In HepG2 cells, diosmetin produced an approximately 30 μM IC50 in a 96-hour MTT assay. The reported IC50 was similar with and without α-naphthoflavone, while luteolin was more active. Thus, the cellular MTT response cannot be attributed solely to CYP1A-dependent conversion. [2]
Diosmetin inhibition of recombinant CYP1 EROD activity
Biochemical assay · Human recombinant CYP1A1 and CYP1B1 supersomes; 7-ethoxyresorufin O-deethylation assay [1]
Diosmetin reduced this probe-substrate reaction. Reported Ki estimates were calculated from IC50 and substrate kinetic parameters; they are not direct binding constants or evidence of inhibition of every CYP1 reaction.
Literature-Reported Treatment Conditions
- Treatment concentration
- 0.0025–25 μM flavonoid range
- Exposure duration
- 15 min at 37 °C
- Method
- Fluorescence quantification of resorufin; IC50-derived Ki using Ki = IC50/(1 + [S]/Km).
- Vehicle
- DMSO stock solutions; final DMSO percentage not specified.
- Co-treatment
- No drug combination.
- Reported limits
- Fixed 7-ethoxyresorufin concentration used for each inhibition curve and final vehicle fraction are not specified in §4.2; no independent recalculation of Ki is claimed.
Methods and source locations
Compound reported in the paper: Diosmetin; Compound label in the paper: Diosmetin
Evidence concerns the reported diosmetin aglycone; no salt conversion or Adooq lot equivalence is established.
Table 1; §2.1, §2.3.1 and §4.1–4.2; Figure 1 caption
Inhibition of CYP1A1-catalyzed EROD activity: Calculated from inhibition curves; at least n = 3 determinations (Table 1). — Table 1, diosmetin row; §2.1 and §4.2
Inhibition of CYP1B1-catalyzed EROD activity: Calculated from inhibition curves; at least n = 3 determinations (Table 1). — Table 1, diosmetin row; §2.1 and §4.2
Formation of luteolin from diosmetin in HepG2 cells
Cell-based study · Human hepatoma HepG2 cells [2]
A metabolite coeluting with luteolin appeared after diosmetin exposure. Formation was attenuated by α-naphthoflavone, supporting a CYP1A contribution under these conditions rather than proving an exclusive enzyme mechanism.
Literature-Reported Treatment Conditions
- Treatment concentration
- 30 μM diosmetin for Figures 2–3
- Exposure duration
- 0, 12 and 30 h sampling
- Method
- Reversed-phase HPLC with authentic standards and a 0.4 μM luteolin spike for the coelution check.
- Vehicle
- DMSO stock diluted in DMEM; final DMSO percentage not stated for this assay.
- Co-treatment
- Parallel exposure with the CYP1A inhibitor α-naphthoflavone as a mechanistic control.
- Reported limits
- α-Naphthoflavone concentration for Figure 3 is not specified in its caption or §2.5; concentrations from the MTT or cell-cycle assays are not transferred.
Methods and source locations
Compound reported in the paper: Diosmetin; Compound label in the paper: Diosmetin
Evidence concerns the reported diosmetin aglycone; no salt conversion or Adooq lot equivalence is established.
§2.1, §2.5, §2.7, §3.1–3.3; Figures 2–3
Luteolin-like metabolite formation and attenuation by CYP1A inhibitor: Figures 2–3; n=3 determinations/experiments, error bars SD. No exact concentrations digitized from bars. — §3.2–3.3; Figures 2A–C and 3A–B; §2.5 and §2.7
Diosmetin and luteolin concentration responses in HepG2 cells
Cell-based study · Human hepatoma HepG2 cells; MTT endpoint [2]
Diosmetin showed an approximately 30 μM IC50 in the presence and absence of α-naphthoflavone. Luteolin was more active in the same assay. The unchanged diosmetin IC50 limits a simple claim that CYP1A metabolism is required for this MTT response.
Literature-Reported Treatment Conditions
- Treatment concentration
- 0.078–40 μM flavonoid range
- Exposure duration
- 96 h
- Method
- MTT assay, parallel diosmetin and luteolin concentration-response series, with and without α-naphthoflavone.
- Vehicle
- Final vehicle percentage for Figure 5 is not stated; 0.1% DMSO from other assays is not assigned here.
- Co-treatment
- α-Naphthoflavone control at 0.5–1 μM per §2.8. Separate diosmetin-plus-luteolin combination panels are not adopted as single-compound evidence.
- Reported limits
- Figure 5 does not specify the final vehicle percentage or exact α-naphthoflavone concentration for each single-agent panel.
Methods and source locations
Compound reported in the paper: Diosmetin; Compound label in the paper: Diosmetin
Evidence concerns the reported diosmetin aglycone; no salt conversion or Adooq lot equivalence is established.
§2.1, §2.8–2.9, §3.5; Figure 5A–B and shared caption
Inhibition of the MTT-based cellular proliferation/viability endpoint: Values reported in §3.5; Figure 5A–B viewed. n=3 experiments, error bars SD; no curve-derived extra precision. — §3.5; Figure 5A–B and caption; §2.8
