Safety assessment of EPA-rich triglyceride oil produced from yeast: genotoxicity and 28-day oral toxicity in rats.

The 28-day repeat-dose oral and genetic toxicity of eicosapentaenoic acid triglyceride oil (EPA oil) produced from genetically modified Yarrowia lipolytica yeast were assessed. Groups of rats received 0 (olive oil), 940, 1880, or 2820 mg EPA oil/kg/day, or fish oil (sardine/anchovy source) by oral gavage. Lower total serum cholesterol was seen in all EPA and fish oil groups. Liver weights were increased in the medium and high-dose EPA (male only), and fish oil groups but were considered non-adverse physiologically adaptive responses. Increased thyroid follicular cell hypertrophy was observed in male high-dose EPA and fish oil groups, and was considered to be an adaptive response to high levels of polyunsaturated fatty acids. No adverse test substance-related effects were observed on body weight, nutritional, or other clinical or anatomic pathology parameters. The oil was not mutagenic in the in vitro Ames or mouse lymphoma assay, and was not clastogenic in the in vivo mouse micronucleus test. In conclusion, exposure for 28 days to EPA oil derived from yeast did not produce adverse effects at doses up to 2820 mg/kg/day and was not genotoxic. The safety profile of the EPA oil in these tests was comparable to a commercial fish oil.

Safety assessment of EPA-rich oil produced from yeast: Results of a 90-day subchronic toxicity study.

The safety of eicosapentaenoic acid (EPA) oil produced from genetically modified Yarrowia lipolytica yeast was evaluated following 90 days of exposure. Groups of rats received 0 (olive oil), 98, 488, or 976 mg EPA/kg/day, or GRAS fish oil or deionized water by oral gavage. Rats were evaluated for in-life, neurobehavioral, anatomic and clinical pathology parameters. Lower serum cholesterol (total and non-HDL) was observed in Medium and High EPA and fish oil groups. Lower HDL was observed in High EPA and fish oil males, only at early time points. Liver weights were increased in High EPA and Medium EPA (female only) groups with no associated clinical or microscopic pathology findings. Nasal lesions, attributed to oil in the nasal cavity, were observed in High and Medium EPA and fish oil groups. No other effects were attributed to test oil exposure. Exposure to EPA oil for 90 days produced no effects at 98 mg EPA/kg/day and no adverse effects at doses up to 976 mg EPA/kg/day. The safety profile of EPA oil was comparable to that of GRAS fish oil. These results support the use of EPA oil produced from yeast as a safe source for use in dietary supplements.

Evaluation of a 15-day screening assay using intact male rats for identifying steroid biosynthesis inhibitors and thyroid modulators.

An in vivo screening assay using intact adult male rats has been evaluated for its ability to detect four endocrine-active compounds (EACs) via oral (gavage) administration. The test compounds included the aromatase inhibitor fadrozole (FAD), the testosterone biosynthesis inhibitor ketoconazole (KETO), and the thyroid modulators phenobarbital (PB) and propylthiouracil (PTU). Three of the test compounds (KETO, PB, and PTU) have been previously evaluated in the 15-day intact male assay with compound administration via intraperitoneal injection (ip). For the current studies, male rats were dosed for 15 days via oral gavage and euthanized on the morning of test day 15. The endpoints evaluated included final body and organ weights (liver, thyroid gland, testes, epididymides, prostate, seminal vesicles with fluid, accessory sex gland unit [ASG]), serum hormone concentrations (testosterone [T], estradiol [E2], dihydrotestosterone [DHT], luteinizing hormone [LH,] follicle stimulating hormone [FSH], prolactin [PRL], T(3), T(4), thyroid stimulating hormone [TSH]), and histopathology of the testis, epididymis, and thyroid gland; positive results for each endpoint are described below. In addition, an evaluation of immune system endpoints (humoral immune function, spleen and thymus weights, and spleen cell number) was conducted on a subset of animals dosed with either KETO or PB. FAD and KETO decreased the weights for the androgen-dependent tissues and caused similar patterns of hormonal alterations (decreased serum T and DHT; increased serum FSH and/or LH). In addition, KETO caused spermatid retention. For FAD and KETO, effects on thyroid parameters were not indicative of thyroid toxicity. PB and PTU caused thyroid effects consistent with thyroid modulators (increased thyroid weight, decreased serum T(3) and T(4), increased serum TSH, thyroid follicular cell hypertrophy/hyperplasia, and colloid depletion). In addition, PB increased relative liver weight and altered reproductive hormone concentrations (decreased serum DHT, PRL, LH; increased serum E2). Orally administered KETO and PB did not alter the primary humoral immune response to sheep red blood cells (SRBC), although spleen weights were increased at the highest doses for both compounds. In the current study, all four test substances were identified as endocrine-active. The effects that were observed in the current study via oral (gavage) compound administration were similar to the responses that were observed by the ip route in previous studies for KETO, PB, and PTU. Overall, the sensitivity (i.e., the dose required to elicit similar magnitude responses) between the ip and oral routes of administration were similar for the three EACs that were examined by both routes of administration. This article, in addition to the > 20 compounds that have already been examined using the 15-day intact male assay, supports this assay as a viable screening assay for detecting EACs, and also illustrates that the ability to identify EACs using the intact male assay will be equivalent regardless of the route of compound administration.

