The active fraction extracted from dragon's blood displayed an inhibitory effect on alpha-glucosidase activity with an IC50 of 0.152 mg/mL, which is nearly half of the crude material. Its inhibition on alpha-glucosidase was noncompetitive. In addition, when this fraction was orally administered to mice dosed with Acarbose (20 mg/kg), the active fraction (100, 300, 500 mg/kg) significantly suppressed increase of blood glucose levels after sucrose loading in a dose-dependent manner. These results suggest that this extract from dragon's blood exerts an anti-diabetic effect by suppressing intestinal carbohydrate absorption and thereby reducing the postprandial increase of blood glucose.

A new dihydrochalcone, 4'-hydroxy-4,2'-dimethoxy-dihydrochalcone, was isolated from Chinese dragon's blood, the red resin of Dracaena cochinchinensis. Its structure was established by spectrum analysis.

Abstract. The interaction between loureirin B (Lour B) and human serum albumin (HSA) was investigated by fluorescence and UV-vis absorption spectroscopy. Experimental results indicated that loureirin B had a strong ability to quench the intrinsic fluorescence of HSA through a dynamic quenching procedure. The fluorescence quenching data revealed that the quenching constants (K SV ) 2.68 × 10 4 , 3.30 × 10 4 and 4.10 × 10 4 l/mol at 300, 310 and 320 K, respectively. Based on the thermodynamic parameters obtained, the positive values of enthalpy change ΔH and entropy change ΔS suggested that hydrophobic forces played a major role in the interaction of Lour B with HSA. According to Förster theory of energy transfer, the distance r between HSA and Lour B was calculated to be 2.85 nm. Furthermore, the effect of Lour B on the conformation of HSA was analyzed by synchronous fluorescence and three-dimensional fluorescence spectra.

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