Species differences in toxicokinetic parameters of glycidol after a single dose of glycidol or glycidol linoleate in rats and monkeys.

Glycidol fatty acid esters (GEs) have been identified as contaminants in refined edible oils. Although the possible release of glycidol (G) from GEs is a concern, little is known about the conversion of GEs to G in the human body. This study addressed the toxicokinetics of glycidol linoleate (GL) and G in male Crl:CD(SD) rats and cynomolgus monkeys. Equimolar amounts of GL (341 mg/kg) or G (75 mg/kg) were administered by gavage to each animal. G was found in both species after the G and GL administration, while plasma GL concentrations were below the lower limit of quantification (5 ng/ml) in both species. In rats, the administration of GL or G produced similar concentration-time profiles for G. In monkeys, the C(max) and AUC values after GL administration were significantly lower than those after G administration. The oral bioavailability of G in monkeys (34.3%) was remarkably lower than that in rats (68.8%) at 75 mg/kg G administration. In addition, plasma G concentrations after oral administration at three lower doses of GL or G were measured in both species. In monkeys, G was detected only at the highest dose of G. In contrast, the rats exhibited similar plasma G concentration-time profiles after GL or G administration with significantly higher G levels than those in monkeys. In conclusion, these results indicate that there are remarkable species differences in the toxicokinetics of GEs and G between rodents and primates, findings that should be considered when assessing the human risk of GEs.

Genotoxicity studies of glycidol fatty acid ester (glycidol linoleate) and glycidol.

Glycidol fatty acid esters (GEs) are found in refined edible oils. Safety concerns have been alleged due to the possible release of glycidol (G), an animal carcinogen. We evaluated the genotoxic potential of glycidol linoleate (GL), a primary GE found in an edible oil (diacylglycerol oil), and G, using three established genotoxicity tests (a bacterial reverse mutation test, an in vitro chromosomal aberration test, and an in vivo bone marrow micronucleus test) under GLP conditions complying with all OECD guidelines. In the bacterial reverse mutation test, GL and G showed positive responses. The positive responses of GL were less than those of G and observed only in strains detecting point mutations where G showed remarkably positive responses. G was involved in the positive response of GL. In the chromosomal aberration test, GL did not induce chromosome aberrations whereas G induced structural chromosome aberrations in the presence and absence of metabolic activation. In the bone marrow micronucleus test, neither GL nor G induced significant increases of micronucleated immature (polychromatic) erythrocytes in bone marrow of test animals. Based on the above results as well as pertinent information on toxicokinetics, GL itself does not play a key role in genotoxic action.

Safety assessment of heat-sterilized green tea catechin preparation: a 6-month repeat-dose study in rats.

Evidence suggests that the purported health benefits associated with green tea consumption are related to tea catechins. In the present study, potential adverse effects of a standardized heat-sterilized green tea catechin (GTC-H) preparation was investigated following gavage administration to rats at doses of 0, 120, 400, 1200 mg/kg/day for 6 months. A decaffeinated high-dose group (1200 mg/kg/day) (GTC-HDC), was included for comparison. A possibly test article-related clinical finding of intermittent increased activity was noted in the 400 and 1200 mg/kg/day GTC-H groups, but was not considered to be adverse. Lower body weight gains without any decrease in food consumption were noted in the high-dose (1200 mg/kg/day)-treated GTC-H and GTC-HDC females. In the high-dose male GTC-H group, a lower total motor activity count for the 60-min session was noted prior to dosing at the study week 25 evaluations compared to the control group. Similar changes were not observed in the GTC-HDC group. Based on the results of this study, the no-observed-adverse-effect level (NOAEL) for GTC-H was 1200 mg/kg/day for males, the highest dose tested, and 400mg/kg/day for females based on reduced body weight gains. The NOAEL for GTC-HDC was 1200 mg/kg/day for males and could not be determined in females.

Effects of green tea catechin on embryo/fetal development in rats.

