Endoplasmic Reticulum Stress-Activated PERK-eIF2α-ATF4 Signaling Pathway is Involved in the Ameliorative Effects of Ginseng Polysaccharides against Cisplatin-Induced Nephrotoxicity in Mice.

Although previous studies have reported that saponins (ginsenosides, the major active and most representative ingredients in Panax ginseng C.A. Meyer) exerted a good ameliorative effect on cisplatin (CP)-induced acute kidney injury in animal models, little attention has been paid to a large number of polysaccharides isolated and purified from ginseng. This work aimed to investigate the protective effect and the possible molecular mechanism of ginseng polysaccharide (WGP) on CP-induced kidney toxicology in mice. The results from biomarker analysis including serum creatinine (CRE) and blood urea nitrogen (BUN) confirmed the protective effect of WGP at 200 and 400 mg/kg on CP-induced renal-toxicology. We found that WGP reduces the apoptosis of kidney cells by inhibiting endoplasmic reticulum (ER) stress caused by CP, which is manifested by increased phosphorylation of PERK. In addition, the apoptosis-associated with caspase 3 activation in renal cells induced by CP was inhibited after administration of WGP, and the phosphorylation levels of PI3K and AKT were also reduced significantly. We also demonstrated that after exposure to CP, the unfolded protein response signaling pathway PERK-eIF2α-ATF4 axis was significantly activated, manifested by increased phosphorylation of eIF2α and increased expression of ATF4 and CHOP. Interestingly, the WGP administration improves this situation. Furthermore, the supplement of WGP inhibited the overexpression of nuclear factor-kappa B p65 (NF-κB p65) and tumor necrosis factor-α (TNF-α) caused by CP exposure. In short, for the first time, our findings indicated that WGP could effectively prevent CP-induced ER stress, inflammation, and apoptosis in renal cells, in part, by regulating the PI3K/AKT and PERK-eIF2α-ATF4 signaling pathways.

Alleviative effects of 20(R)-Rg3 on HFD/STZ-induced diabetic nephropathy via MAPK/NF-κB signaling pathways in C57BL/6 mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Diabetic nephropathy (DN) is a major complication of diabetes. The kidney disease develops in nearly 20%-40% of type 2 diabetes (T2D) patients. Ginseng is the root of Panax ginseng C. A. Meyer and has been used in prevention and treatment of diseases for more than 2000 years as a traditional oriental medicine. The 20(R)-ginsenoside Rg3, an active saponin isolated from ginseng, can prevent and treat many diseases. The object of this research was to explore the alleviative effects of 20(R)-Rg3 on DN in mice. MATERIALS AND METHODS: The T2D animal model was induced by continuous access to a high fat diet (HFD) combined with a single injection of 100 mg/kg streptozotocin (STZ) in C57BL/6 mice. The mice were treated by oral gavage of the 20(R)-Rg3 (10, 20 mg/kg) for 8 weeks. Functional and histopathological analyses of the kidneys were then performed. Protein expression levels of MAPKs and NF-κB signal pathways in the kidney were evaluated by western blotting. The expressions of HO-1 and NF-κB in the kidney were measured by fluorescent labeling staining. Other assessments including fasting blood glucose (FBG) levels, blood lipids, oxidative indicators, and inflammatory factors were all performed. RESULTS: Abnormally elevated FBG levels were observed in HFD/STZ mice, contributing significantly to the occurrence of DN. Simultaneously, HFD/STZ mice showed the rise of serum total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) levels, and the decrease in high density lipoprotein cholesterol (HDL-C). DN was evidenced by the overproduction of malondialdehyde (MDA), decreased levels of superoxide dismutase (SOD) and catalase (CAT) enzymatic activities, high levels of serum blood urea nitrogen (BUN) and creatinine (Cr). Simultaneously, the results of the immunofluorescence assay showed an increased expression level in NF-κB p65 while a decrease in antioxidant enzyme HO-1 was observed. Herein, 20(R)-Rg3 treatment for 8 weeks not only attenuated FBG levels and advanced glycation end products (AGEs) levels but also improved insulin (INS) level, blood lipids, oxidative stress, and renal function by regulating MAPKs and NF-κB signal pathways in DN mice. CONCLUSION: Taken together, the findings from the present study explicitly confirmed that 20(R)-Rg3 exerted ameliorative effects on DN mice via improving anti-oxidative activity and reducing renal inflammation.

Ginsenoside Rb3 provides protective effects against cisplatin-induced nephrotoxicity via regulation of AMPK-/mTOR-mediated autophagy and inhibition of apoptosis in vitro and in vivo.

