Icariin attenuated oxidative stress induced-cardiac apoptosis by mitochondria protection and ERK activation

[Icariin alleviates lipid peroxidation after spinal cord injury in rats]

OBJECTIVE

To assess the effects of intragastric administration of icariin on lipid peroxidation after spinal cord injury in rats.

METHODS

Seventy-two healthy adult male SD rats were randomized equally into icariin group, control group and sham-operated group. In the control and icariin groups, spinal cord injury was induced using modified Allen's method, and the rats in the sham-operated group underwent laminotomy without damaging the spinal cord. Immediately after the surgery, the rats in icariin group were subjected to intragastric administration of icariin (100 mg/kg), and those in the control and sham-operated groups received an equal volume of saline in the same manner once a day. At 24 h after the operation, malondialdehyde (MDA) content was detected using thiobarbituric acid method, superoxide dismutase (SOD) activity was measured with xanthine oxidase method, and the water content in the spinal cord was measured using dry-wet weight method. At 48 h after the operation, the ultrastructure of the spinal cord was observed with transmission electron microscopy and scored using Kaptanoglu scoring method. The motor function of the rats was assessed using BBB scoring at 7, 14, 21 and 28 days after the operation.

RESULTS

At 24 h after the operation, MDA content was significantly higher in the control group and icariin group than in the sham-operated group, and was significantly lower in icariin group than in the control group (P<0.05); SOD activity was significantly higher in icariin group than in the control group, and was both significantly lower than that in the sham-operated group (P<0.05). At 48 h after operation, the water content and ultrastructure score of the spinal cord were the highest in sham-operated group (P<0.05), and were significantly lower in icariin group than in the control group (P<0.05). At all the time points of measurement, the BBB scores were significantly lower in the control and icariin groups than in the sham-operated group (P<0.05), and were significantly higher in icariin group than in the control group (P<0.05).

CONCLUSION

Icariin can significantly reduce MDA content, increase SOD activity, and ameliorate lipid peroxidation, spinal cord edema, and histopathological damage of the spinal cord to improve motor function of rats with spinal cord injury.

Epimedium koreanum Ameliorates Oxidative Stress-Mediated Liver Injury by Activating Nuclear Factor Erythroid 2-Related Factor 2

Oxidative stress induced by reactive oxygen species is the main cause of various liver diseases. This study investigated the hepatoprotective effect of Epimedium koreanum Nakai water extract (EKE) against arachidonic acid (AA)[Formula: see text][Formula: see text][Formula: see text]iron-mediated cytotoxicity in HepG2 cells and carbon tetrachloride (CCl₄-)-mediated acute liver injury in mice. Pretreatment with EKE (30 and 100[Formula: see text][Formula: see text]g/mL) significantly inhibited AA[Formula: see text][Formula: see text][Formula: see text]iron-mediated cytotoxicity in HepG2 cells by preventing changes in the expression of cleaved caspase-3 and poly(ADP-ribose) polymerase. EKE attenuated hydrogen peroxide production, glutathione depletion, and mitochondrial membrane dysfunction. EKE also increased the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), transactivated anti-oxidant response element harboring luciferase activity, and induced the expression of anti-oxidant genes. Furthermore, the cytoprotective effect of EKE against AA[Formula: see text][Formula: see text][Formula: see text]iron was blocked in Nrf2 knockout cells. Ultra-performance liquid chromatography analysis showed that EKE contained icariin, icaritin, and quercetin; icaritin and quercetin were both found to protect HepG2 cells from AA[Formula: see text][Formula: see text][Formula: see text]iron via Nrf2 activation. In a CCl₄-induced mouse model of liver injury, pretreatment with EKE (300[Formula: see text]mg/kg) for four consecutive days ameliorated CCl₄-mediated increases in serum aspartate aminotransferase activity, histological activity index, hepatic parenchyma degeneration, and inflammatory cell infiltration. EKE also decreased the number of nitrotyrosine-, 4-hydroxynonenal-, cleaved caspase-3-, and cleaved poly(ADP-ribose) polymerase-positive cells in hepatic tissues. These results suggest EKE is a promising candidate for the prevention or treatment of oxidative stress-related liver diseases via Nrf2 activation.

Icariin improves Fanconi anemia hematopoietic stem cell function through SIRT6-mediated NF-kappa B inhibition

Icariin (ICA) is a flavonoid glucoside derived from the Epimedium plant genus, which has potent regenerative properties and is used in western medicine to treat impotence. Recently, ICA has generated great interest in improving hepatic stellate cell function and cardiac rejuvenation. However, how this natural component functions in hematopoiesis remains unexplored. Here we have examined the role of ICA on hematopoietic stem cells (HSCs) using the cancer-prone disease model of Fanconi anemia (FA), an inherited bone marrow failure syndrome with extremely high risk of leukemic predisposition. We show that ICA reverses the less quiescent status of HSCs deficient for the Fanca or Fancd2 gene, and improves the ability of these mutant stem cells to form colony formation units (CFU) in vitro and reconstitutes hematopoiesis in transplanted recipients. Further analysis reveals that ICA upregulates enzyme activity of the chromatin binding protein SIRT6 in Fanca^-/- and Fancd2^-/- HSCs, both of which have an intrinsic low SIRT6 activity. Furthermore, forced expression of SIRT6 blocks the natural decline of quiescent HSCs in Fanca^-/- or Fancd2^-/- mice and improves the repopulating capacity of these mutant HSCs in irradiated recipients. Mechanistically, ICA enhances SIRT6-mediated H3K9 deacetylation on the promoter of NF-κB and represses the expression of NF-κB target genes. Together, our findings indicate that ICA improves the function of HSCs by stimulating SIRT6 activity and contributes to the regenerative effect of ICA.

