## 2 Results and Discussion
### Review of the Bioactivity and Acute Toxicity of Main Absorbed Constituents  
The bioactivity and acute toxicity of the main absorbed constituents (3,5-DMT, 2,3,5-TMT, 3,4,5-TMT, methyleugenol, safrole, eugenol, and kakuol) were reviewed and the results were as follows. It was found that 3,4,5-TMT has anti-inflammatory activity in vitro through the pathway of suppressing lipopolysaccharide-induced NO production [22]. It was also found that 3,5-DMT has a sedative effect [23]. Methyleugenol has anti-inflammatory [24], analgesic [25], spasmolytic [26], antiallergy [27], cardioprotective [28], and anticonvulsive [29] activity. Safrole, reported to be a  
Figure 4: Proposed metabolic pathways of some volatile constituents of ARR. toxic constituent in ARR, is carcinogenic and its metabolites can inhibit the respiratory center [30]. Eugenol can be used in the treatment of diseases associated with oxidative stress and inflammatory responses through the inhibition of enzymes and oxidative processes [31]. As mentioned at the beginning of this paper, in traditional Chinese medicine, the toxicity of ARR powder is a matter worthy of attention. It was reported that the median oral lethal dose (LD50) of powder, decoction, and volatile oil of ARR (AHM root) in mice was 4.8 g/kg, 240 g/kg, and 2.53 mL/kg, respectively [32]. For its very small LD50, the volatile oil is considered to be the substance that causes the toxicity of ARR powder. Since the decoction can be used safely in a larger dose, whereas the dose of powder is strictly restricted, and the acute toxicity of ARR decreases significantly after boiling water decoction, we considered that the difference in the absorbed compounds between the powder- and decoction-treated groups should be the main factor responsible for the toxicity of ARR powder. In this research, 3,5-DMT, safrole, and methyleugenol were detected as the main constituents of ARR in the power-treated group, which distributed into the blood and all eight organ samples (brain, heart, lungs, spleen, liver, kidney, stomach, and small intestine). In contrast, in the decoction-treated group, 3,5-DMT, safrole, and methyleugenol were not found in blood and organs related to ARR toxicity (brain, heart, and lung). The peak area ratios of 3,5-DMT, safrole, and methyleugenol in these organs between the two groups were as follows: liver--4198, 4062, and 397; kidney--2430, 1367, and 173; small intestine--6101, 6411, and 1793. The results are shown in Table 4.  
On the other hand, 3,5-DMT, methyleugenol, and safrole have a lower polarity and stronger volatility and are easier to lose during decoction. It was reported that after 1 h decoction, the amount of safrole decreased by more than 92%, resulting in the equivalent of no more than 0.20 mg/g safrole remaining in the aqueous extract. Similarly, the content of methyleugenol decreased by more than 60% [14]. Therefore, we can speculate that methyleugenol, safrole, and 3,5-DMT may be the main toxic constituents in the volatile oil of ARR. At present, there are a few reports on the acute toxicity of safrole, and its LD50 was calculated as follows: rat (oral)--1950 mg/kg; mouse (oral)--2350 mg/kg; mouse (subcutaneous)--1020 mg/kg [33]. The LD50 of methyleugenol was also evaluated, and the values were: rat (oral)-1179 mg/kg; mouse (intraperitoneal)--540 mg/kg; mouse (intravenous)--112 mg/kg [33], and mouse (intravenous) > 640 mg/kg [34]. The LD50 of 3,5-DMT has not been reported. In addition, considering that methyleugenol and safrole are not highly toxic compounds and their oral LD50 values are reported to be 1179 (rat) and 2350 mg/kg (mouse), respectively, the acute toxicity of other compounds detected in the blood of the powder-treated group were also investigated. The results show that these compounds also showed low oral toxicity, and their LD50 values are shown in Table 5.