Evidence suggests that the health benefits associated with green tea consumption are related to tea catechins. The objective of this study was to evaluate potential maternal and fetal effects of standardized heat-sterilized green tea catechins (GTC-H). GTC-H was gavage administered to mated female rats from gestation day 6 through 17, at doses of 0, 200, 600, and 2000 mg/kg/day. There were no GTC-H-related deaths or macroscopic findings. During the entire gestation period in the high-dose (2000 mg/kg/day)-treated group and during days 6-9 and 6-18 in the 600 mg/kg/day group, mean body weight gain was lower. Mean feed consumption was lower during gestation days 6-9 in the 600 mg/kg/day group and during gestation days 6-9 and 9-12 in the 2000 mg/kg/day group. Compared to the control group, mean body weights in the 600 and 2000 mg/kg/day groups were up to 5.1% and 7.7% lower during gestation days 9-20. GTC-H administration did not affect mean gravid uterine weights or intrauterine growth and survival. There were no GTC-H-related fetal malformations or developmental variations. Based on the results of this study, the no-observed-adverse-effect level (NOAEL) for GTC-H was 200mg/kg/day for maternal toxicity, and 2000 mg/kg/day for embryo/fetal development.

Safety studies of pseudo-ceramide SLE66. Part 3: Effects on embryo/fetal development in rats.

SLE66 a synthetic pseudo-ceramide, has been shown to reduce dryness/scaling/itching of human skin. Naturally occurring ceramides have been claimed to play a crucial role in cell proliferation, differentiation, and apoptosis including processes important for embryogenesis. The objective of this study was to evaluate the potential maternal and fetal effects of SLE66. SLE66 was administered orally (gavage) to mated female Crl:CD(SD)IGS BR rats (25/group) once daily from gestation day 6 through 19, at dose levels of 0 (control), 150, 400 or 1000 mg/kg/day. No treatment-related clinical or internal (macroscopic) findings were noted and all animals survived to the scheduled necropsy on gestation day 20. SLE66 administration did not affect mean maternal body weights, body weight gains, net body weights, net body weight gains, gravid uterine weights, or feed consumption. Similarly, SLE66 administration did not affect intrauterine growth and survival related parameters such as viable fetuses, pre-implantation loss, early and late resorptions, fetal weight and fetal sex. No SLE66-related fetal malformations or developmental variations were noted. Based on the results of this study, a dose level of 1000 mg/kg/day (highest dose used) was considered as the no-observed-adverse-effect level (NOAEL) for both maternal and developmental toxicity.

Safety assessment of dietary diacylglycerol oil: a two-generation reproductive toxicity study in rats.

Diacylglycerol (DAG) oil is a novel edible oil with similar taste and usability characteristics as conventional edible oils. Recent studies suggest that DAG oil may be helpful in the prevention and management of obesity. The objective of the present two-generation study was to evaluate potential adverse effects of DAG oil on reproductive processes. DAG oil was administered via gavage to rats (30/sex/group) for at least 70 days prior to mating, at dose levels of 0, 1.25, 2.5 or 5.0 ml/kg/day (0, 1160, 2320 and 4630 mg/kg/day). An additional group received a triacylglycerol (TAG) oil with a similar fatty acid composition to DAG oil. The rats were treated throughout the mating, gestation and lactation periods. Administration of DAG or TAG oil did not reveal any toxicologically significant effects on reproductive performance (mating, fertility and copulation/conception indices). DAG oil did not affect mean gestation lengths, the process of parturition, spermatogenic parameters, organ weights, histopathologic findings, mean numbers of pups born, implantation sites and unaccounted sites. F1 and F2 pup viability, live litter sizes, body weights, mean age of attainment of balanopreputial separation and vaginal patency were similar to those in the control group. Based on the results of this study, a dose level of 5.0 ml/kg (4630 mg/kg/day) was considered as the no-observed-adverse-effect level for reproductive and systemic toxicity, and neonatal toxicity.

