Detection of Sagebrush Defensive Chemistry Using Liquid Chromatography Mass Spectrometry

Sagebrush ( Artemisia tridentate ), the most common shrub in North America, contains a diverse profile of defensive chemicals making it toxic to most animals. However, sage grouse ( Centrocercus urophasianus ) have evolved to subsist on sagebrush; up to 90% of their winter diet consists of sagebrush. To understand how grouse can tolerate sagebrush defensive chemistry, metabolism of these compounds through cytochrome P450s (CYPs) was investigated in vitro . A model system using mouse liver CYPs and individual or combinations of sagebrush compounds was developed. Liquid chromatography mass spectrometry (LCMS) enabled tracking of kaempferol and scopoletin substrate metabolism. Appearance of the product of kaempferol metabolism, quercetin, was also detected. A combination of kaempferol and scopoletin substrates retained a similar rate of metabolism as individual compounds. This protocol can be further utilized with CYP enzymes from sage grouse liver and authentic compounds extracted from sagebrush to characterize in vitro the metabolic processes utilized by sage grouse in feeding on sagebrush. A better understanding of sagebrush and sage grouse at the chemical level will be useful in efforts to preserve optimal habitat.