Introduction
According to the relevant statistics, the incidence of coronary heart disease (CHD)
and the associated pathogenic factors has increased every year worldwide.[1 ]
[2 ] Lipid-lowering drugs such as niacin drugs and antithrombotic drugs are currently
used for CHD in clinics.[3 ] Despite their effectiveness, these drugs show certain side effects.[4 ] It is well known that natural product is an excellent candidate for alternative
medicine for disease management. Bulbus eleutherinis is a famous traditional Dai medicine with good therapeutic effect and low toxicity. It is a whole herb of Eleutherine plicata originated from tropical America,[5 ]
[6 ] and its multiple conventional functions, such as promoting blood circulation, relieving
swelling and pain, detoxifying, as well as dehumidifying, make it suitable for treating
chest tightness, shortness of breath, and CHD.[7 ]
[8 ]
[9 ] Currently, Bulbus eleutherinis is widely used in the treatment of CHD in the clinic, especially for the Dai nationality living in Yunnan Province, China.[10 ]
[11 ]
Bulbus eleutherinis contains naphthoquinone derivatives, glucosides, and a small amount of hydrazine.[12 ]
[13 ]
[14 ] Previous studies showed that naphthoquinone in the ethanol extract of Bulbus eleutherinis can significantly improve blood viscosity and enhance hypoxia tolerance in myocardial
ischemic animals,[15 ]
[16 ]
[17 ]
[18 ] and thereby plays a key role in anti-CHD effect of the herb. Several naphthoquinone
derivatives, such as isoeleutherin, eleutherin, and eleutherol, have been investigated
as the main active fractions for CHD therapy.[19 ]
[20 ]
[21 ]
Danshen Injection is a commonly used drug in clinical treatment of CHD. Evidence suggested
that in comparison with Danshen Injection, the active compounds mentioned above (isoeleutherin, eleutherin, and eleutherol)
significantly increase coronary blood flow without side effects and toxicities,[10 ] and have the value of developing new drugs for CHD threapy.[7 ] At present, the research on the active ingredients of Bulbus eleutherinis has a certain foundation. It is necessary to study the in vivo metabolism of the active ingredients in Bulbus eleutherinis to investigate its druggability more comprehensively.
In 2009, a high-performance liquid chromatography (HPLC) detection method for the
three active compounds (isoeleutherin, eleutherin, and eleutherol) in Bulbus eleutherinis was reported by Liu et al.[22 ] However, the determination of these three active compounds in vivo after oral administration has not yet been reported. In this study a reliable and
useful ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)
method has been developed to obtain pharmacokinetics (PK) and tissue distribution
data of the three active compounds in rat plasma simultaneously after po (oral) and
iv (intravenous) administration. A series of conditions and validation projects were
verified. By obtaining the PK and tissue distribution parameters of the drug in the
body, the action site and time of the drug in the body can be analyzed, which can
provide a reference and basis for the subsequent research on the metabolism of active
ingredients, mechanism of action, and new drug development.
Experimental
Chemicals and Reagents
Isoeleutherin (> 96%, HPLC), eleutherin (> 98%, HPLC), and eleutherol (> 98%, HPLC)
were purchased from Chengdu Herbpurify Co., Ltd (Chengdu, China). Betamethasone (HPLC
purity > 98%, internal standard [IS]) was purchased from Innochem Technology Co.,
Ltd (Peking, China). The structures of four compounds are provided in [Fig. 1 ]. The methanol and acetonitrile of chromatographic grade were purchased from ANPEL
(Shanghai, China). UPLC grade formic acid was purchased from Merck (Darmstadt, Germany).
Bulbus eleutherinis (Yunnan, China) were purchased from Yunnan Jinfa Pharmaceutical Co., Ltd. (Yunnan,
China). Millipore Alpha-Q system (Billerica, Massachusetts, United States) was used
to prepare ultra-pure water. Medicinal materials were stored in Xishuangbanna Prefecture
Dai Medicine Research Center in School of Pharmacy, Shanghai Jiao Tong University.
