Design, Synthesis and Biological Evaluation of Nitrate Derivatives of Sauropunol A and B as Potent Vasodilatory Agents

Easy Access to Sauropunols A-D: Synthesis and Spectroscopy Correlation of Their Natural Methyl and Ethyl Glycosides

3,6-Anhydro-2-deoxy-hexofuranoside, the natural product core, is present in natural sauropunols (A-D) and in their natural methyl and ethyl glycosides, now, namely, sauropunol H and sauropunol F. The easily synthesized d-glucose-derived 3,6-anhydro-1,2-O-isopropylidene-5-O-benzoyl-α-d-glucofuranose was elaborated to final targets employing the TsOH·H2O-catalyzed glycosylation reaction with seven different alcohols, subsequent radical deoxygenation, and appropriate deprotection reactions involving mild conditions with excellent functional group tolerance. A short total synthesis of sauropunols (A-D), sauropunol H, and the first total synthesis of sauropunol F are reported herein. The correlation of spectroscopy data of sauropunol H and sauropunol F has been derived through these syntheses.

Preclinical study for the ameliorating effect of l-ascorbic acid for the oxidative stress of chronic administration of organic nitrates on myocardial tissue in high sucrose/fat rat model

Background

The therapeutic activity of Glyceryl trinitrate (GTN) is mainly regulated by liberating nitric oxide (NO) and reactive nitrogen species (RNS). During this biotransformation, oxidative stress and lipid peroxidation inside the red blood cells (RBCs) occur. Hemoglobin tightly binds to NO forming methemoglobin altering the erythrocytic antioxidant defense system.

Aim

The principal objective of our research is to show the ameliorating effect of l-ascorbic acid for the deleterious effects of chronic administration of nitrovasodilator drugs used in cardiovascular diseases such as oxidative stresses and tolerance.

Method

We studied some biochemical parameters for the oxidative stress using groups of high sucrose/fat (HSF) diet Wistar male rats chronically orally administered different concentrations of Isosorbide-5-mononitrate (ISMN) 0.3 mg/kg, 0.6 mg/kg and 1.2 mg/kg. Afterwards, we evaluated the role of l-ascorbic acid against these biochemical changes in cardiac tissues.

Results

Chronic treatment with organic nitrates caused elevated serum levels of lipid peroxidation, hemoglobin derivatives as methemoglobin and carboxyhemoglobin, rate of hemoglobin autoxidation, the cellular levels of the pro-inflammatory cytokines marker (NF-κB) and apoptosis markers (caspase-3) in the myocardium muscles in a dose-dependent manner. Meanwhile, such exposure caused a decline in the enzymatic effect of SOD, GSH and CAT accompanied by a decrease in the level of mitochondrial oxidative stress marker (nrf2) in the myocardium muscles and a decrease in the serum iron and total iron-binding capacity (TIBC) in a dose-dependent manner. Concomitant treatment with l-ascorbic acid significantly diminished these changes for all examined parameters.

Conclusion

Chronic administration of organic nitrates leads to the alteration of the level of oxidative stress factors in the myocardium tissue due to the generation of reactive oxygen species. Using l-ascorbic acid can effectively ameliorate such intoxication to overcome nitrate tolerance.

Isolation and characterization of secondary metabolites from the leaves of Sauropus spatulifolius Beille and their potential biological assays

Eight new compounds (1-8), along with three known related compounds (9-11) were isolated from the leaves of Sauropus spatulifolius Beille. Their structures and configurations were elucidated by means of spectrometric and the modified Mosher's method. Among the new compounds, compounds 1 and 2 were identified as ethyl 3, 6-anhydro-2-deoxy-β-D-arabino-hexofuranoside (1) and ethyl 3, 6-anhydro-2-deoxy- hexofuranoside (2). Compounds 3-5 were the 2-acetylpyrrole derivatives and identified as 2-(2-acetyl-1H-pyrrol-1-yl)-4-hydroxybutyric acid (3), methyl 4-(2-acetyl-lH-pyrrol- 1-yl) butanoate (4) and 1, 4-bis (2-acetyl-1H-pyrrol-1-yl) butane (5), respectively. Compound 6 was elucidated as 7-megastigmane-3, 8, 9-triol. Compounds 7, 8 were identified as kaempferol-3-O-2-deoxy-β-D-glucoside (7) and kaempferol-3-O-β-D- glucopyranosyl-(1-6)-2-deoxy-β-D-glucoside (8). In addition, the cytotoxic activities of all the compounds were also evaluated, where compounds 3, 5, 7, 9\10 and 11 exhibited the magnificent inhibition activity on lung fibroblast differentiation induced by TGF-β1with low toxicity against the RLE-6TN cell.

Cytoprotective Effects of Dinitrosyl Iron Complexes on Viability of Human Fibroblasts and Cardiomyocytes

Nitric oxide (NO) is an important signaling molecule that plays a key role in maintaining vascular homeostasis. Dinitrosyl iron complexes (DNICs) generating NO are widely used to treat cardiovascular diseases. However, the involvement of DNICs in the metabolic processes of the cell, their protective properties in doxorubicin-induced toxicity remain to be clarified. Here, we found that novel class of mononuclear DNICs with functional sulfur-containing ligands enhanced the cell viability of human lung fibroblasts and rat cardiomyocytes. Moreover, DNICs demonstrated remarkable protection against doxorubicin-induced toxicity in fibroblasts and in rat cardiomyocytes (H9c2 cells). Data revealed that the DNICs compounds modulate the mitochondria function by decreasing the mitochondrial membrane potential (ΔΨm). Results of flow cytometry showed that DNICs were not affected the proliferation, growth of fibroblasts. In addition, this study showed that DNICs did not affect glutathione levels and the formation of reactive oxygen species in cells. Moreover, results indicated that DNICs maintained the ATP equilibrium in cells. Taken together, these findings show that DNICs have protective properties in vitro. It was further suggested that DNICs may be uncouplers of oxidative phosphorylation in mitochondria and protective mechanism is mainly provided by the leakage of excess charge through the mitochondrial membrane. It is assumed that the DNICs have the therapeutic potential for treating cardiovascular diseases and for decreasing of chemotherapy-induced cardiotoxicity in cancer survivors.