A review of the safety evidence on recombinant human lactoferrin for use as a food ingredient.

Published studies on the glycosylation, absorption, distribution, metabolism, excretion, and safety outcomes of orally ingested recombinant human lactoferrin (rhLF) were reviewed in the context of unanswered safety questions, including alloimmunization, allergenicity, and immunotoxicity potential of rhLF during repeated exposure. The primary objective was to summarize current safety data of rhLF produced in transgenic host expression systems. Overall, results from animal and human studies showed that rhLF was well tolerated and safe. Animal data showed no significant toxicity-related outcomes among any safety or tolerability endpoints. The no observed adverse effect levels (NOAEL) were at the highest level tested in both iron-desaturated and -saturated forms of rhLF. Although one study reported outcomes of rhLF on immune parameters, no animal studies directly assessed immunogenicity or immunotoxicity from a safety perspective. Data from human studies were primarily reported as adverse events (AE). They showed no or fewer rhLF-related AE compared to control and no evidence of toxicity, dose-limiting toxicities, or changes in iron status in various subpopulations. However, no human studies evaluated the immunomodulatory potential of rhLF as a measure of safety. Following this review, a roadmap outlining preclinical and clinical studies with relevant safety endpoints was developed to address the unanswered safety questions.

Dose Range-Finding Toxicity Study in Rats With Recombinant Human Lactoferrin Produced in Komagataella phaffii.

The oral toxicity of recombinant human lactoferrin (rhLF, Helaina rhLF, Effera™) produced in Komagataella phaffii was investigated in adult Sprague Dawley rats by once daily oral gavage for 14 consecutive days. The study used groups of 3-6 rats/sex/dose. The vehicle control group received sodium citrate buffer, and the test groups received daily doses of 200, 1000, and 2000 mg of rhLF in sodium citrate buffer per kg body weight. Bovine LF at 2000 mg/kg body weight per day was used as a comparative control. Clinical observations, body weight, hematology, clinical chemistry, iron parameters, immunophenotyping, and gross examination at necropsy were used as criteria for detecting the effects of treatment in all groups and to help select dose levels for future toxicology studies. Quantitative LF levels were also analyzed as an indication of bioavailability. Overall, administration of Helaina rhLF by once daily oral gavage for 14 days was well tolerated in rats at levels up to 2000 mg/kg/day, or 57 × Helaina's intended commercial use in adults, and indicating that a high dose of 2000 mg/kg/day is appropriate for future definitive toxicology studies.

Self- assembled lactoferrin-conjugated linoleic acid micelles as an orally active targeted nanoplatform for Alzheimer's disease.

Alzheimer's disease (AD) is neurological disorder characterized by dementia which causes severe problems with behavior, thinking and memory. Systemic administration of therapeutics to the central nervous system (CNS) is usually associated with very low efficiency due to presence of blood brain barrier (BBB), which only allows permeation of few types of molecules from the circulation to the CNS. As an alternative, naturally amphiphilic micelles can be utilized to enhance targeted drug delivery to the brain. In this sense, lactoferrin (LF) was covalently attached to conjugated linoleic acid (CLA) via carbodiimide coupling reaction to form a new micellar nanoplatform with particle size of about 53 nm. Afterwards, fabricated micelles were further loaded once again with CLA to enhance its delivery to the CNS. In vitro drug release study revealed that CLA exhibited sustained release at pH 6.8, associated with good hemocompatibility without any remarkable in vivo toxicity in terms of liver and kidney functions. Moreover, in vivo studies showed that the fabricated micelles manifested enhanced in vivo biodistrbution in brain tissue due to the active targeting potential of LF. Additionally, drug-loaded LF-CLA micelles exhibited enhanced cognitive capabilities, reduced brain oxidative stress, inflammation, apoptosis and acetylcholine esterase activity, besides a decline in the deposition of amyloid ß peptide1-42 in aluminum chloride Alzheimer's-induced animal model. CLA-based micelles could be a promising CNS actively targeted delivery system with a sophisticated potential to reduce AD symptoms.

Antiviral effects of nisin, lysozyme, lactoferrin and their mixtures against bovine viral diarrhoea virus.

