Fluorescence spectra and measurement of phylloerythrin (phytoporphyrin) in plasma from clinically healthy sheep, goats, cattle and horses

Abstract

AIM: To measure the background concentration of phylloerythrin in plasma from clinically healthy sheep, goats, cattle and horses on pasture.

METHODS: Blood samples were taken from 34 sheep of the Dala breed, 20 female Norwegian dairy goats, 35 Norwegian Red cows and 34 horses of different breeds. All animals were grazing green pasture when blood samples were taken. Blood samples were collected from each of four clinically healthy newborn lambs, goats, calves and foals, and pooled into one sample per species. Plasma samples were analysed for phylloerythrin by fluorescence spectroscopy, using a Perkin-Elmer LS-50B luminescence spectrometer equipped with a red-sensitive photo- multiplier. The fluorescence spectra of phylloerythrin in plasma from the adult ruminants were compared with those in plasma from the neonatal ruminants, to which a known concentration of phylloerythrin had been added.

RESULTS: Plasma obtained from the adult ruminants had spectral characteristics similar to those of phylloerythrin, namely weak emission peaks at 650 and 711 nm, when excited at 425 nm. Emission spectra obtained from plasma from the neonatal ruminants showed no fluorescence at these wavelengths. On average, 0.012 (SD 0.004), 0.06 (SD 0.04), and 0.05 (SD 0.03) μmol/l phylloerythrin were present in plasma samples from the sheep, goats, and cattle, respectively. The fluorescence spectra of plasma from the newborn foals were similar to spectra of plasma from adult horses, with weak emission at 669 nm.

CONCLUSION: Small concentrations of phylloerythrin were detected in plasma from clinically healthy sheep, goats and cattle, but none could be detected in plasma from clinically healthy horses.

KEY WORDS:

• Phylloerythrin
• photosensitiser
• photosensitisation