Uncariae Ramulus Cum Uncis (Gou-Teng), the dried hook-bearing stems of several Uncaria plants (Rubiaceae), is a wellknown herbal medicine in China. The clinical application of Gou-Teng is bewildered for the morphological and chemical similarity between different species. In order to discern their chemical and biological difference, an ultra-fast liquid chromatography equipped with ion trap time-of-flight mass spectrometry (UFLC-IT/TOF-MS) combining with melatonin (MT 1 and MT 2 ) and 5-hydroxytryptamine (5-HT 1A and 5-HT 2C ) receptors agonistic assay in vitro was conducted on seven Uncaria species. As a result, 57 compounds including 35 indole alkaloids, ten flavonoids, five triterpenoids, five chlorogenic analogues, and two other compounds were characterized based on their MS/MS patterns and UV absorptions. Specifically, cadambine-type and corynanthein-type alkaloids were exclusively present in U. rhynchophylla and U. scandens, whereas corynoxine-type alkaloids were commonly detected in all the seven Uncaria plants. Three Uncaria species, U. rhynchophylla, U. macrophylla, and U. yunnanensis showed obviously agnostic activity on four neurotransmitter receptors (MT 1 , MT 2 , 5-HT 1A , and 5-HT 2C ). This first-time UFLCMS-IT-TOF analyses integrated with biological assay on seven Uncaria plants will provide scientific viewpoints for the clinical application of Gou-Teng.We dedicate this paper to Prof. Sun Han-Dong on the occasion of his 80th birthday.
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Graphic AbstractKeywords Uncariae Ramulus Cum Uncis · Uncaria plants · LCMS-IT-TOF analyses · Melatonin and 5-hydroxytryptamine receptors