Protective effect of fermented Red ginseng on a transient focal ischemic rats

Red ginseng and fermented red ginseng were prepared, and their composition of ginsenosides and antiischemic effect were investigated. When ginseng was steamed at 98-100 degrees C for 4 h and dried for 5 h at 60 degrees C, and extracted with alcohol, its main components were ginsenoside Rg3> ginsenoside Rb1 > ginsenoside Rb2. When the ginseng was suspended in water and fermented for 5 days by previously cultured Bifidobacterium H-1 and freeze-dried (fermented red ginseng), its main components were compound K > ginsenoside Rg3 > or = ginsenoside Rh2. Orally administered red ginseng extract did not protect ischemia-reperfusion brain injury. However, fermented red ginseng significantly protected ischemica-reperfusion brain injury. These results suggest that ginsenoside Rh2 and compound K, which was found to be at a higher content in fermented red ginseng than red ginseng, may improve ischemic brain injury.     

Comparison of the pharmacological effects of Panax ginseng and Panax quinquefolium

Medical application of Panax ginseng was first found in "Shen-Nong Herbal Classic"around 200 AD Panax quinquefolium was first introduced in "Essential of Materia Medica" in 1694 in China. The most important bioactive components contained in P ginseng and P quinquefolium are ginseng saponins (GS). The contents of ginsenoside Rb1, Re, and Rd in P quinquefolium are higher than they are in P ginseng. In P ginseng, the contents of Rg1,Rb2, and Rc are higher than they are in P quinquefolium. P ginseng had a higher ratio of Rg1: Rb1, and which was lower in P quinquefolium. After steaming for several hours, the total GS will decrease. However, some ginsenosides (Rg2, 20R-Rg2, Rg3, Rh1 and Rh2) increase, while others (Rb1, Rb2, Rb3, Rc, Rd, Re, and Rg1) decrease. However, variation, especially in P quinquefolium, is high. P ginseng and P quinquefolium are general tonics and adaptogens. Rg1 and Rb1 enhance central nervous system (CNS) activities, but the effect of the latter is weaker. Thus, for the higher contents of Rg1, P ginseng is a stimulant, whereas the Rb1 contents of P quinquefolium are mainly calming to the CNS. Re, Rg1, panaxan A and B from P ginseng are good for diabetes. Re and Rg1 enhance angiogenesis, whereas Rb1, Rg3 and Rh2 inhibit it. Rh2, an antitumor agent, can be obtained from Rb1 by steaming. The content of Re in P quinquefolium are higher than in P ginseng by 3-4 times. The vasorelax, antioxidant, antihyperlipidemic, and angiogenic effects of Re are reported. Thus, for the CNS "hot," wound healing and hypoglycemic effects, P ginseng is better than P quinquefolium. For anticancer effects, P quinquefolium is better.     

Transformation of ginseng saponins to ginsenoside rh<Subscript>2</Subscript> by acids and human intestinal bacteria and biological activities of their transformants

When ginseng water extract was incubated at 60 degrees C in acidic conditions, its protopanaxadiol ginsenosides were transformed to ginsenoside Rg3 and delta20-ginsenoside Rg3. However, protopanaxadiol glycoside ginsenosides Rb1, Rb2 and Rc isolated from ginseng were mostly not transformed to ginsenoside Rg3 by the incubation in neutral condition. The transformation of these ginsenosides to ginsenoside Rg3 and delta20-ginsenoside Rg3 was increased by increasing incubation temperature and time in acidic condition: the optimal incubation time and temperature for this transformation was 5 h and 60 degrees C resepectively. The transformed ginsenoside Rg3 and delta20-ginsenoside Rg3 were metabolized to ginsenoside Rh2 and delta20-ginsenoside Rh2, respectively, by human fecal microflora. Among the bacteria isolated from human fecal microflora, Bacteroides sp., Bifidobacterium sp. and Fusobacterium sp. potently transformed ginsenoside Rg3 to ginsenoside Rh2. Acid-treated ginseng (AG) extract, fermented AG extract, ginsenoside Rh2 and protopanaxadiol showed potent cytotoxicity against tumor cell lines. AG extract, fermented AG extract and protopanaxadiol potently inhibited the growth of Helicobacter pylori.     

