OBJECTIVE

2

To study the metabolites derived from the ethanol extract from the leaves of

Dimocarpus longan

preliminarily in rats

in vivo

， and to provide reference for elucidating the possible metabolic mechanism of the leaves of

D. longan

in lowering blood glucose.

METHODS

2

Ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry （UPLC-Q-TOF-MS/MS） was adopted by taking ethanol extract of

D. longan

leaves， the feces and urine of rats at 0-72 h and 0-48 h after intragastric administration of 33.8 g/kg ethanol extract of

D. longan

leaves （by extract）， the feces and urine of rats at the corresponding time after intragastric administration of normal saline （blank control） as samples. The accurate relative molecular weight， formula and fragment information of the compounds were collected， and the compounds were speculated and identified by matching with the database and spectrum library of the instrument， and comparing with the reference substance and relevant literature.

RESULTS

2

A total of eight compounds were identified in urine and feces of rats， including 2 prototype components and 6 metabolites. Three compounds （including two prototype components as quercetin， luteolin and one metabolite as luteolin or kaempferol） in feces of rats were identified； five compounds （all metabolites） in urine of rats were identified， involving metabolites of quercetin， luteolin or kaempferol. Metabolites mainly included the products of methylation， glucuronidation and oxidation.

CONCLUSIONS

2

After intragastric administration， the ethanol extract from the leaves of

D. longan

is mainly metabolized in rats through methylation， glucuronidation and other pathways. The identified compounds are mostly metabolites of quercetin and luteolin.