title: Investigation of skin permeation, ex vivo inhibition of venom-induced tissue destruction, and wound healing of African plants used against snakebites.
abstract: BACKGROUND
  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.
  
  
  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.
  
  
  CONCLUSIONS
  On the basis of this study, topical treatment with plant extracts for snakebite-induced tissue necrosis cannot be recommended.
authors: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors: Marianne
authors: M
authors: Molander
authors: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors: Dan
authors: D
authors: Staerk
authors: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Hanne
authors: H
authors: Mørck Nielsen
authors: Department of Dermatology and Venerology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
authors: Johanna M
authors: JM
authors: Brandner
authors: Departement de Medecine Traditionelle, School of Pharmacy, Bamako, Mali.
authors: Drissa
authors: D
authors: Diallo
authors: Department of Biology and Wildlife Resources Management, Faculty of Sciences, National Pedagogical University, Kinshasa, Democratic Republic of the Congo.
authors: Chifundera
authors: C
authors: Kusamba Zacharie
authors: Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3201, South Africa.
authors: Johannes
authors: J
authors: van Staden
authors: 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.
authors: Anna K
authors: AK
authors: Jäger
mesh_terms: D016475:3T3 Cells / Q000187:drug effects; D000287:Administration, Topical; D017954:Africa South of the Sahara; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D006801:Humans; D051379:Mice; D032126:Paullinia / Q000737:chemistry; D008517:Phytotherapy / Q000379:methods*; D010936:Plant Extracts / Q000493:pharmacokinetics / Q000627:therapeutic use*; D012867:Skin / Q000187:drug effects / Q000473:pathology*; D012909:Snake Bites / Q000188:drug therapy*; D012910:Snake Venoms / Q000493:pharmacokinetics / Q000494:pharmacology; D013552:Swine; D029861:Tamarindus / Q000737:chemistry; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D010936:Plant Extracts; D012910:Snake Venoms
keywords: Africa; Franz diffusion cell; Snake venom; Traditional use; Wound healing scratch assay