Tissue-specific chemical profiling and quantitative analysis of bioactive components of Cinnamomum cassia by combining laser-microdissection with UPLC-Q/TOF–MS

Background: Cinnamomi Cortex, the dried stem bark of Cinnamomum cassia Presl (Rougui in Chinese) has been widely used in traditional Chinese medicine, cooking and perfumery for thousands of years. Traditionally, the Cinnamomi Cortex of thick size is considered to be of good quality; however, there is no scientific data to support this point. Considering that essential oils are the main bioactive components, Cinnamomi Cortex of greater variety and amount essential oils is thought to be of better quality. In this study, laser microdissection coupled with ultra-high performance liquid chromatography-quadrupole/time-of-flight-mass spectrometry (UPLC-Q/TOF–MS) was applied to profile the essential oils in different tissues of Cinnamomi Cortex and to determine if there is a correlation between the essential oil content and the stem bark thickness. Results: We report the tissue-specific metabolic profiles of different grades of Cinnamomi Cortex. Nineteen chemical components were unequivocally or tentatively identified in the chromatogram of the test samples. The results indicate that the bioactive components, the essential oils, were mainly present in the phloem. Conclusion: Phloem thickness is the key character for evaluating the quality of Cinnamomi Cortex. Our results can be of great importance in improving the cultivation, harvesting, and processing of Cinnamomi Cortex, as well as enhancing its effects in clinical applications.