Fragmentation investigation of seven arylnaphthalide lignans using liquid chromatography/tandem quadrupole time-of-flight mass spectrometry

Untargeted-based metabolomics analysis and in vitro/in silico antiviral activity of extracts from Phyllanthus brasiliensis (Aubl.) Poir

INTRODUCTION

This study describes the molecular profile and the potential antiviral activity of extracts from Phyllanthus brasiliensis, a plant widely found in the Brazilian Amazon. The research aims to shed light on the potential use of this species as a natural antiviral agent.

METHODS

The extracts were analysed using liquid chromatography-mass spectrometry (LC-MS) system, a potent analytical technique to discover drug candidates. In the meantime, in vitro antiviral assays were performed against Mayaro, Oropouche, Chikungunya, and Zika viruses. In addition, the antiviral activity of annotated compounds was predicted by in silico methods.

RESULTS

Overall, 44 compounds were annotated in this study. The results revealed that P. brasiliensis has a high content of fatty acids, flavones, flavan-3-ols, and lignans. Furthermore, in vitro assays revealed potent antiviral activity against different arboviruses, especially lignan-rich extracts against Zika virus (ZIKV), as follows: methanolic extract from bark (MEB) [effective concentration for 50% of the cells (EC50 ) = 0.80 μg/mL, selectivity index (SI) = 377.59], methanolic extract from the leaf (MEL) (EC50  = 0.84 μg/mL, SI = 297.62), and hydroalcoholic extract from the leaf (HEL) (EC50  = 1.36 μg/mL, SI = 735.29). These results were supported by interesting in silico prediction, where tuberculatin (a lignan) showed a high antiviral activity score.

CONCLUSIONS

Phyllanthus brasiliensis extracts contain metabolites that could be a new kick-off point for the discovery of candidates for antiviral drug development, with lignans becoming a promising trend for further virology research.

Identification of Daphne genkwa and Its Vinegar-Processed Products by Ultraperformance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry and Chemometrics

Crude herbs of Daphne genkwa (CHDG) are often used in traditional Chinese medicine to treat scabies baldness, carbuncles, and chilblain owing to their significant purgation and curative effects. The most common technique for processing DG involves the use of vinegar to reduce the toxicity of CHDG and enhance its clinical efficacy. Vinegar-processed DG (VPDG) is used as an internal medicine to treat chest and abdominal water accumulation, phlegm accumulation, asthma, and constipation, among other diseases. In this study, the changes in the chemical composition of CHDG after vinegar processing and the inner components of the changed curative effects were elucidated using optimized ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Untargeted metabolomics, based on multivariate statistical analyses, was also used to profile differences between CHDG and VPDG. Eight marker compounds were identified using orthogonal partial least-squares discrimination analysis, which indicated significant differences between CHDG and VPDG. The concentrations of apigenin-7-O-β-d-methylglucuronate and hydroxygenkwanin were considerably higher in VPDG than those in CHDG, whereas the amounts of caffeic acid, quercetin, tiliroside, naringenin, genkwanines O, and orthobenzoate 2 were significantly lower. The obtained results can indicate the transformation mechanisms of certain changed compounds. To the best of our knowledge, this study is the first to employ mass spectrometry to detect the marker components of CHDG and VPDG.

Comprehensive study of Anthriscus sylvestris lignans

Wild chervil (Anthriscus sylvestris) is a widespread, wild-growing herbaceous plant from Apiaceae family, known for high content of lignans related to podophyllotoxin, and thus representing a promising new source for their industrial isolation. The data on detailed chemical profile of A. sylvestris lignans are still lacking. By combining fractionation with non-targeted LC-DAD-ESI-MS/MS metabolite profiling, we have identified, fully or tentatively, 46 lignans, 12 of which were never reported in A. sylvestris and 19 in any biological source. The dominant lignans were found to be nemerosin, yatein, deoxypodophyllotoxin, podophyllotoxin, podophyllotoxone and guayadequiol. In addition to well-known dibenzylbutyrolactones, aryltetralins and 7-oxygenated aryltetralins, we found several oxygenated lignan classes previously undescribed in A. sylvestris - 7-hydroxy, 7-oxo and 8-hydroxydibenzylbutyrolactones, a 7'-oxotetrahydrofuran and a 7-hydroxyarylnaphthalene. To facilitate future rapid classification and identification of lignans in raw extracts, UV, MS and NMR spectral features of different lignan classes are described.

Alkaloid profiling of the traditional Chinese medicine Rhizoma corydalis using high performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry

Since alkaloids are the major active constituents of Rhizoma corydalis (RC), a convenient and accurate analytical method is needed for their identification and characterization. Here we report a method to profile the alkaloids in RC based on liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS/MS). A total of 16 alkaloids belonging to four different classes were identified by comparison with authentic standards. The fragmentation pathway of each class of alkaloid was clarified and their differences were elucidated. Furthermore, based on an analysis of fragmentation pathways and alkaloid profiling, a rapid and accurate method for the identification of unknown alkaloids in RC is proposed. The method could also be useful for the quality control of RC.

Electrospray tandem mass spectrometry analysis of methylenedioxy chalcones, flavanones and flavones

RATIONALE

Several methylenedioxy chalcones, flavanones and flavones substituted with mono-, di- and trimethoxy groups have been used in the treatment of proliferative conditions like cancer and inflammatory diseases. The application of these flavonoids in biology requires an analytical method to ensure a detailed knowledge of their structures after drug metabolism.

METHODS

Electrospray ionization mass (ESI-MS) and tandem mass (ESI-MS/MS) spectra were acquired using a Q-TOF 2 instrument. Fragmentation patterns and their pathways were analyzed by CID-MS(2-3) spectra acquired in a LXQ linear ion trap mass spectrometer using standard isolation and excitation procedures (activation q value of 0.25, activation time of 30 ms). ESI-MS and ESI-MS(n) conditions: spray voltage 5 kV, nitrogen 8.00 sheath gas flow rate (arb), heated capillary temperature 275°C, capillary voltage 10.99 V; tube lens voltage 75.01 V.

RESULTS

The ESI-MS/MS spectra of chalcones were nearly identical to their corresponding isomeric flavanones with (0,α)A(+)/(1,3)A(+) and (0,1')B(+)/(1,4)B(+) cleavages. Other common losses are of (•)CH3, H2O, HCHO and C2H2O. The characteristic loss of C2H2O and absence of a (0,α)B(+)/(1,3)B(+) product ion allows to distinguish between the 2- or 4-methoxy-substituted chalcones and flavanones. Common losses of (•)CH3, (•)CH3 and (•)H, and C2H2O2 characteristic for the presence of methylenedioxy groups were observed in flavones.

CONCLUSIONS

The substitution pattern on the B-ring leads to distinct base peak formation in the flavones. In addition, differentiation of isomers with methoxy substituents in ortho and para positions of the B-ring was achieved using MS/MS in chalcones and flavanones. This method will be helpful for identification of these compounds in biological mixtures.