主要人参皂甙的分布和比例及人参产品的质量控制

采用反相高效液相色谱法，对１５０多种西洋参、人参及三七的根、叶及其产品进行了分析。以８种主要的人参皂甙Ｒｇ，Ｒｅ，Ｒｆ，Ｒｂ１，Ｒｃ，Ｒｂ２，Ｒｇ２和Ｒｄ作为对照品，来评价人参及其产品的质量，这８种人参皂甙的分布及其比例在对人参及其商品的定性、定量分析方面具有显著的意义。本文首次提出了单体皂甙的含量比率这一有价值的数据在人参品种及不同用药部位鉴定方面的有效性。     

A comparative study on commercial samples of ginseng radix

A total of 37 commercial samples of Ginseng Radix, the origins of which belonged to Panax ginseng C. A. Meyer, P. quinquefolia Linn. (American ginseng), and P. notoginseng Burkill (sanchi-ginseng), respectively, were collected from the Taiwan herbal markets. The contents of nine ginsenosides, Rb(1), Rb(2), Rc, Rd, Re, Rf, Rg(1), Rg(2), R(0), and three malonylginsenosides, mRb(1), mRb(2), mRc, in these samples were determined by high-performance liquid chromatography. It was found that the saponin contents in P. notoginseng and P. quinquefolia were generally higher than in P. ginseng. The ginsenosides that were of the highest contents in the white-ginseng, red-ginseng, and shihchu-ginseng samples of P. ginseng were Rb(1) and Rg(1); those in the root-hair of P. ginseng were Rb(1) and Re, those in P. notoginseng were Rb(1), Rg(1) and Rd, and those in P. quinquefolia were Rb(1), Re, and mRb(1). Among the samples, those of P. quinquefolia did not contain Rf and Rg(2), whilst those of shihehu-ginseng and red-ginseng of P. ginseng contained none or only traces of the malonylginsenosides. From the data of chemical analysis of a herb's constituents and its external appearance, we can postulate not only the quality but also the origin of the herb.     

The protective effects of ginsenosides on human erythrocytes against hemin-induced hemolysis.

Panax ginseng has been used in traditional Chinese medicine to enhance stamina and capacity to deal with fatigue and physical stress. Many reports have been devoted to the effects of ginsenosides on many in vitro or in vivo experimental systems. The major aim of this work is to investigate the protective effects of 12 individual ginsenosides including Rb1, Rb3, Rc, Rd, Re, Rg1, Rg2, Rg3, Rh1, Rh2, R1 and pseudoginsenoside F11, together with the central structures of aforementioned ginsenosides, 20(S)-protopanaxadiol (PD) and 20(S)-protopanaxatriol (PT), on hemin-induced hemolysis of human erythrocytes. This is because hemin can induce hemolysis by accelerating the potassium leakage, dissociating skeletal proteins and prohibiting some enzymes in the membrane of erythrocyte. Thus, the structure-activity-relationship (SAR) between ginsenosides and protective effects has been screened in this in vitro experimental system. It is found that Rh2 and Rg3 intensify hemolysis in the presence of hemin, and initiate hemolysis even in the absence of hemin. All the other ginsenosides protect human erythrocytes against hemin-induced hemolysis more or less. The overall sequence is Rc>Rd>Re approximately Rb1>Rg1 approximately Rh1>Rb3 approximately Rg2 approximately R1 approximately F11 approximately PT. In addition, the protective effects of PD and PT have been detected, and found that PD promotes hemolysis appreciably, whereas PT protects erythrocytes efficiently. Moreover, the protective effects of PT ginsenosides are similar to PT itself, and the protective effects of PD ginsenosides vary remarkably, demonstrating that the positions of the sugar moieties make the protective activities of ginsenosides complicated. Especially, sugar moiety at 20-position is critical for PD ginsenosides to inhibit hemolysis, whereas hydroxyl group at 3-position is important for PT ginsenosides. The present result may be useful for understanding the SAR of ginsenosides.     