OBJECTIVES: Based on previous reports that ginsenosides have been shown to exert better preventive effects on cisplatin-induced kidney injury, the present work aims to evaluate the protective effects of ginsenoside Rb3 (G-Rb3) on cisplatin-induced renal damage and underlying mechanisms in vivo and in vitro. MATERIALS AND METHODS: The protective effect of G-Rb3 on cisplatin-induced acute renal failure in ICR mouse model and HEK293 cell model was investigated, and the underlying possible mechanisms were also explored. For animal experiment, renal function, kidney histology, inflammation, oxidative stress, relative protein molecules involved in apoptosis and autophagy signalling pathways were assessed. In addition, rapamycin (a specific inhibitor of mTOR), compound C (a specific inhibitor of AMPK) and acetylcysteine (NAC, a specific ROS scavenger) were employed to testify the effects of AMPK/mTOR signal pathway on the protective effects of G-Rb3 in HEK293 cells. RESULTS: Pre-treatment with G-Rb3 at doses of 10 and 20 mg/kg for ten days significantly reversed the increases in serum creatinine (CRE), blood urea nitrogen (BUN) and malondialdehyde (MDA), and decrease in glutathione (GSH) content and superoxide dismutase (SOD) activity. Histopathological examination further revealed that G-Rb3 inhibited cisplatin-induced nephrotoxicity. G-Rb3 diminished cisplatin-induced increase in protein expression levels of p62, Atg3, Atg5 and Atg7, and decrease in protein expression level of p-mTOR and the ratio of LC3-I/LC3-II, indicating that G-Rb3 suppressed cisplatin-induced activation of autophagy. Inhibition of autophagy induced inactivation of apoptosis, which suggested that autophagy played an adverse effect on cisplatin-evoked renal damage. Further, we found that G-Rb3 might potentially modulate the expressions of AMPK-related signal pathways. CONCLUSIONS: These findings clearly suggested that G-Rb3-mediated alleviation of cisplatin-induced nephrotoxicity was in part due to regulation of AMPK-/mTOR-mediated autophagy and inhibition of apoptosis in vitro and in vivo.

Arginyl-fructosyl-glucose, a Major Maillard Reaction Product of Red Ginseng, Attenuates Cisplatin-Induced Acute Kidney Injury by Regulating Nuclear Factor κB and Phosphatidylinositol 3-Kinase/Protein Kinase B Signaling Pathways.

Recently, although ginseng ( Panax ginseng C. A. Meyer) and its main component saponins (ginsenosides) have been reported to exert protective effects on cisplatin (CDDP)-induced acute kidney injury (AKI), the beneficial activities of non-saponin on CDDP-induced AKI is little known. This research was designed to explore the protective effect and underlying mechanism of arginyl-fructosyl-glucose (AFG), a major and representative non-saponin component generated during the process of red ginseng, on CDDP-caused AKI. AFG at doses of 40 and 80 mg/kg remarkably reversed CDDP-induced renal dysfunction, accompanied by the decreased levels of serum creatinine and blood urea nitrogen. Interestingly, all of oxidative stress indices were ameliorated after pretreatment with AFG continuously for 10 days. Importantly, AFG relieved CDDP-induced inflammation and apoptosis in part by mitigating the cascade initiation steps of nuclear factor κB signals and regulating the participation of the phosphatidylinositol 3-kinase/protein kinase B signal pathway. In conclusion, these results clearly provide strong rationale for the development of AFG to prevent CDDP-induced AKI.

Dietary α-Mangostin Provides Protective Effects against Acetaminophen-Induced Hepatotoxicity in Mice via Akt/mTOR-Mediated Inhibition of Autophagy and Apoptosis.

