28-Day repeated dose oral toxicity of recombinant human apo-lactoferrin or recombinant human lysozyme in rats

Regul Toxicol Pharmacol. 2008 Jul;51(2):162-7. doi: 10.1016/j.yrtph.2008.03.007. Epub 2008 Apr 8.


Lactoferrin and lysozyme are important proteins of the human innate immune system. These proteins are found in breast milk and have been associated with improved infant health. Recombinant human apo-lactoferrin (apo-rhLF), 1800 and 180mg/kg bw/day, and recombinant human lysozyme (rhLZ), 360 and 36mg/kg bw/day, were orally administered to Wistar rats for 28 days. Apo-rhLF and rhLZ were expressed in rice grain, extracted, purified; the lactoferrin was iron desaturated. The animals were examined for evidence of toxicity; there were no deaths and in-life physical signs were normal. Transient differences in mean food consumption occurred in high dose apo-rhLF and low dose LZ females at week three. There were no biologically significant differences in hematological or clinical chemistry parameters. Necropsy results were normal and microscopic evaluation showed no treatment related changes in animals dosed with 1800mg/kg/day apo-rhLF or 360mg/kg/day rhLZ. The results of the 28-day oral administration demonstrate a lack of toxicity of apo-rhLF and rhLZ in rats. There were no treatment related, toxicologically relevant changes in clinical signs, growth, food consumption, hematology, clinical chemistry, organ weight and pathology. The no observed adverse effect level (NOAEL) is greater than 1800mg/kg/day for apo-rhLF and 360mg/kg/day for rhLZ.

MeSH terms

  • Administration, Oral
  • Animals
  • Apoproteins / administration & dosage
  • Apoproteins / toxicity*
  • Dose-Response Relationship, Drug
  • Drug Administration Schedule
  • Eating / drug effects
  • Female
  • Humans
  • Lactoferrin / administration & dosage
  • Lactoferrin / toxicity*
  • Male
  • Muramidase / administration & dosage
  • Muramidase / toxicity*
  • No-Observed-Adverse-Effect Level
  • Oryza
  • Rats
  • Rats, Wistar
  • Recombinant Proteins / administration & dosage
  • Recombinant Proteins / toxicity
  • Toxicity Tests*


  • Apoproteins
  • Recombinant Proteins
  • apolactoferrin
  • Muramidase
  • Lactoferrin