Puerariae radix (root of Pueraia lobata; Leguminosae) is one of the most important herbs in Korean traditional medicine and
has been frequently used for the treatment of diarrhea, diabetes, cardiovascular disease
and osteonecrosis. Retinopathy is a major cause of vision loss among middle aged and
elderly people. The retinal pigment epithelium (RPE) plays an important role in the
maintenance of photoreceptors in the retina, and RPE cells (ARPE-19) are used to investigate
the pathology and physiology of retinopathy.
The roots of P. lobata were collected in Kyonggi-do, Korea, in April 2005 and were identified by Professor
J.-H. Kim. The major compounds, puerarin, daidzin and daidzein, were isolated from
the EtOH extract of Puerariae radix (PR). We evaluated whether the EtOH extract of
PR and its major compounds could prevent cell death and decrease the membrane permeability
in oxidative stress-induced ARPE-19. PR significantly protected against H2O2-induced
cell death, whereas its major compounds did not inhibit H2O2-induced intracellular
ROS generation.
The effect of PR on the RPE barrier was conducted by measuring paracellular permeability
of dextran in ARPE-19. PR showed significant decrease in the membrane permeability.
Paracellular permeability is related with the alteration in tight junction protein
expression. PR also attenuated the decrease in the expression of ZO-1 and occludin.
ZO-1 expression was altered in response to oxidative damage. To identify the signaling
pathway through which PR exhibits its effects in H2O2-induced cells, we examined the effects of PR on phosphorylation of ERK, p38MAPK,
and JNK. PR significantly suppressed the phosphorylation of pERK, p38 MAPK, and JNK
in ARPE-19 cells, indicating that PR significantly suppressed H2O2-induced ARPE-19 cell death and permeability via phosphorylation of pERK, p38MAPK
and JNK.
Taken together, these results suggest PR to be a potential alternative for preventing
the progression of oxidative stress-related retinopathy.
