Anti-allergic effect of N-acetylneuraminic acid in guinea-pigs

Edible bird’s nest, an Asian health food supplement, possesses anti-inflammatory responses in restoring the symptoms of atopic dermatitis: An analysis of signaling cascades

Edible bird’s nest (EBN) is a Chinese delicacy possessing skin rejuvenating functions. To verify skin anti-inflammatory function of EBN, water extract and enzymatic digest of EBN, as well as the major sialic acid, N-acetyl neuraminic acid (NANA), were probed in TNF-α-treated HaCaT keratinocytes. The mRNA expressions of pro-inflammatory cytokines, e.g., IL-1β, IL-6, TNF-α, and an enzyme responsible for inflammatory response, i.e., Cox-2, as well as filaggrin and filaggrin-2, were markedly altered after treating with different preparations of EBN. The EBN-mediated responses could be accounted by its robust reduction of reactive oxygen species (ROS), NF-κB signaling and phosphorylation of p38 MAPK and JNK, as triggered by TNF-α-induced inflammation. The anti-inflammatory response of EBN was further supported in animal model. In 2,4-dinitrochlorobenzene (DNCB)-induced dermatitic mice, the effects on skin thickness, severity level of damage and scratching behavior, exerted by DNCB, were reversed after EBN treatments, in dose-dependent manners. In parallel, the levels of immune cells and pro-inflammatory cytokines in dermatitic skin were markedly reduced by treatment of EBN preparations. In general, NANA and enzymatic digest of EBN showed better anti-inflammatory responses in both models of in vitro and in vivo. These lines of evidence therefore suggest the possible application of EBN in treating atopic dermatitis.

Effect of fudosteine, a cysteine derivative, on blood flow of tracheal microvasculature increased by airway inflammation

We examined the effect of fudosteine, a cysteine derivative, on blood flow of tracheal microvasculature increased by airway inflammation. Airway inflammation was elicited by sulfur dioxide (SO(2)) exposure for 2 weeks in rabbits. Each drug (500 mg/kg, p.o.) or 0.5% carboxymethylcellulose-Na (control group) was daily administered just before SO(2) exposure. After final SO(2) exposure was finished, blood flow of tracheal microvasculature was measured by blood perfusion monitor. Fudosteine or S-carboxymethylcysteine (S-CMC) significantly suppressed blood flow of tracheal microvasculature increased by SO(2) exposure. However, no effect of fudosteine was observed on the pharmacological microvascular response in trachea of SO(2)-exposed rabbits. On the other hand, fudosteine or S-CMC scavenged superoxide anion generated from rat neutrophils, and enzymatically generated from xanthine oxidase-acetaldehyde reaction. The results suggest that suppressive action in increased tracheal blood flow of fudosteine is due to anti-inflammatory activity, at least in part, via scavenging of superoxide anion.

Comparison of chemical and enzymatic synthesis of 2-acetamido-2-deoxy-D-mannose 6-phosphate: a new approach

Chemical and enzymatic methods to synthesis of 2-acetamido-2-deoxy-D-mannose-6-phosphate (ManNAc-6-P) have been investigated. A new preparative method has been developed although some established procedures were tried. In this new method, a 6-O-acetyl or 4,6-di-O-acetyl group of the per-O-acetylated 2-acetamido-2-deoxy-D-mannose (ManNAc) were regioselectively removed with an esterase from the yellow yeast, Rhodosporidium toruloides, followed by phosphorylation and O-deacetylation under mild conditions. 1H and 13C NMR data spectra of ManNAc-6-P were recorded.

The influence of neuraminidase treatment on tracheal smooth muscle contraction

To examine the role of sialic acid in the respiratory tract, the influence of neuraminidase from Clostridium perfringens was investigated on contractions of isolated guinea-pig and rat trachea and on histamine release from guinea-pig lung tissue. Treatment with 2.0 units/ml of neuraminidase at 37 degrees C and pH 7.4 for 30 min caused an approximately 60% removal of total N-acetylneuraminic acid, a representative sialic acid, from muscle from guinea-pig and rat trachea. Neuraminidase concentration dependently induced histamine release from guinea-pig chopped lung tissue, but has no effect on contractions produced by acetylcholine, histamine and 5-hydroxytryptamine. Pretreatment with 2.0 units/ml of neuraminidase inhibited the contraction induced by antigen (ovalbumin) or compound 48/80. These findings suggest, at least in part, that sialic acids sensitive to neuraminidase are involved in the regulation of histamine release but not tracheal contraction.