1. Simultaneous Extraction and Separation of Liquiritin, Glycyrrhizic Acid, and Glabridin from Licorice Root with Analytical and Preparative Chromatography
Minglei Tian, Hongyuan Yan, and Kyung Ho Row*. Biotechnology and Bioprocess Engineering 2008, 13: 671-676
Licorice, the root of the glycyrrhiza plant species, has been used medicinally for more than 4,000 years. It is a Chinese herb commonly used as an expectorant and to arrest coughing, reduce fever, comfort the stomach, alleviate urgency, and potentiate the effects of various other herbs. Liquiritin (LQ) (Fig. 1A) is has anti-viral properties and antioxidative properties  and is the most prevalent flavonoids in licorice. Glycyrrhizic acid (GA) (Fig. 1B), the most studied active constituent in licorice, is a sweet-tasting material. It is 50 times sweeter than sugar and is widely used as a sweetening additive in the food industry. GA has anti-inflammatory, anti-ulcer, anti-hepatotoxic, and antivirus activities. In many countries, it is used as a major therapeutic agent to treat allergic dermatitis and chronic viral hepatitis. Glabridin (Fig. 1C) is another active component in licorice. It exhibits multiple pharmacological activities, such as antimicrobial activity, cytotoxic activity, and estrogenic and anti-proliferative activity against human breast cancer cells. It also effects on low-density lipoprotein oxidation, melanogenesis, and inflammation and protects mitochondrial functions from oxidative stresses.
2. Copy number variations of functional genes inﬂuence contents of glycyrrhizic acid in Glycyrrhiza uralensis
Ying Liu • Xin-Jie Zhan • Wen-Dong Li. Acta Physiol Plant (2014) 36:1433–1440
Among the components in G. uralensis, glycyrrhizic acid is believed to be the marker active compound. Previous studies have shown that glycyrrhizic acid possesses various biological activities, such as anti-inﬂammatory, antitumor and immune-stimulating activities (Cherng et al. 2004;Hoever et al. 2005; Sasaki et al. 2002;Shibata 2000; Van Rossum and Vulto 1999). However, the content level of glycyrrhizic acid inmost of theG. uralensis cultivars failed to meet the requirement of Chinese pharmacopoeia. Therefore, it is valuable to develop genetically modiﬁed G. uralensis cultivars with enhanced glycyrrhizic acid accumulation.
3. Glycyrrhizic acid (GCA) as 11b-hydroxysteroid dehydrogenase inhibitor exerts protective effect against glucocorticoid-induced osteoporosis
Elvy Suhana Mohd Ramli • Farihah Suhaimi . J Bone Miner Metab (2013) 31:262–273
Liquorice (glycyrrhiza) is a tall erect perennial plant with pinnate leaves foliage of bluish-purple ﬂowers. Glycyrrhizic acid isolated from the licorice root is the main active component of licorice. It is widely applied as sweetener in food and chewing tobacco. It is metabolized to glycyrrhetinic acid, which inhibits 11b-hydroxysteroid dehydrogenase and other enzymes involved in the metabolism of corticosteroids. Glycyrrhetinic acid is 200–1000 times more potent as an inhibitor of 11β-hydroxysteroid dehydrogenase compared to glycyrrhizic acid. Carbenoxolone is a synthetic derivative of glycyrrhetinic acid and inhibits both the 11b-HSD isoenzymes. Studies by Cooper et al. have shown that carbenoxoone treatment did not affect to bone formation markers but signiﬁcantly reduced a bone resorption marker, pyridinoine. However, short term exposure to high levels of glucocorticoids did not change the pyridinoline level. The resorption marker was found to be reduced by blocking osteoclastic 11β-HSD1 activity. Eijken et al. reported that 11β-HSD1 reductase activity was blocked by 18β-glycyrrhetinic acid (GA) in vitro.
4. Development of a monoclonal antibody-based enzyme-linked immunosorbent assay for the analysis of glycyrrhizic acid
Jing Zhao & Gang Li & Bao-min Wang & Wei Liu. Anal Bioanal Chem (2006) 386:1735–1740
Glycyrrhizic acid is a marker of quality for Glycyrrhiza materials. Mizutani et al. reported a MAb-based ELISA for the analysis of GL. The immunogen was synthesized by the NaIO4 method. The polysaccharide residue in the glucuronic acid molecules is specifically oxidized at adjacent hydroxyl residues leaving reactive aldehyde groups. Reductive animation proceeds between the aldehyde group(s) and free amino group(s) of the protein. In our study, the MAb was derived with an immunogen (GL–BSA) conjugated by the active ester method. The two new icELISAs are approximately 20- to 100-fold more sensitive than that reported by Mizutani et al.. The results showed that our immunogen evoked a high-quality antibody against GL.