Quantification of sesquiterpene pyridine alkaloids from genus Tripterygium by band-selective HSQC NMR.

Sesquiterpene pyridine alkaloids (SPAs) are bioactive analogues derived from the genus Tripterygium and have anti-inflammatory and anti-rheumatic properties. Attributed to the similar sesquiterpene structures, the total SPAs showed severe peak overlap in 1D NMR and HPLC, leading to difficulties in identification and quantification. Interestingly, the application of band-selective HSQC NMR that specifically excited the region corresponding to the H-3 of SPAs prompted a signal separation of the total SPAs. Based on the high resolution, 23 SPAs were identified from the band-selective HSQC spectrum. The coupling constants (JCH, JHH) and relaxation times (T1, T2) of SPAs were measured, and it was found that they caused less than 1% attenuation of the HSQC signals, so the HSQC signals of SPAs had almost uniform responses. The concentrations of 23 SPAs were determined by standard curve method, using wilforgine as the calibration. In addition, we extended the pulse length-based concentration determination (PULCON) as a more efficient external standard method to the band-selective HSQC spectrum, and the results showed that the concentrations of alkaloids determined by PULCON were consistent with those measured by standard curve method. The developed quantification approach was validated according to the <761> of United States Pharmacopoeia (USP), demonstrating that the established band-selective HSQC approach is reliable for the rapid quantification of analogues in botanical extracts.

Immunosuppressive Sesquiterpene Pyridine Alkaloids from Tripterygium wilfordii Hook. f.

Tripterygium wilfordii Hook. f. is a well-known traditional Chinese medicine used to treat autoimmune diseases. Sesquiterpene pyridine alkaloids (SPAs) are a major class of components found in this herb that have piqued the interest of researchers due to their complex and diverse structures as well as significant biological activities. In this study, ten new SPAs, wilfordatine A-J (1-10), were isolated from the roots of T. wilfordii, along with ten known analogues (11-20). Their structures were primarily elucidated by extensive 1D and 2D NMR spectroscopic analysis. To search for more immunosuppressive ingredients related to the clinical efficacy of T. wilfordii, the total alkaloids (TA) and compounds 4, 5, and 9-16 were tested for their inhibitory effects on nuclear factor-kappa B (NF-κB) pathway in Lipopolysaccharide (LPS) induced HEK293/NF-κB-Luc cells. Among them, TA, compounds 5, 11, and 16 showed potent immunosuppressive activity, with IC50 values of 7.25 µg/mL, 8.75 µM, 0.74 µM, and 15.66 µM, respectively, and no influence on the cell viability at a concentration of 100 µg/mL (TA) or 100 µM (5, 11, and 16). Accordingly, TA, 5, 11, and 16, especially 11, were identified as promising candidates for further investigation into their potential use as immunosuppressive agents.

[Spectral characteristics of sesquiterpene pyridine alkaloids from Tripterygium plants].

Sesquiterpene pyridine alkaloids are important components in Tripterygium plants, possessing a wide range of pharmacological activities, such as anti-inflammation immunosuppression, anti-tumor, anti-virus, and deinsectization, and are of great research value. They are composed of highly oxidized dihydro-ß-furansquiterpene and pyridine dicarboxylic acid through ester bonds. According to the structural characteristics of pyridine dicarboxylic acid fragments, they can be divided into various structural subtypes. Up to now, more than 110 sesquiterpene pyridine alkaloids have been isolated and identified from Tripterygium plants. This study reviewed the structural features and spectral(i.e., UV, IR, MS, and NMR) characteristics of sesquiterpene pyridine alkaloids and summarized the structural elucidation process in detail to provide references for their further research and development.

Comprehensive Evaluation of the Quality of Tripterygium Glycosides Tablets Based on Multi-Component Quantification Combined with an In Vitro Biological Assay.

Tripterygium glycosides tablets (TGTs) are widely used in clinical practice to treat rheumatoid arthritis and other autoimmune diseases, with significant beneficial effects but also high toxicity, necessitating rigorous quality evaluation and control. In current study, a rapid resolution liquid chromatography tandem electrospray ionization triple quadrupole mass spectrometry (RRLC-ESI-MS/MS) method was developed and validated for the quantitative analysis of 14 components of ten batches of TGTs produced by different manufacturers, including four diterpenoids, three triterpenoids, and seven sesquiterpene alkaloids. Meanwhile, the NO inhibition effects of these TGTs were evaluated in LPS-induced RAW264.7 cells for their downstream anti-inflammatory activities, as well as their cytotoxicity. The results indicate that the TGTs from different manufacturers showed poor quality consistency, as evidenced by large variations in chemical profiles and biological effects, which may increase the risks associated with clinical use. To improve the quality status of TGTs, it is crucial to identify indicator components whose characterization can accurately reflect the efficacy and toxicity of TGTs from which they were derived. Our study reveals that triptolide, triptoquinone B, celastrol, and demethylzelaysteral considerably contributed to the anti-inflammatory activity and/or cytotoxicity of TGTs, implying that they should be further investigated as candidate indicator components for TGT quality control.