[Effects of the combination of active component extracts from Astragalus membranaceus and Panax notoginseng on apoptosis, reactive oxygen species and mitochondrial membrane potential of PC12 cells with oxidative injury]

Study on the pharmacodynamic effect of Rhizoma Dioscoreae polysaccharides on cerebral ischemia-reperfusion injury in rats and the possible mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma Dioscoreae (RD) is the rhizome of Dioscorea opposita Thunb., a traditional Chinese medicine, which can treat hypertension, diabetes, cerebral vasospasm headache and Alzheimer's disease. Meanwhile, RD is the main component of Liuwei Dihuang pill, a Chinese patent medicine. Rhizoma Dioscoreae polysaccharides (RDPS) are the primary active ingredient of RD. Modern medical research confirmed RDPS has multiple pharmacological effects, including neuroprotection, immunoregulation, antioxidant effect in many organs. The primary ischemia/hypoxia injury and secondary reperfusion injury are mainly caused by oxidative stress, which caused by hypoxia, such as free radical generation, energy metabolism disorder, intracellular calcium overload, excitatory amino acid release and inflammatory reaction.

AIM OF THE STUDY

We have investigated the pharmacodynamic effect of RDPS on cerebral ischemia-reperfusion (IR) injury in rats and the possible mechanism in vitro.

MATERIALS AND METHODS

The pharmacodynamic effect of RDPS on IR injury in rats was studied by the construction of the occlusion of middle cerebral artery (MCAO) model, measuring the volume of cerebral infarct area, the content of oxidation index, inflammatory cytokines, and the expression of CaMMKβ in brain tissue. The in vitro study was explored by oxygen-glucose deprivation/glycogen reoxygenation (OGD/R) model, construction of the CaMMKβ interference sequence, measuring the expression of CaMMKβ in BV2 cells before and after inhibition of CaMMKβ, and the influence of RDPS on Nrf2/HO-1 signal pathway, in order to investigate the possible mechanism.

RESULTS

Compared with the model group, the present study showed that RDPS with high-dose and low-dose groups could significantly reduce the volume of cerebral infarction. The content of MDA decreased and the activities of GSH and SOD increased in the two dose groups of RDPS. We confirmed that after RDPS treatment, the levels of IL-6, IL-1 β and TNF-α in brain tissue were lower than those in model group, and the expression of CaMMKβ in brain tissue of rats decreased in the model group, but increased in the groups of RDPS. In the in vitro study, compared with the control group, RDPS could regulate the OGD/R-induced apoptosis of BV2 cells and increase the level of CaMMKβ, Nrf2 and HO-1 induced by OGD/R. To our surprise, these therapeutic effects are no longer present after the inhibition of CaMMKβ protein. The activity of BV2 induced by OGD/R could not be enhanced by RDPS after the inhibition of CaMMKβ protein.

CONCLUSIONS

RDPS has the pharmacodynamic effect in IR injury, which reduce the area of cerebral infarction, up-regulate the activity of anti-oxidant kinase, and down-regulate the inflammatory cytokine. Additionally, RDPS could affect the activation of Nrf2/HO-1 signaling pathway by regulating the expression of CaMMKβ. Our observations justify the RDPS could be a new strategy for IR injury therapy, and the mechanism may be related to the improvement of antioxidant enzyme activity and inhibition of inflammatory reaction.

PNS-R1 inhibits Dex-induced bronchial epithelial cells apoptosis in asthma through mitochondrial apoptotic pathway

