OBJECTIVE: To separate and isolate total flavonoids from Dendrobium nobile leaves, and to investigate its anti-Alzheimer's disease (AD) activity in vitro. METHODS: Total flavonoids were obtained by ultrasonic extraction method and extracted by chloroform, ethyl acetate and butyl alcohol after the obtained extract was dispersed with water. Qualitative analysis was carried out with color reaction and TLC. The content of total flavonoids in extracts was analyzed quantitatively by Aluminum nitrate-sodium nitrite method. Antioxidant activity of extract was investigated by DPPH radical scavenging assay; the inhibitory effect of each extract on Aβ42 protein aggregation was investigated by Thioflavin T assay. Metals (Cu2+, Fe3+, Zn2+) chelating property was studied by UV-vis spectrum scanning to investigate the anti-AD activity in vitro. RESULTS: The flavonoids were found in ethyl acetate, butyl alcohol and aqueous extracts, and their flavonoids contents were 0. 03, 0. 12, 0. 05 mg/mL, respectively. IC50 of three extracts to DPPH free radicals were 0. 021, 0. 011, 0. 013 mg/mL. Inhibitory rates of them to Aβ42 protein aggregation were 43. 77％, 52. 28％, 38. 42％, respectively. Three extracts exerted metal chelating ability which was best in Cu2+. CONCLUSIONS: The total flavonoids from D. nobile leaves have good antioxidant activities, Aβ42 aggregation inhibitory activities and metal chelating activity, show certain anti-AD activity in vitro especially in butyl alcohol extract.

Objective: To explore the effect of 18β-sodium glycyrrhetinic acid on thymic stromal lymphopoietin (TSLP) in nasal mucosa of allergic rhinitis (AR) rats. Methods: One hundred Wistar rats,half male and half female,were randomly divided into 5 groups by random number table method: control group, AR model group,budesonide group,18β-sodium glycyrrhetinic acid at dose of 20 mg/kg and 40 mg/kg groups, with 20 rats in each group. AR animal models were established by ovalbumin (OVA) sensitization in the other four experimental groups. After successful modeling, budesonide and 18β-sodium glycyrrhetinic acid were given in each group,and the detection time points were 2 weeks and 4 weeks. The distribution of TSLP in rat nasal mucosa was detected by immunohistochemistry,and the expression of TSLP in rat nasal mucosa was determined by Western blot at the protein level. The expression of TSLP-mRNA in rat nasal mucosa was detected and compared by real-time fluorescence quantitative PCR (RT-PCR) at mRNA level. The concentrations of IL-4 and OVA-sIgE in rat serum were measured and compared by ELISA. One-way analysis of variance and the least significant difference method were used for the comparison among groups, LSD t test was used for the comparison between the two groups,and the difference was statistically significant (P<0.05). Results: Immunohistochemistry confirmed existence of TSLP in rat nasal mucosa, especially in epithelial cells,endothelial cells and epithelial cilia. Western blot and RT-PCR suggested that the expression of TSLP and TSLP-mRNA in nasal mucosa of AR model group was significantly higher than that of control group (2 weeks TSLP: 1.795 9±0.131 4 vs 0.990 5±0.164 2, 4 weeks TSLP: 1.809 7±0.253 4 vs 0.870 3±0.124 4; 2 weeks TSLP-mRNA:4.582 9±0.697 7 vs 1.108 7±0.081 1, 4 weeks TSLP-mRNA:4.814 4±0.662 8 vs 1.001 0±0.155 3; all P<0.05). After 2 weeks and 4 weeks of drug intervention,the expression of TSLP and TSLP-mRNA was inhibited in nasal mucosa of budesonide group,18β-sodium sodium glycyrrhetinic acid at dose of 20 mg/kg and 40 mg/kg group,which was significantly different from that of AR model group (2 weeks TSLP: (0.897 8±0.081 8)/(1.072 1±0.113 6)/(1.396 6±0.133 9) vs 1.795 9±0.131 4; 4 weeks TSLP: (1.191 0±0.161 3)/(1.141 0±0.152 3)/(1.200 5±0.189 6) vs 1.809 7±0.253 4; 2 weeks TSLP-mRNA: (1.175 6±0.100 9)/(1.254 4±0.078 2)/(2.037 2±0.559 2) vs 4.582 9±0.697 7; 4 weeks TSLP-mRNA: (1.158 3±0.104 3)/(1.224 0±0.034 0)/(1.275 2±0.099 6) vs 4.814 4±0.662 8; all P<0.05), and not significantly different from control group. With the inhibition of TSLP, the concentrations of IL-4 and OVA-sIgE in rat serum were also decreased. Conclusion 18β-sodium glycyrrhetinic acid has obvious inhibitory effect on TSLP in nasal mucosa of AR rats, which can control Th2 type immune inflammatory reaction.