Diabetic nephropathy-related active cyclic peptides from the roots of Brachystemma calycinum

Scavenging of OH and OOH radicals by polyradicals of small polycyclic aromatic hydrocarbons

The hydroxyl and peroxyl radicals, particularly the former, occur abundantly and damage almost all types of materials. Polycyclic aromatic hydrocarbons (PAHs) and their polyradicals (all hydrogens removed) have been considered as models for graphene in some recent studies. Geometries of different adducts of polyradicals of two small PAHs having four and nine benzene rings with an OH or OOH radical each were optimized employing unrestricted density functional theory and two different density functionals. The ground states of all the adducts involving the PAHs had doublet spin multiplicity while those involving the polyradicals had doublet, quartet, sextet, or octet spin multiplicity that was decided on the basis of calculated minimum total energies for optimized geometries. Binding energies of the adducts of an OH or OOH radical at the different sites of the polyradicals of PAHs showed that the OH radical would bind with these systems much more strongly than the OOH radical while both the radicals would bind much more strongly with the polyradicals than with the PAHs. Furthermore, both the OH and OOH radicals are found to bind at the edges of the polyradicals much more strongly than at their interior sites. It is shown that polyradicals can serve as efficient scavengers of OH and OOH radicals and therefore, these materials can be used to protect both biological and non-biological systems from damage due to reactions with these radicals.

Taraxerol, a pentacyclic triterpenoid, from Abroma augusta leaf attenuates diabetic nephropathy in type 2 diabetic rats

Persistent hyperglycaemia coupled with inflammation plays an important role in the pathogenesis of diabetic nephropathy (DN). Present study examined the therapeutic potential of taraxerol isolated from the methanol extract of Abroma augusta leaf against DN using rodent model of type 2 diabetes (T2D). T2D was experimentally induced by high fat diet and a single low-single dose of streptozotocin (35mg/kg, i.p.). Accumulation of serum creatinine, urea, and uric acid, activation of lactate dehydrogenase and creatinin kinase, and release of urinary albumin represented the glomerular damage and the progression of nephropathy in T2D rats. Taraxerol (20mg/kg, p.o.) treatment significantly reinstated the aforementioned changes in biochemical parameters near to normalcy. Molecular mechanism studies demonstrated an impaired signaling cascade, IRS1/PI3K/Akt/AMPK/GLUT4/GSK3β, of glucose metabolism in the skeletal muscle and increase in serum levels of pro-inflammatory cytokines, CRP and MCP1 in T2D rats. Activation of polyol pathway, enhanced production of AGEs, up-regulation of NF-κB/PKCs/PARP signaling, and renal fibrosis was also observed in T2D rats. Taraxerol (20mg/kg, p.o.) treatment stimulated glucose metabolism in skeletal muscle, regulated blood glycaemic status and lipid profile in the sera, reduced the secretion of pro-inflammatory cytokines, and restored the renal physiology in T2D rats. Histological assessments were also in agreement with the above findings. Molecular docking study again supported the probable interactions of taraxerol with PKCβ, PKCδ, NF-κB, PARP, PI3K, IRS, Akt and AMPK. In silico ADME study predicted the drug-likeness character of taraxerol. Results suggest a possibility of taraxerol to be a new therapeutic agent for DN in future.

Traditional medicine, Sobokchukeo‑Tang, modulates the inflammatory response in adipocytes and macrophages

Sobokchukeo-Tang (ST) is a well-known formula that is used for treating primary dysmenorrhea caused by blood stasis syndrome (BSS) in Korea and China. The current study investigated the anti-inflammatory and anti-adipogenesis effects of ST on adipocytes and macrophages. The anti-inflammatory efficacy of ST was evaluated in RAW 264.7 cells and differentiated THP-1 cells. To induce inflammation, the cells were treated with lipopolysaccharide (LPS; 1 µg/ml). Following the induction of inflammation, the levels of proinflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the cell supernatant were detected using enzyme-linked immunosorbent assay. 3T3-L1 preadipocytes differentiated into adipocytes in response to insulin, isobutyl-1-methylxanthine and dexamethasone (MDI). To confirm the anti-adipogenesis efficacy of ST, we investigated Oil Red O staining was performed, triglyceride (TG) and leptin secretion were measured, and the protein expression of lipid metabolism-associated factors was determined. ST significantly inhibited TNF-α and IL-6 production in the LPS-treated RAW 264.7 cells compared with LPS stimulation alone. In addition, the concentrations of IL-6 and TNF-α were significantly inhibited by ST in LPS-treated THP-1 cells. Lipid accumulation was reduced by ST, similarly to the positive control treatment, SB203580. In the ST-treated group, the TG and leptin concentrations were inhibited by up to 50 and 83%, respectively, compared with MDI induction only. The ST-treated group reduced the protein expression of peroxisome proliferator-activated receptor-γ and CCAAT/enhancer-binding protein α compared with MDI induction only. The results of the present study demonstrated that ST exerts anti-inflammatory effects on LPS-treated mouse and human macrophage cell lines. ST inhibited adipogenesis in MDI-induced 3T3-L1 adipocytes, as indicated by the significant reduction in TG and leptin concentrations without cytotoxicity. Thus, ST may be useful as a therapeutic agent for preventing lipid-associated diseases, including obesity and atherosclerosis.