Dexamethasone (Dex) are widely used for the treatment of asthma. However, they may cause apoptosis of bronchial epithelial cells and delay the recovery of asthma. Therefore, it is an urgent problem to find effective drugs to reduce this side effects. Panax notoginseng saponins R1 (PNS-R1) is known to exhibit anti-oxidative and anti-apoptotic properties in many diseases. We aim to investigate whether PNS-R1 can reduce Dex-induced apoptosis in bronchial epithelial cells. In this study, the anti-apoptotic effects of PNS-R1 were investigated by conducting in vitro and in vivo. Annexin V-FITC/PI staining flow cytometry analysis and TUNEL assay were conducted to detect apoptotic cells. Mitochondrial membrane potential was detected by JC-1 analysis. Western blotting and immunohistochemical analysis were conducted to measure caspase3, Bcl-2, Bax, Cyt-c, Apaf-1, cleaved-caspase3 and cleaved-caspase9 levels in lung tissues and 16HBE cells. Our findings demonstrated that Dex could induce apoptosis of bronchial epithelial cells and upregulate caspase3 expression of lung tissues. Western blot showed that Dex increased Bax, Cyt-c, Apaf-1, cleaved-caspase9, cleaved-caspase3 expression and decreased Bcl-2 expression. PNS-R1 could suppress Dex-induced apoptosis of bronchial epithelial cells by inhibiting Bax, Cyt-c, Apaf-1, cleaved-caspase9, cleaved-caspase3 expression and upregulating Bcl-2 expression. Flow cytometry analysis showed PNS-R1 alleviated JC-1 positive cells induced by Dex in 16HBE cells. These results showed that PNS-R1 alleviated Dex-induced apoptosis in bronchial epithelial cells by inhibition of mitochondrial apoptosis pathway. Furthermore, our findings highlighted the potential use of PNS-R1 as an adjuvant drug to treat asthma.

Ginsenoside Rb1 and mitochondria: A short review of the literature

Mitochondria play a central role in various critical cellular processes, including energy synthesis, energy supply and apoptosis. Panax notoginseng, a commonly used traditional Chinese medicine, has various pharmacological effects on the human body. Ginsenosides are representative bioactive components of P. notoginseng. Recently, more attention has focused on ginsenoside Rb1 as an antioxidative and anti-inflammatory agent that can protect the nervous system and the cardiovascular system. Numerous studies have shown that Rb1 exerts these effects by regulating mitochondrial energy metabolism, mitochondrial fission and fusion, apoptosis, oxidative stress and reactive oxygen species release, mitophagy and mitochondrial membrane potential. Thus, the mitochondria are pivotal targets of Rb1. This review summarized the available reports of the effects of ginsenoside Rb1 on the regulation of mitochondria and showed that it has a promising role in treating mitochondrial diseases.

Synergism and mechanism of Astragaloside IV combined with Ginsenoside Rg1 against autophagic injury of PC12 cells induced by oxygen glucose deprivation/reoxygenation

The aim of this study was to explore the effect by which the combination of Astragaloside IV (AST IV) and Ginsenoside Rg1 (Rg1) resisted autophagic injury in PC12 cells induced by oxygen glucose deprivation/reoxygenation (OGD/R). We studied the nature of the interaction between AST IV and Rg1 that inhibited autophagy through the Isobologram method, and investigated the synergistic mechanism via the PI3K I/Akt/mTOR and PI3K III/Becline-1/Bcl-2 signaling pathways. Our results showed that, based on the 50% inhibiting concentration (IC50), AST IV combined with Rg1 at a 1:1 ratio resulted in a synergistic effect, whereas the combination of the two had an antagonistic effect on autophagy at ratios of 1:2 and 2:1. Meanwhile, AST IV and Rg1 alone increased cell survival and decreased lactate dehydrogenase (LDH) leakage induced by OGD/R, reduced autophagosomes and the LC3 II positive patch, down-regulated the LC3 II/LC3 I ratio and up-regulated the p62 protein; the 1:1 combination enhanced these effects. Mechanistic study showed that Rg1 and the 1:1 combination increased the phosphorylation of PI3K I, Akt and mTOR; the effects of the combination were greater than those of the drugs alone. AST IV and the 1:1 combination suppressed the expression of PI3K III and Becline-1, and the combination elevated Bcl-2 protein expression; the effects of the combination were better than those of the drugs alone. These results suggest that after 2 h-OGD followed by reoxygenation for 24h, PC12 cells suffer excessive autophagy and damage, which are blocked by AST IV or Rg1; moreover, the combination of AST IV and Rg1 at a 1:1 ratio of their IC50 concentrations has a synergistic inhibition on autophagic injury. The synergistic mechanism may be associated with the PI3K I/Akt/mTOR and PI3K III/Becline-1/Bcl-2 signaling pathways.

