A special perspective to evaluate the toxicity and quality of Yimucao decoction pieces by probing the chemical distribution and change in its different tissues and medicinal parts

Yimucao is the aerial part of Leonurus japonicus Houtt., which is a very commonly used herb for treating menstrual and maternal diseases. It has been used for thousands of years in Chinese Medicine, and it is recognized to be a non-toxic herb. However, adverse reactions, even lethal case, caused by Yimucao were reported in recent decades. Also, the herb collected in different stages with the varied proportion of leaves and stems was easily found in the markets which induce the unstable quality for clinic use. Thus, the toxicity and quality of this traditional Chinese Materia Medica has already attracted public concern. For Yimucao, alkaloids, diterpenes and flavones are its main chemicals. Previous studies have demonstrated that alkaloids contribute the toxicity and quality of Yimucao. As toxicity and quality of herbs is depends on the amount of its chemical ingredients, to probe the chemical distribution and change in its different tissues and medicinal parts in samples collected from different growing stages will ensure Yimucao with well-controlled quality and safe use in clinic.

The toxic and active compounds in plants are the secondary metabolites that accumulated in tissues and organs, types of compounds and their contents are various in them except for different growing stages. A standardized collection period and suitable proportion of various medical parts will be the first step in order to guarantee a uniform quality. Here, different growing stages of Yimucao will produce different medicinal parts for use, such as the proportion of leaves and stems, whether containing the flowers or fruits, the sizes of leaves and stems. Thus, the chemical profiles of different organs and tissue-specific chemical distributions in leaves and stems are of concern.

In this project, we aim to conduct a comprehensive and systematical study on the distribution of chemicals in tissues and organs, as well as their variation in different growing stages. We will cultivate Leonurus japonicas, the origin of Yimucao, as experimental samples and collect the aerial part in different stages (seedling, vegetative, flowering and harvest stage). By using laser microdissection (LMD), different tissues and cells from leaves and stems can be separated accurately and collected. Ultra-performance liquid chromatography (UPLC) coupled with mass spectrometry (MS) will then be used for the qualitative and quantitative analysis of the dissected tissues and cells. With the results, the best harvest period and medicinal parts of Yimucao can be found out. Furthermore, we will also evaluate the decoction pieces in the market and corroborate the results.

This project can provide valuable scientific data to evaluate the toxicity and quality of Yimucao by standardizing the reasonable medicinal parts with applicable proportion of leaves and stems as well as the harvest time, which is desperately in need for the medication safety and use of this widely used Chinese Materia Medica.