Red American ginseng: ginsenoside constituents and antiproliferative activities of heat-processed Panax quinquefolius roots

Red Asian ginseng ( Panax ginseng C. A. Meyer, Araliaceae) is used in many Oriental countries. In this study, the saponin constituents and anticancer activities of steamed American ginseng ( Panax quinquefolius L.) roots were evaluated. The contents of 12 ginsenosides in the roots were determined using high performance liquid chromatography (HPLC). After the steaming treatment (100 - 120 degrees C for 1 h and 120 degrees C for 0.5 - 4 h), the quantity of 7 ginsenosides decreased and that of 5 others increased. The content of ginsenoside Rg3, a previously recognized anticancer compound, increased significantly when the root was steamed at 120 degrees C for 0.5 - 3 h. The antiproliferative effects of unsteamed and steamed (120 degrees C for 1 h and 2 h) American ginseng root extracts were assayed by the modified trichrome stain (MTS) method using three cancer cell lines (SW-480, HT-29, NSCLC). Heat-processing increased the antiproliferative effect of American ginseng significantly, and the activity of the extract from roots steamed for 2 h was greater than that of roots steamed for 1 h. Chemical constituents and antiproliferative activities of white and red Asian ginseng have also been evaluated. Five representative ginsenosides, Rb1, Rd, Re, Rg2 and Rg3, were studied. Ginsenoside Rg3 had the most potent effect. The antiproliferative activities of red American ginseng are augmented when ginsenoside Rg3 is increased.     

Three new dammarane-type triterpene saponins from the leaves of Panax ginseng C.A. Meyer

Three new dammarane-type triterpene ginsenosides, together with six known ginsenosides, were isolated from the leaves of Panax ginseng C.A. Meyer. The new saponins were named as ginsenoside Rh??, ginsenoside Rh??, and ginsenoside Rh??. Their structures were elucidated as (20S)-3β,6α,12β,20-tetrahydroxydammara-25-ene-24-one 20-O-β-d-glucopyranoside (1), (20S)-3β,12β,20,24,25-pentahydroxydammarane 20-O-β-d-glucopyranoside (2), and (20S,23E)-3β,12β,20,25-tetrahydroxydammara-23-ene 20-O-β-d-glucopyranoside (3) on the basis of 1D and 2D NMR experiments and mass spectra. The known ginsenosides were identified as ginsenoside M(?cd), ginsenoside Rg?, ginsenoside Rb?, gypenoside XVII, gypenoside IX, and 20-(E)-ginsenoside F?.     

Evaluation of antipruritic effects of red ginseng and its ingredients in mice

The anti-pruritic effect of red ginseng (the steamed root of Panax ginseng C.A. Meyer, Araliaceae), a traditional medicine in Asian countries, was investigated in mouse scratching behavior models induced by either compound 48/80 or histamine. Red ginseng and its saponin fraction, but not its polysaccharide fraction, showed an anti-pruritic effect. Representative constituents in the saponin fraction, ginsenosides Rg3 and Rh2, inhibited scratching behavior and vascular permeability. These ginsenosides also inhibited the expression of TNF-alpha and IL-4 induced by IgE-antigen complex in RBL-2H3 cells, as well as acetic acid-induced writhing in mice. These results suggest that red ginseng and its ingredients, ginsenosides Rg3 and Rh2, may inhibit scratching behavior by inhibiting IL-4 and TNF-alpha expression, promoting membrane stability, and inhibiting Ca (++) influx.     

The antistress effect of ginseng total saponin and ginsenoside Rg3 and Rb1 evaluated by brain polyamine level under immobilization stress.

The present study aims to demonstrate the ability of ginseng total saponin (GTS), ginsenosides Rg3 and Rb1 to reduce brain polyamine levels in immobilization-stressed gerbil mice. A previous study reported that ginsenosides had an anti-stress property. So, we tested the anti-stress effect of ginseng by investigating the brain level of polyamine, a well-known stress stimuli marker. We determined the brain polyamine levels under 30-min immobilization stress in pretreating GTS (100 mgkg(-1), oral), ginsenosides Rg3 and Rb1 (10 mgkg(-1), oral, respectively). Then, we compared polyamine levels between the non-stressed mouse and the stressed mouse which had taken saline orally to check the placebo effect. Putrescine (PUT) levels were significantly increased (P < 0.01) in the stressed condition, but it was reduced in pretreatment of GTS, ginsenosides Rg3 (P < 0.01, respectively) and Rb1 (P < 0.001) under 30-min immobilization stressed-mouse. However, other polyamine levels did not change regardless of stressed condition or GTS-, ginsenosides Rg3- and Rb1-treated stressed condition. These results mean that only PUT could be a marker for stress and GTS, ginsenosides Rg3 and Rb1 administration lead to an anti-stress effect. Thus, our studies indicate that GTS, ginsenosides Rg3 and Rb1 may play a neuroprotective role in the immobilization-stressed brain.     

