Ginsenoside Rb2

The roots of Panax ginseng C. A. Mey.

Ginsenoside Rb2 is one of the main bioactive components of ginseng extracts. Rb2 can upregulate GPR120 gene expression.

In Vitro:Ginsenoside Rb2 pre-treatment enhances the anti-inflammatory effect of α-linolenic acid (ALA) and that the enhancing effect is strictly dependent on GPR120 activation. Ginsenoside Rb2 exerts anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated mouse macrophage RAW264.7 cells in vitro by increasing GPR120 expression and subsequently enhancing ω-3 fatty acid-induced GPR120 activation. Ginsenoside Rb2 improves glucose metabolism in hepatocytes by activating AMPK and reduces cholesterol and triacylglycerol levels in 3T3-L1 cells by reducing oxidative damage. Ginsenoside Rb2 exerts anti-apoptosis effects in murine bone marrow-derived mesenchymal stem cells (BMMSCs). MTT assay results show no obvious cytotoxicity of Ginsenoside Rb2 (up to 100 μM) toward RAW264.7 cells in the absence or presence of ALA. The influence of Rb2 on GPR120 expression in RAW264.7 macrophages is investigated by treating the cells with Ginsenoside Rb2 (0.1-100 μM) for 12 h followed by harvesting and lysis. Subsequent Western blot analysis shows that expression of GPR120 is dose-dependently upregulated by Ginsenoside Rb2. Real-time PCR results indicate that incubation of RAW264.7 macrophages with Ginsenoside Rb2 (10 μM) for 12 h leads to a 2.8-fold increase in GPR120 mRNA expression. In addition, this increase in GPR120 expression stimulated by Ginsenoside Rb2 is time dependent and begins as early as 6 h. These results indicate that Rb2 upregulates GPR120 expression in a dose- and time-dependent manner in RAW264.7 macrophages[1].

In Vivo:Ginsenoside Rb2 is an antiviral reagent to protect against rotavirus (RV) infection. When various dosages of Ginsenoside Rb2 (25 to 250 mg/kg) are administered 3, 2 or 1 days before virus challenge, treatment with this Ginsenoside at the dosage of 75 mg/kg 3 days before virus infection most effectively reduces rotavirus (RV) -induced diarrhea. In addition, consecutive administration of Ginsenoside Rb2 (75 mg/kg) 3, 2, and 1 day before virus infection is more effective than single administration on day-3. The consecutive administration of Ginsenoside Rb2 also reduces virus titers in the bowels of RV-infected mice[2].

References:
[1]. Huang Q, et al. Ginsenoside Rb2 enhances the anti-inflammatory effect of ω-3 fatty acid in LPS-stimulated RAW264.7 macrophages by upregulating GPR120 expression. Acta Pharmacol Sin. 2017 Feb;38(2):192-200. [2]. Yang H, et al. Ginsenoside-Rb2and 20(S)-Ginsenoside-Rg3 from Koreanred ginseng prevent rotavirus infection in newborn mice. J Microbiol Biotechnol. 2018 Jan 11.

Ginsenoside-Rb2 displays anti-osteoporosis effects through reducing oxidative damage and bone-resorbing cytokines during osteogenesis.[Pubmed:24933344]

Bone. 2014 Sep;66:306-14.

Reactive oxygen species (ROS) are a significant pathogenic factor of osteoporosis. Ginsenoside-Rb2 (Rb2), a 20(S)-protopanaxadiol glycoside extracted from ginseng, is a potent antioxidant that generates interest regarding the bone metabolism area. We tested the potential anti-osteoporosis effects of Rb2 and its underlying mechanism in this study. We produced an oxidative damage model induced by hydrogen peroxide (H2O2) in osteoblastic MC3T3-E1 cells to test the essential anti-osteoporosis effects of Rb2in vitro. The results indicated that treatment of 0.1 to 10muM Rb2 promoted the proliferation of MC3T3-E1 cells, improved alkaline phosphatase (ALP) expression, elevated calcium mineralization and mRNA expressions of Alp, Col1a1, osteocalcin (Ocn) and osteopontin (Opn) against oxidative damage induced by H2O2. Importantly, Rb2 reduced the expression levels of receptor activator of nuclear factor kappa-B ligand (RANKL) and IL-6 and inhibited the H2O2-induced production of ROS. The in vivo study indicated that the Rb2 administered for 12weeks partially decreased blood malondialdehyde (MDA) activity and elevated the activity of reduced glutathione (GSH) in ovariectomized (OVX) mice. Moreover, Rb2 improved the micro-architecture of trabecular bones and increased bone mineral density (BMD) of the 4th lumbar vertebrae (L4) and the distal femur. Altogether, these results demonstrated that the potential anti-osteoporosis effects of Rb2 were linked to a reduction of oxidative damage and bone-resorbing cytokines, which suggests that Rb2 might be effective in preventing and alleviating osteoporosis.