The mechanism of astragaloside IV promoting sciatic nerve regeneration

3-O-beta-D-xylopyranosyl-6-O-beta-D-glucopyranosyl-cycloastragenol (astragaloside IV), the main active component of the traditional Chinese medicine astragalus membranaceus, has been shown to be neuroprotective. This study investigated whether astragaloside IV could promote the repair of injured sciatic nerve. Denervated sciatic nerve of mice was subjected to anastomosis. The mice were intraperitoneally injected with 10, 5, 2.5 mg/kg astragaloside IV per day for 8 consecutive days. Western blot assay and real-time PCR results demonstrated that growth-associated protein-43 expression was upregulated in mouse spinal cord segments L_4–6 after intervention with 10, 5, 2.5 mg/kg astragaloside IV per day in a dose-dependent manner. Luxol fast blue staining and electrophysiological detection suggested that astragaloside IV elevated the number and diameter of myelinated nerve fibers, and simultaneously increased motor nerve conduction velocity and action potential amplitude in the sciatic nerve of mice. These results indicated that astragaloside IV contributed to sciatic nerve regeneration and functional recovery in mice. The mechanism underlying this effect may be associated with the upregulation of growth-associated protein-43 expression.

Astragaloside IV ameliorates renal fibrosis via the inhibition of mitogen-activated protein kinases and antiapoptosis in vivo and in vitro

Apoptosis of renal tubular cells plays a crucial role in renal fibrosis. Astragaloside IV (AS-IV), a compound extracted from Radix Astragali, has been shown to inhibit renal tubular cell apoptosis induced by high glucose, but its role in preventing chronic renal fibrosis as well as the underlying molecular mechanisms involved still remain obscure. In this study, human kidney tubular epithelial cells induced by transforming growth factor-β1 (TGF-β1) were used to investigate the protective role of AS-IV in antifibrosis. As an in vivo model, mice subjected to unilateral ureteral obstruction (UUO) were administered AS-IV (20 mg/kg) by intraperitoneal injection for 7 days. AS-IV significantly alleviated renal mass loss and reduced the expression of α-smooth muscle actin, fibronectin, and collagen IV both in vitro and in vivo, suggesting that this compound functions in the inhibition of renal tubulointerstitial fibrosis. Furthermore, transferase-mediated dUTP nick-end labeling assay results both in vivo and in vitro showed that AS-IV significantly attenuated both UUO and TGF-β1-induced cell apoptosis and prevented renal tubular epithelial cell injury in a dose-dependent manner. Western blotting results also revealed that the antiapoptotic effect of AS-IV was reflected in the inhibition of caspase-3 activation, which might be mediated primarily by the downregulation of mitogen-activated protein kinase effectors phospho-p38 and phospho-c-Jun N-terminal kinase. These data infer that AS-IV effectively attenuates the progression of renal fibrosis after UUO injury and may have a promising clinical role as a potential antifibrosis treatment in patients with chronic kidney disease.

Antiproliferative effects of protopanaxadiol ginsenosides on human colorectal cancer cells

Ginsenosides are the main biologically active components of ginseng. In this study, seven types of protopanaxadiol ginsenosides were assessed for their antiproliferative activity on the HCT-116 and HT-29 human colorectal cancer cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The experimental results indicated that the native protopanaxadiol ginsenosides Rb1 and Rb2 inhibited the proliferation of the colorectal cancer cells in a dose-dependent manner. The deglycosylation products F2 and CO (from ginsenosides Rb1 and Rb2, respectively) significantly inhibited the growth of the human colorectal cancer cell lines, whereas product C-K (from Rb1 and Rb2) exerted no antiproliferative effects on the cancer cell lines assessed in this study. HT-29 cells were more sensitive to these ginsenosides compared to HCT-116 cells. In addition, the antiproliferative activity of ginsenosides was found to be correlated with the number and type of sugar residues. The potent growth inhibitory effect of protopanaxadiol ginsenosides on cancer cells may be used in the pharmaceutical industry.