BACKGROUND: Bovine viral diarrhoea virus (BVDV), an enveloped, single-stranded, positive-sense RNA virus from the Flaviviridae family, is a globally distributed bovine pathogen. BVDV infection in cattle, despite having a wide range of clinical manifestations, is invariably responsible for significant economic losses. To counteract these losses, various schemes to control and eradicate BVDV have been implemented, although safe drugs effectively inhibiting the replication of the virus are still lacking. The purpose of this study was to characterize the antiviral effect of naturally occurring proteins and peptide, such as bovine lactoferrin, chicken egg lysozyme, and nisin from Lactococcus lactis, used both individually and in combination, against the cytopathic NADL strain of BVDV in vitro. After determining the cytotoxicity level of each protein or peptide to MDBK cells, its antiviral effects were evaluated using virucidal, cytopathic effect inhibition and viral yield reduction assays. In addition, the influence of the tested compounds on the intracellular viral RNA level was determined. RESULTS: The highest efficacy among the single treatments was achieved by bovine lactoferrin, which was effective both at the early stages of viral infection and during its entire course, although the effect weakened over time. Nisin and lysozyme were effective at later stages of infection, and the intensity of their effect did not diminish with time. Nisin+lactoferrin and lysozyme+lactoferrin combinations demonstrated stronger antiviral effects than did the single substances. The nisin+lactoferrin mixture present during the whole period of infection produced the strongest anti-BVDV effect in our entire research on both the extracellular viral titre (titre reduction up to 2.875 log ≈ 99.9%) and the intracellular viral RNA level (reduction up to 89%), and this effect intensified over the incubation time. CONCLUSIONS: The tested substances could be applied in bovine viral diarrhoea prevention and therapy, especially when used in combination.

Antibiotic-Based Conjugates Containing Antimicrobial HLopt2 Peptide: Design, Synthesis, Antimicrobial and Cytotoxic Activities.

Recent studies have shown that modified human lactoferrin 20-31 fragment, named HLopt2, possesses antibacterial and antifungal activity. Thus, we decided to synthesize and evaluate the biological activity of a series of conjugates based on this peptide and one of the antimicrobials with proven antibacterial (ciprofloxacin, CIP, and levofloxacin, LVX) or antifungal (fluconazole, FLC) activity. The drugs were covalently connected to the peptide via amide, methylenecarbonyl moieties, or a disulfide bridge. The antibacterial and antifungal activities were evaluated under Clinical and Laboratory Standard Institute (CLSI) recommended conditions or in a low-salt brain-heart infusion diluted medium (BHI1/100). Results showed that conjugation of the peptide with the drug increased its antimicrobial activity up to 4-fold. Under CLSI-recommended conditions, all the compounds revealed rather low efficiency. Among conjugates, the highest antibacterial activity was recorded for the CIP-Cys-S-S-HLopt2-NH2 (III). In BHI1/100, which had lower differentiating properties, all of the conjugates revealed low MIC and MMC (minimum inhibitory and microbicidal concentrations) values. The disulfide bridge used as a linker in the most active conjugate (III) upon incubation with S. aureus cells is reduced, releasing constituent peptide and CIP-Cys. In addition, we showed that its fluorescently labeled analogue and constituent peptide are able to be internalized into both C. albicans and S. aureus cells. Moreover, the invaluable advantage of the presented conjugates was their low toxicity to mammalian cells and very low hemolytic activity. The current research can form a solid basis for further in vivo studies and drug development.

A 90-day subchronic toxicology screen of genetically modified rice Lac-3 and its effects on the gut microbiota in Sprague-Dawley rats.

A 90-day subchronic toxicology screen of genetically modified (GM) rice Lac-3 expressing human lactoferrin (hLF) and its effects on the gut microbiota were studied in comparison to non-GM rice fed to Sprague-Dawley (SD) rats. Three different dietary concentrations (17.5%, 35% and 70%, w/w) of the GM rice or its corresponding non-GM rice were used. Additionally, the phylotypes of gut microbiota in the control group, the 70% GM rice diet group and the 70% non-GM rice diet group on day 90 were determined by 16S rRNA sequencing. The results of the 90-day subchronic feeding study demonstrated that the GM rice Lac-3 containing human lactoferrin (LF) gene is considered as safe as the non-GM rice. The results of bacterial 16S rRNA sequencing showed that the structure of gut microbiota in the 70% GM group slightly changed when compared with the control group and the 70% non-GM group. There were no significant differences in the microbiota diversity among the three groups.