Inhibitory effects of ginsenoside-rb2 on nicotinic stimulation-evoked catecholamine secretion.[Pubmed:25352764]

Korean J Physiol Pharmacol. 2014 Oct;18(5):431-9.

The aim of the present study was to investigate whether ginsenoside-Rb2 (Rb2) can affect the secretion of catecholamines (CA) in the perfused model of the rat adrenal medulla. Rb2 (3~30 microM), perfused into an adrenal vein for 90 min, inhibited ACh (5.32 mM)-evoked CA secretory response in a dose- and time-dependent fashion. Rb2 (10 microM) also time-dependently inhibited the CA secretion evoked by DMPP (100 microM, a selective neuronal nicotinic receptor agonist) and high K(+) (56 mM, a direct membrane depolarizer). Rb2 itself did not affect basal CA secretion (data not shown). Also, in the presence of Rb2 (50 microg/mL), the secretory responses of CA evoked by veratridine (a selective Na(+) channel activator (50 microM), Bay-K-8644 (an L-type dihydropyridine Ca(2+) channel activator, 10 microM), and cyclopiazonic acid (a cytoplasmic Ca(2+)-ATPase inhibitor, 10 microM) were significantly reduced, respectively. Interestingly, in the simultaneous presence of Rb2 (10 microM) and L-NAME (an inhibitor of NO synthase, 30 microM), the inhibitory responses of Rb2 on ACh-evoked CA secretory response was considerably recovered to the extent of the corresponding control secretion compared with the inhibitory effect of Rb2-treatment alone. Practically, the level of NO released from adrenal medulla after the treatment of Rb2 (10 microM) was greatly elevated compared to the corresponding basal released level. Collectively, these results demonstrate that Rb2 inhibits the CA secretory responses evoked by nicotinic stimulation as well as by direct membrane-depolarization from the isolated perfused rat adrenal medulla. It seems that this inhibitory effect of Rb2 is mediated by inhibiting both the influx of Ca(2+) and Na(+) into the adrenomedullary chromaffin cells and also by suppressing the release of Ca(2+) from the cytoplasmic calcium store, at least partly through the increased NO production due to the activation of nitric oxide synthase, which is relevant to neuronal nicotinic receptor blockade.

Study on the hydroxyl radical scavenging activity changes of ginseng and ginsenoside-Rb2 by heat processing.[Pubmed:17409510]

Biol Pharm Bull. 2007 Apr;30(4):724-8.

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.

The ginsenoside-Rb2 lowers cholesterol and triacylglycerol levels in 3T3-L1 adipocytes cultured under high cholesterol or fatty acids conditions.[Pubmed:19403041]

BMB Rep. 2009 Apr 30;42(4):194-9.

The effects of the Ginsenoside Rb2 (Rb2) on lipid metabolism were characterized in 3T3-L1 adipocytes to evaluate their utility for treating obesity. While the amounts of total cholesterol and triacylglycerol (TAG) were markedly increased in the adipocytes treated with high amounts of cholesterol and fetal bovine serum (FBS), the test groups treated with Rb2 showed levels that were close to normal. The effect of Rb2 on these cells was comparable to that of lovastatin. Rb2 enhanced the expression of the sterol regulated element binding protein (SREBP) mRNA whereas treatment with cholesterol and FBS led to a reduction in the abundance of this transcript. The activity of fatty acid synthetase (FAS) was lower in the cholesterol group compared to the Rb2 treatment group suggesting that the observed decrease in cholesterol levels and activated SREBP was mediated by Rb2. Treatment with Rb2 also resulted in a decrease in TAG levels in adipocytes cultured under high fatty acid conditions. This effect was mediated by stimulating the expression of SREBP and Leptin mRNA, suggesting that Rb2 might be a valuable component capable of lowering the levels of lipids.

Protective effect of ginsenoside-Rb2 from Korean red ginseng on the lethal infection of haemagglutinating virus of Japan in mice.[Pubmed:23717160]

J Ginseng Res. 2013 Mar;37(1):80-6.

