Tissue Distribution of Engeletin in Mice by UPLC-MS/MS

Introduction: Engeletin is the main active component in the engelhardia leaf that promotes circulation and removes stasis, and has hypoglycemic, hypolipidemic, and anti-inflammatory actions. The aim of this study was to develop an ultra-performance liquid chromatography- tandem mass spectrometry method to detect engeletin in plasma and tissues and investigate its absorption, distribution, and mechanism in mice, which could provide very useful information for its pharmacological effect in vivo. Materials and Methods: Twenty-five mice were intraperitoneally injected with 20 mg/kg engeletin, and five mice were sacrificed using 4% chloral hydrate 0.25, 0.5, 2, 4, and 6 h later. The tissues (brain, kidney, heart, liver, spleen, and lung) and blood were collected. Acetonitrile precipitation was applied to remove protein and further process the mouse plasma and tissue homogenate samples. Multiple reactions monitoring mode in negative mode was used to quantify the engeletin. Results and Conclusion: Linearity of engeletin in plasma and tissues was good (R2 > 0.995), within the range of 2-2,000 ng/mL in plasma and 2-2,000 ng/g in tissues, and the lower limit of quantitation was 2 ng/mL in plasma and 2 ng/g in tissues. Inter-day precision of engeletin in plasma or tissues (brain, kidney, heart, liver, spleen, and lung) was < 14%, and intra-day precision was < 15%. After the mice were intraperitoneally injected with engeletin (20 mg/kg), the distribution in kidney and liver was the highest, followed by blood, spleen, lung, heart, and brain. Engeletin concentration in the brain was low, suggesting that engeletin can penetrate through the blood brain barrier, which could also help with engeletin investigations of the brain.