[Acute oral toxicity and 90 days feeding test of recombinant human lactoferrin].

OBJECTIVE: To study the edible safety of recombinant human lactoferrin( rh LF) expressed from transgenic cow mammary gland bioreactor. METHODS: According to the food additive safety toxicology evaluation procedures and method, acute oral toxicity in rats and 90 day subchronic toxicity test in mice were done to evaluate the edible safety of rh LF. RESULTS: Acute oral toxicity test indicated that rh LF was no toxic effect during the observation period, mouse acute oral LD50 of recombinant human lactoferrin was greater than 20 000 mg/kg. 90 days feeding test indicated that there was no-observedadverse-effect-level after givening 300 times rh LF recommended dose of animals body, toxicological parameters NOAEL was 10. 00 g/( kg·d). CONCLUSION: According to the acute toxic dose graduation standard, rh LF was nonpoisonous. Rh LF was no-observedadverse-effect-level and no subchronic toxicity after givening 300 times rh LF recommended dose of animals body. According to the result, rh LF was no potential food safety risk.

In vitro and in vivo toxicity assessment of alginate/eudragit S 100-enclosed chitosan-calcium phosphate-loaded iron saturated bovine lactoferrin nanocapsules (Fe-bLf NCs).

Lactoferrin has been known to have antimicrobial properties. This research was conducted to investigate the toxicity of Alginate/EUDRAGIT® S 100-enclosed chitosan-calcium phosphate-loaded Fe-bLf nanocapsules (NCs) by in vitro and in vivo assays. Brine shrimp lethality assay showed that the LC50 value of NCs was more than 1mg/mL which indicated that NCs was not toxic to Brine shrimp. However, the LC50 values for the positive control potassium dichromate at 24h is 64.15µg/mL, which was demostrated the toxic effect against the brine shrimp. MTT cytotoxicity assay also revealed that NCs was not toxic against non-cancerous Vero cell line with IC50 values of 536µg/mL. Genotoxicity studies by comet assay on Vero cells revealed that NCs exerted no significant genotoxic at 100µg/mL without tail or shorter comet tail. Allium cepa root assay carried out at 125, 250, 500 and 1000µg/mL for 24h revealed that the NCs was destitute of significant genotoxic effect under experimental conditions. The results show that there is no significant difference (p>0.05) in mitotic index between the deionized water and NCs treated Allium cepa root tip cells. In conclusion, no toxicity was observed in NCs in this study. Therefore, nontoxic NCs has the good potential to develop as a therapeutic agent.

Intranasal delivery of α-asarone to the brain with lactoferrin-modified mPEG-PLA nanoparticles prepared by premix membrane emulsification.

Alpha-asarone is a bioactive component of Acorus tatarincuii Schott with low bioavailability, which is often used for treatments of various brain diseases in clinical setting. This study was to formulate biodegradable methoxy polyethylene glycol-polylactic acid (mPEG-PLA) nanoparticles (NPs) surface-modified by lactoferrin (Lf), for delivering α-asarone into the brain following intranasal administration. Alpha-asarone NPs were prepared by premix membrane emulsification. The relative parameters were optimized by a Box-Behnken experimental design. The particle size, zeta potential, and dispersibility index of NPs and Lf-NPs were characterized. Their ex vivo permeation, pharmacokinetics, distribution in the brain and other tissue, brain targeting, and toxicity were investigated. Following intranasal administration, Lf-NPs had a better permeability and no significant poor bioavailability compared to NPs; the area under curve from 0 to 12 h of α-asarone in Lf-NPs of the olfactory bulb, hippocampus, olfactory bundles, and thalamus were 2.14-, 4.17-, 3.62-, and 1.96-fold of those in NP group, respectively. Lactoferrin could enhance the efficacy of brain targeting with NPs and reduce its liver accumulation. Toxicity of NPs on nasal mucosal cilia and epithelial cells was also decreased by Lf. To summarize, these results demonstrate that Lf-NPs of α-asarone have potential as a carrier for nose-to-brain delivery of α-asarone for brain diseases.