Korean red ginseng has been shown to possess a variety of biological activities. However, little is known about antiviral activity of ginsenosides of Korean red ginseng. Here, we investigated the protective effect by oral administration of various ginsenosides on the lethal infection of haemagglutinating virus of Japan (HVJ) in mice. In a lethal infection model in which almost all mice infected with HVJ died within 15 days, the mice were administered orally (per os) with 1 mg/mouse of dammarane-type (ginsenoside-Rb1, -Rb2, -Rd, -Re, and -Rg2) or oleanolic acid-type (ginsenoside-Ro) ginsenosides 3, 2, and 1 d before virus infection. Ginsenoside-Rb2 showed the highest protective activity, although other dammarane-type and oleanolic acid-type ginsenosides also induced a significant protection against HVJ. However, neither the consecutive administration with a lower dosage (300 mug/mouse) nor the single administration of ginsenoside-Rb2 (1 mg/mouse) was active. In comparison of the protective activity between ginsenoside-Rb2 and its two hydrolytic products [20(S)- and 20(R)-ginsenoside-Rg3], 20(S)-ginsenoside-Rg3, but not 20(R)-ginsenoside-Rg3, elicited a partial protection against HVJ. The protective effect of ginsenoside-Rb2 and 20(S)-ginsenoside-Rg3 on HVJ infection was confirmed by the reduction of virus titers in the lungs of HVJ-infected mice. These results suggest that ginsenoside-Rb2 is the most effective among ginsenosides from red ginseng to prevent the lethal infection of HVJ, so that this ginsenoside is a promising candidate as a mucosal immunoadjuvant to enhance antiviral activity.

Inhibition of tumor angiogenesis and metastasis by a saponin of Panax ginseng, ginsenoside-Rb2.[Pubmed:7522731]

Biol Pharm Bull. 1994 May;17(5):635-9.

We studied the effect of ginsenoside-Rb2 extracted from Panax ginseng on angiogenesis and metastasis produced by B16-BL6 melanoma cells in syngeneic mice. Intravenous administration of ginsenoside-Rb2 on day 1, 3 or 7 after tumor inoculation achieved a remarkable reduction in the number of vessels oriented toward the tumor mass, but did not cause a significant inhibition of tumor growth. The anti-angiogenic effect was dose-dependent ranging from 10 to 500 micrograms/mouse. In contrast, intra-tumoral or oral administration of ginsenoside-Rb2 caused a marked inhibition of both neovascularization and tumor growth. Ginsenoside-Rb2 did not affect the growth of rat lung endothelial (RLE) cells, B16-BL6 melanoma cells or various types of murine normal cells in vitro. The invasion of RLE cells into the reconstituted basement membrane (Matrigel), which is considered to be an essential event in tumor neovascularization, was inhibited by ginsenoside-Rb2 in a concentration-dependent fashion, while ginsenoside-Rb2 did not inhibit the haptotactic migration of endothelial cells to fibronectin-substrate. Multiple administrations of ginsenoside-Rb2 after the intravenous inoculation of B16-BL6 melanoma cells resulted in a significant inhibition of lung metastasis as compared with the untreated control. These results suggest that the inhibition of tumor-associated angiogenesis by ginsenoside-Rb2 may partly contribute to the inhibition of lung tumor metastasis.

Suppressive properties of ginsenoside Rb2, a protopanaxadiol-type ginseng saponin, on reactive oxygen species and matrix metalloproteinase-2 in UV-B-irradiated human dermal keratinocytes.[Pubmed:25774540]

Biosci Biotechnol Biochem. 2015;79(7):1075-81.

Ginsenosides, also known as ginseng saponins, are the principal bioactive ingredients of ginseng, which are responsible for its diverse pharmacological activities. The present work aimed to assess skin anti-photoaging properties of Ginsenoside Rb2 (Rb2), one of the predominant protopanaxadiol-type ginsenosides, in human epidermal keratinocyte HaCaT cells under UV-B irradiation. When the cultured keratinocytes were subjected to Rb2 prior to UV-B irradiation, Rb2 displayed suppressive activities on UV-B-induced reactive oxygen species elevation and matrix metalloproteinase-2 expression and secretion. However, Rb2 at the used concentrations was unable to modulate cellular survivals in the UV-B-irradiated keratinocytes. In brief, Rb2 possesses a protective role against the photoaging of human keratinocyte cells under UV-B irradiation.

Ginsenoside Rb2 is one of the main bioactive components of ginseng extracts. Rb2 can upregulate GPR120 gene expression. Ginsenoside Rb2 has antiviral effects.

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