Xanthopterin hydrate, an unconjugated pteridine compound, is the main component of the yellow granule in the Oriental hornet bear wings, produces a characteristic excitation/emission maximum at 386/456 nm[2]. Xanthopterin hydrate(XPT) causes renal growth and hypertrophy in rat.Xanthopterin hydrate inhibits RNA synthesis.In Vitro: Xanthopterin (7.8-250 mM; 24 hours) show a significant reduction in mitochondrial activity with respect to controls (IC50=109 mM)[2].