Human lactoferrin induces asthmatic symptoms in NC/Nga mice.

Lactoferrin in commercial supplements is known to exert anti-viral and anti-allergic effects. However, this is the first study to evaluate the induction of allergic airway inflammation in NC/Nga mice. Human lactoferrin was administered intraperitoneally with aluminum oxide for sensitization. Five days later, lactoferrin was inoculated intranasally for 5 days, and then on the 12th day, the single inoculation of lactoferrin intranasally was performed as a challenge. On the 13th day, airway hypersensitivity was assessed (AHR), a bronchoalveolar fluid (BALF) cell analysis was conducted, serum IgE and serum lactoferrin-specific IgG and IgE levels as well as the mRNA expression levels of cytokines and chemokines in the lung were measured, and a histopathological analysis of the lung was performed. Human lactoferrin increased AHR, the number of eosinophils in BALF, serum lactoferrin-specific IgG levels, and the mRNA levels of IL-13, eotaxin 1, and eotaxin 2. Moreover, the accumulation of inflammatory cells around the bronchus and the immunohistochemical localization of arginase I and human lactoferrin were detected. Collectively, these results indicate that human lactoferrin induced allergic airway inflammation in mice. Therefore, the commercial use of human lactoferrin in supplements warrants more intensive study.

Apoptotic effects of bovine apo-lactoferrin on HeLa tumor cells.

Lactoferrin (Lf), a cationic iron-binding glycoprotein of 80 kDa present in body secretions, is known as a compound with marked antimicrobial activity. In the present study, the apoptotic effect of iron-free bovine lactoferrin (apo-bLf) on human epithelial cancer (HeLa) cells was examined in association with reactive oxygen species and glutathione (GSH) levels. Apoptotic effect of iron-free bovine lactoferrin inhibited the growth of HeLa cells after 48 hours of treatment while the diferric-bLf was ineffective in the concentration range tested (from 1 to 12.5 µM). Western blot analysis showed that key apoptotic regulators including Bax, Bcl-2, Sirt1, Mcl-1, and PARP-1 were modulated by 1.25 µM of apo-bLf. In the same cell line, apo-bLf induced apoptosis together with poly (ADP-ribose) polymerase cleavage, caspase activation, and a significant drop of NAD+ . In addition, apo-bLf-treated HeLa cells showed a marked increase of reactive oxygen species level and a significant GSH depletion. On the whole, apo-bLf triggered apoptosis of HeLa cells upon oxygen radicals burst and GSH decrease.

Lactoferrin nanoparticle mediated targeted delivery of 5-fluorouracil for enhanced therapeutic efficacy.

Malignant melanoma is an aggressive form of skin cancer with high mortality rates. Common treatments for malignant melanoma involve a combination of radiotherapy and chemotherapy with fluorouracil (5-FU). A major challenge with melanoma treatment is active resistance to chemotherapeutic drugs. Superior treatment outcome lies on balance involving optimum therapeutic doses and the side effects associated with dose escalation. The study aimed to efficiently entrap 5-FU in lactoferrin nanoparticles (LfNPs) in an attempt to enhance its therapeutic efficacy. 5-FU loaded lactoferrin nanoparticles (5-FU-LfNPs) were prepared by sol-oil method with a narrow size distribution of 150±20nm 5-FU-LfNPs exhibits high encapsulation efficiency (64±2.3%) and increased storage stability at 4°C. Competitive ligand binding and lysosomal colocalization studies suggested a receptor mediated uptake for LfNPs internalization in B16F10 cells. Moreover, 5-FU-LfNPs show a pH dependent drug release similar to endosomal pH (pH 5 and 6). In addition compared to free 5-FU, 5-FU- LfNPs showed a higher intracellular uptake, prolonged retention and improved cytotoxicity (2.7-fold) in melanoma cells (B16F10). To conclude, LfNPs represent a superior nano-carrier for the targeted delivery of 5-FU in melanoma cells intended for the efficient treatment of melanoma though detailed in vivo investigations are warranted.

The six amino acid antimicrobial peptide bLFcin6 penetrates cells and delivers siRNA.