Safety assessment of heated diacylglycerol oil: subchronic toxicity study in rats.

Diacylglycerol oil is an edible oil with similar taste and usability characteristics as conventional edible oil rich in triacylglycerol oil. The objective of the present study was to evaluate potential adverse effects of heated diacylglycerol and triacylglycerol oil in rats following subchronic administration. The heated diacylglycerol and triacylglycerol oils were prepared separately following deep frying potato slices at 180 degrees C for 8h per day for three days. Sprague Dawley rats were fed diets containing different ratios (concentrations) of heated to unheated diacylglycerol oil. The ratio of heated to unheated diacylglycerol was as follows: 0%/5.5% (control-1; Group 1), 1.0%/4.5% (Group 2), 2.75%/2.75% (Group 3), and 5.5%/0% (Group 4). Two additional groups received the feed containing 5.5% of unheated or 5.5% of heated triacylglycerol oil. Compared to the unheated oils, feeding of heated diacylglycerol or triacylglycerol oil did not reveal any toxicologically significant changes in clinical observation, body weights, body weight gains, feed consumption, ophthalmic examinations, functional observational battery and motor activity, clinical pathology evaluations and organ weights. Similarly, terminal necropsy did not reveal treatment-related gross or histopathology findings. Based on the results of this subchronic study, the no-observed-effect levels (NOELs) of heated diacylglycerol or triacylglycerol oil were 5.5%, the highest levels tested. The mean dietary exposure levels at the highest dose for the heated diacylglycerol and triacylglycerol oil for male and female rats ranged from 3,178 to 4,120 mg/kg/day.

Effects of dietary diacylglycerol oil on embryo/fetal development in rats.

Diacylglycerol (DAG) oil is an edible oil with similar taste and usability characteristics as conventional edible oil. Recent studies suggest that use of DAG oil may be helpful in the prevention and management of obesity. This study evaluated the potential maternal and fetal effects of DAG oil, following exposure to pregnant rats, during the critical period of major organogenesis. DAG oil was administered via gavage to four groups of mated female Crl:CD(SD)IGS BR rats (25/group) once daily from gestation day 6 through 17, at dose levels of 0, 1.25, 2.5 or 5.0 ml/kg/day (0, 1160, 2320 and 4630 mg/kg/day) with total volume made to 5 ml/kg/day with triacylglycerol (corn) oil. No mortality or treatment-related clinical or internal findings were noted in any of the groups. Compared to animals in control group, mean maternal body weights, body weight gains, net body weights, net body weight gains, gravid uterine weights, and food consumption were not affected by DAG oil administration. Similarly, intrauterine growth and survival were not affected by DAG oil administration. No DAG oil-related fetal malformations or developmental variations were noted. A maternal maximum tolerated dose for DAG oil was not achieved in this study. Based on the results of this study, a dose level of 5.0 ml/kg (4630 mg/kg/day) was considered as no-observed-adverse-effect level (NOAEL) for both maternal and developmental toxicity.

28-Day oral (gavage) toxicity studies of green tea catechins prepared for beverages in rats.

The beneficial health effects associated with drinking green tea are widely considered to be due primarily to tea catechins. Heat treatment of marketed green tea beverages for sterilization causes epimerization and/or polymerization of tea catechins. Safety studies on heat-treated tea catechins are limited. The objective of the present study was to evaluate potential adverse effects, if any, of two standardized green tea catechin (GTC) preparations: one that underwent heat sterilization (GTC-H) and one that was not heat-sterilized (GTC-UH). A decaffeinated preparation of the GTC-H (GTC-HDC) was also evaluated to ascertain if any effects were due to caffeine. The GTC preparations were administered to rats once daily at levels up to 2000 mg/kg/day for 28 days. There were no deaths attributable to the GTC preparations. The clinical condition of the animals, functional observational battery, motor activity, clinical pathology evaluations, organ weights, and gross necropsy findings were unaffected by any of the GTC preparations. GTC-HDC or GTC-UH dosing had no effects on body weights or microscopic findings, whereas lower body weights and food consumption were observed in the 1000 and 2000 mg/kg/day GTC-H group males. The no observed-adverse-effect level (NOAEL) for localized gastric effects for GTC-H was 1000 mg/kg/day. No other target organs were identified. Thus, the NOAEL for systemic toxicity following oral administration was 2000 mg/kg/day for GTC-H, GTC HDC, and GTC-UH under the conditions of this study.

