Systematic metabolite profiling of N-acetyldopamine oligomers from Cicadae Periostracum in rats by ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry.

• Comprehensive metabolic profile of NOCP and dimer B in vivo was revealed for the first time. • 34 prototypes and 15 metabolites were identified or assigned in biosamples of NOCP group, while the prototype and 8 metabolites were characterized in biosamples of dimer B group. • Oxidation, and hydrogenation were supposed to be the major phase I reactions, while methylation, sulfation, and glucuronidation were the main phase II reactions of NOCP and dimer B. • NOCP and dimer B were mainly absorbed in the form of metabolites, and metabolites are probably the major bioactive forms of NOCP and dimer B. Cicadae Periostracum (CP), the cast-off shell of Cryptotympana atrata , is specified in Chinese Pharmacopoeia for relieving fever and eliminating ulcer. N -acetyldopamine oligomers are the major characteristic bioactive components with antioxidant and anti-inflammatory activities that may be responsible for the efficacy of CP. However, the exposed components and metabolites of N -acetyldopamine oligomers of CP (NOCP) in vivo are still unknown. In present study, the metabolic profile of total NOCP and N -acetyldopamine dimer B in rats were systematically investigated by ultra-high liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). In biosamples of NOCP group, 34 prototypes and 15 metabolites were identified or tentatively characterized, including 5 metabolites in plasma, 3 prototype and 9 metabolites in urine, 2 metabolites in bile, 34 prototypes and 8 metabolites in feces, respectively. In dimer B group, the prototype and 8 metabolites were identified, including 2 metabolites in plasma, 4 metabolites in urine, 1 metabolite in bile and 5 metabolites in feces, respectively. Oxidation, and hydrogenation were supposed to be the major phase I reactions, while methylation, sulfation, and glucuronidation were the main phase II reactions of NOCP and dimer B. M10 and M13 might undergo enterohepatic circulation in rats. It is concluded that NOCP and dimer B were mainly absorbed in the form of metabolites, and metabolites are probably the major bioactive forms of NOCP and dimer B. The outcomes of this study provided helpful information for extensively elucidating biological and pharmacological mechanisms of NOCP. [ABSTRACT FROM AUTHOR]