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Research Article | DOI: https://doi.org/DOI:10.31579/2693-2156/096
1 Private HealthResearch Laboratory, Kagawa,Japan
2 Professor Emeritus,Kagawa University, Kagawa,Japan
*Corresponding Author: Shigeru Suna, Private Health Research Laboratory, 14-22 Shinkita-machi, Takamatsu-shi, Kagawa 760-0001, Japan.
Citation: Shigeru Suna, and Masaaki Tokuda, (2024), Effects of monosaccharides administration on rat DEHP toxicity, J Thoracic Disease and Cardiothoracic Surgery, 5(4); DOI:10.31579/2693-2156/096
Copyright: © 2024, Shigeru Suna. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 30 April 2024 | Accepted: 15 May 2024 | Published: 25 May 2024
Keywords: D-glucose; D-fructose; D-allulose; D-allose; allitol; DEHP
Di(2-ethylhexyl) phthalate (DEHP), a suspected endocrine disruptor, causes hepatomegaly, testicular damage, and other toxic effects in oral administration experiments using rats. MEHP, a DEHP metabolite, is directly responsible for these toxicities; the potent oxidative stress generated by MEHP is thought to be closely involved.
To elucidate the relationship between the hydroxyl radical scavenging activity of monosaccharides, including rare sugars, and DEHP toxicity, D-glucose, D-fructose, D-allulose, D-allose and allitol were mixed 1.0 w/v% in drinking water and administered to 4-week-old male SD rats for 1 week with 1% w/w DEHP mixed food.
D-Allulose had a strong inhibitory effect on testicular atrophy, and D-Allose had a significant inhibitory effect on hepatomegaly.Furthermore, plasma ALT levels in the D-allulose and D-allose-treated groupswere significantly lowerthan those in the control group and the group treated with DEHP alone. These results may be due to the anti-inflammatory and anti-cell death effects of the monosaccharides through their hydroxyl radical scavenging action. Although allitol did not prevent DEHP-induced hepatomegaly and testicular atrophy, but prevented DEHP-induced reduction in weight gain. MEHP induced oxidative stress can disrupt thyroid hormones, which plays an important role in the process of skeletal muscle formation. The weight loss may be due to MEHP-induced thyroid dysfunction. Allitol may counteract MEHP- induced thyroid dysfunction.
Di(2-ethylhexyl) phthalate (DEHP), a suspected endocrine disruptor, is used as a plasticizer in polyvinyl chloride (PVC) in ratios ranging from a few percent to tens of percent [1-3]. DEHP is known to cause hepatic peroxisome proliferation and testicular atrophy in rats as an oral toxicity of DEHP [4-11]. However, recently, toxic effects on the testes have been observed at even lower concentration levels than those conventionally used for detection, and there is growing concernabout the health effects of exposure to low concentrations of DEHP [13].
In oral administration experiments using rats and other animals, DEHP itself is hardly absorbed into the body, but mono(2- ethylhexyl) phthalate (MEHP), which is hydrolyzedby lipase in the digestive tract, is absorbed and distributed in the body, and is thought to be involvedin the development of toxicityin the testes and liver [14-16]. Recently, the involvement of reactive oxygen species (ROS) in the mechanism of germ cell apoptosis induction by MEHP has been clarified [17, 18].
On the other hand, many monosaccharides, including rare sugars, are known to exhibitantioxidant effects basedon hydroxyl radical scavenging [19-24], and may have a protective effect against DEHP-induced testicular toxicity and liver toxicity.
Therefore, the authors investigated the effects of some monosaccharides, including rare sugars on DEHP toxicity in animal experiments.
Figure 1. Molecular structures of D-glucose, D-fructose, D-allulose, D-allose and allitol.
Male Charles River Sprague-Dawley (SD) rats were used as experimental animals, and were fed a rat diet made by Oriental Yeast and a diet mixed with DEHP (97% or higher purity). Rare sugars (98% or higher purity) were provided by the Kagawa University Rare Sugar Research Center. Other ingredients were commercial grade reagents.
