Molecular dynamics simulation on the dissolution process of Kaempferol cluster

The solid-liquid extraction is an effective method to extract bioactive components from crude medicinal herbs. The dissolution of bioactive molecules is the key to efficient solid-liquid extraction. In this work, a five-nanosecond molecular dynamics simulation was carried out to study the dissolution mechanism of a cluster, including 15 kaempferol molecules in a cubic solvent box of 6 nm. The theoretical and experimental infrared and Raman spectra were taken to confirm the low-energy kaempferol conformers for building the cluster. The effects of ethanol concentration and temperature on the kaempferol dispersion efficiency are investigated. The simulation results show that different concentration of ethanol solution has different dissolution behavior. Because of the intermolecular interaction between kaempferol and solvent, the kaempferol cluster can be decomposed gradually. In order to quantitatively describe the diffusion process of kaempferol cluster, the radial distribution function of the barycenter of the cluster around kaempferol molecules, the number of H-bond between kaempferol molecules, the solvent accessible area of the cluster, the dissolution free energy and the diffusion constant are analyzed. The results show that the optimal dispersion condition is at 80-90% of the ethanol concentration and 323.15 K of the system temperature, which agree with the experiment of extraction. This research provides new insight into the dissolution process of kaempferol on the nanosecond scale. Also, the result of molecular dynamics (MD) can effectively predict the extraction conditions of the actual experiment. (C) 2020 Elsevier B.V. All rights reserved.