Figures
![Figure 1.](/tables/JFB-19-0136-g001.jpg)
Figure 1. Stability of apigenin in transport buffer solution at pH 7.4 incubated over 180 min at 37 °C. Stock solution of apigenin was diluted to a final concentration of DMSO (0.4%) in transport buffer solution containing HBSS supplemented with 1.8 mM CaCl2 and 100 µM ascorbic acid.
![Figure 2.](/tables/JFB-19-0136-g002.jpg)
Figure 2. Passage of phenol red across Caco-2 cell monolayers after 1 h incubation. DMEM containing phenol red was applied to the apical compartment whereas PBS was loaded to the basolateral compartment, then incubated for 1 h at 37 °C.
![Figure 3.](/tables/JFB-19-0136-g003.jpg)
Figure 3. LC-ESI-MS/MS spectra of apigenin (a) and generated metabolite (b) detected in the basolateral compartment after incubation of bioaccessible apigenin prepared in modified HBSS on the apical compartment.
![Figure 4.](/tables/JFB-19-0136-g004.jpg)
Figure 4. LC-ESI-MS/MS spectra of apigenin (a) and generated metabolite (b) detected in the apical compartment after incubation of bioaccessible apigenin prepared in modified HBSS on the basolateral compartment.
![Figure 5.](/tables/JFB-19-0136-g005.jpg)
Figure 5. Transport of apigenin and its metabolite across Caco-2 cell monolayers from apical to basolateral (a→b) and basolateral to apical (b→a) directions.
Tables
Table 1. LC-MS/MS of apigenin and its metabolite formed after incubation using Caco-2 cells monolayer as a model of the human intestinal epithelium
Peak | Compound | Retention time (min) | Theoretical [M-H]− (m/z) | Experimental [M-H]− (m/z) | Fragment ion [M-H]− (m/z) |
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1 | Apigenin | 17.29 | 269.0467 | 269.0498 | 176.9943 112.9858 68.9968 |
2 | Apigenin glucuronide | 14.86 | 445.0849 | 445.0767 | 269.0453 217.0033 141.0168 113.0241 |
Table 2. Metabolism of apigenin by Caco-2 cells
Metabolite | Transport | Metabolite production (pmol/cm2·min) |
---|
Apical | Basolateral |
---|
The culture incubated for 2 h in the presence of bioaccessible apigenin. a→b indicates the transport of compounds from apical to basolateral, b→a indicates the transport of compounds from basolateral to apical. a: Apical; b: Basolateral |
Apigenin | a→b | 51.33 ± 2.08 | 27.99 ± 1.40 |
b→a | 37.29 ± 1.94 | 43.65 ± 2.22 |
Apigenin glucuronide | a→b | 4.61 ± 0.56 | 5.71 ± 0.48 |
b→a | 6.55 ± 0.87 | 5.31 ± 0.52 |