Fig. 1 Chemical structures of analytes.
UPLC-MS/MS Condition
Chromatography separation was operated by an ACQUITY UPLC system (Waters, Milford,
Massachusetts, United States). Waters Cortecs C18 column (1.7 μm, 2.1 mm × 50 mm)
was used in chromatography with a flow rate at 0.40 mL/min. The column temperature
and the autosampler temperature were set as 45°C and 4°C, respectively. The gradient
elution of 0.1% aqueous formic acid (A) and acetonitrile (B) were selected as mobile
phases. The process is listed as follows: 30–39% B at 0–3.3 minutes, 39–95% B at 3.3–3.4 minutes,
95–95% B at 3.4–4.4 minutes, 95–30% B at 4.4–4.5 minutes, 30% B at 4.5–6.0 minutes.
The injection volume was 3 μL. The AB SCIEX Qtrap 5500 LC/MS/MS system (SCIEX, United
States) with an electron spray ionization source in multiple reaction monitoring (MRM)
mode was used as a MS analysis tool. The detection was performed under the following
conditions: s = source temperature (at set point): 550.0°C, positive ion mode, GS1:
40 psi, GS2: 40 psi, CUR: 45 psi, CXP:15V, DP: 100 V, EP: 10 V. Quantitative analysis
of analytes in MRM mode to determine the transition of precursor ions to specific
product ions (m /z ): isoeleutherin, m /z 273.1 [M + H]+ → m /z 229.0 (collision energy, CE: 17 V), eleutherin, m /z 273.1 [M + H]+ → m /z 229.0 (CE: 17 V), eleutherol, m /z 244.8 [M + H]+ →m /z 227.1 (CE: 23 V), IS, m /z 393.2 [M + H]+ → m /z 373.2 (CE: 17 V). The data were processed with MultiQuant 2.1 Software (SCIEX, California,
United States).
Determination of Isoeleutherin, Eleutherin, and Eleutherol
Naphthoquinone in Bulbus eleutherinis was obtained by purifying the ethanol extract of the medicinal material using macroporous
adsorption resin, and 0.03 g of which was weighed and dissolved ultrasonically in
25 mL methanol. The solution was filtered with 0.22 μm microporous membrane, and the
content of isoeleutherin, eleutherin, and eleutherol was determined using UPLC-MS/MS
conditions mentioned above. The contents of isoeleutherin, eleutherin, and eleutherol
in naphthoquinone were 6.37, 23.13, and 9.71%, respectively.
Animals
Male Sprague Dawley (SD) rats (180–220 g) were used for the study. The rats were housed
in a professional animal breeding room (relative humidity: 55–60%, temperature: 25°C)
for 1 week. Experimental operation of rats was in strict accordance to the animal
experiment's ethical requirements. The animal study was reviewed and approved by the
Institutional Animal Care and Use Committee of Shanghai Jiao Tong University. Rats
were given free access to drinking water throughout the experiment and kept fasting
for 24 hours before the experiment.
Preparation of Standard Working Solution and Quality Control Samples
Isoeleutherin, eleutherin, and eleutherol were dissolved in methanol to obtain a mixed
standard stock solution (isoeleutherin: 1 μg/mL, eleutherin: 3.84 μg/mL, eleutherol:
0.498 μg/mL). The mixed stock solution was diluted with methanol to prepare a series
of different concentration gradient mixed standard solutions. A 2.0 ng/mL IS solution
was prepared from betamethasone solution (500 μg/mL) with methanol.
Rats were sacrificed in a professional animal breeding room (relative humidity: 55–60%,
temperature: 25°C), and then blood and tissues (heart, liver, kidney, small intestine)
were collected. The blood was centrifuged (5,000 rpm, 4°C) to obtain plasma. Tissues
were flushed with saline to remove blood or other contents, and blotted dry with filter
paper. The accurately weighed tissue was then homogenized using a tissue homogenizer
in saline (four times the tissue weight).
