20-Hydroxyecdysone identification in performance horses – case reports and review

Abstract

This case report presents the first reported identifications of 20-hydroxyecdysone in post-event blood samples from an Endurance horse and a Harness horse racing in New South Wales, Australia. 20-Hydroxyecdysone is a plant secondary metabolite structurally related to testosterone and used by plants to discourage insect predation. 20-Hydroxyecdysone is found in many plants including spinach and is not infrequently identified at low concentrations in mammalian systems including in humans. Given its steroid-related structure, 20-hydroxyecdysone has been reported to enhance athletic performance in humans, although at this time 20-hydroxyecdysone is simply being monitored by the World Anti-Doping Agency (WADA) [31] . The Harness horse identification led the Harness Racing New South Wales (HRNSW) authorities to evaluate the home pastures of the horse in question, where they recovered at least three plants containing significant concentrations of 20-hydroxyecdysone. The HRNSW stewards were satisfied that the 20-hydroxyecdysone identification was due to "environmental contamination emanated from plants" in the trainer's establishment and did not impose a penalty on the trainer. These findings show that the pasture plant steroid 20-hydroxyecdysone is found in pasture plants from which it is bioavailable to equines and can present as low part per billion concentrations in equine blood samples, as has also been noted in humans. Based on these Australian identifications of 20-hydroxyecdysone in pasture plants and also in equine blood samples and the HRNSW decision not to penalize the trainer involved and the likelihood of no pharmacological response to pasture plant exposure to this substance we now present 2 parts per billion in equine blood/plasma as an appropriate regulatory cut-off or Screening Limit of Detection (SLOD) for 20-hydroxecdysone in equine blood/plasma.