Force spectroscopy of multivalent binding of riboflavin-conjugated dendrimers to riboflavin binding protein.

Putative riboflavin receptors are considered as biomarkers due to their overexpression in breast and prostate cancers. Hence, these receptors can be potentially exploited for use in targeted drug delivery systems where dendrimer nanoparticles with multivalent ligand attachments can lead to greater specificity in cellular interactions. In this study, the single molecule force spectroscopy technique was used to assess the physical strength of multivalent interactions by employing a riboflavin (RF)-conjugated generation 5 PAMAM dendrimer G5(RF)n nanoparticle. By varying the average RF ligand valency (n = 0, 3, 5), the rupture force was measured between G5(RF)n and the riboflavin binding protein (RFBP). The rupture force increased when the valency of RF increased. We observed at the higher valency (n = 5) three binding events that increased in rupture force with increasing loading rate. Assuming a single energy barrier, the Bell-Evans model was used to determine the kinetic off-rate and barrier width for all binding interactions. The analysis of our results appears to indicate that multivalent interactions are resulting in changes to rupture force and kinetic off-rates.

Polygoni Rhizoma inhibits inflammatory response through inactivation of nuclear factor-kappaB and mitogen activated protein kinase signaling pathways in RAW264.7 mouse macrophage cells.

The objective of this study was to determine the antiinflammatory effects of Polygoni Rhizoma (PR), an Oriental medicinal herb, in interleukin 1 beta (IL-1ß) and lipopolysaccharide (LPS)-stimulated RAW264.7 mouse macrophage cells. PR significantly reduced the production of pro-inflammatory cytokines such as IL-6, tumor necrosis factor alpha (TNF-α) and pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase 2 (COX-2) and prostaglandin E2 (PGE2) even at a concentration of 1 µg/mL in the cells. In addition, PR inhibited the transcriptional activity of NF-κB as well as the degradation and phosphorylation of inhibitory kappa B alpha (IκBα). Furthermore, PR suppressed the phosphorylation of extracellular signal regulated kinase 1/2 (ERK1/2), p38 and c-Jun N-terminal kinase 1/2 (JNK1/2) in IL-1ß and LPS-treated RAW264.7. The results suggest that PR exerts an antiinflammatory property by inhibiting iNOS, COX-2, TNF-α and IL-6 production in association with inactivation of the NF-κB and MAPK signaling pathways in RAW 264.7 cells.

Analgesic and anti-inflammatory effects of ethyl acetate fraction of Polygonum cuspidatum in experimental animals.

Polygonum cuspidatum (PC) has been used for the treatment of arthritis and urinary diseases in traditional medicine. Despite recent evidence that PC has anti-oxidant, anti-tumoral, and anti-inflammatory effects, analgesic and anti-inflammatory effects of PC have not been elucidated yet in vivo. Thus, in the present study, analgesic and anti-inflammatory effects of ethyl acetate extract of PC (EAPC) were investigated in vivo for the first time. Hot plate test and tail-flick test revealed that EAPC at 200 mg/kg exerts analgesic effect (p < 0.05). In contrast, EAPC did not show significant analgesic effect in acetic acid-induced writhing test. Serotonin-induced paw edema model and Freund's complete adjuvant (FCA)-induced adjuvant arthritis model were used to examine anti-inflammatory effect of EAPC in vivo. In serotonin-induced paw edema model, EAPC suppressed swelling inflammatory response within 12 min after serotonin injection, at both 100- and 200-mg/kg dose (p < 0.05). Consistently, in FCA-induced adjuvant arthritis model, FCA at 200 mg/kg significantly suppressed FCA-induced joint swelling within 3 days (p < 0.05), whereas FCA at 100 mg/kg showed the similar result within 5 days (p < 0.05). Furthermore, EAPC effectively inhibited positive responses of c-reactive protein and rheumatoid factor compared to untreated control. Taken together, our findings suggest that EAPC can be a potent candidate for rheumatoid arthritis treatment.

Alcohol-fermented soybean increases the expression of receptor-interacting protein 2 and IκB kinase ß in mouse peritoneal macrophages.

Soybean is a useful component of traditional Korean medicine with well-documented health-promoting effects. We investigated the effects of alcohol-fermented soybean (AFS) on immune function. When AFS treatment was used in combination with recombinant interferon-γ (rIFN-γ), there was a marked cooperative induction of nitric oxide (NO) and tumor necrosis factor (TNF)-α production in mouse peritoneal macrophages. AFS increased the expression of inducible NO synthase mRNA and protein in rIFN-γ-primed macrophages. Treating macrophages with pyrrolidine dithiocarbamate, an inhibitor of nuclear factor-κB (NF-κB), decreased the synergistic effects of AFS. In addition, AFS in combination with rIFN-γ increased the phosphorylation of p38 and c-Jun N-terminal kinase (JNK) but not extracellular signal-regulated kinase. However, AFS had no effect on phosphorylation of mitogen-activated protein kinases by itself. The p38 inhibitor SB203580 or the JNK inhibitor SP600125 inhibited the AFS-induced NO and TNF-α production. When AFS was used in combination with rIFN-γ, there was a co-operative activation of NF-κB and receptor-interacting protein 2 (Rip2)/IκB kinase (IKK)-ß. Our results indicate that AFS increases the production of NO and TNF-α through the activation of Rip2/IKK-ß in rIFN-γ-primed macrophages.

Effects of berberine on angiotensin-converting enzyme and NO/cGMP system in vessels.

The present study was designed to examine the relaxant and anticonstrictive effects of berberine in the isolated thoracic aorta in rats. Intravenous injection of berberine lowered the mean arterial pressure (MAP) of anesthesized rats in a dose-dependent manner. The angiotensin-converting enzyme (ACE) activities were inhibited significantly by the addition of berberine in a dose-dependent manner of which the IC50 value of berberine for ACE was 42 micrograms/ml (125 microM). In the endothelium-intact rings, angiotensin I-induced contraction was markedly attenuated by prior exposure of aortic rings to berberine. Treatment of the intact aortic rings with berberine (10 micrograms/ml) increased the NOx and cGMP productions relative to the vehicle-treated group. Berberine induced a dose-dependent relaxation in phenylephrine-precontracted aortic rings, but NG-nitro-L-arginine methyl ester (L-NAME)-pretreated intact aortic rings or functional removal of the endothelium attenuated the berberine-induced relaxation without an effect on maximum response. These results suggest that berberine has a hypotensive effect, at least in part, via the inhibition of ACE and direct release of NO/cGMP in the vascular tissues.