Saponins of Panax japonicus Confer Neuroprotection against Brain Aging through Mitochondrial Related Oxidative Stress and Autophagy in Rats.

BACKGROUND: Oxidative stress and mitochondrial dysfunction play a vital role in the pathogenesis of brain aging. Saponins from Panax japonicus (SPJ) have attracted much attention for their potential to attenuate age-related oxidative stress as the main ingredient in rhizomes of Panax japonicus. OBJECTIVE: This study aimed to investigate the neuroprotective effects of SPJ on natural aging rats as well as the underlying mechanisms regarding oxidative stress and mitochondrial pathway. METHODS: Sprague-Dawley rats were divided into control groups (3-, 9-, 15- and 24-month old groups) and SPJ-treated groups. For SPJ-treated groups, SPJ were orally administrated to 18-month old rats at doses of 10 mg/kg, 30 mg/kg and 60 mg/kg once daily. Control groups were given the same volume of saline. After the treatment with SPJ or saline for six months, the cortex and hippocampus were rapidly harvested and deposited at -80°C after the rats were decapitated under anesthesia. The neuroprotective effects of SPJ were estimated by histopathological observation, TUNEL detection, biochemical determination and western blotting. RESULTS: SPJ improved pathomorphological changes in neuronal cells and decreased apoptosis in the cortex and hippocampus of aging rats, increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), Na+/K+-ATPase, Ca2+-ATPase and Ca2+/Mg2+-ATPase whereas, decreased malondialdehyde (MDA) contents in the cortex of aging rats. Furthermore, the SPJ increased silent mating type information regulation 2 homolog-1 (SIRT1) protein expression, decreased acetylated level of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) in the cortex and hippocampus of aging rats, and reversed the aging-induced decline of Forkhead box O3 (Foxo3a), Superoxide Dismutase 2 (SOD2), microtubule-associated protein light chain 3 (LC3II) and Beclin1 levels in the cortex and hippocampus. CONCLUSION: Our data showed that SPJ conferred neuroprotection partly through the regulation of oxidative stress and mitochondria-related pathways in aging rats.

Saponins from Panax japonicus attenuate age-related neuroinflammation via regulation of the mitogen-activated protein kinase and nuclear factor kappa B signaling pathways.

Neuroinflammation is recognized as an important pathogenic factor for aging and related cognitive disorders. Mitogen-activated protein kinase and nuclear factor kappa B signaling pathways may mediate neuroinflammation. Saponins from Panax japonicus are the most abundant and bioactive members in rhizomes of Panax japonicus, and show anti-inflammatory activity. However, it is not known whether saponin from Panax japonicus has an anti-inflammatory effect in the aging brain, and likewise its underlying mechanisms. Sprague-Dawley rats were divided into control groups (3-, 9-, 15-, and 24-month-old groups) and saponins from Panax japonicus-treated groups. Saponins from Panax japonicus-treated groups were orally administrated saponins from Panax japonicus at three doses of 10, 30, and 60 mg/kg once daily for 6 months until the rats were 24 months old. Immunohistochemical staining and western blot assay results demonstrated that many microglia were activated in 24-month-old rats compared with 3- and 9-month-old rats. Expression of interleukin-1ß, tumor necrosis factor-α, cyclooxygenase-2, and inducible nitric oxide synthase increased. Each dose of saponins from Panax japonicus visibly suppressed microglial activation in the aging rat brain, and inhibited expression levels of the above factors. Each dose of saponins from Panax japonicus markedly diminished levels of nuclear factor kappa B, IκBα, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38. These results confirm that saponins from Panax japonicus can mitigate neuroinflammation in the aging rat brain by inhibition of the mitogen-activated protein kinase and nuclear factor kappa B signaling pathways.

Chikusetsusaponin V attenuates lipopolysaccharide-induced liver injury in mice.

Chikusetsusaponin V (CsV), a saponin from Panax japonicus, has been reported to inhibit inflammatory responses in lipopolysaccharide (LPS)-induced macrophage cells. However, whether CsV could alleviate LPS-induced liver injury in vivo and the potential mechanisms involved remain unclear. In the present study, we investigated the anti-inflammatory effects of CsV on LPS-induced acute liver injury in mice and further explored the potential mechanisms involved. Our results showed that CsV significantly attenuated elevation of alanine transaminase (ALT) and aspartate aminotransferase (AST) levels and improved liver histopathological changes in LPS-induced mice. In addition, CsV decreased serum tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) levels and inhibited mRNA expressions of inducible nitric oxide synthase (iNOS), TNF-α and IL-1ß in LPS challenged mice. Furthermore, CsV inhibited nuclear factor kappa B (NF-κB) activation by downregulating phosphorylated NF-κB, IκB-α, ERK, c-Jun N-terminal kinase (JNK) and p38 levels in the liver tissue, which ultimately decreased nucleus NF-κB protein level. In conclusion, our data suggested that CsV could be a promising drug for preventing LPS challenged liver injury since it attenuated LPS-induced inflammatory responses, partly via inhibiting NF-κB and MAPK signaling pathways.