Icariin Prevents IL-1β-Induced Apoptosis in Human Nucleus Pulposus via the PI3K/AKT Pathway

Purpose

To explore the effect and possible mechanism of icariin, a prenylated flavonol glycoside derived from the Chinese herb Epimedium sagittatum that was applied to IL-1β pretreated human nucleus pulposus (NP) cells.

Methods

Human NP cells were isolated from intervertebral discs of patients with scoliosis and lumbar spondylolisthesis. The cells were divided into five groups: A (blank control); B (20 ng/ml IL-1β); C (20 ng/ml IL-1β + 20 μM icariin); D (20 μM icariin + 20 ng/ml IL-1β + 25 μM LY294002); E (20 ng/ml IL-1β + 25 μM LY294002). For each of the five groups, the CCK8, apoptosis rates, ROS rates, and JC-1 rates were determined and an electron micrograph was performed. Different expression levels of apoptosis proteins and proteins in the PI3K/AKT pathway were detected via western blot.

Results

We found that the damage effects on human nucleus pulposus cells from 20 ng/ml of IL-1β exposure were attenuated by icariin. When the PI3K/AKT pathway was blocked by LY294002, a specific inhibitor of this pathway, the protective effect of icariin was impaired. In summary, icariin might be a protective traditional Chinese medicine, which prevents inflammation-induced degeneration of intervertebral discs partly through the PI3K/AKT pathway.

Jujuboside A attenuates norepinephrine-induced apoptosis of H9c2 cardiomyocytes by modulating MAPK and AKT signaling pathways

Cardiomyocyte apoptosis is closely associated with the pathogenesis of heart failure. Jujuboside A (JUA) is a type of saponin isolated from the seeds of Zizyphus jujuba. In traditional Chinese medicine, it is believed that JUA possesses multiple biological effects, including antianxiety, antioxidant and anti‑inflammatory activities. The present study aimed to evaluate the effects of JUA on norepinephrine (NE)‑induced apoptosis of H9c2 cells and to investigate its underlying mechanisms. Rat H9c2 cardiomyocytes were pretreated with JUA and were then exposed to NE as an in vitro model of myocardial apoptosis. A cell viability assay, scanning electron microscopy, transmission electron microscopy, flow cytometry assay, acridine orange/ethidium bromide staining, reverse transcription‑quantitative polymerase chain reaction and western blotting, all revealed that NE induced H9c2 cell apoptosis. The results demonstrated that NE inhibited cell viability, and enhanced cell damage and apoptosis of H9c2 cells. Conversely, pretreatment with JUA was able to reverse NE‑induced decreased cell viability and increased apoptosis. Furthermore, JUA suppressed upregulation of the B‑cell lymphoma 2 (Bcl‑2)‑associated X protein/Bcl‑2 ratio, and inhibited the increased protein expression levels of cleaved caspase‑3 and cleaved caspase‑9 following NE exposure. However, the protein expression levels of cleaved caspase‑12 and cleaved caspase‑8 were not significantly altered following exposure to NE or JUA pretreatment. In addition, in JUA‑pretreated cells, the protein expression levels of phosphorylated (p)‑p38 and p‑c‑Jun N‑terminal kinase were downregulated compared with in NE‑treated cells. Furthermore, JUA regulated the activation of extracellular signal‑regulated kinase (ERK) in NE‑treated cells and significantly increased the expression levels of p‑AKT. Taken together, these data suggested that JUA may protect against NE‑induced apoptosis of cardiomyocytes via modulation of the mitogen‑activated protein kinase and AKT signaling pathways. Therefore, JUA may be considered a potential therapeutic strategy for the treatment of heart disease.

Cardioprotective effect of KR-33889, a novel PARP inhibitor, against oxidative stress-induced apoptosis in H9c2 cells and isolated rat hearts

Oxidative stress plays a critical role in cardiac injury during ischemia/reperfusion (I/R). Despite a potent cardioprotective activity of KR-33889, a novel poly (ADP-ribose) polymerase inhibitor, its underlying mechanism remains unresolved. This study was designed to investigate the protective effects of KR-33889 against oxidative stress-induced apoptosis in rat cardiomyocytes H9c2 cells and isolated rat hearts. H₂O₂ caused severe injury to H9c2 cells, mainly due to apoptosis, as revealed by TUNEL assay. However, KR-33889 pretreatment significantly attenuated H₂O₂-induced apoptosis of H9c2 cells, which was accompanied by decrease in expression of both cleaved caspase-3 and Bax and increase in Bcl-2 expression and the ratio of Bcl-2/Bax. KR-33889 also significantly enhanced the expression of anti-oxidant enzymes including heme oxygenase-1, Cu/Zn-superoxide dismutase (SOD), Mn-SOD, and catalase, thereby inhibiting production of intracellular ROS. Furthermore, KR-33889 reversed H₂O₂-induced decrease in phosphorylation of Akt, GSK-3β, ERK1/2, p38 MAPK, and SAPK/JNK during most H₂O₂ exposure time. In globally ischemic rat hearts, KR-33889 inhibited both I/R-induced decrease in cardiac contractility and apoptosis by increasing Bcl-2, decreasing both cleaved caspase-3 and Bax expression, and enhancing expression of anti-oxidant enzymes. Taken together, these results suggest that KR-33889 may have therapeutic potential to prevent I/R-induced heart injury in ischemic heart diseases mainly by reducing oxidative stress-mediated myocardial apoptosis.