3.2. Effects of the A. radix extract on type II 5a-reductase activity and cell proliferation
It is well known that androgens cause hair regression and balding in genetically predisposed individuals.
Several studies implicate the type II 5a-reductase as the key factor in these processes [15,24]. Previously, we demonstrated that an extract of Sophora flavescens had an inhibitory effect on the type II 5areductase [25].
To determine whether the A. radix extract had an inhibitory effect on the type II 5areductase,
we performed the 5a-reductase inhibition assay. However, there was no obvious inhibitory
effect of the extract on 5a-reductase (data not shown). Thus, we decided to investigate the effect of the A. radix extract on the growth of cells in vitro.
To this end, we used two different cell types, immortalized keratinocyte HaCaT cells and primary cultures of human hair DP cells. First, we tested the The hair growth promoting effect of Asiasari radix effect 93 Fig. 2 Effects of the Asiasari radix extract on protein synthesis. The isolated murine vibrissae follicles were treated with the A. radix extract and 1 mCi/ml of L-[35S]cysteine for 72 h. Radioactivity was measured by liquid scintillation counter. The results are shown as the mean values _ S.E. of quadruplicate measurements
(*P < 0.05 vs. control).
Fig. 3 Concentration-dependent cytotoxicity of the Asiasari radix extract in HaCaT (A) and DP (B) cells. The cells were treated for 24 h with the indicated concentrations
of the A. radix extract. After an additional incubation for 4 h with 1 mg/ml MTT, the formation of formazan was determined at 570 nm in an ELISA reader.
The results are shown as the mean values _ S.E. of triplicate
measurements (*P < 0.05 vs. control).
cytotoxicity of the A. radix extract using the MTT
assay. The A. radix extract showed cytotoxic effects
for both cells at concentrations higher than 0.0001%
(Fig. 3). Based on these results, we evaluated the
mitogenic effects of A. radix at doses lower than
0.0001%, using the [3H]thymidine incorporation
assay. As shown in Fig. 4, the A. radix extract at a
dose of 0.00001% increased the proliferation of
HaCaT and DP cells to 106.5% and 115.6%, respectively,
as compared to the control treatment.