Cell-penetrating peptides (CPPs) are a new class of vectors with high pharmaceutical potential to deliver bioactive cargos into cells. Here, we characterized bLFcin(6) , a six amino acid peptide derived from bovine lactoferricin, as a CPP. Uptake of bLFcin(6) was measured by flow cytometry. The ability to delivery siRNA was analyzed in HeLa cells. bLFcin(6) exhibited concentration-dependent uptake and intracellular distribution. Below 7.5 µm, uptake of bLFcin(6) was significantly lower than uptake of TAT (P < 0.05) because bLFcin(6) has fewer cationic amino acids. Compared to CPP(5) (RLRWR) and CPP(6) (PFVYLI), bLFcin(6) had a significantly higher internalization ratio above 2.5 µm because it has two tryptophan residues. Uptake of bLFcin(6) starts with an ionic cell-surface interaction. It is then rapidly internalized by lipid raft-dependent macropinocytosis, followed by release from macropinosomes into the cytosol and nucleus. Moreover, bLFcin(6) formed stable electrostatic complexes with siRNA and delivered siRNA into cells, resulting in significant knockout activity at both the mRNA and protein levels. The knockout activity of siRNA delivered by bLFcin(6) was similar to that mediated by TAT, although knockout by bLFcin(6) required a higher molar ratio. In this study, bLFcin(6) was tested for its ability to act as an siRNA-delivering CPP.

Lactoferrin-conjugated dendritic nanoconstructs for lung targeting of methotrexate.

The present investigation was aimed at developing and exploring the potential of lactoferrin (Lf)-conjugated dendritic nanocomposite for lung targeting of methotrexate (MTX). The 5.0 G poly(propylene imine) (PPI) dendrimer and Lf-conjugated 5.0 G PPI dendrimer were synthesized and characterized by Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and transmission electron microscopy. The entrapment efficiency, in vitro release, and hemolytic toxicity were assessed. Pharmacokinetic and organ distribution studies were carried out to evaluate in vivo targeting potential of developed system. The pharmacokinetic studies showed that elimination half-life of MTX-loaded plain PPI dendrimer (10.41 ± 2.12 h, p < 0.05) and MTX-loaded Lf-conjugated PPI dendrimer (12.23 ± 1.53 h, p < 0.01) was significantly higher than the free drug (5.85 ± 1.19 h). Organ distribution assessment of different formulations displayed significant (p <0.05) higher accumulation of drug in lungs by MTX-Lf-PPI (1329 ± 26.7 ng/g of tissue) as compared with MTX-PPI (721 ± 23.4 ng/g of tissue) and free MTX (575 ± 19.7 ng/g of tissue) after 6 h of administration. The result suggested that Lf-conjugated 5.0 G PPI dendrimer-based formulations to be approximately 1.5 times and 2.5 times superior to plain 5.0 G PPI dendrimer as well as pure MTX, respectively, for lung targeting of anticancer drugs.

Development of tissue conditioner capable of binding with anti-microbial protein lactoferrin.

PURPOSE: This study focused on the anti-microbial protein human lactoferrin (hLF) commonly found in saliva, and tried to develop biocompatible dental materials that have higher anti-microbial effects. METHODS: A lyophilized cation exchange resin was added to tissue conditioner at 4 wt% and 8 wt%. The amount of hLF binding to the tissue conditioner and their anti-microbial effect against Candida albicans was investigated. Then their mechanical properties and cytotoxicity were examined. RESULTS: Tissue conditioner containing cation exchange resin was bound with hLF and had an anti-microbial effect against C. albicans. In addition, their physical properties were sufficient and they were harmless to human fibroblasts. CONCLUSION: The clinical application of cation exchange resin for tissue conditioner can be effective for the prevention and treatment of denture stomatitis and systemic opportunistic infections since it is thought that these materials will increase the local concentration of anti-microbial protein in saliva at the lesion site.

Lactoferricin treatment decreases the rate of cell proliferation of a human colon cancer cell line.