A 20.0 μL of the mixed standard solution was added to 40.0 μL of blank plasma or 20
μL of blank tissue homogenate. The supernatant was obtained by centrifugation after
mixing evenly with calibration standard. Calibration standards included a serial of
concentrations of isoeleutherin (1–200 ng/mL), eleutherin (3.84–768 ng/mL), and eleutherol
(0.498–99.6 ng/mL). Four concentrations of analytes were used to prepare lower limit
of quantification (LLOQ) and quality control (QC) samples of plasma as follows: 1,
2, 50, and 150 ng/mL of isoeleutherin; 3.84, 7.68, 192, and 576 ng/mL of eleutherin;
0.498, 0.996, 24.9, and 74.7 ng/mL of eleutherol. Three concentrations of analytes
were used to prepare QC samples of tissue as follows: 2, 5, and 15 ng/mL of isoeleutherin;
7.68, 19.2, and 38.4 ng/mL of eleutherin; 0.996, 2.49, and 4.98 ng/mL of eleutherol.
Preparation of Plasma and Tissue Sample Containing IS
For plasma sample preparation, 180 μL of IS solution was mixed with 40 μL of plasma
sample. The protein precipitate was removed by centrifugation at 13,000 rpm for 10 minutes.
For tissue sample preparation, 180 μL of IS solution was mixed with 20 μL of tissue
homogenate and the protein precipitate was removed by centrifugation at 13,000 rpm
for 10 minutes. The supernatant was transferred to the injection vial, and then detected
by the UPLC-MS/MS condition mentioned above.
Selectivity
The blank biological samples (plasma samples, tissue samples) from six different rats
were evaluated to determine the selectivity of UPLC-MS/MS method. The chromatograms
of blank biological matrix samples and the three compounds (isoeleutherin, eleutherin,
and eleutherol) were compared to confirm the presence of any interference.
Linearity and the Lower Limit of Quantification
Calibration curves of isoeleutherin, eleutherin, and eleutherol were obtained by measuring
the ratio of the peak response of different compound concentrations in the rat plasma
and tissue samples to the IS peak area (weighting factor was 1/x
2 ). The LLOQ was determined by a signal to noise ratio of 10:1 as the lowest concentration
in the standard curve.
Recovery and Matrix Effect
The extraction recoveries and matrix effects were determined by evaluating QC samples
prepared according to the method in the “Preparation of Standard Working Solution
and Quality Control Samples” part mentioned above (n = 6). The extraction recoveries of isoeleutherin, eleutherin, and eleutherol were
determined by calculating the ratio of extracted samples versus extracts of blanks
spiked with the analyte postextraction. The peak areas of the three compounds from
the postprocessed sample and the standard solutions were compared to calculate the
matrix effects.
Precision and Accuracy
The precision and accuracies of compounds were determined by evaluating QC samples
prepared according to the method in the “Preparation of Standard Working Solution
and Quality Control Samples” part mentioned above (n = 6). The intra-accuracies and inter-accuracies were obtained by comparing the spiked
concentrations and the calculated concentration of QC samples for 1 or 3 days. Intra-precision
and inter-precision were validated by calculating the repeatability of the concentration
measured by the QC samples for 1 or 3 days.
Stability Tests of Isoeleutherin, Eleutherin, and Eleutherol in Rat Plasma
The stability tests of isoeleutherin, eleutherin, and eleutherol in rat plasma samples
were performed by determining six replicate QC samples in three storage environments.
The QC samples were stored at 25°C for 6 hours. The contents of the three compounds
were determined to evaluate the short-term stability. Their freeze–thaw stability
was evaluated by determining the concentration in the QC samples after three freeze
and thaw cycles. Autosampler stability was conducted by evaluating changes in the
active compounds of the QC samples placed at 4°C for 8 hours in the autosampler.
Pharmacokinetics Study
The active compounds were added to 0.5% sodium carboxymethylcellulose and mixed well.
