Inhibition of Rat 5α-Reductase Activity and Testosterone-Induced Sebum Synthesis in Hamster Sebocytes by an Extract of Quercus acutissima Cortex

Table 2

Quantification of inhibitory effect of constituents in extract of BK from cortex of Quercus acutissima.

	Inhibitory activity on 5α-reductase (% of control)
BK constituent	Concentration (μmol/L)				IC50 (μmol/L)
	0.1	1	10	100
Tetragalloyl glucose	3.3 ± 0.5	18.7 ± 0.4	63.2 ± 3.0	102.8 ± 1.2	8.1
Pentagalloyl glucose	5.4 ± 1.3	36.1 ± 6.5	83.5 ± 1.3	107.9 ± 2.2	2.5
Eugeniin	4.2 ± 1.0	13.9 ± 0.5	62.5 ± 0.6	114.6 ± 0.6	10.9
1-Desgalloyl eugeniin	4.6 ± 0.2	9.2 ± 1.6	52.5 ± 2.4	107.9 ± 0.9	12.6
Casuarinin	6.4 ± 1.4	10.8 ± 0.7	59.0 ± 2.0	110.1 ± 0.5	10.5
Castalagin	4.9 ± 0.5	6.3 ± 1.2	70.7 ± 3.2	113.3 ± 7.6	8.0
Stenophyllanin C	5.6 ± 0.6	4.6 ± 0.5	63.1 ± 0.4	102.3 ± 2.2	7.2
(−)-Epicatechin gallate	4.6 ± 0.2	4.9 ± 0.2	5.9 ± 0.3	69.4 ± 1.2	10–100
(−)-Epigallocatechin gallate	3.7 ± 0.1	4.4 ± 0.4	5.3 ± 0.3	58.6 ± 2.7	10–100

Testosterone (3.5 μmol/L) was incubated for 30 min in an assay solution containing rat liver microsomes (40 μg/mL), cofactors, and test sample at indicated concentrations. Testosterone remaining in the reaction was extracted with ethyl acetate after incubation and quantified by HPLC. Data are shown as relative amounts of testosterone, which are percentages of the control testosterone alone reaction. = 3. Hamamelitannin, fraxin, gallic acid, methyl gallate, (+)-catechin, (−)-gallocatechin, (+)-gallocatechin, and (+)-taxifolin did not have any effect on 5α-reductase activity at a concentration of 100 μmol/L.