Synthesis of Monogallic Acid Conjugates of Quercetin at the 3-, 7-, and 4′-Hydroxyl Groups through Selective Protection of Hydroxyl Groups

Journal of the Korean Chemical Society

article

Jongyun Jang¹  Dong Wook Kang¹ 

[1]Department of Pharmaceutical Science and Technology, Natural Science Research Institute & Advanced Healthcare Industry Research Center, Catholic University of Daegu

关键词: Quercetin;    Gallic acid;    Conjugate;    Flavonoid;    Esterification;   

DOI  :  10.5012/jkcs.2019.63.2.138

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

Flavonoid, a secondary metabolite of plants, aids in building the body’s resistance to bacteria, viruses, and allergens as well as cancer, in addition to preventing oxidative action. It is therefore being studied for the purpose of developing therapeutic agents for various diseases.1,2 Epigallocatechin gallate (EGCG), a type of catechin contained in green tea, inhibits the expression of enhancer of zeste homolog 2 (EZH2), a methyltransferase. EGCG is being developed as a treatment for colorectal cancer3 and as a potential therapeutic agent for Alzheimer’s disease by reducing β-amyloid and plaque.4 In addition, it has been reported that ROS signaling associated with apoptosis in endothelial cells inhibits H2O2-induced apoptosis by regulating the expression of Bcl-2 and Bax.5 EGCG has also bene demonstrated to show about 100 times stronger anti-influenza effect in cell and animal experiments6 as compared to Tamiflu, which was used as a treatment for the prevalent H1N1 flu in 2009.7 However, EGCG is not suitable for use as a drug because it has been shown that a daily intake of 800 mg or more may increase the risk of liver damage.8 Thus, Thapa et al. synthesized the analogous quercetin-3-gallate (Fig. 1), and antiviral tests showed the effective dose for 50% virus reduction (ED50) are similar to those of EGCG, with a higher therapeutic index.6 In this study, quercetin-3-gallate was synthesized more easily than in the previous method. Quercetin-7-gallate and quercetin-4′-gallate, which had not been previously synthesized, were also prepared.

【 授权许可】

Unknown