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Abstract: Arctiin, an important lignan compound in Fructus Arctii, has been reported to possess various kinds of bioactivities. Previous studies on the pharmacokinetic of arctiin after oral administration showed that it had a rapid absorption phase followed by a sharp but lasting disappearance. To gain deep insight into the action mechanism of arctiin, the excretion and metabolism of arctiin in vivo should be further studied. In this paper, three metabolites were isolated and identified in rat feces as (−)-enterolactone (M-1), (−)-arctigenin (M-2) and [(2R,3R)-2-(3′-hydroxybenzyl)-3-(3″,4″-dimethoxybenzyl)-butyrolactone] (M-3). Based on the structures of three metabolites, possible metabolic pathways of arctiin in rats are proposed. At the same time, the cumulative excretion rate of arctiin and its metabolites in rat urine and feces were determined, indicating that arctiin was excreted 19.84% in urine and 1.80% in feces, respectively, enterolactone, the most main metabolite, was excreted 35.80% in feces. These results provide very important information for understanding the metabolism and excretion of arctiin in vivo and speculating its action mechanism, they can provide useful information and reference for further metabolic investigations on arctiin in humans. [Copyright &y& Elsevier]

Background. The aim of this work was to study the toxic effects and target organs of Mosla chinensis Maxim (MCM) in rats and provide theoretical basis for clinical medication. Methods. The subchronic toxicity study was conducted on 60 male and female SD rats using the fixed-dose method for the treatment groups and 20 male and female SD rats for the control. At the subchronic toxicity study, the water extract of MCM with fixed doses of 0.2 g/kg/day, 2 g/kg/day, and 20 g/kg/day was administered for 90 days intragastric, and the control group was given the same amount of distilled water. After 90 days, the general conditions of the rats were observed. Assessment on safety of the extract was conducted by a subchronic toxicity test which mainly examined alteration occurrence in gut flora and urine metabolism. Results. There was no significant difference in physical signs, reactivity, and stool characteristics in the four groups. Compared with the control group, the number of red blood cells in the male 2 g/kg/day group and the female 0.2 g/kg/day group was significantly different (P < 0.05). The detection of serum biochemical indicators showed that MCM has an effect on liver and kidney function but has no physiological significance. The level of low-density lipoprotein in male rats was lower than that in the control group (P < 0.05). Compared with the control group, the blood glucose levels of female rats in the 0.2 g/kg/day, 2 g/kg/day, and 20 g/kg/day groups were significantly increased (P < 0.05). As far as the diversity of intestinal flora is concerned, feeding MCM for 90 days has an influence on the distribution of intestinal flora. The content of lactic acid bacteria increased, and the ratio of hard bacteria to Bacteroides (f/b) was also affected, but there was no significant difference. Conclusions. These findings showed that the long-term intragastric administration of the MCM is safe to use within its dose recommendation. But it could have a slight effect on the metabolism of uric acid by changing the composition of intestinal flora and affecting the metabolism of tryptophan. [ABSTRACT FROM AUTHOR]