α‐glucosidase inhibitors have been used to treat diabetes for many years. Recently, natural products have attracted much attention, because they are kinds of safety source to screen α‐glucosidase inhibitor. In this study, we separated two monomers (quercitrin and afzelin) from Houttuynia cordata with notable inhibitory activity against α‐glucosidase, and evaluated inhibitory kinetics and the binding mechanisms. The 50% inhibitory concentration (IC50) of the quercitrin and afzelin were 0.231±0.033 mg/mL and 0.215±0.004 mg/mL, which were lower than the IC50 of acarbose. The inhibitory type between α‐glucosidase and the two monomers was a competitive inhibition, which is similar to acarbose and could compete binding sites. The fluorescence spectroscopy showed that quercitrin and afzelin statically quenched the fluorescence of α‐glucosidase. Circular dichroism and molecular docking analyses indicated that quercitrin and afzelin changed the alpha‐helix structure of α‐glucosidase and bound with the key amino acids through hydrophobic interactions, hydrogen bonds and salt bridge interaction. This study is the first time to clarify the inhibitory kinetics and binding mechanisms of quercitrin and afzelin on α‐glucosidase.

To raise the accuracy of the shortest path ray tracing, it is usually necessary to represent the model with dense grids and nodes, and to increase ray directions emanating from a secondary source, or to improve the results with other algorithms. All these measures bring forth many additional computations. The fast algorithm presented in this paper greatly enhances the efficiency of the traditional shortest path ray tracing with more efficient management of wavefront nodes and more efficient computation of the secondary wave propagation. The bucket sort is applied to manage wavefront nodes, which is superior to the heap sort used in the tradition method. In addition, both Snell's law and the traveltime information of waves from neighboring nodes are considered to determine the effective propagation area of a secondary source. Thus, many unnecessary propagation directions are excluded. Numerical tests show that the speed of the fast algorithm is about several to more than ten times of that of the traditional method.

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