Marianne Molander1, Dan Staerk1, Hanne Mørck Nielsen2, Johanna M Brandner3, Drissa Diallo4, Chifundera Kusamba Zacharie5, Johannes van Staden6, Anna K Jäger7. 1. Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark. 2. Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. 3. Department of Dermatology and Venerology, University Hospital Hamburg-Eppendorf, Hamburg, Germany. 4. Departement de Medecine Traditionelle, School of Pharmacy, Bamako, Mali. 5. Department of Biology and Wildlife Resources Management, Faculty of Sciences, National Pedagogical University, Kinshasa, Democratic Republic of the Congo. 6. Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3201, South Africa. 7. Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark. Electronic address: anna.jager@sund.ku.dk.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE: Snakebite envenomation causes 5000-10,000 mortalities and results in more than 5-15,000 amputations in sub-Saharan Africa alone every year. The inaccessibility of antiserum therapy is a vast problem, and only about 2.5% of the actual need for antiserum in Africa is covered. Numerous plants have shown in vitro inhibitory activity against one or more of the hydrolytic enzymes involved in snakebite-induced necrosis. However, a more thorough examination of the plant species in ex vivo and in vitro cell assay models is needed to test their ability to inhibit necrosis. MATERIALS AND METHODS: Extracts which had previously shown in vitro inhibitory activity against necrosis enzymes, were tested in an ex vivo air-liquid-interface model, and a wound healing scratch assay as well as for their ability to permeate the skin barrier and inhibit venom induced cell death. RESULTS: Of the 14 water extracts and 16 ethanol extracts tested at a concentration of 10 μg/mL, only the ethanol extracts of Tamarindus indica and Paullinia pinnata resulted in a small but significant increase in cell migration of around 10% compared to treatment with buffer after 24h treatment. The remaining extracts showed no effect, or they even delayed the cell migration compared to the treatment with buffer. After 48 h treatment, 10 of the tested extracts showed a decreased cell migration compared to no treatment. At a 100 μg/mL concentration all the extracts inhibited cell migration and five extracts killed some of the cells, while four extracts killed all the cells. Ten of the thirty extracts were tested in a Franz cell set-up but none of the extracts tested did permeate the skin barrier over a 48 h period, and will therefore be of very limited use topically in the initial treatment of snakebites in its present form. None of the extracts were able to directly interact with the enzyme to lower the cell toxicity of the venom. Two extracts, Dichrostachys cinerea and Grewia mollis, were tested in the ex vivo model, but none of them inhibited the tissue destruction caused by venom. CONCLUSION: On the basis of this study, topical treatment with plant extracts for snakebite-induced tissue necrosis cannot be recommended.
ETHNOPHARMACOLOGICAL RELEVANCE: Snakebite envenomation causes 5000-10,000 mortalities and results in more than 5-15,000 amputations in sub-Saharan Africa alone every year. The inaccessibility of antiserum therapy is a vast problem, and only about 2.5% of the actual need for antiserum in Africa is covered. Numerous plants have shown in vitro inhibitory activity against one or more of the hydrolytic enzymes involved in snakebite-induced necrosis. However, a more thorough examination of the plant species in ex vivo and in vitro cell assay models is needed to test their ability to inhibit necrosis. MATERIALS AND METHODS: Extracts which had previously shown in vitro inhibitory activity against necrosis enzymes, were tested in an ex vivo air-liquid-interface model, and a wound healing scratch assay as well as for their ability to permeate the skin barrier and inhibit venom induced cell death. RESULTS: Of the 14 water extracts and 16 ethanol extracts tested at a concentration of 10 μg/mL, only the ethanol extracts of Tamarindus indica and Paullinia pinnata resulted in a small but significant increase in cell migration of around 10% compared to treatment with buffer after 24h treatment. The remaining extracts showed no effect, or they even delayed the cell migration compared to the treatment with buffer. After 48 h treatment, 10 of the tested extracts showed a decreased cell migration compared to no treatment. At a 100 μg/mL concentration all the extracts inhibited cell migration and five extracts killed some of the cells, while four extracts killed all the cells. Ten of the thirty extracts were tested in a Franz cell set-up but none of the extracts tested did permeate the skin barrier over a 48 h period, and will therefore be of very limited use topically in the initial treatment of snakebites in its present form. None of the extracts were able to directly interact with the enzyme to lower the cell toxicity of the venom. Two extracts, Dichrostachys cinerea and Grewia mollis, were tested in the ex vivo model, but none of them inhibited the tissue destruction caused by venom. CONCLUSION: On the basis of this study, topical treatment with plant extracts for snakebite-induced tissue necrosis cannot be recommended.
Authors: N T Q Alves; R M Ximenes; R J B Jorge; J A M Silveira; J V A Santos; F A P Rodrigues; P H S Costa; F A F Xavier; J S A M Evangelista; A Havt; V C G Soares; M H Toyama; A N A Oliveira; R M Araújo; R S Alves; H S A Monteiro Journal: Braz J Med Biol Res Date: 2018-12-03 Impact factor: 2.590