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

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, λmax = 353 nm) and plasma protein - albumin (λmax = 340 nm) with the Stern-Volmer constants 16.4 × 103 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).