**1. Introduction**

Peroxisome proliferator-activated receptor (PPAR)-γ is the primary molecular target for insulin-sensitizing thiazolidinedione drugs. These drugs activate PPAR-γ, increasing the number of small adipocytes that differentiate from preadipocytes and inducing apoptosis in large adipocytes. Because small adipocytes function normally, whereas large adipocytes hyperproduce and hypersecrete adipocytokines, an increased ratio of small adipocytes to large adipocytes improves insulin resistance. Therefore, compounds with PPAR-γ ligand-binding activity may be useful for the prevention and improvement of type 2 diabetes, a representative

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insulin resistance syndrome. We found that the EtOH extract of *Glycyrrhiza glabra* roots and the EtOAc extract of *G. uralensis* roots exhibited higher activity than did the other materials tested. Bioassay-guided fractionation of these extracts resulted in the isolation of 52 phenolics, including 11 novel ones [1, 2].

In this chapter, we describe the results of the bioassay-guided fractionation of *G. glabra* and *G. uralensis* roots using a GAL-4-PPAR-γ chimera assay method.
