Licorice flavonoids

IX. ANTI-HELICOBACTER PYLORI ACTIVITY OF LICORICE FLAVONOIDS... 

Okuda et al. have reported that some licorice flavonoids, isolico-flavonol (171), glycycoumarin (172), licochalcones A and B (213 and 214), glycyrrhisoflavone (250) and licopyranocoumarin (256), inhibit the cytopathic activity of HIV (427). Shibata et al. have reported that licochalcone A (213) shows anti-tumor promoting activity in a two-stage mouse skin carcinogenesis experiment (428). Inhibitory activity of... 

Chalcones are one of the classes of flavonoids well known for their antiplasmodial properties. Licochalcone A (65), isolated from Chinese licorice roots, was shown to display strong in vitro activity against both chloroquine-susceptible (3D7) and chloroquine-resistant (Dd2) P. falciparum strains it also displayed a strong in vivo acitivity in mice infected with P. yoelii, when administered intraperitoneally or orally for 3 to 6 days. The compound appeared to inhibit the growth of the parasites at all stages (rings, trophozoites, and schizonts). Although licochalcone and some derivatives interred the clinical trials as anti-malarials, none of them have ever made it to the market due to severe toxicity observed in phase II clinical trials. 

Kitagawa, I. et al.. Chemical studies of Chinese licorice-roots. I. Elucidation of five new flavonoid constituents from the roots of Glycyrrhiza glabra collected in Xinjiang, Chem. Pharm. Bull., 42, 1056, 1994. 

Flatano, T. et al., Acylated flavonoid glycosides and accompanying phenolics from licorice. 

Table 16.2 lists more than 80 examples of new isoprenylated chalcones reported in the period 1992 to 2003 (see also Figure 16.7). Almost half of the compounds described here are from the Leguminosae, a trend that is also evident in earlier surveys. Other plant families that are well represented in Table 16.2 are the Moraceae and the Cannabinaceae. The literature on isoprenylated flavonoids in general has been reviewed by Barron and Ibrahim to the end of 1994 57 jjjg phenolic constituents of Glycyrrhiza species (licorice), among which are many isoprenylated chalcones, were the subject of an extensive review that includes literature published up to the end of 1996. Nomura and Hano have reviewed the literature on isoprenylated phenolic compounds of the Moraceae to the end of 1993. More recent descriptions of isoprenylated flavonoids are available for the hop plant, Humulus lupulus (Cannabinaceae),and the Moraceae genera Artocarpus and Dorstenia. ... 

Han, S.J., Ryu, S.N., and Kang, S.S., A new 2-arylbenzofuran with antioxidant activity from the black colored rice (Oryza sativa L.) bran. Chemical Pharmaceutical Bulletin, 52, 1365, 2004. Hatano, T. et al.. Minor flavonoids from licorice. Phytochemistry, 55, 959, 2000. 

Hatano T, Kagawa H, Yasuhara T, Okuda T. Two new flavonoids and other constituents in licorice root their relative astringency and radical scavenging effects. Chemical Pharmaceulical Bulletin. 1988 36(6) 2090-2097. 

We also screened anti-MRSA flavonoids [115] in the course of the study of anti-Helicobacter pylori flavonoids from licorice described in Chapter X. In our screening (Table 6), glabrene (24), licoisoflavone B (67), and gancaonin I (126) also exhibited anti-MRSA effect. Among these compounds, 23, 24, 27, 59, 61, 62, 63, 67, and 126 exhibited relatively high anti-bacterial activities against B. subtilis (HI7), Table 7. 

The simple chalcone 70 has distributed widely in Glycyrrhizin plants as a minor constituent, and its glycosides are main flavonoids of licorice as described in Chapter 1. Recently, Okuyama et al. reported inhibition effect of the chalcone (70) on azoxymethane-induced murine colon aberrant crypt foucus formation and carcinogenesis [116]. 

Liu B, Yang J, Wen Q, Li Y. 2008. Isoliquiritigenin, a flavonoid from licorice, relaxes guinea-pig tracheal smooth muscle in vitro and in vivo Role of cGMP/PKG pathway. Eur J Pharmacol 587 257-266. 

Aviram, M., Vaya, J., and Fuhrman, B., Licorice root flavonoid antioxidants reduce LDL oxidation and attenuate cardiovascular diseases, in Herbal medicines Molecular basis of biological activity and health, Packer L., Halliwel B., and Nam Qng, C. (eds.), Marcel Dekker, New York, 27, 595, 2004. 

Those that have been identified in recent times include flavonoids,212-214 aurothiomalate,215 hydrangenol,216 occurring in the leaves of Hydrangea, tannins,217 derivatives of tranilast,218 curcumin,219 an extract of the spice turmeric, glycyrrhizin,220 found in the roots and rhizomes of licorice (Glycyrrhiza glabra), used as an effective antiinflamatory agent in Chinese medicine. 

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