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This study investigated whether or not Citrus unshiu peel extract (CPE) affects fat accumulation in livers of rats fed an ethanol-containing liquid diet. Initially, male Sprague-Dawley rats were housed individually in stainless steel, wire-bottomed cages with free access to a Lieber-Decarli control liquid diet. Rats were divided by body weight into three groups of eight each: one group of rats was fed the Lieber-Decarli control liquid diet devoid of ethanol (control), another was fed the Lieber-Decarli ethanol diet (ethanol), and third was fed the same ethanol diet except containing CPE. All three groups were fed their respective diets for 6 weeks. Serum and liver lipids were analyzed and liver histology performed. Body weight did not differ among the groups over the 6-wk duration. Histology images showed that CPE administration significantly improved fat accumulation in livers, which was induced by ethanol diet. Serum levels of transaminases and lipids also were reduced by CPE consumption. Taken together, the results indicate that CPE may protect ethanol-induced fatty liver by lowering fat accumulation in both the liver and blood. The protective effects of CPE appear to be due to its phenolic contents.

Evidence suggests that dietary indole, particularly rich in cruciferous vegetables, may reduce the risk of cardiovascular diseases. Endosulfan is a residual organochlorine pesticide, which is detected in fruits, vegetables, and crops. In this study, we investigated the effect of luminal indole on endosulfan transport in the small intestine in mesenteric lymph duct-cannulated rats. The duodenum was also cannulated and a fasting phosphate buffered saline-glucose solution was infused overnight at 3 mL/hr. After recovery, a lipid emulsion containing [2,3-14C] endosulfan (14C-endosulfan) was infused into the duodenum for 8 hours. The tested rats were infused with the same lipid emulsion, but with indole. Samples from the lymph-fistula were collected hourly, and the luminal contents and mucosa were collected at the end of the infusion. The lymph flow in the mesenteric lymph did not differ between the two groups. However, the intestinal absorption of both endosulfan and cholesterol were significantly decreased by indole. The amount of radioactive endosulfan, which remained in the mucosa, was greater in the indole-infused rats due to the decreased transport of endosulfan into the lymph. This study indicates that the indole decreases the intestinal transport of endosulfan into the mesenteric lymph.

Water-soluble citrus peel extract (WCE) from Citrus unshiu was studied for its anti-alcoholic fatty liver activities through chronic oral administration to Sprague Dawley (SD) rats. WCE, which was prepared by ultrasound-assisted extraction (UAE), was co-supplemented with ethanol (2.87 ml/rat/day) at low and high dosages (278 and 576 mg/rat/day, respectively) for 6 weeks. Ethanol consumption significantly elevated both total cholesterol (TC) and triglyceride (TG) concentrations in the serum of SD rats; otherwise co-administration of WCE lowered both serum TG and TC levels. Ethanol consumption caused a hepatic lipid content of 227 mg/g liver after 6 weeks whereas co-administration of WCE, especially at high dosage, significantly reduced it to 187 mg/g of liver. Analysis of hepatic fatty acids revealed that WCE suppressed conjugation of oleic acid into TG. These results support probable application of WCE as an anti-alcoholic fatty liver agent.

Recently, we have demonstrated that green tea extract (GTE) decreases the intestinal absorption of benzo[a]pyrene (BAP), which is an extremely lipophilic food contaminant. The present study was conducted to examine if an enteral infusion of GTE would influence the biliary secretion of BAP and lipids in rats. Female rats were fed an AIN-93G diet with or without (control) GTE at 5 g/㎏ diet for 4 week. Following the 4-week dietary treatment, rats with bile duct cannula were infused continuously for 8 hr at 3.0 ㎖/hr via a duodenal catheter with a lipid emulsion containing 4.0 μ㏖ BAP labeled with ¹⁴C (¹⁴C-BAP), 20.7 μmol cholesterol, 452 μ㏖ triolein, and 3.1 μ㏖ α-tocopherol, and 396.0 μ㏖ Na-taurocholate with or without 76.1 ㎎ GTE powder in PBS buffer (pH, 6.4). Bile was collected hourly via bile cannula for an 8 hr period. Our results showed that bile flow did not differ between groups. However, the biliary secretion of ¹⁴C-BAP was significantly enhanced by GTE infusion, compared with those infused with the lipid emulsion alone. However, GTE did not affect the biliary outputs of cholesterol, fat, phospholipid and α-tocopherol. These findings indicate that GTE has a profound stimulatory effect on the biliary excretion of BAP in rats, without affecting other biliary lipids. The mechanism(s) by which GTE enhances the biliary secretion of BAP remains to be investigated.

Recently, we showed that green tea extract (GTE) markedly lowers the intestinal absorption of ¹⁴C-benzo[a]pyrene (¹⁴C-BaP) and enhances its secretion into the biliary route, suggesting a protective role for GTE against body burden. These findings indicate that green tea could be used as an effective dietary means against the toxicity of BaP. The present study, therefore, was designed to investigate if green tea intake could affect the tissue distribution and deposition of ¹⁴C-BaP in rats. Male Sprague-Dawley rats had free access to a nutritionally adequate AIN-93G diet and deionized water. At ∼340 g of weight, the rats were injected intraperitoneally with 27.4 kBq of [4-¹⁴C]-BaP and 5.0 ㎎ of BaP dissolved in 300 ㎕ of olive oil and then assigned randomly to the following two groups: one group (GTE) of rats was fed the AIN-93G diet with GTE via drinking water at approx. 4.7 ㎎ of catechins/d, whereas the other was fed the same diet but without GTE (control). At 4 wk of dietary treatment with GTE, animals were euthanized and heart, liver, brain, spleen, kidney, retroperitoneal fat, testis, and epididymal fat were collected, weighed, and analyzed for tissue ¹⁴C-BaP. Both the control and GTE groups continuously gained weight throughout the study, but there was no significant difference between the groups. No significant differences were observed in the weights of heart, liver, brain, spleen, kidney, retroperitoneal fat, testis, and epididymal fat. However, the radioactivities of ¹⁴C-BaP, expressed in dpm/g, were significantly lower in the heart, liver, brain, spleen, and epididymal fat of rats receiving GTE as compared to their respective controls. These data indicate that green tea intake markedly lowers tissue accumulation of ¹⁴C-BaP. Taken together, these findings suggest that the decreased tissue levels of BaP by GTE intake may be associated with lowered intestinal absorption of BaP and its enhanced secretion into the bile.