Oral administration of a single dose of 50 mg/kg (3.18 mg/kg of isoeleutherin, 11.57 mg/kg
of eleutherin, 4.86 mg/kg of eleutherol) was selected based on effective dose results
from previous laboratory pharmacodynamics experiments and the lowest dose that could
be quantified in plasma. Blood samples (0.10–0.15 mL) were obtained from the eyelids
subsequently at 0.033, 0.083, 0.167, 0.25, 0.5, 1, 2, 4, 6, 8, 12, and 24 hours after
oral administration. Similarly, blood samples were collected at 0.083, 0.167, 0.25,
0.5, 1, 2, 4, 6, 8, 12, and 24 hours after iv (10 mg/kg in glycerin). Plasma samples
were obtained by centrifuging the blood samples to take the supernatant. Plasma samples
were prepared according to sample preparation, and detection was performed using the
UPLC-MS/MS condition mentioned above. The PK results (including t
1/2 , T
max , C
max , AUC0-t
, AUC0-∞ , AUC0-t /0-∞ ) were analyzed based on the noncompartmental method by PK solver software (version
2.0, China Pharmaceutical University).
Tissue Distribution
For tissue distribution study, the SD rats were randomly divided into three groups
(n = 5). Various tissue samples (heart, liver, small intestine, kidney) were collected
at 10 minutes, 30 minutes, and 120 hours after po of 0.1 g/kg of effective parts,
which is the lowest dose that could be quantified in the tissue. Subsequently, the
tissues were immediately rinsed with normal saline to remove the blood or other content
and blotted dry with filter paper. The accurately weighed tissues were homogenized
using a tissue homogenizer in normal saline (four times the tissue weight) and stored
at −80°C until analysis. The tissue samples were operated with the same procedure
as described in section “Preparation of Plasma and Tissue Sample Containing IS”.
Results and Discussion
UPLC and MS/MS Condition Optimization
To obtain suitable chromatographic results, a series of chromatographic conditions
were tested and selected for the standards, including analysis time, peak shape, and
response intensity. The results showed that acetonitrile had high efficiency as an
organic phase. The best separation effect was achieved with 0.1% aqueous formic acid
as the aqueous phase.
The standard solution was injected into the mass spectrometer only, for scan with
positive ion mode and negative ion mode, respectively. The mass spectrum showed that
the positive ion mode could give better results. The target was to select the precursor
ion and the product ion after detection in positive ion mode. The UPLC-MS/MS method
established in this study has better sensitivity than the previously reported HPLC,
and is suitable for the detection of biological samples or samples with low content.
At the same time, the new method greatly reduces the detection time. The MS/MS spectra
of isoeleutherin, eleutherin, and eleutherol are shown in [Fig. 2 ].
Fig. 2 Product ion mass spectra of (A ) isoeleutherin, (B ) eleutherin, and (C ) eleutherol.
There were no reports of the method of internal standard yet. 2-Methoxy-1,4-naphthoquinone,
betamethasone, and 5-hydroxy-1,4-naphthoquinone were selected as candidates. The experiment
showed that the response of 5-hydroxy-1,4-naphthoquinone in QC samples was too low,
as shown in [Fig. 3A ]. The retention time of 2-methoxy-1,4-naphthoquinone was far from the retention time
of the target compound ([Fig. 3B ]). By comparing the retention time and intensity of the response of the three compounds,
betamethasone, an anti-inflammatory drug, was selected as internal standard.
Fig. 3 Typical MRM chromatograms of (A ) 5-hydroxy-1,4-naphthoquinone in blank plasma samples; (B ) 2-methoxy-1,4-naphthoquinone in blank plasma samples; and (C ) betamethasone in blank plasma samples. MRM, multiple reaction monitoring.
Selectivity
The typical MRM chromatograms of the blank sample, isoeleutherin, eleutherin, eleutherol,
and IS in blank plasma samples and plasma samples are shown in [Fig. 4 ]. There was no overlap or interaction at the retention time of compounds and IS.
