Photocatalytic Reaction And Kinetics Analysis Of Imperatorin With Amino Acids

There are many physiological activities of imperatorin in Angelica, such as anti-inflammatory, anti-bacterial, anti-pathogenic, anti-tumor and cardiovascular protection. It also can be reacted with protein or nucleic acid under light induction. But the report of reaction mechanism between imperatorin and protein have not been seen. In this paper, the photocatalytic reaction and main influence factors were researched by the reaction beweteen imperatorin, and mixed with cysteine representd the most active amino acids of protein, aspartic acid representd acidic amino acids, arginine represented basic amino under incandescent, UV, and without illumination. The production was separated, purified, characterized and the kinetic was analysised to explore the photocatalytic reaction mechanisms.It was showed that disulfide β-sulfhydryl acetic acid derivative is generated by the deamination, dehydrogenation, oxidation of cysteine during UV irradiation. 4-hydroxy-2,4-diene-1valericacid, 5-methyl-4-hydroxy-dihydro-furan-dimer and both hydrate, derivatives of imperatorin added C11 prenyl, 8-iso-pentane-benzopyranfurosemide dimer is generated from the reaction of imperatorin during UV irradiation. The maximum absorption wavelength of imperatorin and the mixture moves from the 300 nm to 309 nm, which is due to the loss of the isopentenyl. Three new substances of the peak time 6.3,8.2 and 23.6min are generated in the mixture. The substance of Rf 0.41 and peak time 6.3min is confirmed as 8-hydroxy-benzopyran–furosemide by purified of semi-preparative HPLC, HPLC-MS, 1HNMR and 13 CNMR. It was also showed 8-benzo α-pyrone-2’-S-cysteine ethyl ether is generated of mixture by HRMS during UV irradiation.It was showed the maximum absorption wavelength of the mixture imperatorin with aspartic acid, arginine irradiated moves from the 300 nm to 309 nm by UV. There is a new spot of Rf0.41 on TLC plate. It was proved that reaction mechanism of imperatorin with amino acids is similar under UV irradiation.The experimental datas of TLC, HPLC, HPLC-MS, 1HNMR and 13 CNMR confirm the reaction mechanism of imperatorin reacted with cysteine during UV irradiation, C11 olefinic bondof conjugated double bond system is activated by accepting energy from ultraviolet photons. The electron density is decreased of C8 oxygen atom and C11 olefinic bond. Then C11 is nucleophilic attacked by sulfur atom of cysteine to generate 8-benzo α-pyrone-2’-S-cysteine ethyl ether.The reaction is affected by imperatorin concentration and light illumination distance. The reaction completion time and the initial concentration is linear relationship between the correlation coefficient of 0.98 when energy provided by the light source, the area and the distance are content. The reaction completion time and the square of the distance is linear relationship between the correlation coefficient of 0.98 when energy provided by the light source, the area and the initial concentration are content. On the basis of the first order reaction kinetics model, 20℃, the kinetic equation of imperatorin and cysteine under UV irradiation is y=0.1458-0.0326 x.