The experiments were conducted under the conditions of 22-24℃ of temperature and 50-60% relative humidity at the Laboratory Animal Center of Kagawa University. The experiment protocols had the approval by the Kagawa University Animal Committee. D-glucose, D-fructose, D-allulose, D-allose and allitol (Figure 1) were mixed 1.0 w/v% in drinking water and administered to 4- week-oldmale SD rats for 1 week with 1% w/w DEHP mixed food. The administration experiment was repeated in units of 6 rats per group.
At the first week after administration, blood was drawn from the heartunder ether anesthesia, and the testes,liver, and other organs were removed and weighed.
Plasma isolated from rat blood was used to measure the following parameters:
Plasma levels of glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, HDL cholesterol, triglycerides.
The analyzer was a Hitachi Model 7600 Automated Analyzer (Hitachi).
Results were expressed as means ± standard deviations (SD). Statistical analysis was performed by one-way ANOVA test followed by Dunnett's postanalysis test for multiple comparisons. p <0>
Body weight and organweights are shown in Table 1, 2 and 3, and blood biochemical test results are shown in Table 4, 5 and 6. Final body weights of DEHP alone and DEHP plus D-glucose, D- fructose, D-allulose or D-allose, were statistically significantly lower than those of the control group. Significant inhibition of weight suppression was observed in the DEHP plus allitol group. As shown in Table 2, the degreeof testicular atrophyof DEHP in terms of relative testicular weight (testes/body weight %) was DEHP (0.62) ≈ DEHPplus allitol (0.58) > D-glucose (0.75) ≈ D- allose (0.72) > D-allulose (0.82) ≈ control (0.88). D-allulose showed the strongest and statistically significant inhibition of testicular atrophy. As shown in Table 3, the degree of DEHP hepatomegaly in terms of liver weight (relative weight %) was DEHP (7.8) ≈ DEHP+D-allitol (7.7) ≈ D-glucose (7.6) ≥ D- allulose (7.3) > DEHP+D-allose (6.9) versus control (4.8). D- allose significantly suppressed hepatomegaly, while D-allulose showed insignificant suppression (p=0.052).
| Group | n | Initial body weight (g) | Final bodyweight (g) | ||||
| mean | SD | mean | SD | ||||
| Control | 18 | 97.1 | 4.3 | 159.2 | 9.1 | ### | |
| DEHP | 18 | 94.3 | 5.0 | 141.3 | 8.4 | *** | |
| DEHP+Glucose | 6 | 94.0 | 4.8 | 136.2 | 5.9 | *** | |
| DEHP+Fruktose | 6 | 99.0 | 3.6 | 145.7 | 5.3 | ** | |
| DEHP+Allulose | 12 | 95.1 | 4.5 | 137.0 | 4.6 | *** | |
| DEHP+Allose | 12 | 96.7 | 4.4 | 135.0 | 10.6 | *** | |
| DEHP+Allitol | 6 | 99.0 | 3.0 | 153.9 | 6.5 | ## | |
*p<0.05, **p≤0.01, ***p<0.001, as compared to control. p<0.05, p<0.01, p<0.001, as compared to DEHP alone.
Table 1. Initial and final body weights
Group |
n | Testes (g) | Relative testicular weight (%) | ||||
| mean | SD | mean | SD | ||||
| Control | 18 | 1.40 | 0.11 | ### | 0.88 | 0.05 | ### |
| DEHP | 18 | 0.87 | 0.20 | *** | 0.62 | 0.15 | *** |
| DEHP+Glucose | 6 | 1.02 | 0.24 | *** | 0.75 | 0.15 | |
| DEHP+Fruktose | 6 | 0.99 | 0.20 | *** | 0.68 | 0.13 | ** |
| DEHP+Allulose | 12 | 1.13 | 0.22 | **, ## | 0.82 | 0.16 | ## |
| DEHP+Allose | 12 | 0.97 | 0.25 | *** | 0.73 | 0.18 | ** |
| DEHP+Allitol | 6 | 0.89 | 0.12 | *** | 0.58 | 0.10 | *** |
*p<0.05, **p<0.01, ***p<0.001, as compared to control. #p<0.05, ##p<0.01, ###p<0.001, as compared to DEHP alone.