[Protective Effects of Total Saponins from Panax japonicus on H2O2Induced Injury via Mitochondia Pathway in SH-SY5Y Cells].

OBJECTIVE: To investigate the protective mechanism of total saponins from Panax japonicus (SPJ) on H2O2 induced injury in SH-SY5Y cells. METHODS: SH-SY5Y cells were divided into three groups: blank control group, model group (600 µmol/L H2O2) and drug treatment groups. Different concentrations of SPJ (0.1, 1, 5 and 20 µg/mL) were incubated with SH-SY5Y cells for 12 hours prior to exposing to 600 µmol/L H2O2 for another 12 h. Mitochondrial membrane potential (MMP) was detected by JC-1 method. Protein expressions of Sirt1 , PGC-1α, Foxo3a, LC3-II and Beclin1 were detected by Western blotting. RESULTS: Compared to the H2O2 model group, SPJ pretreatment significantly increased MMP level and enhanced the protein expressions of Sirt1, PGC-1α, Foxo3a, LC3-II and Beclin1. CONCLUSION: SPJ exerts protective effect on H2O2 induced SH-SY5Y cell injury through mitochondria pathway.

[Study on protective effect of total saponins of Panax japonicus on LPS-induced RAW264. 7 cell inflammation through NF-kappaB pathway].

OBJECTIVE: To observe the anti-inflammatory effect of total saponins of Panax japonicus on LPS-induced RAW264. 7 macrophages. METHOD: The effect of total saponins of P. japonicus of different concentrations on RAW264. 7 cell viability was determined with the MTT method. The NO kit assay was adopted to detect the NO release of total saponins of P. japonicus to LPS-induced RAW264. 7 cells. The enzyme linked immunosorbent assay (ELISA) was used to detect the secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin 1-beta (IL-1beta). The reverse transeriptase-polymerase chain reaction (RT-PCR) was used to determine the expression of inducible nitric oxide synthase (iNOS) ,TNF-alpha,IL-1beta. The protein expression of nuclear transcription factor-kappaB p65 (NF-kappaB p65) was tested by Western blot. RESULT: The safe medication range of total saponins of P. japonicus was less than 80 mg x L(-1). Compared with the LPS model group, total saponins of P. japonicus high, middle and low dose groups (0.1, 1, 10, 40 mg x L(-1)) could significantly reduce the secretion of NO, TNF-alpha, IL-1beta of LPS-induced RAW264. 7 cells, and inhibit the expressions of iNOS, TNF-alpha and IL-1beta mRNA and the protein expression of NF-kappaB p65. CONCLUSION: This study preliminarily proves the protective effect of total saponins of P. japonicus on LPS-induced RAW264.7 macrophages. Its action mechanism may be related to NF-kappaB signal pathway.

Chikusetsu saponin V attenuates MPP+-induced neurotoxicity in SH-SY5Y cells via regulation of Sirt1/Mn-SOD and GRP78/caspase-12 pathways.

Studies have shown that saponins from Panax japonicus (SPJ) possess neuroprotective effects. However, whether Chikusetsu saponin V (CsV), the most abundant member of SPJ, can exert neuroprotective effects against 1-methyl-4-phenylpyridinium ion (MPP+)-induced cytotoxicity is not known. In this study, we aimed to investigate the neuroprotective effects of CsV on MPP+-induced cytotoxicity in human neuroblastoma SH-SY5Y cells and explore its possible mechanisms. Our results show that CsV attenuates MPP+-induced cytotoxicity, inhibits ROS accumulation, and increases mitochondrial membrane potential dose-dependently. We also found that levels of Sirt1 protein and Mn-SOD mRNA significantly decreased in MPP+-treated group but were restored with CsV treatment in a dose-dependent manner. Furthermore, GRP78 protein and Caspase-12 mRNA levels were elevated by MPP+ exposure but reversed by CsV treatment. CsV inhibited the MPP+-induced downregulation of Bcl-2 and up-regulation of Bax in a dose-dependent manner and, thus, increased the ratio of Bcl-2/Bax. Overall, these results suggest that Sirt1/Mn-SOD and GRP78/Caspase-12 pathways might be involved in the CsV-mediated neuroprotective effects.