桑叶经霜前后次生代谢产物表达差异分析

Differential Expression of Secondary Metabolites in Mulberry Leaves before and after Frost

为研究桑叶经霜采收的合理性,采用高效液相色谱-质谱法分析桑叶中黄酮类成分,并建立高效液相色谱法同时分析绿原酸、芦丁、异槲皮苷、紫云英苷4个成分含量及柱前衍生化-高效液相色谱荧光检测法分析桑叶1-脱氧野尻霉素(1-deoxynojirimycin,DNJ)含量,研究不同季节黄酮类成分、4个单体成分及生物碱(DNJ)动态变化规律。结果表明,桑叶黄酮类成分在7、8月份气温较高时含量较低,10、11月份经霜后达最大值;DNJ在7、8月份气温较高时含量最高,9、10月份随着气温下降含量下降,经霜后更低。生物碱类成分对桑叶疏散风热、清热润肺等功效可能影响较小,桑叶经霜药用可能与黄酮类成分有关。

In order to validate whether or not frosted mulberry leaves have better quality, the flavonoids of mulberry leaves were identified by high performance liquid chromatography-mass spectrometry(HPLC-MS), the contents of four main components, namely chlorogenic acid, rutin, isoquercitrin, and astragalin were simultaneously determined by HPLC and the content of 1-deoxynojirimycin(DNJ) was assayed by pre-column derivatization HPLC with fluorescence detection. We investigated dynamic changes in the flavonoid composition and the contents of four individual flavonoids and DNJ in mulberry leaves across seasons. The results showed that the contents of flavonoids in mulberry leaves were lower in July and August when temperature was high and reached their maximum in November or October after frost. The DNJ content of mulberry leaves in July and August reached its maximum and then decreased in September or October with declining temperature to its minimum after frost. It is concluded that alkaloids may contribute little to the functions of mulberry leaves in evacuating wind-heat, clearing away lung-heat and moistening dryness. The medicinal components of frosted mulberry leaves may be associated with flavonoids. This study can provide a theoretical basis for elucidating scientific connotation of frosted mulberry leaves.