Establishment of tandem mass spectrometric fingerprint of novel antineoplastic curcumin analogues using electrospray ionization

Establishment of the tandem mass spectrometric fingerprints of taxane-based anticancer compounds

RATIONALE

Compounds in the taxane drug family are among the most successful and effective chemotherapeutic agents used in the treatment of solid tumors, such as breast, ovarian, and prostate cancers. The tandem mass spectrometric (MS/MS) fragmentation behavior of these compounds is described in detail, and a generalized MS/MS fingerprint is established for the first time.

METHODS

Five compounds, namely paclitaxel, docetaxel, cabazitaxel, cephalomannine, and baccatin III, were evaluated. A hybrid quadrupole orthogonal time-of-flight (Q-TOF) mass spectrometer was used to obtain accurate mass measurements, whereas MS/MS and second-generation MS/MS (MS³ ) analyses were performed using a triple quadrupole-linear ion trap mass spectrometer. Both instruments were equipped with an electrospray ionization source operated in the positive ion mode.

RESULTS

All taxanes showed an abundant singly charged [M + H]⁺ species in the single-stage analysis with mass accuracies less than 3 ppm. The evaluated compounds exhibited common fragmentation behavior in their MS/MS analysis, which allowed for the production of a universal fragmentation pattern. MS³ experiments confirmed the genesis of the various product ions proposed in the fragmentation pathway. In addition, diagnostic product ions were originated from a cleavage in the ester bond between the core diterpene ring structure and the side chain.

CONCLUSIONS

Varying functional groups present in these compounds resulted in unique product ions that are specific to each structure. The established MS/MS fingerprints will be used in the near future for identification and for the development of multiple reaction monitoring liquid chromatography-MS/MS quantification methods.

Tandem mass spectrometric analysis of novel caffeine scaffold-based bifunctional compounds for Parkinson's disease

RATIONALE

Novel bifunctional compounds composed of a caffeine scaffold attached to nicotine (C₈ -6-N), 1-aminoindan (C₈ -6-I), or caffeine (C₈ -6-C₈ ) were designed as therapeutics or diagnostics for Parkinson's disease (PD). In order to probe their pharmacological and toxicological profile, an appropriate analytical method is required. The goal of this study is to establish a tandem mass spectrometric fingerprint for the development of quantitative and qualitative methods that will aid future assessment of the in vitro and in vivo absorption, distribution, metabolism, excretion (ADME) and pharmacokinetic properties of these lead bifunctional compounds for PD.

METHODS

Accurate mass measurement was performed using a hybrid quadrupole orthogonal time-of-flight mass spectrometer while multistage MS/MS and MS³ analyses were conducted using a triple quadrupole linear ion trap mass spectrometer. Both instruments are equipped with an electrospray ionization (ESI) source and were operated in the positive ion mode. The source and compound parameters were optimized for all three tested bifunctional compounds.

RESULTS

The MS/MS analysis indicates that the fragmentation of C₈ -6-N and C₈ -6-I is driven by the dissociation of the nicotine and 1-aminoindan moieties, respectively, but not caffeine. A significant observation in the MS/MS fragmentation of C₈ -6-C₈ suggests that a previously reported loss of acetaldehyde during caffeine dissociation is instead a loss of CO₂ .

CONCLUSIONS

The collision-induced tandem mass spectrometry (CID-MS/MS) analysis of these novel bifunctional compounds revealed compound-specific diagnostic product ions and neutral losses for all three tested bifunctional compounds. The established MS/MS fingerprint will be applied to the future development of qualitative and quantitative methods.

A classification of liquid chromatography mass spectrometry techniques for evaluation of chemical composition and quality control of traditional medicines

Natural products (NPs) and traditional medicines (TMs) are used for treatment of various diseases and also to develop new drugs. However, identification of drug leads within the immense biodiversity of living organisms is a challenging task that requires considerable time, labor, and computational resources as well as the application of modern analytical instruments. LC-MS platforms are widely used for both drug discovery and quality control of TMs and food supplements. Moreover, a large dataset generated during LC-MS analysis contains valuable information that could be extracted and handled by means of various data mining and statistical tools. Novel sophisticated LC-MS based approaches are being introduced every year. Therefore, this review is prepared for the scientists specialized in pharmacognosy and analytical chemistry of NPs as well as working in related areas, in order to navigate them in the world of diverse LC-MS based techniques and strategies currently employed for NP discovery and dereplication, quality control, pattern recognition and sample comparison, and also in targeted and untargeted metabolomic studies. The suggested classification system includes the following LC-MS based procedures: elemental composition determination, isotopic fine structure analysis, mass defect filtering, de novo identification, clustering of the compounds in Molecular Networking (MN), diagnostic fragment ion (or neutral loss) filtering, manual dereplication using MS/MS data, database-assisted peak annotation, annotation of spectral trees, MS fingerprinting, feature extraction, bucketing of LC-MS data, peak profiling, predicted metabolite screening, targeted quantification of biomarkers, quantitative analysis of multi-component system, construction of chemical fingerprints, multi-targeted and untargeted metabolite profiling.

A Novel Triple Stage Ion Trap MS method validated for curcumin pharmacokinetics application: A comparison summary of the latest validated curcumin LC/MS methods

Even through more sensitive methods for quantifying trace levels of curcumin in plasma were urgently needed, beyond tandem mass spectrometry, the Paul trap MS/MS/MS has never been tested for curcumin quantification. Because of its unique trap function to accumulate target compounds selectively by optimizing multiple stage MS experiments, it showed great potential to remove background issues reported at low concentration ranges. A novel Triple stage Ion Trap Mass Spectrometry coupled with High Performance Liquid Chromatography (HPLC-ITMS/MS/MS) method has been developed and validated as a curcumin quantification method, for the first time. The use of isotope labeled curcumin-d6 as a novel internal standard (IS) is suggested and tested according to FDA validation procedure. A simplified sample preparation is introduced and validated by coupling a novel acetonitrile precipitation with molecular weight cut-off size exclusion method. This method demonstrated excellent recovery rate of 96.69%-109.26% and minimum matrix effect of 95.40%-110.98%. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for curcumin in rat plasma were 0.1 ng/ml and 1 ng/ml respectively. The linear calibration curve for quantifying curcumin in rat plasma was 1-3000 ng/ml (r² > 0.99) with intra-day and inter-day RSD and accuracy within ±5.11%. Its application in a Pharmacokinetics (PK) study demonstrated detection of curcumin at a very low plasma level (1.0 ng/ml) and it would be applied to larger sample size animal and clinical pharmacokinetic studies. The presented ITMS/MS/MS quantification method has shown its advantages, including better sensitivity, accuracy, precision, wider calibration range and simplicity in sample preparation, when comparing with other curcumin LC/MS analysis methods in the latest 4 years.