| Propolis, a kind of fragrant sticky collidal solids, was used to seal the hive bees to fight against pathogenic microorganism invasion, which have several biological compounds and pharmacological properties. Recent studies show whether propolis has anti-diabetes by mainly using the SD rat model with diabetes mellitus at home and abroad. There are few reports about the mechanism of propolis having anti-diabetes. Therefore, in this paper, propolis was studied, including extraction, components analysis and contents of polyphenols of propolis from North-central parts of China, determination of the inhibition and the mechanism on a-glucosidase and the effect on the structure of a-glucosidase, and studying the inhibitory effect on advanced glycation end products(AGEs), which is one of reasons of inducing complication of diabetes.1. Using raw propolis from North-central parts of China as material, total phenolics and total flavonoids content in extracts of propolis by75%ethanol-water assisted by ultrasound were estimated and the preliminary qualitative and quantitative analysis of components in extracts of various regions was done by using HPLC, and then the region of propolis was simulated. The chemical composition of propolis collected from different regions varies and Hebei province and Shanxi province have highest total phenolics and total flavonoids content in extracts respectively, with199.41mg gallic acid/g raw propolis and368.28mg rutin/g raw propolis. By identifying the components in extracts, we found that the highest quantity of caffeic acid、kaempferol、pinocembrin、chrysin、galangin and benzyl cinnamate in extracts of propolis from Henan province was11.14、3.80、53.49、63.21、40.24and7.76mg/g raw propolis, respectively, and propolis from Liaoning province have highest quantity of apigenin with6.78mg/g raw propolis. Regional analysis showed that propolis from Henan province and Shanxi province has great similarity, one from Hebei province、Shandong province and Liaoning province has great similarity and one from Anhui province、Hubei province、Heilongjiang province and Gansu province has great similarity, but propolis from Beijing has relatively similarity with each other above.2. Take Beijing propolis powder into different concentration of ethanol-water solution assisted by ultrasound, centrifuged and take supernatant, freeze dried and different ethanol extracts of propolis (EEP) were obtained. The propolis extracts (PES) were separated by AB-8macroporous resin, and3components named PEFS-1、PEFS-2and PEFS-3were obtained. Total phenolics and total flavonoids content in different propolis extracts and isolates were measured and the chemical composition was analyzed by using HPLC. Results indicated that the highest total flavonoids was697.36mg rutin/g EEP in the75%ethanol extracts of propolis and the highest total phenolic content was386.50mg gallic acid/g EEP in the25%EEP in different concentration ethanol extracts of propolis. In different isolates of propolis, PEFS-1has the highest total phenolic content with513.62mg gallic acid/g EEP and PEFS-2has the highest total flavonoids content with832.17mg rutin/g EEP. HPLC profile showed that PEFS-1has the majority of phenolic acids, PEFS-2has the majority of flavanoids and the compounds of PEFS-3are mainly ester and a small quantity of complex structure of flavanoids.Anti-diabetes activity in vitro of different extracts of propolis and isolates by using a-glucosidase model. Results showed that different extracts of propolis and isolates could effectively inhibit the activity of a-glucosidase. The75%ethanol extracts of propolis (75%EEP) showed the highest inhibitory effect on a-glucosidase and sucrase from baker’s yeast and rat intestinal acetone powder and the water extract of propolis(WEP) showed the highest inhibitory effect on maltase from rat intestinal acetone powder in all extracts. The highest inhibitory activity against sucrase and maltase was observed by PEFS-1and the highest inhibitory activity against a-glucosidase was observed by PEFS-2. The WEP,25%EEP and PEFS-1showed competitive inhibition,75%EEP and PEFS-2indicated uncompetitive inhibition, and50%EEP,95%EEP,100%EEP and PEFS-3exhibited mixed uncompetitive inhibition.3. The interaction between different extracts of propolis and isolates and a-glucosidase from baker’s yeast was observed by the method of Fluorescence spectroscopy, UV-visible spectroscopy and isothermal titration calorimetry. As results showed, different extracts of propolis and isolates could effectively quench the endogenous fluorescence of a-glucosidase, particularly PEFS-2having the strongest effect of fluorescence quenching. The WEP,25%EEP,95%EEP and PEFS-1mainly showed static quenching assisted by dynamic quenching, and75%EEP,100%EEP, PEFS-2and PEFS-3mainly indicated dynamic quenching assisted by static quenching. However,50%showed dynamic quenching at low concentration and static quenching at high concentration. The structure change of a-glucosidase induced by different extracts propolis and isolates was indicated by UV-visible spectroscopy and isothermal titration calorimetry.4. In order to evaluate the inhibition of different extracts of propolis and isolate on the complication of diabetes, the inhibitory effect and mechanism of them on the total advanced glycation endproducts (AGEs), pentosidine and Nε-(carboxymethyl)lysine (CML) were researched by using BSA-Glucose, BSA-MGO and BSA-GO model. Results showed that different extracts of propolis and isolates could effectively inhibit the formation of the total AGEs and pentosidine, particularly75%EEP and PEFS-2. However, the inhibitory effect of different extracts of propolis and isolate on the formation of CML was relatively poor. Compared with others, the WEP and PEFS-1have stronger ability of trapping reactive carbonyl by the analysis of Fluorescence spectroscopy and SDS-SPAG. Different extracts of propolis and isolates is mainly inhibiting the oxidation of glycation protein and secondary trapping reactive carbonyl to inhibit the formation of AGEs. |
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