Acetaminophen overdose-induced hepatotoxicity is the most common cause of acute liver failure in many countries. Previously, alpha-mangostin (α-MG) has been confirmed to exert protective effects on a variety of liver injuries, but the protective effect on acetaminophen-induced acute liver injury (ALI) remains largely unknown. This work investigated the regulatory effect and underlying cellular mechanisms of α-MG action to attenuate acetaminophen-induced hepatotoxicity in mice. The increased serum aminotransferase levels and glutathione (GSH) content and reduced malondialdehyde (MDA) demonstrated the protective effect of α-MG against acetaminophen-induced hepatotoxicity. In addition, α-MG pretreatment inhibited increases in tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β) caused by exposure of mice to acetaminophen. In liver tissues, α-MG inhibited the protein expression of autophagy-related microtubule-associated protein light chain 3 (LC3) and BCL2/adenovirus E1B protein-interacting protein 3 (BNIP3). Western blotting analysis of liver tissues also proved evidence that α-MG partially inhibited the activation of apoptotic signaling pathways via increasing the expression of Bcl-2 and decreasing Bax and cleaved caspase 3 proteins. In addition, α-MG could in part downregulate the increase in p62 level and upregulate the decrease in p-mTOR, p-AKT and LC3 II /LC3 I ratio in autophagy signaling pathways in the mouse liver. Taken together, our findings proved novel perspectives that detoxification effect of α-MG on acetaminophen-induced ALI might be due to the alterations in Akt/mTOR pathway in the liver.

Caspase-Mediated Anti-Apoptotic Effect of Ginsenoside Rg5, a Main Rare Ginsenoside, on Acetaminophen-Induced Hepatotoxicity in Mice.

Frequent overdose of acetaminophen (APAP) is one of the most common and important incentives of acute hepatotoxicity. Prior to this work, our research group confirmed that black ginseng (Panax ginseng, BG) showed powerful protective effects on APAP-induced ALI. However, it is not clear which kind of individual ginsenoside from BG plays such a liver protection effect. The objective of the current investigation was to evaluate whether ginsenoside Rg5 (G-Rg5) protected against APAP-induced hepatotoxicity and the involved action mechanisms. Mice were administrated with G-Rg5 at two dosages of 10 or 20 mg/kg for 7 consecutive days. After the last treatment, all of the animals that received a single intraperitoneal injection of APAP (250 mg/kg) showed severe liver toxicity after 24 h, and the liver protection effects of G-Rg5 were examined. The results clearly indicated that pretreatment with G-Rg5 remarkably inhibited the production of serum tumor necrosis factor (TNF-α) and interleukin-1ß (IL-1ß) compared with the APAP group. Meanwhile, G-Rg5 decreased the hepatic malondialdehyde (MDA) content, the protein expression levels of 4-hydroxynonenal (4-HNE) and cytochrome P450 2E1 (CYP2E1) in the liver tissues. G-Rg5 decreased APAP caused the hepatic overexpression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Furthermore, analysis of immunohistochemistry and Western blotting also indicated that G-Rg5 pretreatment inhibited activation of apoptotic pathways mainly via increasing the expression of Bcl-2 protein, decreasing the expression of Bax protein, proliferating cell nuclear antigen (PCNA), cytochrome c, caspase-3, caspase-8, and caspase-9. Liver histopathological observation provided further evidence that pretreatment with G-Rg5 could significantly inhibit hepatocyte necrosis, inflammatory cell infiltration, and apoptosis caused by APAP. In conclusion, the present study clearly demonstrates that G-Rg5 exerts a liver protection effect against APAP-induced acute hepatotoxicity mainly via a caspase-mediated anti-apoptotic effect.

Structural modification of ginsenoside Rh(2) by fatty acid esterification and its detoxification property in antitumor.

Ginsenoside Rh(2), one of the most important ginsenosides with anticancer properties in red ginseng, has been developed as principal antitumor ingredient for clinical use. However, the cytotoxicity test in human hepatocyte cell line QSG-7701 (IC(50) 37.3µM) indicated that Rh(2) might show strong cytotoxic side-effect on the normal liver cells. For blunting the toxicity, Rh(2) was structurally modified by reacting with octanoyl chloride to give a dioctanoyl ester of Rh(2) (D-Rh(2)) in the present study. MTT assay in QSG-7701 cell line in vitro showed that the cytotoxicity of D-Rh(2) on human hepatocyte cells (IC(50) 80.5µM) was significantly lower than that of Rh(2). While antitumor xenograft assay in mice bearing H22 liver cancer cells in vivo showed that the antitumor activity of D-Rh(2) retained to be strong as that of Rh(2). According to previous pharmacokinetic studies, the fatty acid esterification of Rh(2) might be of detoxification reaction to cells. Additionally, D-Rh(2) showed significant enhancement on increasing thymus index at the dose of 10mg/kg compared with vehicle treated control group. Thus, D-Rh(2) might indirectly affect tumor growth by stimulating lymphocytes to become cytotoxic to tumor cells. Finally, our findings suggested that D-Rh(2), the fatty acid ester of Rh(2), might attenuate the side-effect by detoxification to human normal cell and could be a more potential candidate for developing as an antitumor drug.