Cholesterol-derived novel anti-apoptotic agents on the structural basis of ginsenoside Rk1

Ginsenoside Rk1 attenuates radiation-induced intestinal injury through the PI3K/AKT/mTOR pathway

Radiation-induced intestinal injury (RIII) frequently occurs during radiotherapy; however, methods for treating RIII are limited. Ginsenoside Rk1 (RK1) is a substance that is derived from ginseng, and it has several biological activities, such as antiapoptotic, antioxidant and anticancer activities. The present study was designed to investigate the potential protective effect of Rk1 on RIII and the potential mechanisms. The results showed that RK1 treatment significantly improved the survival rate of the irradiated rats and markedly ameliorated the structural injury of the intestinal mucosa observed by histology. Treatment with RK1 significantly alleviated radiation-induced intestinal epithelial cell oxidative stress apoptosis. Moreover, RNA-Seq identified 388 differentially expressed genes (DEGs) and showed that the PI3K-AKT pathway might be a key signaling pathway by which RK1 exerts its therapeutic effects on RIII. The western blotting results showed that the p-PI3K, p-AKT and p-mTOR expression levels, which were increased by radiation, were markedly inhibited by Rk1, and these effects were reversed by IGF-1. The present study demonstrates that Rk1 can alleviate RIII and that the mechanism underlying the antiapoptotic effects of RK1 may involve the suppression of the PI3K/Akt/mTOR pathway. This study provides a promising therapeutic agent for RIII.

Ginsenoside Rk1 bioactivity: a systematic review

Ginsenoside Rk1 (G-Rk1) is a unique component created by processing the ginseng plant (mainly Sung Ginseng (SG)) at high temperatures. The aim of our study was to systematically review the pharmacological effects of G-Rk1. We utilized and manually searched eight databases to select in vivo and in vitro original studies that provided information about biological, pharmaceutical effects of G-Rk1 and were published up to July 2017 with no restriction on language or study design. Out of the 156 papers identified, we retrieved 28 eligible papers in the first skimming phase of research. Several articles largely described the G-Rk1 anti-cancer activity investigating "cell viability", "cell proliferation inhibition", "apoptotic activity", and "effects of G-Rk1 on G1 phase and autophagy in tumor cells" either alone or in combination with G-Rg5. Others proved that it has antiplatelet aggregation activities, anti-inflammatory effects, anti-insulin resistance, nephroprotective effect, antimicrobial effect, cognitive function enhancement, lipid accumulation reduction and prevents osteoporosis. In conclusion, G-Rk1 has a significant anti-tumor effect on liver cancer, melanoma, lung cancer, cervical cancer, colon cancer, pancreatic cancer, gastric cancer, and breast adenocarcinoma against in vitro cell lines. In vivo experiments are further warranted to confirm these effects.

Ginsenoside Rk1 ameliorates paracetamol-induced hepatotoxicity in mice through inhibition of inflammation, oxidative stress, nitrative stress and apoptosis

Background

Frequent overdose of paracetamol (APAP) has become the major cause of acute liver injury. The present study was designed to evaluate the potential protective effects of ginsenoside Rk1 on APAP-induced hepatotoxicity and investigate the underlying mechanisms for the first time.

Methods

Mice were treated with Rk1 (10 mg/kg or 20 mg/kg) by oral gavage once per d for 7 d. On the 7th d, all mice treated with 250 mg/kg APAP exhibited severe liver injury after 24 h, and hepatotoxicity was assessed.

Results

Our results showed that pretreatment with Rk1 significantly decreased the levels of serum alanine aminotransferase, aspartate aminotransferase, tumor necrosis factor, and interleukin-1β compared with the APAP group. Meanwhile, hepatic antioxidants, including superoxide dismutase and glutathione, were elevated compared with the APAP group. In contrast, a significant decrease in levels of the lipid peroxidation product malondialdehyde was observed in the ginsenoside Rk1-treated group compared with the APAP group. These effects were associated with a significant increase of cytochrome P450 E1 and 4-hydroxynonenal levels in liver tissues. Moreover, ginsenoside Rk1 supplementation suppressed activation of apoptotic pathways by increasing Bcl-2 and decreasing Bax protein expression levels, which was shown using western blotting analysis. Histopathological observation also revealed that ginsenoside Rk1 pretreatment significantly reversed APAP-induced necrosis and inflammatory infiltration in liver tissues. Biological indicators of nitrative stress, such as 3-nitrotyrosine, were also inhibited after pretreatment with Rk1 compared with the APAP group.

Conclusion

The results clearly suggest that the underlying molecular mechanisms in the hepatoprotection of ginsenoside Rk1 in APAP-induced hepatotoxicity may be due to its antioxidation, antiapoptosis, anti-inflammation, and antinitrative effects.

Direct endothelial junction restoration results in significant tumor vascular normalization and metastasis inhibition in mice

Tumor blood vessels are leaky and immature, which causes inadequate blood supply to tumor tissues resulting in hypoxic microenvironment and promotes metastasis. Here we have explored tumor vessel modulating activity of Sac-1004, a recently developed molecule in our lab, which directly potentiates VE-cadherin-mediated endothelial cell junction. Sac-1004 could enhance vascular junction integrity in tumor vessels and thereby inhibit vascular leakage and enhance vascular perfusion. Improved perfusion enabled Sac-1004 to have synergistic anti-tumor effect on cisplatin-mediated apoptosis of tumor cells. Interestingly, characteristics of normalized blood vessels namely reduced hypoxia, improved pericyte coverage and decreased basement membrane thickness were readily observed in tumors treated with Sac-1004. Remarkably, Sac-1004 was also able to inhibit lung and lymph node metastasis in MMTV and B16BL6 tumor models. This was in correlation with a reduction in epithelial-to-mesenchymal transition of tumor cells with considerable diminution in expression of related transcription factors. Moreover, cancer stem cell population dropped substantially in Sac-1004 treated tumor tissues. Taken together, our results showed that direct restoration of vascular junction could be a significant strategy to induce normalization of tumor blood vessels and reduce metastasis.

Sac-0601 prevents retinal vascular leakage in a mouse model of diabetic retinopathy

Endothelium integrity is important for the normal functioning of vessels, the disruption of which can lead to disease. The blood-retinal barrier required for normal retinal function is compromised in diabetic retinopathy, causing retinal vascular leakage. Previously, we demonstrated the ability of Sac-0601[((2R,3S)-3-acetoxy-6-((3S,10R,13R,17R)-10,13-dimethyl-17-((R)-6-methylheptan-2-yl)-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-yloxy)-3,6-dihydro-2H-pyran-2-yl)methyl acetate], a pseudo-sugar derivative of cholesterol, to increase survival of retinal endothelial cells. In the present study, we evaluated the ability of Sac-0601 to prevent retinal vascular leakages in vitro and in vivo. Sac-0601 treatment blocked VEGF-induced formation of actin stress fibers and stabilized the cortical actin ring in retinal endothelial cells. It also inhibited degradation of occludin, an important tight junction protein, and blocked VEGF-induced disruption of its linear pattern at the cell border. The [(14)C] sucrose permeability assay demonstrated that Sac-0601 was able to prevent VEGF-induced retinal endothelial permeability. The compound inhibited the vascular leakage in retina of mice intravitreally injected with VEGF. And it also significantly reduced the leakage in retina of diabetic retinopathy mice model. Taken together, our findings suggest the potential therapeutic usefulness of Sac-0601 for retinal vascular permeability diseases.