Table 1 Recombinant human monoamine oxidase (hMAO) inhibitory activity of isoliquiritigenin and its enzyme kinetic parameters.

From: Isoliquiritigenin, a potent human monoamine oxidase inhibitor, modulates dopamine D1, D3, and vasopressin V1A receptors

Compounds

hMAO-A

hMAO-B

SId

IC50†

Kib

Inhibition typec

IC50†

Kicb

Kiub

Inhibition typec

Isoliquiritigenin

0.68 ± 0.03

0.16 ± 0.00

Competitive

0.33 ± 0.02

0.094 ± 0.00

0.71 ± 0.01

Mixed

2.06

l-Deprenyl⋅HCla

13.84 ± 2.14

–

–

0.11 ± 0.002

–

–

–

125.81

Clorgyline⋅HCla

0.02 ± 0.00

–

–

–

–

–

–

–

  1. ND: not determined; (–): not tested.
  2. †The IC50 value (μM) was calculated as mean ± standard deviation of triplicate assays.
  3. aPositive control, expressed as µM.
  4. bThe hMAO inhibition constants (Ki) were obtained from secondary plots.
  5. chMAO inhibition type was determined using Lineweaver–Burk and Dixon plots.
  6. dThe selectivity index (SI) was determined as the ratio of IC50 for hMAO-A inhibition to IC50 for hMAO-B inhibition.
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