Medicinal Plants Classification Biosynthesis and ... - Index of

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Hua-Bin Li, Dan Li, Ren-You Gan et al.
structural diversity and the pronounced biological activities encountered in the
flavonoids of Scutellaria baicalensis indicate that this class of compounds is worthy of
further studies that may lead to new drug discovery. The review provides an account on
our research work combined with a reference of the information obtained in both the
English and Chinese literature.
Keywords: Scutellaria baicalensis; Flavonoid; Biosynthesis; Bioactivity
1. Introduction
Scutellaria baicalensis (S. baicalensis) Georgi is one of the most widely used medicinal
plants in some Asian countries, and is officially listed in the Chinese Pharmacopoeia. Its
roots have been used for anti-inflammation, anticancer, decreasing blood pressures, reducing
the total cholesterol level, treating bacterial and viral infections of the respiratory and the
gastrointestinal tract, cleaning away heat, moistening aridity, purging fire and detoxifying
toxicosis. This plant also possesses cholagogic, diuretic, and cathartic actions. Some
concentrated composite herbal preparations that contain S. baicalensis Georgi as a major
ingredient in their prescriptions are widely used in oriental countries [Lu, Jiang & Chen,
2003; Ministry of Health, 1995; Tang & Eisenbrand, 1992; Zhang et al., 2003]. S. baicalensis
Georgi contains a variety of flavones, phenylethanoids, amino acids, sterols and essential
oils, but studies on its chemical components and biological activities have been mainly
confined to the flavones because they are the main active components in S. baicalensis
Georgi [Nishikawa et al., 1999; Shen, 2000; Sichuan College of Medical Sciences, 1979;
Zheng, Dong & She, 1998]. This chapter provides up-to-date coverage of this class of
flavonoids in regard to chemical structures, natural resources, biosyntheses, analytical
methods and biological activities, and special attention is paid to both biosyntheses and
biological activities. The review provides an account on our research work combined with a
reference of the information obtained in both the English and Chinese literature.
2. Chemical Structures
The dried roots of S. baicalensis Georgi contain over 30 kinds of flavonoids [Tang &
Eisenbrand, 1992]. In recent years, several minor new flavonoids (2S)-5, 7, 2', 5'tetrahydroxyflavanone,
(2S)-5, 7, 2', 5'-tetrahydroxyflavanone 7-O-beta-D-glucopyranoside
and 6, 2'-dihydroxy-5, 7, 8, 6'-tetramethoxyflavone were also separated and identified from S.
baicalensis Georgi [Wang et al., 2002; Yin, 2006]. Baicalin, baicalein, wogonin, wogonin 7-
O-glucuronide, oroxylin A, and oroxylin A 7-O-glucuronide are the main active components
in S. baicalensis Georgi [Li, Jiang & Chen, 2004; Shen, 2000; Zheng, Dong & She, 1998],
and their chemical structures are shown in Figure 1.