Table 2: Testicular weights
| Group | n | Liver (g) | Relative liverweight (%) | ||||
| mean | SD | mean | SD | ||||
| Control | 18 | 7.67 | 0.64 | ### | 4.82 | 0.24 | ### |
| DEHP | 18 | 10.99 | 1.25 | *** | 7.77 | 0.69 | *** |
| DEHP+Glucose | 6 | 10.32 | 0.51 | *** | 7.59 | 0.47 | *** |
| DEHP+Fruktose | 6 | 11.83 | 0.66 | *** | 8.12 | 0.30 | *** |
| DEHP+Allulose | 12 | 10.00 | 0.51 | ***, ### | 7.31 | 0.45 | *** |
| DEHP+Allose | 12 | 9.37 | 0.90 | ***, ### | 6.95 | 0.35 | ***, ### |
| DEHP+Allitol | 6 | 11.83 | 0.66 | *** | 7.70 | 0.54 | *** |
*p<0.05, **p<0.01, ***p<0.001, as compared to control. #p<0.05, ##p<0.01, ###p<0.001, as compared to DEHP alone.
Table 3. Liver weights
As shown in Table 4, plasma glucoselevels were significantly
suppressed in the group treated with DEHP alone compared to the control. D-glucose and D-allulose restored plasma glucose levels, while D-allose and allitol did not. DEHP alone and DEHP plus monosaccharide treatments had significantly lower triglycride levelsthan controls. As shown in Table 5, plasma total- cholesterol and HDL-cholesterol in the DEHP alone and DEHP
plus monosaccharide treated groups were significantly lower than controls.
Plasma ALT levels in the DEHP plus D-allulose, or D-allose treated groups were significantly lower than controls and DEHP alone (Table 6).
Group |
n | Glucose (mg/dL) | Triglycerides (mg/dL) | ||||
| mean | SD | mean | SD | ||||
| Control | 18 | 206.2 | 56.7 | # | 46.2 | 21.5 | ### |
| DEHP | 18 | 174.2 | 27.8 | * | 24.8 | 9.5 | *** |
| DEHP+Glucose | 6 | 185.0 | 15.8 | 19.7 | 4.3 | ** | |
| DEHP+Fruktose | 6 | - | - | - | - | ||
| DEHP+Allulose | 12 | 183.8 | 23.7 | 26.0 | 8.5 | ** | |
| DEHP+Allose | 12 | 167.8 | 15.1 | * | 31.0 | 12.9 | * |
| DEHP+Allitol | 6 | 170.5 | 11.5 | * | 24.8 | 9.5 | ** |
*p<0.05, **p<0.01, ***p<0.001, as compared to control. #p<0.05, ##p<0.01, ###p<0.001, as compared to DEHP alone.
Table 4. Plasma levels of glucose and triglycerides
| Group | n | AST (U/L) | ALT (U/L) | ||||
| mean | SD | mean | SD | ||||
| Control | 18 | 202.6 | 155.3 | 56.4 | 16.0 | ||
| DEHP | 18 | 160.6 | 86.9 | 57.7 | 16.8 | ||
| DEHP+Glucose | 6 | 134.8 | 41.8 | 44.0 | 5.8 | ||
| DEHP+Fruktose | 6 | - | - | - | - | ||
| DEHP+Allulose | 12 | 121.6 | 48.5 | 43.9 | 8.6 | # | |
| DEHP+Allose | 12 | 138.8 | 107.3 | 41.5 | 7.6 | *, ## | |
| DEHP+Allitol | 6 | 116.3 | 25.8 | 44.8 | 6.3 | ||
*p<0.05, **p<0.01, ***p<0.001, as compared to control. #p<0.05, ##p<0.01, ###p<0.001, as compared to DEHP alone.
