栀子蓝色素的结构及其对单胺氧化酶B的抑制活性考察

Structure of Gardenia Blue Pigment and Its Inhibitory Activity on Monoamine Oxidase B

目的:研究栀子蓝色素的化学结构及其对单胺氧化酶B(MAO-B)的抑制活性,为栀子环烯醚萜类资源性化学成分的合理利用及价值提升寻求潜在可行途径。方法:采用纤维素酶催化水解栀子环烯醚萜苷类化合物得到其苷元,经与氨基酸反应,D101型大孔树脂柱色谱及制备液相色谱分离纯化,获得栀子蓝色素单体,综合运用核磁共振波谱和质谱技术鉴定其结构;以苯甲胺为MAO-B反应底物,与栀子蓝色素单体体外孵育,采用高效液相色谱法检测苯甲胺的代谢产物苯甲醛生成量,以甲醇(A)-50 mmol·L^(-1)磷酸钾缓冲液(B,pH 3.2)(2∶3)为流动相,检测波长245 nm,以评价栀子蓝色素化合物对MAO-B的抑制效果。结果:合成并鉴定了8种栀子蓝色素(栀子蓝色素A~H)。在MAO-B抑制试验中,与栀子苷比较,栀子蓝色素D,E的抑制活性明显增强(P<0.05);与6β-羟基京尼平苷比较,栀子蓝色素G,H的抑制活性明显增强(P<0.05,P<0.01),这4种栀子蓝色素均表现出比原型化合物更好的MAO-B抑制活性。结论:栀子蓝色素为一分子氨基酸与一分子环烯醚萜形成的简单化合物,部分栀子蓝色素具有比原型化合物更好的MAO-B抑制活性,不同底物生产出的栀子蓝色素存在活性差异,可基于试验优选制备高价值栀子蓝色素,扩展栀子蓝色素的应用范围,丰富栀子环烯醚萜类成分的综合利用途径。

Objective:To study the chemical structure of gardenia blue pigment and its inhibitory activity against monoamine oxidase B(MAO-B),in order to seek a potential feasible way for rational utilization and value enhancement of iridoids in Gardeniae Fructus.Method:Iridoid glycosides in Gardeniae Fructus were hydrolyzed by cellulase to obtain their aglycones and reacted with amino acids.Then,the products were purified by column chromatography packed with D101 macroporous resin and preparative liquid chromatography to obtain gardenia blue pigments,and the gardenia blue pigments were identified by nuclear magnetic resonance(NMR)and mass spectrometry(MS).Benzylamine was used as the reaction substrate of MAO-B and in vitro incubated with gardenia blue pigment monomers,high performance liquid chromatography(HPLC)was employed to determine the production of benzaldehyde for evaluating the inhibitory effect of gardenia blue pigments on MAO-B,the mobile phase was methanol(A)-50 mmol·L^(-1)potassium phosphate buffer(B,pH 3.2)(2∶3),and the detection wavelength was 245 nm.Result:Eight compounds of gardenia blue pigment A-H were synthesized and identified.In MAO-B inhibition test,compared with geniposide,the inhibitory activity of gardenia blue pigment D and E was significantly enhanced(P<0.05).Compared with the 6β-hydroxygeniposide,the inhibitory activity of gardenia blue pigment G and H was significantly enhanced(P<0.05,P<0.01).All the four gardenia blue pigments showed better MAO-B inhibitory activity than the prototype compounds.Conclusion:Gardenia blue pigment is a simple compound formed by one molecule of amino acid and one molecule of iridoid.Some gardenia blue pigments have better MAO-B inhibitory activity than the prototype compounds.The activity of gardenia blue pigment produced by different substrates is different,and the highvalue gardenia blue pigment can be prepared based on experimental optimization,which can expand the application range of gardenia blue pigment and enrich the comprehensive utilization of iridoids from Gardeniae Fructus.