Isoeleutherin, eleutherin, eleutherol, and IS are approximate at 2.35, 2.53, 3.02,
and 1.37 minutes, respectively. The UPLC-MS/MS method was shown to have acceptable
selectivity.
Fig. 4 Typical MRM chromatograms of isoeleutherin, eleutherin, and eleutherol and IS in
rat plasma. (A ). MRM chromatograms of blank plasma; (B ) MRM chromatograms of blank plasma spiked with the three analytes at 24.9, 50, 192
ng/mL and IS; and (C ) MRM chromatograms of plasma sample collected at 4 hours after oral administration
of naphthoquinone in Bulbus eleutherinis (50 mg/kg). IS, internal standard; MRM, multiple reaction monitoring.
Calibration, Linearity, LLOQ, and Detection
The calibration curves of isoeleutherin, eleutherin, and eleutherol in plasma and
various tissue homogenates are displayed in [Table 1 ]. The calibration curves of the above three compounds showed qualified linearity
(r = 0.9983–0.9997). The LLOQ for all analytes were 1.00, 3.84, and 0.498 ng/mL. The
results confirmed that their linear ranges met the requirements of PK.[23 ]
Table 1
Calibration curves and linear ranges of the analytes (n = 6)
Analyte
Calibration curve
r
Linear range (ng/mL)
LLOQ (ng/mL)
Plasma
Isoeleutherin
y = 0.1989x + 0.0753
0.9983
1–200
1
Eleutherin
y = 0.0478x + 0.0022
0.9987
3.84–768
3.84
Eleutherol
y = 0.6355x − 0.0942
0.9997
0.498–99.6
0.498
Heart
Isoeleutherin
y = 0.1689x + 0.0409
0.9989
1–20
1
Eleutherin
y = 0.0362x + 0.0015
0.9991
3.84–76.8
3.84
Eleutherol
y = 0.7075x + 0.0758
0.9995
0.498–9.96
0.498
Liver
Isoeleutherin
y = 0.1819x + 0.0533
0.9993
1–20
1
Eleutherin
y = 0.0412x + 0.0023
0.9994
3.84–76.8
3.84
Eleutherol
y = 0.6012x + 0.0104
0.9997
0.498–9.96
0.498
Small intestine
Isoeleutherin
y = 0.1605x + 0.0592
0.9999
1–20
1
Eleutherin
y = 0.0325x + 0.0051
0.9990
3.84–76.8
3.84
Eleutherol
y = 0.5202x + 0.0405
0.9988
0.498–9.96
0.498
Renal
Isoeleutherin
y = 0.1701x − 0.01537
0.9991
1–20
1
Eleutherin
y = 0.0352x + 0.0041
0.9990
3.84–76.8
3.84
Eleutherol
y = 0.5212x − 0.0321
0.9999̀
0.498–9.96
0.498
Abbreviation: LLOQ, lower limit of quantification.
Recovery and Matrix Effect
As shown in [Table 2 ], LLOQ samples and three concentrations of QC samples in plasma were selected to
determine the recoveries and matrix effects. The mean recoveries of isoeleutherin,
eleutherin, and eleutherol were 87.41–103.39, 97.90–99.79, and 89.55–103.33%, respectively.
The matrix effects of the three compounds in plasma ranged from 89.62 to 113.08%.
