. An earlier report has shown that ECV activates neutrophils and releases neutrophil extracellular traps (NETs) that blocks blood vessels leading to severe tissue necrosis. However, the direct involvement of SVMPs in the release of NETs is not clear. Here, we investigated the direct involvement of EC SVMPs in observed pathological symptoms in a preclinical setup using specific Zn++ metal chelator, Tetraethyl thiuram disulfide (TTD)/disulfiram. TTD potently antagonizes the activity of SVMPs-mediated ECM protein degradation in vitro and skin hemorrhage in mice. In addition, TTD protected mice from ECV-induced footpad tissue necrosis by reduced expression of citrullinated H3 (citH3) and myeloperoxidase (MPO) in footpad tissue. TTD also neutralized ECV-induced systemic hemorrhage and conferred protection against lethality in mice. Moreover, TTD inhibited ECV-induced NETosis in human neutrophils and decreased the expression of peptidyl arginine deiminase (PAD) 4, citH3, MPO, and p-ERK. Further, we demonstrated that ECV-induced NETosis and tissue necrosis are mediated via PAR-1-ERK axis. Overall, our results provide an insight into SVMPs-induced toxicities and the promising protective efficacy of TTD can be extrapolated to treat severe tissue necrosis complementing anti-snake venom (ASV).

Thrombin-like serine protease, antiquorin from Euphorbia antiquorum latex induces platelet aggregation via PAR1-Akt/p38 signaling axis

Plant latex proteases (PLPs) are pharmacologically essential and are integral components of traditional medicine in the management of bleeding wounds. PLPs are known to promote blood coagulation and stop bleeding by interfering at various stages of hemostasis. There are a handful of scientific reports on thrombin-like enzymes characterized from plant latices. However, the role of plant latex thrombin-like enzymes in platelet aggregation is not well known. In the present study, we attempted to purify and characterize thrombin-like protease responsible for platelet aggregation. Among tested plant latices, Euphorbia genus latex protease fractions (LPFs) induced platelet aggregation. In Euphorbia genus, E. antiquorum LPF (EaLPF) strongly induced platelet aggregation and attenuated bleeding in mice. The purified thrombin-like serine protease, antiquorin (Aqn) is a glycoprotein with platelet aggregating activities that interfere in intrinsic and common pathways of blood coagulation cascade and alleviates bleeding and enhanced excision wound healing in mice. In continuation, the pharmacological inhibitor of PAR1 inhibited Aqn-induced phosphorylation of cPLA₂, Akt, and P38 in human platelets. Moreover, Aqn-induced platelet aggregation was inhibited by pharmacological inhibitors of PAR1, PI3K, and P38. These data indicate that PAR1-Akt/P38 signaling pathways are involved in Aqn-induced platelet aggregation. The findings of the present study may open up a new avenue for exploiting Aqn in the treatment of bleeding wounds.

Drupin, a cysteine protease from Ficus drupacea latex accelerates excision wound healing in mice

Wound healing is a tightly regulated physiological process that restores tissue integrity after injury. Plant latex proteases (PLPs) are considered an integral part in herbal wound care as it interferes at different phases of the wound healing process. Although many studies have reported the involvement of PLPs in healing process, an in-depth investigation is required to understand the molecular mechanism. Hence, the effect of PLPs with fibrinolytic activity on wound healing was investigated systematically using mouse excision wound model. Among 29 latices from Ficus genus tested, Ficus drupacea exhibited potent fibrinolytic activity. Cysteine protease responsible for fibrinolysis was purified from the F. drupacea latex named it as drupin, tested for its wound healing efficacy. The accelerated wound healing was mediated by downregulation of matrix metalloprotease (MMP)-9 without altering MMP-8 expression. Besides, drupin enhanced the rate of collagen synthesis at the wound site by increasing arginase 1 activity. And also, drupin increased the expression of arginase 1 in macrophages and involved in cell proliferation, and migration via MAP kinase and PI3K/Akt pathways. Overall, the present study highlights the interference of drupin in wound healing by increased arginase 1 activity and collagen synthesis, and cell proliferation and migration.