Natural Proline-Rich Cyclopolypeptides from Marine Organisms: Chemistry, Synthetic Methodologies and Biological Status

Peptides have gained increased interest as therapeutics during recent years. More than 60 peptide drugs have reached the market for the benefit of patients and several hundreds of novel therapeutic peptides are in preclinical and clinical development. The key contributor to this success is the potent and specific, yet safe, mode of action of peptides. Among the wide range of biologically-active peptides, naturally-occurring marine-derived cyclopolypeptides exhibit a broad range of unusual and potent pharmacological activities. Because of their size and complexity, proline-rich cyclic peptides (PRCPs) occupy a crucial chemical space in drug discovery that may provide useful scaffolds for modulating more challenging biological targets, such as protein-protein interactions and allosteric binding sites. Diverse pharmacological activities of natural cyclic peptides from marine sponges, tunicates and cyanobacteria have encouraged efforts to develop cyclic peptides with well-known synthetic methods, including solid-phase and solution-phase techniques of peptide synthesis. The present review highlights the natural resources, unique structural features and the most relevant biological properties of proline-rich peptides of marine-origin, focusing on the potential therapeutic role that the PRCPs may play as a promising source of new peptide-based novel drugs.

Anti-diabetic nephropathy compounds from Cinnamomum cassia

ETHNOPHARMACOLOGICAL RELEVANCE

The bark of Cinnamomum cassia, called 'Rou-Gui', a traditional spice and medicine in China, is used to treat diseases resulted from kidney yang deficiency, including diabetic nephropathy. The aim of this study is to investigate the anti-diabetic nephropathy activity of Rou-Gui and the active compounds in it.

MATERIALS AND METHODS

The air-dried bark of C. cassia was extracted with 90% EtOH, the obtained residue was successively partitioned by petroleum ether, EtOAc, and n-BuOH followed by concentrating to give petroleum ether (RG-1), EtOAc (RG-2), n-BuOH (RG-3), and water fraction (RG-4), respectively. The anti-diabetic nephropathy activity of fraction (RG-1-4) was evaluated in vitro by inhibiting the expression of fibronectin, monocyte chemoattractant protein-1 and interleukin-6 in high-glucose-induced mesangial cells. By bioassay screenings, repeated column chromatography on fractions of RG-1, 2, and 3, led to the isolation of 23 compounds, whose structures were determined by extensive spectroscopic analyses, and the anti-diabetic nephropathy activity of the isolated compounds was also evaluated.

RESULTS

Four new sesquiterpenoids, cinnamoids A-D (1-4), a new natural product (5), and 18 known compounds (6-23) were isolated from the EtOH extract of the bark of C. cassia under the bioassay-guided screenings. The anti-diabetic nephropathy activity assay showed that fractions of RG-1, 2, and 3 could significantly inhibit the production of fibronectin, monocyte chemoattractant protein-1 and interleukin-6 in high-glucose-stimulated mesangial cells at the concentration of 50 μg/ml; and sesquiterpenoids 5, 6, 14 and compound 20 could significantly inhibit the expression of fibronectin, monocyte chemoattractant protein-1 and interleukin-6 at the concentration of 50 μM.

CONCLUSIONS

The results revealed that sesquiterpenoids may be the active compounds in C. cassia bark on diabetic nephropathy which provided new evidences for the traditional use of this herb to treat diabetic nephropathy and associated kidney diseases.

The anti-inflammation effect of Moutan Cortex on advanced glycation end products-induced rat mesangial cells dysfunction and High-glucose-fat diet and streptozotocin-induced diabetic nephropathy rats

ETHNOPHARMACOLOGICAL RELEVANCE

Moutan Cortex (MC, family: Paeonia suffruticosa Andr.) is a well-known traditional herbal medicine that has been shown to hold a protective effect on inflammation in several diseases. However, its anti-inflammatory activity on diabetic nephropathy (DN) has been less reported. The present study was conducted to evaluate the potential attenuation activities of MC on inflammation in AGEs-induced rat mesangial cells dysfunction and high-glucose-fat diet and streptozotocin (STZ)-induced DN rats and explore the possible mechanism underlying its DN effect.

MATERIALS AND METHODS

The inflammation in mesangial cells (HBZY-1) was induced by 200 μg/ml advanced glycation end products (AGEs). DN rats model was established by an administration high-glucose-fat diet and an intraperitoneal injection of STZ (30 mg/kg). Interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) level in cell supernatant and rats serum were detected by appropriate kits. A co-culture system of mesangial cells and macrophages was performed to evaluate the migration of macrophages. Immunohistochemical assay was applied to examine transforming growth factor beta1 (TGF-β1), IL-6, MCP-1 and intercellular adhesion molecule-1 (ICAM-1) expression in kidney tissues of rats. Furthermore, western blot analysis was carried out to examine TGF-β1, IL-6, MCP-1, ICAM-1 and RAGE protein expressions in mesangial cells.

RESULTS

Pretreatment with MC could significantly inhibit AGEs-induced migration of macrophages in the co-culture system of mesangial cell and macrophage. MC could decrease IL-6 and MCP-1 levels in serum of DN rats in a dose-dependent manner. Furthermore, MC also improved the blood glucose, serum creatinine and urine protein levels. Both immunocytochemistry analysis and western blot analysis showed that MC decreased significantly the over-expression of IL-6, MCP-1, TGF-β1, ICAM-1 and RAGE in mesangial cells or kidney tissues. Additionally, the protein expression of proinflammatory cytokine could also be down-regulated by the pretreatment of RAGE-Ab (5 μg/ml).

CONCLUSION

These findings indicated that the extract of MC had an amelioration activity on the inflammation in AGEs-induced mesangial cells dysfunction and high-glucose-fat diet and STZ-induced DN rats. The protective effect might be associated with the intervention of MC via target of RAGE. These findings suggested that MC might be a benefit agent for the prevention and treatment of DN.