The extraction recoveries and matrix effect for the three analytes (at three different
QC concentrations) and IS in various tissues are shown in the Supporting Information
([Tables S1 ] and [S2 ] [online only]). The results showed that the recoveries and matrix effect of the
three analytes in the tissue homogenate ranged from 85 to 115%. It indicated that
the matrix effect and recovery was insignificant under current processing methods.[23 ]
Table 2
Recovery and matrix effect of isoeleutherin, eleutherin, and eleutherol in rat plasma
(n = 6)
Analyte
Concentration
(ng/mL)
Recovery (%)
Matrix effect (%)
Mean
RSD
Mean
RSD
Isoeleutherin
1
103.39
9.99
98.11
6.20
2
96.98
7.13
99.15
4.18
50
87.41
7.60
97.92
4.25
150
98.60
5.30
102.68
3.59
Eleutherin
3.84
99.79
9.36
110.69
6.83
7.68
98.27
6.39
106.62
3.49
192
97.90
9.46
113.08
4.30
576
98.14
6.21
108.40
6.09
Eleutherol
0.498
103.33
8.06
89.62
10.87
0.996
99.84
6.82
98.67
2.91
24.9
89.55
7.81
95.19
5.19
74.7
102.04
7.89
97.87
4.59
Abbreviation: RSD, relative standard deviation.
Precision and Accuracy
The results of precision and accuracy in plasma were obtained by measuring four concentrations
of QC samples. The results are shown in [Table 3 ]. The precision of each analyte was below 13.04%. At the same time, the accuracy
of each analyte was acceptable, ranged from 91.56 to 110.75%. The results of precision
in various tissues are presented in the Supporting Information ([Table S3 ], online only). The results show that the precision of the three analytes in the
tissue homogenate is within ± 15%, indicating the stability and high reliability of
the method.[23 ]
Table 3
Precision and accuracy of isoeleutherin, eleutherin, and eleutherol in rat plasma
Analyte
Spiked concentration (ng/mL)
Intra-batch (n = 6)
Inter-batch (n = 6 × 3)
Measured concentration (mean ± SD, ng/mL)
Precision
(RSD, %)
Accuracy
(RE, %)
Measured concentration (mean ± SD, ng/mL)
Precision
(RSD, %)
Accuracy
(RE, %)
Isoeleutherin
1
0.98 ± 0.04
4.58
97.92
1.10 ± 0.11
10.28
110.75
2
2.017 ± 0.13
6.52
100.29
2.03 ± 0.29
5.88
100.50
50
50.30 ± 1.16
2.30
100.60
52.37 ± 2.80
5.34
104.75
150
148.08 + 3.97
2.68
98.72
151.67 ± 14.73
9.71
101.11
Eleutherin
3.84
3.61 ± 0.06
1.53
94.10
3.52 ± 0.40
11.25
91.56
7.68
7.35 ± 0.15
2.06
95.73
7.86 ± 0.70
8.88
102.28
192
211.5 ± 20.17
9.54
110.17
199.63 ± 26.03
13.04
103.97
576
596.33 ± 20.45
3.43
103.53
585.79 ± 68.95
11.77
101.70
Eleutherol
0.498
0.52 ± 0.05
9.27
105.07
0.51 ± 0.05
9.52
102.03
0.996
1.02 ± 0.05
4.82
102.59
0.97 ± 0.06
6.03
97.23
24.9
25.85 ± 0.42
1.64
103.83
25.55 ± 1.32
5.16
102.62
74.7
79.04 ± 3.85
4.87
105.81
74.42 ± 4.67
6.28
99.63
Abbreviations: RSD, relative standard deviation; RE, relative error; SD, standard
deviation.
Stability
Stabilities of the three compounds in plasma were determined under different conditions.
As shown in [Table 4 ], after three freeze–thaw cycles, the analytes displayed excellent stability in plasma
(104.28–114.61%). Simultaneously, insignificant changes were found at 4°C for 8 hours
(98.18–110.42%) and at 25°C for 6 hours (87.83–114.62%), suggesting that the three
compounds have good stability under the tested conditions.[23 ]
Table 4
Stability of isoeleutherin, eleutherin, and eleutherol in rat plasma (n = 5)
Analyte
Concentration (ng/mL)
Content Change (%)[a ]
Content Change (%)[b ]
Content Change (%)[c ]
Isoeleutherin
2
95.51
104.28
107.06
50
101.39
111.96
110.42
150
99.28
110.81
108.16
Eleutherin
7.68
87.83
113.86
98.18
192
105.41
104.47
109.05
576
103.61
109.12
104.50
Eleutherol
0.996
94.39
106.87
107.55
24.9
114.62
114.61
105.66
74.7
99.26
113.73
104.34
a QC samples were stored at 25°C for 6 hours.
b QC samples were stored at freeze–thaw cycles.
c QC samples were placed at 4°C for 8 hours in the autosampler.
