Metabolite Profiling of Clerodendranthus spicatus by UHPLC‐Q‐Orbitrap HRMS and Evaluation of Antioxidant and Tyrosinase Activation Activities

Clerodendranthus spicatus (Thunb.) C.Y. Wu (CS), a perennial herb, is known for its extensive pharmacological activities. In this study, the antioxidant and tyrosinase activation properties of CS extract were evaluated, and its metabolites were analyzed using ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). The total polyphenol content of the extract was 61.06 ± 0.322 mg/g (gallic acid equivalent), and the total flavonoid content was 89.56 ± 2.21 mg/g (rutin equivalent). The extract exhibited potent antioxidant activity, with half-maximal inhibitory concentrations (IC₅₀) of 0.264 ± 0.0127 mg/g for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and 0.523 ± 0.00340 mg/g for 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS⁺) radical scavenging. Moreover, the CS extract significantly activated tyrosinase diphenolase in a concentration-dependent manner. Metabolite profiling revealed 1095 compounds, including 259 primary metabolites and 836 secondary metabolites. Among them, lipids, terpenoids, and flavonoids were the main ones. They have powerful biological activities, including antioxidant, anti-inflammatory, antibacterial, and anti-tumor. Baicalin tetramethyl ethers and 3,4',5,6,7-pentamethyl flavonoids were identified as the most abundant compounds, and they may be the signature metabolites of CS. These findings provide a solid foundation for the development and utilization of CS in functional foods, pharmaceuticals, and cosmetics.