Application Of Molecular Simulation On Molecular Derivation And Functional Design Of Monascus Dye

First, the dominant conformation of Monascorubrin and the water soluble Monascorubrin in the condition of 1atm, 298.15K was established respectively, through molecular mechanics and molecular dynamics. Then based on the dominant conformation ,the charge population and reaction activity of the molecules were studied ,through density function theory calculation; Meanwhile ,the stability of the Monascus dye on different conditions was interpreted ,with the simulation of the potential energy of the aqueous solution in periodic boundary conditions by molecular dynamics. In the end, the molecule with acid soluble quality was designed, and its quality was anticipated by molecular simulation. On the other hand, the simulation results were validated by real experiments.The results of the calculation of Monascorubrin by DFT were shown as below. The net charge of the conjugated system was -0.41845, consisting of C1, C3, C4, C5, C6, C7,C9, C10, C11, C12 and 021, about 14.3 percent of total negative charge in the whole molecule; Meanwhile, the positive charge was mainly populated in C3, C16, C19, with the net charge of 0.12957,0.1164,0.156964 respectively. On the other hand, through the theory calculation, it was speculated that there were three active reaction positions in the Monascorubrin molecule, for example, the intramolecular ester group composed of C19, O20, 028, C2; and the other two carbonyl groups, consisting of C3, O21 and C16, 017 respectively. Based on the above analysis, the principle of its derivation is interpreted.The result of molecular dynamics simulation showed that the potential energy of the Monascus solution system arose with the temperature increasing, that is to say the interaction of the molecules within the system intensified continuously, and the system went toward the more unstable state, which accorded with the result shown from heat stability testing of Monascus solution. The molecular dynamics in the solution of different pH values showed that the potential energy of the system was in the lower level about -32500kcal, with the pH value from 4.0 to 10.0. However, the energy increased sharply with the pH value below 3.5, and the system energy was in the higher level, which would lead to the imbalance of the equilibrium. On the other hand, the energy also increased sharply when the pH value above 11.0, leading to unstable state .In a word, all of the statistic interpreted the stability of the water soluble Monascus dye solution in the different kind of pH value.Furthermore, it was speculated that there were three active reaction positions in the water soluble Monascorubrin molecule, by the calculation of DFT on the module. Thereinto, the hydroxyl group composed of 019 and H20 was of high reaction activity, and would easily react on the nucleophile such as carboxylic acid anhydride,acyl halide on the condition of Lewis acid.In the end, the acid soluble Monascus dye was prepared and its property was characterized, based on the simulation results. The testing showed that the new derivative was of high solubility in acid solution. It could be solvated completely even in the solution of pH1.0, and the metal ions had no effect on its stability except iron ion. Its stability against sunlight was little higher than its water soluble counterpart and it would still fade under the long-term exposure on sunlight. However, the stability of the new ramification against heat was excellent.