Evaluation of a 15-day screening assay using intact male rats for identifying antiandrogens.

An in vivo screening assay using intact adult male rats has been evaluated for its ability to detect six antiandrogenic compounds via oral administration. The test compounds included cyproterone acetate (CPA), flutamide (FLUT), p,p'-DDE (DDE), di-n-butyl phthalate (DBP), linuron (LIN), and vinclozolin (VCZ). Two of the test compounds (DDE and FLUT) have been previously evaluated in the 15-day intact male assay with compound administration via intraperitoneal injection (ip). For the current studies, male rats were dosed for 15 days via oral gavage and euthanized on the morning of test day 15. The endpoints evaluated included final body and organ weights (liver, thyroid gland, testes, epididymides, prostate, seminal vesicles with fluid, accessory sex gland unit [ASG]), serum hormone concentrations (testosterone [T], estradiol [E2], dihydrotestosterone [DHT], luteinizing hormone [LH], follicle stimulating hormone [FSH], prolactin [PRL], T(3), T(4), and thyroid stimulating hormone[TSH]), and histopathology of the testis, epididymis, and thyroid gland; positive results for each endpoint are described below. In addition, an evaluation of immune system endpoints (humoral immune function, spleen and thymus weights, and spleen cell number) was conducted on a subset of animals dosed with either DDE or FLUT. All six endocrine-active compounds (EACs) increased relative liver weight. FLUT and VCZ caused the typical pattern for an androgen receptor (AR) antagonist, although not all endpoints were statistically significant for VCZ: decreased ASG weights, hormonal alterations (increased T, DHT, LH, and FSH), and induced Leydig cell hypertrophy and/or hyperplasia. CPA caused effects consistent with its mixed AR antagonist/progesterone receptor agonist activity: it decreased ASG weights, caused hormonal alterations (increased T and E2; decreased FSH), and caused spermatid retention. DBP, a compound with antiandrogen-like activity via a nonreceptor mediated mechanism, caused hormonal alterations (decreased T, DHT, and E2; increased LH, FSH, and PRL) and induced general testicular degeneration. LIN, a weak AR antagonist, decreased ASG weights, caused hormonal alterations (decreased T, DHT, and LH; increased E2), and caused spermatid retention. Unlike the other AR antagonists evaluated, DDE, a weak AR antagonist, did not alter reproductive parameters. All six antiandrogens caused some effects on thyroid parameters, although only CPA, DDE, and VCZ caused results consistent with a potential thyroid-modulator. FLUT and DDE did not alter the primary humoral immune response to SRBC, spleen or thymus weights, or spleen cell number. In the current study, 5 of the six test substances were identified as endocrine-active substances consistent with their known/proposed mechanism(s) of action. The effects that were observed in the current study via oral (gavage) compound administration were similar to the responses that were observed by the ip route in previous studies for DDE and FLUT. This report, in addition to the > 20 compounds that have already been examined using the 15-day intact male assay, supports this assay as a viable screening assay for detecting EACs, and also illustrates that the ability to identify EACs using the intact male assay will be equivalent regardless of the route of compound administration.