Food components modify the risk of cancer at a large number of sites but the mechanism of action is unknown. In the present investigation, we studied the effect of the peptide lactoferricin derived from bovine milk lactoferrin on human colon cancer CaCo-2 cells. The cells were either untreated or treated with 2.0, 0.2, or 0.02 microM lactoferricin. Cell cycle kinetics were investigated with a bromodeoxyuridine DNA flow cytometric method. The results show that lactoferricin treatment slightly but significantly prolonged the S phase of the cell cycle. Lactoferricin treatment lowered the level of cyclin E1, a protein involved in the regulation of genes required for G(1)/S transition and consequently for efficient S phase progression. The slight prolongation of the S phase resulted in a reduction of cell proliferation, which became more apparent after a long treatment time.

Lactoferrin-conjugated PEG-PLA nanoparticles with improved brain delivery: in vitro and in vivo evaluations.

The lactoferrin (Lf) conjugated poly (ethyleneglycol)-poly (lactide) nanoparticle (Lf-NP) was constructed in this paper as a novel biodegradable brain drug delivery system with evaluation of its in vitro and in vivo delivery properties. Lf was thiolated and conjugated to the distal maleimide functions surrounding on the pegylated nanoparticles to form the Lf-NP. The existence of Lf on the surface of Lf-NP was verified by TEM observation and XPS analysis. The Lf ELISA results confirmed the biorecognitive activity of Lf after the coupling procedure and suggested the average number of Lf conjugated on each nanoparticle was around 55. To evaluate the brain delivery properties of the Lf-NP, a fluorescent probe, coumarin-6 was incorporated into it. The uptake of Lf-NP by bEnd.3 cells was shown significantly higher than that of unconjugated nanoparticle (NP). Following an intravenous administration, a near 3 folds of coumarin-6 were found in the mice brain carried by Lf-NP compared to that carried by NP. Cell viability experiment results confirmed good safety of the biodegradable Lf-NP. The significant in vitro and in vivo results suggest that Lf-NP is a promising brain drug delivery system with low toxicity.

28-day repeated dose oral toxicity of recombinant human holo-lactoferrin in rats.

Recombinant human holo-lactoferrin (holo-rhLF) was orally administered, via gavage, to Wistar rats at 1000, 500 and 100mg/kgbw/day for 28 days. The test article, holo-rhLF, was expressed in rice grain, extracted, purified and saturated with iron. During the 28-day period, animals were examined for evidence of toxicity. On day 29, the animals were exsanguinated, examined for gross pathology, and tissues preserved for histopathology. There were no deaths caused by holo-rhLF and in-life physical signs were generally normal. Although statistical differences were noted in some hematology, clinical chemistry and heart/body weight ratios, they were of questionable biological significance. A significantly greater total iron binding capacity (TIBC) was detected in the blood of male animals dosed with holo-rhLF. Serum was analyzed for the presence of IgG and IgE antibodies; demonstrating low levels of IgG antibodies to the human protein, but no increase in IgE antibodies. There was no increase in serum lactoferrin levels. The results of the 28-day oral administration demonstrate a lack of toxicity of holo-rhLF in rats. There were no treatment related, toxicologically relevant changes in clinical signs, growth, food consumption, hematology, clinical chemistry, organ weights or pathology. The no observed adverse effect level (NOAEL) is greater than 1000 mg/kg/day.

Lack of chronic oral toxicity of chemopreventive bovine lactoferrin in F344/DuCrj rats.

Studies were undertaken to determine whether bovine lactoferrin (bLF) and related compounds, shown to prevent carcinogenesis in the colon and other organs in rats, have any toxic effects in long-term feeding studies. In experiment I, male F344/DuCrj rats received a basal diet containing 0.2% bLF for 40 weeks. No adverse findings were noted, furthermore, serum triglyceride level was significantly decreased to 72% of the control level, suggesting preventive effects against the metabolic syndrome. In experiment II, male and female F344/DuCrj rats were fed a basal diet containing 0.02, 0.2, 2.0 and 5.0% bLF, 2.0% bLF hydrolysate (bLF-H) or 0.1% lactoferricin (LFcin), a peptide derived from bLF, for 60 weeks in males and 65 weeks in females. No toxicological effects, including carcinogenicity, were evident in either sex. The results of the studies provide subjective support for safety of clinical studies of bLF for supplement use.

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

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.