Sensitivity improvement of kukoamine determination by complexation with dihydrogen phosphate anions in capillary zone electrophoresis

Kukoamine A attenuates insulin resistance and fatty liver through downregulation of Srebp-1c

Nonalcoholic fatty liver disease (NAFLD) refers to a pathological condition of hepatic steatosis. Insulin resistance is believed to be the key mechanism mediating initial accumulation of fat in the liver, resulting in hepatic steatosis. Kukoamine A (KuA), a spermine alkaloid, is a major bioactive component extracted from the root barks of Lycium chinense (L. chinense) Miller. In the current study, we aimed to explore the possible effect of KuA on insulin resistance and fatty liver. We showed that KuA significantly inhibited the increase of fasting blood glucose level and insulin level, and the glucose levels in response to glucose and insulin load in HFD-fed mice, which was in a dose-dependent manner. KuA dose-dependently decreased the histological injury of liver, levels of hepatic triglyceride (TG), and serum AST and ALT activities in HFD-fed mice. The increase of serum levels of TNFɑ, IL-1β, IL-6 and C reactive protein in HFD-fed mice was inhibited by KuA. HFD feeding-induced increase of hepatic expression of Srebp-1c and its target genes, including fatty acid synthase (FAS) and acetyl CoA carboxylase 1 (ACC1), was significantly inhibited by KuA. Moreover, upregulation of Srebp-1c notably inhibited KuA-induced improvement of insulin-stimulated glucose uptake, decrease of lipid accumulation and H₂O₂ level in palmitic acid-treated AML-12 cells. In conclusion, we reported that KuA inhibited Srebp-1c and downstream genes expression and resulted in inhibition of lipid accumulation, inflammation, insulin resistance and oxidative stress. Overall, our results provide a better understanding of the pharmacological activities of KuA against insulin resistance and hepatic steatosis.

Development and validation of a rapid and sensitive UPLC-MS/MS method for quantification of kukoamine B in human plasma: Application to a clinical pharmacokinetic study

A rapid, accurate and robust method was firstly developed using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) assay to quantify kukoamine B, which is a novel drug under clinical development for the treatment of sepsis, in human plasma. Solid-phase extraction (SPE) was used to extract kukoamine B from human plasma. The extracts were separated on a Waters Acquity HSS T3 column (2.1×50mm i.d., 1.8μm) with a gradient elution method, using mobile phases of A (formic acid-water (1:1000, v/v)) and B(formic acid-methanol (1:1000, v/v)). Kukoamine B and internal standard (5-deuterated isotope kukoamine B) were detected under the multiple-reaction monitoring mode by an API 5500 triple quadrupole mass spectrometer with electrospray ionization. The method showed good linearity from 0.100 to 50.0ng/mL according to 1/x² weighted linear regression analysis. Inter- and intra-batch precision of kukoamine B were less than 15% and the accuracy was within 85-115%. The extraction recoveries and matrix effect of kukoamine B at three concentration levels were consistent. The sensitivity, specificity and stabilities under various conditions were validated. In conclusion, the validation results showed that this method was rapid, accurate, robust and can successfully fulfill the requirement of clinical pharmacokinetic study of kukoamine B mesylate in Chinese healthy subjects.

Identification and Characterization of Kukoamine Metabolites by Multiple Ion Monitoring Triggered Enhanced Product Ion Scan Method with a Triple-Quadruple Linear Ion Trap Mass Spectrometer

Kukoamines are a series of bioactive phytochemicals conjugated by a polyamine backbone and phenolic moieties. Understanding the structural diversity of kukoamine metabolites in plants is meaningful for drug discovery. In this study, an LC-MS/MS method was established for kukoamine profiling and characterization from lycii cortex (LyC) via a triple-quadrupole linear ion trap mass spectrometry (Q-TRAP). On the basis of the typical fragmentation of kukoamine, a diagnostic ion, which represents the features of the backbone and phenolic substitute, was chosen as the product ion for precursor ion scan, and then the screened precursor ions were applied to a successive multiple ion monitoring triggered enhanced product ion scan (MIM-EPI) to simultaneously present the profile survey and MS/MS acquisition. Because the MIM narrowed the ion scan range in Q1 and the ion trap enhanced the ion fragments passing through Q2, the qualitative capability of quadrupole MS can be greatly improved, especially for capture of the uncommon metabolites. There are 12 kukoamine metabolites identified from LyC, with either spermine or spermidine backbone and with conjugation of one to three dihydrocaffeoyls or other kinds of phenolic moieties. Except for kukoamines A and B, other metabolites were identified in LyC for the first time. This approach can be utilized for metabolite identification in other substrates.