Zoey’s metabolome showed increased urinary losses of biopterin. I was asked by the research scientist if I was supplementing with biopterin at the time of submitting urine samples. I was not. I suspect the cause of her losses of urinary biopterin are due to the damaging effects of sulfite toxicity on qBH2. Sulfite can bind to quinone dihydrobiopterin causing decreased recycling of qBH2 to BH4.
Adapated from: https://pmc.ncbi.nlm.nih.gov/articles/PMC8573752/figure/F3/
Sulfite-qBH2 interaction: https://sci-hub.st/https://onlinelibrary.wiley.com/doi/10.1007/s10545-011-9279-7
Prolonged sulfite exposure effects on NADPH https://pubmed.ncbi.nlm.nih.gov/25777939/