Reduction of electrically evoked neural activity by ginseng saponin in rat hippocampal slices

It is well established that ginseng saponin has positive influences on various neural diseases, but little is known about its electrophysiological effects in the central nervous system. In this study, we examined the electrophysiological effects of ginseng saponin in rat hippocampal slices. Total saponin from ginseng root reduced the slope of fEPSPs (field excitatory postsynaptic potentials) in the CA1 area in a dose-dependent manner (9.1 +/-5.4%, 48.4+/-12.1%, and 60.5+/-15.3% at 10, 50, and 100 microg/ml, respectively), which was reversed within 10 min of washout. Seven different ginsenosides resulted in varied degrees of fEPSPs reduction. The rank order of reduction was Rb1, Rg1 >Rg2, Rh1, Rc>Rd, Re within a range of 5-64% reduction. No difference in the suppressive action between protopanaxadiol (Rb1, Rc, Rd) and protopanaxatriol (Rg1, Rg2, Re, Rh1) saponins was shown; the slope of fEPSPs was reduced by 38% and 40% on average, respectively. The possible role of gamma-aminobutyric acid (GABA(A)) receptor in the suppressive action of ginseng saponins was tested using whole cell patch recording in acutely isolated hippocampal neurons. Ginsenosides did not induce chloride current nor modified GABA-induced current. Also, the suppressive effect of ginsenosides on fEPSPs was still observed in the presence of the GABA(A) receptor antagonist, bicuculline methiodide 50 microM. These results suggest that the suppressive effect is not attributable to regulation of GABA(A) receptor activation.     

Quantitative analysis of ginsenosides Rb1, Rg1, and Re in American ginseng berry and flower samples by ELISA using monoclonal antibodies

Quantitative analysis of ginsenosides Rb1, Rg1, and Re in American ginseng berry and flower samples, which were collected in various months throughout the year, was performed by enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies. The American ginseng flower had the highest content of ginsenosides Rb1, Rg1, and Re (GRb1, GRg1, and GRe). The content of GRb1, GRg1, and GRe decreased in going from young through to ripe berry.     

Asian ginseng enhances the anti-proliferative effect of 5-fluorouracil on human colorectal cancer: Comparison between white and red ginseng

Previous studies showed that Asian ginseng, Panax ginseng C.A. Meyer, may have anti-cancer properties. However, there is limited data exploring the use of Asian ginseng as an adjuvant to chemotherapy, and minimal mechanistic studies related to their possible synergistic activities. In this study, the content of 8 ginsenosides, Rb1, Rb2, Rb3, Rc, Rd, Re, Rg1 and Rg3, in the extracts of white ginseng (WG) and red ginseng (RG) were determined by HPLC. Using HCT-116 human colorectal cancer cells, we compared the efficacy of WG and RG. We evaluated the synergy between ginseng and 5-fluorouracil (5-FU), and explored the mechanism of their anti-proliferative effects. As single extract, WG or RG used at concentrations of 0.1, 0.2 and 0.3 mg/mL, inhibited HCT-116 cell proliferation in a concentration-related manner. WG at 0.2 mg/mL did not show obvious synergy with 5-FU co-treatment, while RG at 0.2 and 0.3 mg/mL significantly enhanced the anti-proliferative effects of 5-FU at concentrations of 10, 50 and 100 μM (P < 0.05). Using flow cytometric assay, RG 0.3 mg/mL did not affect cancer cell apoptotic induction activity. However, the RG induced cell cycle arrest in the G1 phase, while 5-FU arrested the cell in the S phase. Different ginsenoside profiles are responsible for the observed differences in pharmacological effects. The effects of 8 ginsenosides on HCT-116 cells were assayed. Rd and Rg3 showed positive anti-proliferative effect. Our data suggested a potential for RG as an adjuvant therapy in the treatment of colorectal cancer, via a synergistic action.     

Drying of steamed Asian ginseng (Panax ginseng) roots by microwave-hot air combination

Steamed Asian ginseng (Panax ginseng) roots were dried by a combined microwave-hot air method in a modified experimental microwave oven. Hot air drying was used as a reference method. The drying time to achieve the desired moisture level (10%) as well as the ginsenoside contents and the color of the final product were determined. The ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf, Rg1 and Ro were analyzed by HPLC. Compared with hot air drying, the combined microwave-hot air drying method resulted in a substantial decrease (approximately 30-40%) in drying time and had little influence on the ginsenoside contents and the color of the final product.     

