Table 1.

Neuroprotective effects of 4 triterpene saponin from P. radix against glutamate-induced toxicity in primary cultured rat cortical cells ^a.

Compounds	Cell viability b (%)
	0.1	1	10
Control c	100
Glutamate-treated c, e	0
Platycodin A	13.6 ± 0.4*	32.5 ± 4.8*	52.4 ± 3.8***
Platycodin C	11.6 ± 2.8	20.3± 2.5	16.3 ± 2.1
Platycodin D	16.5 ± 2.7	21.6 ± 2.1	26.5 ± 3.7
Deapioplatycodin D	22.3 ± 3.8	21.2 ± 1.3	26.5 ± 2.0
APV f	10.9 ± 2.2	23.9 ± 2.8	40.0 ± 3.8*
MK-801 g	51.8 ± 4.8**	63.8 ± 5.4***	72.8 ± 4.9***
CNQX h	28.3 ± 3.4*	41.5 ± 3.6*	51.5 ± 4.8***

• ^a 
  Rat cortical cell cultures were incubated with test compounds for 1h. The cultures were then exposed to 100 μM glutamate for 24 hrs. After the incubation, the cultures were assessed for the extent of neuronal damage;
• ^b 
  Cell viability was measured by the LDH assay;
• ^c 
  LDH released from control and glutamate-treated cultures were 11.9 ± 1.2 and 48.3 ± 4.1 units/mL, respectively;
• ^d 
  Cell viability was calculated as 100 x (LDH released from glutamate-treated-LDH released from glutamate+test compound-treated)/(LDH released from glutamate-treated-LDH released from control). The values shown are the mean ± STD of three experiments (3-4 cultures per experiment). Results differ significantly from the glutamate-treated: ^* p < 0.05, ^** p < 0.01, ^*** p < 0.001;
• ^e 
  Glutamate-treated value differed significantly from the untreated control at the level of p < 0.001;
• ^f 
  APV: DL-2-amino-5-phosphonovaleric acid, a competitive NMDA receptor antagonist;
• ^g 
  MK-801: dizocilpine maleate, a noncompetitive NMDA receptor;
• ^h 
  CNQX: 6-cyano-7-nitroquinoxaline-2,3-dione, non-NMDA receptor antagonist.