The active component screening of Anoectochilus roxburghii and the functional study on inhibition of melanogenesis in zebrafish.

The aim of this study is to explore the active components of Anoectochilus roxburghii capable of inhibiting melanin formation using chemical separation and extraction and functional analysis. Anoectochilus roxburghii were extracted with alcohol and separated into three groups: the total extraction group, alcohol extracted group and alcohol precipitated group. Zebrafish embryos at 0.75 h post-fertilization were exposed to various concentrations of the three groups of extracts, and analyzed at 72 h, using semi-quantitative RT-PCR and in situ hybridization. The results showed that the alcohol extracts inhibit melanogenesis most significantly in the zebrafish embryos. The mRNAs of melanin-related genes, such as silv, tyr, tyrp1a, were down-regulated by the alcohol extracts spatially and temporally. The alcohol extracts also inhibited the activity of tyrosinase, a key enzyme in melanogenesis, in a dosage dependent manner. In addition, the alcohol extracts also display a remarkable inhibitory effect on melanin synthesis through down-regulation of mRNAs of melanin-related genes and tyrosinase activity in zebrafish embryos, in which a large amount of melanin has already been synthesized. Such inhibitory effect could be reversed after the withdrawal of the alcohol extracts. Our results showed that the alcohol extracts of Anoectochilus roxburghii can significantly inhibit zebrafish melanogenesis, supporting the notion that Anoectochilus roxburghii could potentially be used in the development and production of natural whitening products.

Neuroprotective effects of NSTyr on cognitive function and neuronal plasticity in rats of chronic cerebral hypoperfusion.

The neuroprotective effects of N-stearoyl-L-tyrosine (NSTyr) on cognitive function and neuronal plasticity during chronic cerebral hypoperfusion (CCH) in rats were investigated. After induction of CCH, NSTyr was administered daily for 3 months intraperitoneally. Cognitive functions were evaluated by Morris water maze and hippocampal long-term potentiation (LTP). Neuropathological changes were examined using light micrograph and Fluoro-Jade B staining. Neuronal plasticity was assessed by measuring the expression of MAP-2, GAP-43 and synaptophysin on hippocampal regions of rats with immunohistochemistry and western blotting. CCH resulted in significant spatial memory impairment and inhibition of LTP, and led to neurodegeneration in the CA1 region of the hippocampus in the model rats compared with the sham-operated rats. In the model rats treated with NSTyr, cognitive function improved. The expression levels of MAP-2 and synaptophysin protein in hippocampal areas in the model rats were less than those in the sham-operated rats, and increased in the model rats treated with NSTyr. However, no statistical significance of GAP-43 expression among the sham, model and NSTyr groups was observed. These data indicate that NSTyr exerts protective effects on cognitive function of rats after CCH, which may be related to the changes of neurodegeneration and neuronal plasticity in the hippocampal area of rats.

Synthesis of Lipoamino acids and their activity against cerebral ischemic injury.

A series of lipoamino acids were synthesized and their neuroprotective effect against brain ischemia induced by oxygen-glucose deprivation (OGD) on rat cerebral slices was evaluated. Among these compounds, N-stearoyl-L-tyrosine (4), N-stearoyl-L-serine (5) and N-stearoyl-L-threonine (6) exhibited good neuroprotective activity. We found that the neuroprotective activity of lipoamino acids depended on the acyl group, the presence of a free carboxylic function and a free hydroxyl group at the branched chain of the amino acids. The results also showed that 5 was the most active compound, protecting rat brain slices against OGD as well as hydrogen peroxide (H(2)O(2)) insult at the range of 1-10 M.

[Effect of premix schedule on crystal formation of compound calcium phosphate cements].

PURPOSE: To investigate the effect of premix schedule on crystal formation of self-hardening calcium phosphate cements (CPC). METHODS: CPC were prepared by mixing cement powders of tetracalcium phosphate(TTCP) with a cement liquid of phosphate acid saline solution. TTC-CPC, chitosan-CPC and chitosan-TTC-CPC were investigated with different premix schedules. The crystal formation was investigated by X-ray diffraction(XRD) and field scanning electron microscope(FSEM). RESULTS: TTC and chitosan both affected the phase transition and crystal character in CPC. Chitosan, as organic additive, regulated the regular crystal formation and inhibited the phase transition of TTCP into OCP. CONCLUSIONS: The premix schedule affects the crystal formation and phase transition, which may affect its biocompatibility and bioactivities in vivo.