Senecio serratuloides var. in wound healing: efficacy and mechanistic investigations in a porcine wound model
Date
2015-09-16
Authors
Gould, Alan Nicolas
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Abstract
Senecio serratuloides is widely used for wound healing in South Africa but minimal
information regarding its efficacy is available. Furthermore toxic pyrrolizidine
alkaloids may be present. The following investigation sought firstly to evaluate the
efficacy and safety of Senecio serratuloides in a porcine wound model; secondly to
assess for a potential mechanism and finally isolate and identify fractions in in-vitro
assays.
Assessment of Efficacy and Safety
Materials and Methods: Deep partial thickness and full thickness wounds were
created on 9 pigs. Treatment included an occlusive dressing (negative control),
activated carbon, or the Senecio preparation. Wounds were monitored using
photographic documentation, pH measurement and histological analysis (skin
thickness and collagen content). Toxicity was monitored on blood and liver samples.
Results and Discussion: Efficacy of Senecio serratuloides was established with a
significantly thicker epidermis, maximal at day 7 post-operative, 2 days before the
controls. Effects on collagen content was negligible with no toxicity detected.
Mechanistic investigation
Materials and Methods: Wound fluid was analysed for IL-10, IL-12, IL-1β, IL-6, IL-8,
TNF-α using flow cytometry based assays. Tyrosine phosphorylation and cellular
proliferation was assessed using dual immunofluorescence staining.
Results and Discussion: IL-1β levels were significantly greater in the Senecio
treatment. Tyrosine phosphorylation increased to day 9 post-operative where it
stabilised in all groups. In the same period, cellular proliferation was sustained in the
Senecio treated wounds but not in the controls. Keratinocyte proliferation was
identified as the target for in-vitro assays.
Extraction, Isolation and Partial Identification using In-vitro Proliferation
Assays.
Materials and Methods: The plant was fractionated using solid phase extraction
cartridges. Keratinocytes were grown under standard conditions in 96-well plates.
Cellular proliferation was assessed spectrophotometrically using a resazurin dye
technique. Active fractions were analysed using gas chromatography and mass
spectrometry.
Results and Discussion: Identified fractions increased the rate of proliferation by 300-
400%. Potential lead compounds were identified. Importantly, pyrrolizidine alkaloids
could not be detected.
Conclusion
Senecio serratuloides is efficacious in treating deep partial thickness wounds without
inducing liver toxicity. Sustained keratinocyte proliferation linked to tyrosine
phosphorylation may be an underlying mechanism. Although successful, in-vitro
detection of active fractions requires further characterisation.
Description
A dissertation submitted to the Faculty of Health Sciences, University of the
Witwatersrand, in fulfilment of the requirements for the degree of Doctorate of
Philosophy.
Keywords
Senecio serratuloides, porcine wound model, deep partial thickness wound, epidermal thickness, collagen, inflammatory cytokines, Tyrosine phosphorylation, proliferating cell nuclear antigen, plant extraction and fractionation, proliferation assays, gas chromatography and mass spectrometry, alkaloids, wound healing