Licorice

Effects on Enzymes

UGT Enzyme	Effects	Strength	Dosage	Verified in Man
UGT1A1	Inhibition by Isoliquiritigenin	95.2% [3]	100 μM	?
UGT1A1	Inhibition by Liquiritigenin	K(i) 9.1 μM [1]	?	?
UGT1A3	Inhibition by Glycyrrhetinic acid	K(i) 0.2  μM [2]	?	?
UGT1A3	Inhibition by Isoliquiritigenin	76.1% [3]	100 μM	?
UGT1A6	Inhibition by Isoliquiritigenin	78.9% [3]	100 μM	?
UGT1A7	Inhibition by Isoliquiritigenin	87.2% [3]	100 μM	?
UGT1A8	Inhibition by Isoliquiritigenin	67.2% [3]	100 μM	?
UGT1A9	Inhibition by Isoliquiritigenin	94.8% [3]	100 μM	?
UGT1A9	Inhibition by Liquiritigenin	K(i) 3.2 μM [1]	?	?
UGT1A10	Inhibition by Isoliquiritigenin	91.7% [3]	100 μM	?
UGT2B7	Inhibition by Glycyrrhetinic acid	K(i) 1.7 μM [2]	?	?
P450 Enzyme	Effects	Strength	Dosage	Verified in Man
CYP2B6	Inhibition by Glabridin	63%[5][4]	30 μM	?
CYP2C9	Inhibition by Glabridin	50%1[5]	100 μM	?
CYP2C19	Inhibition	?	?	?
CYP2D6	Inhibition from root extract	70%[6]	IC50=515 μM/ml	?
CYP2D6	Inhibition by Glabridin	15%[5]	100 μM	?
CYP2E1	No inhibition by Glabridin	0%[5]	100 μM	?
CYP3A4	Inhibition from root extract	>70%[6]	IC50=345 μM	?
CYP3A4	Inhibition by Glabridin	54%[5]	10 μM	?

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Bibliography

1. Deglycosylation of Liquiritin Strongly Enhances its Inhibitory Potential Towards UDP-Glucuronosyltransferase (UGT) Isoforms.

Guo B, Fan XR, Fang ZZ, Cao YF, Hu CM, Yang J, Zhang YY, He RR, Zhu X, Yu ZW, Sun XY, Hong M, Yang L. PubMed: PMID: 23065713

2. Glycyrrhetinic Acid Exhibits Strong Inhibitory Effects Towards UDP-Glucuronosyltransferase (UGT) 1A3 and 2B7.

Huang YP, Cao YF, Fang ZZ, Zhang YY, Hu CM, Sun XY, Yu ZW, Zhu X, Hong M, Yang L, Sun HZ. PubMed: PMID: 23148031

3. Isoliquiritigenin showed strong inhibitory effects towards multiple UDP-glucuronosyltransferase (UGT) isoform-catalyzed 4-methylumbelliferone (4-MU) glucuronidation.

Lu H, Fang ZZ, Cao YF, Hu CM, Hong M, Sun XY, Li H, Liu Y, Fu X, Sun H. PubMed: PMID: 23237733

4. Shufeng Zhou, Hwee-Ling Koh, Yihuai Gao,

Zhi-yuan Gong, Edmund Jon Deoon Lee; Herbal bioactivation: The good, the bad and the ugly; Life Sciences 74 (2004) 935 – 968; April 2003; DOI:10.1016/j.lfs.2003.09.035 (Download Attached PDF Document)

5. The licorice root derived isoflavan glabridin inhibits the activities of human cytochrome P450S 3A4, 2B6, and 2C9.

Kent UM, Aviram M, Rosenblat M, Hollenberg PF. PubMed: PMID: 12019199

6. CYP3A4 and CYP2D6 inhibitory activities of Indonesian medicinal plants.

Usia T, Iwata H, Hiratsuka A, Watabe T, Kadota S, Tezuka Y. PubMed PMID: 16360935

Footnotes

1. Glabridin shows competitive inhibition of CYP2C9.