Inhibitory effects of Korean red ginseng and its genuine constituents ginsenosides Rg3, Rf, and Rh2 in mouse passive cutaneous anaphylaxis reaction and contact dermatitis models

The inhibitory effects of the Korean red ginseng (steamed root of Panax ginseng C.A. MEYER, family Araliaceae) saponin fraction (KRGS) and its constituents ginsenosides Rg3, Rf, and Rh2 in mouse passive cutaneous anaphylaxis (PCA) and contact dermatitis models were measured. Orally administered KRGS and its genuine ginsenosides potently inhibited the PCA reaction induced by IgE. However, when these ginsenosides were intraperitoneally administered, ginsenoside Rh2 showed the most potent inhibition. The ginsenoside Rh2 also the most potently inhibited the beta-hexosaminidase release from RBL-2H3 cells induced by IgE with antigen. KRGS administered topically at a dose of 0.1% suppressed ear swelling in an oxazolone-induced mouse contact dermatitis model by 38.8%. Its constituents ginsenosides Rg3, Rf, and Rh2 at a concentration of 0.05% also potently suppressed mouse ear swelling by 47.5%, 34.8%, and 49.9% at 16 d, respectively. These ginsenosides also significantly reduced mRNA expression levels of cyclooxygenase (COX)-2, interleukin (IL)-1beta, tumor necrosis factor-alpha and interferon-gamma induced by oxazolone applied to mouse ears. However, the ginsenosides, except for ginsenoside Rh2, almost did not notably reduce IL-4 levels. The ginsenoside Rh2 also potently inhibited COX-2 and inducible NO synthetase protein expression in liphopolysaccharide-stimulated RAW264.7 cells. Based on these findings, KRGS and its ginsenosides are suggested to improve atopic and contact dermatitis by regulating expression of cytokines.     

Effects of ginsenosides,active components of ginseng,on nicotinic acetylcholine receptors expressed in Xenopus oocytes

We investigated the effects of ginsenosides, the active ingredient of ginseng, on neuronal or muscle-type nicotinic acetylcholine receptor channel activity expressed in Xenopus oocytes after injection of cRNA encoding bovine neuronal alpha3beta4, alpha7 or human muscle alphabetadeltavarepsilon subunits. Treatment with acetylcholine elicited an inward peak current (I(ACh)) in oocytes expressing nicotinic acetylcholine receptor subtypes. Cotreatment with ginsenoside Rg2 and acetylcholine inhibited I(ACh) in oocytes expressing with alpha3beta4 or alphabetadeltavarepsilon but not in oocytes expressing alpha7 nicotinic acetylcholine receptors. The inhibition of I(ACh) by ginsenoside Rg2 was reversible and dose-dependent. The half-inhibitory concentrations (IC50) of ginsenoside Rg2 were 60.2+/-14.1 and 15.7+/-3.5 microM in oocytes expressing alpha3beta4 and alphabetadeltavarepsilon nicotinic acetylcholine receptors, respectively. The inhibition of I(ACh) by ginsenoside Rg2 was voltage-independent and noncompetitive. Other ginsenosides besides ginsenoside Rg2 also inhibited I(ACh) in oocytes expressing alpha3beta4 or alphabetadeltavarepsilon nicotinic acetylcholine receptors. The order of potency for the inhibition of I(ACh) was ginsenoside Rg2>Rf>Re>Rg1>Rc>Rb2>Rb1 in oocytes expressing alpha3beta4 nicotinic acetylcholine receptors and was ginsenoside Rg2>Rf>Rg1>Re>Rb1>Rc>Rb2 in oocytes expressing alphabetadeltavarepsilon nicotinic acetylcholine receptors. These results indicate that ginsenosides might regulate nicotinic acetylcholine receptors in a differential manner and this regulation might be one of the pharmacological actions of Panax ginseng.     

