A Fragmentation Study on Four Unusual Secoiridoid Trimers,Swerilactones H–K,by Electrospray Tandem Mass Spectrometry

Swerilactones H–K(1–4)as four unprecedented secoiridoid trimers represent a new type of natural product,which has attracted much interest of natural chemists due to their novel skeletons and promising bioactivity.In order to well understand their MS fragmentation behaviors,they were investigated by electrospray ionization ion-trap time-of-flight multistage product ion mass spectrometry(ESI-IT-TOF-MSn)for the first time.The protonated molecules([M?H]?)of swerilactones J and K,and deprotonated molecules([M-H]-)of swerilactones H,J and K were readily observed in the conventional single-stage mass spectra(MS);however only the[M?Cl]-ion for swerilactone I was obtained in negative mode.Based on the MSn study,the fragmentation pathways of swerilactones H and I in negative mode,and swerilactones J and K in both positive and negative modes were proposed.The neutral losses of H_(2)O,CO,CO_(2)and C_(2)H_(4)O moieties are the particular elimination from the precursor ions due to the presence of hydroxyl,d-lactone and 1-O-ethyl moieties in their structures,of which the retro-Diels–Alder cleavage was the most particular dissociation.The fragment ions at m/z 341 and 291 in negative mode can be considered as the diagnostic ions for secoiridoid trimers.This investigation will provide valuable information for their fast characterization from complicated natural mixtures and extensive understanding their structural architectures.

A Fragmentation Study on Four Oligostilbenes by Electrospray Tandem Mass Spectrometry

Oligostilbenes have attracted much interest due to their intricate structures and diverse bioactivities.In this study,two stilbene dimers,(−)-7,8-cis-ε-viniferin(1)and carasiphenol A(2),and two trimers,suffruticosol A(3)and suffruticosol C(4),were investigated by electrospray ionization ion-trap time-of-flight multistage mass spectrometry(ESI-IT-TOF-MS^(n)).Based on the MS^(n) study,the fragmentation pathways and diagnostic ions of four oligostilbenes in both positive and negative modes were proposed.The consecutive elimination of phenol(C_(6)H_(6)O)and resorcinol(C_(6)H_(6)O_(2))moieties were the particular dissociation for oligostilbenes due to the presence of 1,2-diphenylethylene nucleus.The present MS^(n) fragmentation study will provide valuable information for the fast characterization of oligostilbenes from complicated natural mixtures.

HPLC-MS/MS法在广谱筛查吗啡醇类药物的探索

In this article,the fragmentation rule of 6 O6-Opioids on LC-MS/MS was investigated and a characteristic path of fragmentation about O6-Opioids was found.According to the characteristic path of fragmentation,system analysis of the O6-Opioids using LC-MS/MS with a precursor scan method monitoring m/z 165 was developed and validated.The validation result shown that the method is specific,sensitive,reproducible and stable.

Analysis of aristolochic acids, aristololactams and their analogues using liquid chromatography tandem mass spectrometry

More than 80 aristolochic acids(AAs) and aristololactams(ALs) have been found in plants of the Aristolochiaceae family, but relatively few have been fully studied. The present study aimed at developing and validating a liquid chromatography tandem mass spectrometry(LC/MS^n) for the analysis of these compounds. We characterized the fragmentation behaviors of 31 AAs, ALs, and their analogues via high performance liquid chromatography coupled with electrospray ionization mass spectrometry. We summarized their fragmentation rules and used these rules to identify the constituents contained in Aristolochia contorta, Ar. debilis, Ar. manshurensis, Ar. fangchi, Ar. cinnabarina, and Ar. mollissima. The AAs and ALs showed very different MS behaviors. In MS1 of AAs, the characteristic pseudomolecular ions were [M + NH_4]^+, [M + H]^+, and [M + H - H_2O]^+. However, only [M + H]^+ was found in the MS1 of ALs, which was simpler than that of AAs. Distinct MSn fragmentation patterns were found for AAs and ALs, showing the same skeleton among the different substituent groups. The distribution of the 31 constituents in the 6 species of Aristolochia genus was reported for the first time. 25 Analogues of AAs and ALs were detected in this genus. A hierarchical schemes and a calculating formula of the molecular formula of these nitrophenanthrene carboxylic acids and their lactams were proposed. In conclusion, this method could be applied to identification of similar unknown constituents in other plants.