No enhancing effects of diacylglycerol oil on tumor development in a medium-term multi-organ carcinogenesis bioassay using male F344 rats.

The modifying potential of diacylglycerol (DAG) oil on tumor development was investigated in a medium-term multi-organ carcinogenesis bioassay. DAG oil is a cooking oil that contains >80% diglycerides, <20% triglycerides and <5% monoglycerides. Male 6-week-old F344 rats (20 in each group) were sequentially treated with five carcinogens for initiation in different organ target sites for 4 weeks (DMBDD treatment), and then administered DAG oil at dietary levels of 0% (control), 1.375%, 2.75% or 5.5% [triacylglycerol (TGs), with the same fatty acid composition as DAG oil were also added at dietary levels of 5.5%, 4.125%, 2.75% and 0%, respectively, to maintain the same lipid level], or 5.5% high linoleic acid TG (HLTG), 5.5% high oleic acid TG (HOTG), or 5.5% medium-chain TG (MCTG) (as reference substances, mostly consisting of triacylglycerols) admixed into AIN-93G semi-synthetic diet, for an additional 24 weeks. Controls received standard diet without any supplementation as non-treated control. All animals were killed at the end of week 28, and the major organs were carefully examined for preneoplastic and neoplastic lesions. No DAG oil treatment-related changes were noted in survival, general conditions, body weights, food consumption and organ weights. Upon quantitative analysis of glutathione S-transferase placental form (GST-P) positive foci of the liver, DAG oil was not found to exert any effects. The incidence of colon adenomas was significantly increased in rats given 1.375% DAG oil, but not 2.75% and 5.5% DAG oil, when compared to the control (5.5% TG group) value. Furthermore, incidences and multiplicity of hyperplasias and adenomas and/or adenocarcinomas were comparable across all DAG oil-treated groups. In contrast, incidences of colon adenomas and/or adenocarcinomas were significantly increased in rats given 5.5% HOTG, and adenomas with MCTG, but not 5.5% HLTG, as compared to the 5.5% TG value. Preneoplastic and neoplastic lesions induced by DMBDD treatment in various organs other than the large intestine were comparable in all cases. Thus, the current results indicate that DAG oil may not exert modifying potential on tumor development, even in the colon because of the lack of dose-dependence. DAG oil was equivalent to HOTG (standard cocking oil composed of naturally occurring fatty acids), with regard to colon tumor development. Further dose-response study concerning HOTG may be needed to confirm whether the enhancing effect of large intestine carcinogenesis exert or not.

A 24-month dietary carcinogenicity study of DAG in mice.

This study evaluated the possible carcinogenic effects of DAG (diacylglycerol) oil when given in the diet at levels up to 6.0% for 24 months to mice. Dietary fat was provided by DAG and/or the control article, TG (triacylglycerol oil). Dietary concentrations (% DAG/% TG) were 0%/6.0% (TG control), 1.5%/4.5%, 3.0%/3.0%, and 6.0%/0%. An additional control group received the standard rodent diet (fat content 4.5%). The clinical condition of the animals, ophthalmic findings, palpable mass occurrence, body weights and gross and histopathologic findings were unaffected by DAG in comparison to TG. The findings in DAG-treated groups were no different than those observed in the TG control group. The standard basal diet had 4.5% fat content. Both TG and/or DAG, when presented separately or together in the diet at a total fat level of 6.0%, resulted in some differences relative to the basal diet control (lower survival, higher body weights, lower food consumption, and higher incidences of macroscopic and microscopic findings), presumably related to the higher dietary fat content and/or the semi-purified diet. However, these parameters were similar in groups fed a diet with 6.0% dietary fat that was either DAG or TG. Thus, DAG at dietary concentrations up to 6.0% for 24 months produced no signs of systemic toxicity and had no effect on the incidence of neoplastic findings.

