Wild parsnip (Pastinaca sativa)-induced photosensitization.

This study investigates the impact of wild parsnip (Pastinaca sativa) on photosensitization in horses and goats. The research identifies five compounds in the plant using HPLC-MS and MS/MS analysis and examines potential exposure routes, with topical exposure seeming the most likely to cause photosensitivity. Photodermatitis, specifically superficial necrotizing dermatitis, was found to result, but there was no evidence of other allergic or inflammatory components.

Research Focus and Process

• The research was conducted to understand the effects of wild parsnip (Pastinaca sativa) on livestock and human photosensitization. Photosensitization is a skin condition that is caused by exposure to certain chemicals and sunlight. It was noticed that horses grazing on wild parsnip were demonstrating symptoms of this condition.
• In order to investigate the cause, five furanocoumarins were identified in the plant using High Performance Liquid Chromatography Mass Spectrometry (HPLC-MS) and Tandem Mass Spectrometry (MS/MS). Furanocoumarins are organic chemical compounds produced by a variety of plants. The identified furanocoumarins were xanthotoxin, bergapten, isopimpinellin, imperatorin, and a putative methoxyimperatorin.

Experiment & Findings

• The researchers fed goats with this wild parsnip but found that they were largely unaffected. This suggests that not all animals react to the plant the same way.
• Xanthotoxin, one of the furanocoumarins identified in the plant, was not detected in the serum of parsnip-fed goats or in the serum of goats dosed orally or intravenously with purified xanthotoxin. This indicates that even direct ingestion or application of the substance does not necessarily result in photosensitization.
• The experiment showed that cutaneous application of the compounds, i.e., application to the skin, resulted in severe photodermatitis in goats and a horse. Therefore, it was established that topical exposure to wild parsnip is the most likely cause of the photosensitivity.

Conclusion

• The conclusion drawn from this research was that contact with wild parsnip led to a specific skin condition known as superficial necrotizing dermatitis. This condition is consistent with photodermatitis, a skin response to light after exposure to certain chemicals.
• No evidence was found of other allergic or inflammatory components, indicating that the skin reaction was purely due to the combination of exposure to wild parsnip and sunlight.

The implication of these findings is that caution should be exercised to prevent contact with wild parsnip, particularly in sunny conditions, where light exposure can trigger the photosensitivity reactions.