Study on the hydroxyl radical scavenging activity changes of ginseng and ginsenoside-Rb2 by heat processing

The free radical scavenging activities of Panax ginseng C.A. MEYER are known to increase by heat processing. Phenolic acids and Maillard reaction products (MRPs) have been suggested as active free radical scavenging components from our previous research, but heat processing-induced chemical and activity changes of ginsenosides considering the Maillard reaction have not yet been fully elucidated. In this study, we investigated the hydroxyl radical (.OH) scavenging activity changes of ginsengs and ginsenoside-Rb2 (Rb2)) by heat processing using an electron spin resonance spectrometer. Especially, Rb2 was heat processed with the same amount of glycine, a frequently used amino acid in the Maillard reaction model system. As a result, the .OH scavenging activities and brown compound levels of ginseng and glycine-Rb2 mixture were increased by heat processing. However, the increase in .OH scavenging activities were not in accordance with the extents of browning. On the other hand, less-polar ginsenosides such as Rg3, Rg5, and Rk1 were generated from the glycine-Rb2 mixture by heat processing. The sugar moieties at carbon-20 of Rb2 were separated by the steaming process, less-polar ginsenosides were produced, and then the separated sugar moieties were thought to form MRPs with glycine. From the .OH scavenging activity tests of Rb2, glycine, less-polar ginsenosides, and maltol, the increase in .OH scavenging activity was thought to be more closely related to the generation of .OH scavenging ginsenosides such as 20(S)-Rg3 and Rg5 by heat processing than MRPs.     

Medicinal history and ginsenosides composition of Panax ginseng rhizome, "Rozu"

Ginseng is prepared from Panax ginseng C.A. Meyer root. The root of wild P. ginseng has long tortuous rhizome called traditionally "Rozu" in Japanese. In the present historical studies on ginseng, it has been proven that ginseng has sometimes been used after removing "Rozu" due to its emetic effects. However, ginseng with "Rozu" is prescribed in almost all the present Kampo formulations used clinically in China and Japan. Possible reasons for this are (1) some formulations including "Rozu" have been used for vomiting resulting from the retention of fluid in the intestine and stomach, "tan-in" in Japanese, and (2) the present cultivated ginseng has shorter "Rozu" than wild ginseng. Furthermore, it is proved that "Rozu", rich in ginsenoside Ro with oleanane-type aglycone, is distinguished from ginseng roots rich in ginsenosides Rb1 and Rg1 with dammarane-type aglycone. This is the first report to declare the distribution of ginsenosides in underground parts of wild P. ginseng. Ginsenoside Ro is a minor ginsenoside in ginseng whereas it is the major ginsenoside in P. japonicus rhizome (chikusetsu-ninjin in Japanese). Ginsenoside Ro is characterized by antiinflammatory effects which differ from ginsenosides Rb1 and Rg1 responsible for adaptogenic effects of ginseng. These results suggest that "Rozu" containing both oleanane- and dammarane-type ginsenosides might be a promising raw material distinct from ginseng root or P. japonicus rhizome.     

不同产地红参中总皂苷及人参皂苷Rg1、Re、Rb1的含量比较

目的测定不同产地红参中总皂苷及人参皂苷Rg1、Re、Rb1的含量。方法利用紫外分光光度法、高效液相色谱法比较不同产地红参中总皂苷及人参皂苷Rg1、Re、Rb1的含量。结果不同产地的红参总皂苷及人参皂苷Rg1、Re、Rb1的含量相差相对较大。结论应该重视红参的种植、采收、加工炮制等的进一步规范化研究。     

Ginsenosides from Panax ginseng differentially regulate lymphocyte proliferation

We have examined the immunosuppressive effects of representative ginsenosides (Rb1, Rb2, Re and Rg1) from Panax ginseng C. A. Meyer on CD4+ and CD8+ lymphocyte proliferation. Ginsenosides differentially modulated lymphocyte proliferation induced by concanavalin A (Con A), lipopolysaccharide (LPS), phytohemaglutinin (PHA) and interleukin-2 (IL-2). Thus, Rb1 and Re significantly enhanced Con A-induced lymphocyte proliferation, whereas Rg1 did not affect the proliferation. Interestingly, however, Rb2 strongly blocked Con A, LPS and PHA-induced lymphocyte proliferation with the IC50 values of 21.8, 29.0 and 24.0 microM, respectively. Moreover, Rb2 inhibited Con A-stimulated IL-2 production with an IC 50 of 13.3 microM. In the IL-2-stimulated CD8+ T cell (CTLL-2) proliferation assay, Re and Rg1 showed strong suppressive effects with IC50 values of 57.5 and 64.7 microM, respectively. In contrast, neither Rb1 nor Rb2 did inhibit CTLL-2 cell proliferation at tested concentrations. These results suggest that ginsenosides from P. ginseng may modulate lymphocyte proliferation in a different manner.