A chronic dietary toxicity study of DAG (diacylglycerol) in Beagle dogs.

The potential chronic toxic effects of DAG (diacylglycerol) when administered orally for 12 months were evaluated in this dietary study in Beagle dogs. DAG is a cooking oil which contains >80% diglycerides, <20% triglycerides and 5% monoglycerides. For this study, a special diet was prepared with no dietary fat so that all of the dietary fat could be provided by DAG, at various concentrations together with a control oil. The control oil, TG (triacylglycerol), was prepared to contain >85% triglycerides, <10% diglycerides and 5% monoglycerides. The fatty acid composition for DAG and TG was closely matched. Dietary concentrations of 0% DAG/9.5% TG (TG control), 1.5% DAG/8.0% TG, 5.5% DAG/4.0% TG, and 9.5% DAG/0% TG were presented daily, seven days per week, for 52 weeks. A second concurrent control group received the standard basal diet (Certified Canine LabDiet 5007, which has a fat content of 9.5%). The basal diet, control article-treated and DAG-treated groups each consisted of four male and four female dogs. Treatment was initiated in prejuvenile (2.5-month-old) dogs. Statistical evaluations compared the DAG-treated groups both to the basal diet and 9.5% TG control groups. The clinical condition of the animals, body weights, body weight gains and food consumption were unaffected by DAG. Hematology and urinalysis parameters were unaffected. No serum chemistry changes indicative of a toxic effect were observed. There were no effects noted on ECG data. No test article-related gross or histopathologic findings or changes in organ weights were observed. While there were no identifiable differences between the effects of TG and DAG, both caused some differences relative to the basal diet (lower food consumption, higher alkaline phosphatase, cholesterol and triglycerides). These differences were not toxicologically significant and were attributed to the differences in the diet rather than the fat source. Thus, DAG at dietary concentrations up to 9.5% for one year had no effect on normal canine growth and development, in comparison to TG.

A 24-month dietary carcinogenicity study of DAG (diacylglycerol) in rats.

Toxicologic and carcinogenic effects of DAG (diacylglycerol) oil, administered in diet for 24 months to Crl:CD((R))(SD)-IGS BR rats, were evaluated using diet-restricted and ad libitum-fed groups. All dietary fat (consistently 5.5%) was provided by DAG and/or the control article, TG (triacylglycerol) oil. Dietary concentrations (% DAG/% TG) were 0%/5.5%, 1%/4.5%, 2.75%/2.75% and 5.5%/0%. Separate groups were fed the 0%/5.5% and 5.5%/0% diets ad libitum. Another group received the standard rodent diet (fat content 4.5%) on the restricted feeding regimen. Clinical condition, ophthalmic findings, palpable mass occurrence, body composition, clinical pathology parameters and incidence of neoplastic lesions were unaffected by DAG in comparison to TG. Groups fed the 5.5% (DAG and/or TG) fat diet when compared to the 4.5% fat diet group displayed lower survival, higher body weights, organ weights, percent body fat, higher fat-related serum chemistry parameters, incidence of microscopic changes in the heart, kidneys, liver, bone marrow, spleen, and incidences of pituitary and mammary gland neoplasms. Parameters more affected in all the ad libitum groups than in the restricted diet groups (regardless of test article) fed the same diet included survival, body weights, body fat, fat-related serum chemistry parameters, and incidences of heart, kidney and liver microscopic changes. However, the DAG and TG ad libitum-fed groups were not different from one another. Thus, DAG-treated animals had no higher risk of carcinogenic effects than rats fed on similar feeding regimens with a diet in which all dietary fat came from TG.