The «in vivo» study of blood 5-fluorouracil content by quenching of intrinsic protein fluorescence

Abstract The dynamics of blood fluorescence (FL) after intravenous injection of 5-fluorouracil (FU) to oncology patients taking chemotherapy were investigated. It was demonstrated that FU quenches FL of water solutions of tryptophan (Trp) (total concentration is 1.0 × 10 −5  mol L −1 , λ max = 353 nm) and plasma protein – albumin ( λ max = 340 nm) with the Stern–Volmer constants 16.4 × 10 3  L mol −1 and 52 L mol −1 , accordingly. The quenching of both Trp and albumin FL by 5-fluorouracil was concluded to proceed via the static mechanism of reversible photoinduced electron transfer (PET).