Pharmacokinetic Study
As shown in [Fig. 5 ], the plasma concentration curve of the three active compounds in Bulbus eleutherinis was obtained using a verified detection method after oral and intravenous administration.
The mean PK parameters are displayed in [Table 5 ]. The half-lives (t
1/2 ) of isoeleutherin, eleutherin, and eleutherol were 6.11, 7.30, and 3.07 hours, respectively.
Their absolute oral bioavailabilities were 5.38, 4.64, and 2.47%, respectively. The
results showed that they reached the maximum concentration in a short time. However,
their bioavailability is low. According to the results, there is a possibility that
most of the active ingredients do not enter the body circulation in the intestinal
tract but are directly excreted, so follow-up research on the absorption mechanism
and in vivo metabolism of the three active ingredients is necessary.
Fig. 5 Mean plasma concentration–time curves of three analytes after intravenous administration
(10 mg/kg) and oral administration (50 mg/kg) to rats. Data are presented as mean ± standard
deviation (n = 6).
Table 5
Pharmacokinetic parameters of naphthoquinone in Bulbus eleutherinis in SD rats
PK parameters
Isoeleutherin
Eleutherin
Eleutherol
iv
Po
iv
po
iv
po
t
1/2 (min)
279.686 ± 99.05
366.55 ± 59.43
330.09 ± 70.64
489.11 ± 110.76
126.86 ± 13.83
184.03 ± 39.77
T
max (min)
–
15 ± 0
–
25 ± 8.90
–
20 ± 7.07
C
max (ng/mL)
631.96 ± 9.49
24.50 ± 3.26
1,739.13 ± 89.01
76.87 ± 12.83
543.39 ± 22.47
28.32 ± 7.10
AUC0-t
(ng/mL × min)
18,649.22 ± 1,229.65
4,525.88 ± 901.29
60,089.26 ± 2,218.14
13,789.47 ± 4,764.36
17,629.90 ± 3,727.02
2,047.63 ± 684.88
AUC0-∞ (ng/mL × min)
18,799.83 ± 1,307.42
5,059.32 ± 835.31
62,948.35 ± 4,078.59
15,189.65 ± 2,579.49
17,925.43 ± 3,744.45
2,209.46 ± 655.16
AUC0-t /0-∞
0.992 ± 0.003
0.900 ± 0.02
0.963 ± 0.03
0.907 ± 0.017
0.984 ± 0.003
0.920 ± 0.033
Abbreviations: AUC 0-t
, the area under the curve (0–t ); AUC0-∞ , the area under the curve (0–∞); AUC0-t /0-∞ , the area under the curve (0–t )/(0–∞); C
max , maximum concentration; iv, intravenous; PK, pharmacokinetic; po, oral; t
1/2 , half-life; T
max , peak time.
Tissue Distribution
The measurement results in the tissue are all within the standard curve range. The
overview of the tissue distribution of the three components is shown in [Fig. 6 ]. The content of isoeleutherin in the liver and intestine is relatively high, and
the content begins to decrease after 30 minutes. The content of eleutherin is less
in the kidney, the content of eleutherin is higher in the small intestine, and the
content reaches the highest in the kidney at 30 minutes; the distribution of eleutherol
in the tissues of eleutherin is similar, and the content of both the small intestine
and the kidney is similar. The highest is reached at 30 minutes. All the three components
reached the highest concentration in the heart at 10 minutes, indicating that the
drug can take effect in a short time.
Fig. 6 The distributed amount of three analytes at 10, 30, and 120 minutes after oral administration
to rats. Data are presented as mean ± standard deviation (n = 6).