Table 5. Plasma levels of ALT and AST
| Group | n | Total-cholesterol (mg/dL) | HDL-cholesterol (mg/dL) | ||||
| mean | SD | mean | SD | ||||
| Control | 18 | 90.1 | 14.1 | ### | 36.4 | 4.2 | ### |
| DEHP | 18 | 65.2 | 5.0 | *** | 26.4 | 3.3 | *** |
| DEHP+Glucose | 6 | 65.8 | 5.2 | *** | 24.5 | 2.2 | *** |
| DEHP+Fruktose | 6 | - | - | - | - | ||
| DEHP+Allulose | 12 | 66.1 | 9.7 | *** | 26.3 | 3.3 | *** |
| DEHP+Allose | 12 | 70.8 | 8.2 | *** | 28.3 | 4.0 | *** |
| DEHP+Allitol | 6 | 72.8 | 14.4 | ** | 28.7 | 4.7 | *** |
*p<0.05, **p<0.01, ***p<0.001, as compared to control. #p<0.05, ##p<0.01, ###p<0.001, as compared to DEHP alone
Table 6. Plasma levels of total cholesterol and HDL cholestero
After oral administration, DEHP, distributed in the body primarily as MEHP, stimulates peroxisome proliferator-activated receptors and increases carbohydrate and lipid metabolism. The oxidative stress produced may be closely related to DEHP toxicity, including hepatomegaly and testicular atrophy [4-12]. In the present oral administration experiments of DEHP and monosaccharides, D-Allulose showed the strongest and significant testicular atrophy inhibitory effect, suggesting that D-allose, D- glucose, and D-fructose have a slightinhibitory effect on testicular atrophy. The liver weights of the D-allose-treated groups were significantly lower than those of the group treated with DEHP alone. Furthermore, plasma ALT levels in the D-allulose and D- allose-treated groups were significantly lower than those in the control and the group treatedwith DEHP alone.These results may be attributed to the anti-inflammatory and anti-cell death effects of monosaccharides due to their hydroxyl radical scavenging action. Plasma glucoseconcentrations were significantly lower in the group treated with DEHP alone than in the controlgroup, but not in the D-allulose-treated group. This suggests that D-allulose
inhibits DEHP -induced glycemic suppression; MEHP -induced PPAR-γ can promote lipid metabolism, whilethe reactive oxygen species produced can promote insulin secretion [25-27]. The antioxidant D-allulose may regulate insulin hypersecretion and protect pancreatic function [28, 29].
Allitol did not prevent DEHP-induced hepatomegaly and testicular atrophy, but prevented DEHP-induced reduction in weight gain. MEHP induced oxidative stress can damage thyroid tissue and lower thyroid hormones [30-33] which plays an important role in the process of skeletal muscle formation [34]. The weight loss may be due to MEHP-induced thyroid dysfunction. Allitol may counteract MEHP-induced thyroid dysfunction.
D-Allulose had a stronginhibitory effect on testicular atrophy,and D-Allose had a significant inhibitory effect on hepatomegaly. Furthermore, plasma ALT levels in the D-allulose and D-allose- treated groups were significantly lower than those in the control group and the grouptreated with DEHP alone. These results may be due to the anti-inflammatory and anti-cell death effects of the monosaccharides through their hydroxyl radical scavenging action. Although allitol did not prevent DEHP-induced hepatomegaly and testicular atrophy, but prevented DEHP-
induced reductionin weight gain. MEHP inducedoxidative stress can disruptthyroid hormones, which plays an important role in the process of skeletal muscleformation. The weightloss may be due to MEHP-induced thyroid dysfunction. Allitol may counteract MEHP-induced thyroid dysfunction.
This work was supported by a Grants-in-Aid for Rare Sugar Research of Kagawa University. The author appreciates the help of colleagues in the Kagawa University.
Authors declare that there is no conflict of interests.
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