Table 1.
Liquorice compounds, mechanisms of action and potential clinical use.
| Compound (Numbers refer to the compound numbers in Figure 2) |
Pharmacological group | Therapeutic actions | Potential clinical use |
|---|---|---|---|
| Liquorice root extract | Flavonoids, isoflavonoids, triterpenoids, chalcones as aglycones or their O-glucosides |
• Antioxidant, lipid peroxidation
19
• Inhibition of opioid tolerance (α2A-adrenoceptor antagonism) 56 |
Postoperative sore throat* Laxative* Expectorant* Psoriasis & eczema* |
| Glycyrrhizinic acid, glycyrrhizin, GLA, 1 | Triterpenoid saponin | • Antiviral 9,11
• Neuroprotective 8 (HMGB1 inhibition) • Anti-inflammatory & antinociceptive 23-37 (Cox-2 inhibition via NF-κB, PI3K, mPGE, 11β-HSD, HMGB1 inhibition) • Inhibition of opioid tolerance and OIH 54 (HMGB1 inhibition) • Reduction of NP, anxiety and depression 60-61 (inhibition of HMGB1) • Anticancer 16 |
Chronic hepatitis C* SARS COVID-19 Scaffold for the synthesis of anticancer drugs Rheumatoid arthritis Endometriosis Ischaemic brain injury |
| Isoliquiritin, 2 | trans-Chalcone O-glucoside | • Antidepressant 62-64
(increased 5-HT & NA) • Antihyperalgesic, antiallodynic effects in NP 22 (spinal 5-HT) |
Analgesia |
| Glycyrrhetic acid, glycyrrhetinic acid, enoxolone, GRA, 3 Carbenoxolone, 4** | Triterpenoid Semisynthetic triterpenoid |
• Anti-inflammatory and anticancer
24
(inhibition of COX-2 via 11β-HSD)
• Antinociception 42 (tachykinin receptor antagonism) • Lowering of intracellular cortisol and enhancement of insulin sensitivity 71 (inhibition of 11β-HSD) |
Diabetes type 2* |
| Glabridin, 5 | Isoflavane-type isoflavonoid | • Anti-inflammatory
46
• Antinociception 46 (activation of BKCa channels, downregulation of NO and TRPV channels) |
|
| Licochalcone A, 6 | trans-Chalcone | • Anti-inflammatory 31 (COX-2 inhibition) | |
| Isoliquiritigenin, 7 | trans-Chalcone | • Anti-inflammatory
30
(COX-2 inhibition) • Antinociception 45 (inhibition of Nav-channels) |
|
| Liquiritin, 8 | Flavanone O-glucoside | • Anti-inflammatory
48
(downregulation of proinflammatory cytokines, upregulation of the anti-inflammatory cytokine IL-10) • Antidepressant 62,63 (increased 5-HT & NA) • Antihyperalgesic, antiallodynic 48 (inhibition of astrocyte and microglia activation, axon and myelin sheath repair) |
11β-HSD = 11β-hydroxysteroid dehydrogenase; HMGB1, high mobility group box 1; NA, noradrenaline; NP, neuropathic pain, OIH, opioid-induced hyperalgesia; mPGE, microsomal prostaglandin E.
*Already in clinical use/positive RCTs
**
licenced drug for Diabetes type 2 in the UK