Diagnostic Ions Research Articles

Integration of diagnostic ions, molecular network and chemometrics to illustrate the chemical mechanism of Radix Astragali processed with honey

Radix Astragali (RA) is one of the most frequently used traditional Chinese medicine (TCM) in China, and honey-processed RA (HRA) is its common processing product. Thus far, their comprehensive chemical differences are not well understood. In this work, an integrated approach using Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) combined with diagnostic ions, molecular network (MN) and chemometrics was established to profile their chemical characterizations and illustrate the chemical mechanism of RA processed with honey. A total of 226 compounds were tentatively identified including 50 flavonoid glycosides, 26 flavonoid aglycone, 56 saponins, 30 organic acids, 18 amino acids, 3 coumarins and 43 other compounds, of which 33 compounds were characterized according to MN. Their chemical differences were further investigated by integrating of multivariate statistical analysis, student's t-test analysis, linear regression analysis and MN. Consequently, multivariate statistical analysis showed that the raw and processed RA were different form each other. Besides, 33 different compounds were found to be significantly altered by student's t-test analysis. Apart from this, linear regression analysis indicated 42 and 120 compounds underwent the significant varieties. The potential chemical reactions induced by honey-processing, such as possible hydrolysis reactions and isomerization reactions, were speculated based on these variations coupled the areas changes of the nodes in MN. This study provided an efficient strategy to illustrate the chemical mechanism of TCM processing.

Chemical characterization of dicaffeoyl polyamine derivatives to understand specific secondary metabolites in goji berry

Goji berries are among the most valuable edible and medicinal crops worldwide due to their richness in healthy compounds. Dicaffeoyl polyamine derivatives (DCPAds) contain a considerable number of isomers and are prominent specialized metabolites in goji berries. Very little has been achieved thus far in the evaluation of these compounds because of the lack of standards. The characterization and natural variation of DCPAds in goji berry remain unclear. The present study focused on the comprehensive characterization and quantitative analysis of DCPAds in goji berries using liquid chromatography- mass spectrometry. A strategy was developed to determine the fragmentation patterns of authentic standards. Three diagnostic ions were used as characteristic markers to quickly identify these compounds in goji berries. Furthermore, the natural variation and differential spatiotemporal accumulation patterns of seven DCPAds in 94 goji berry batches were revealed. In addition, principal component analysis of metabolomics data grouped the wild and cultivated samples, while green samples and those at other developmental stages could also be discriminated. These results improve our understanding of DCPAds in goji berries, which can provide essential data for chemical insight into further phytochemical studies, metabolite identification, and quality control of goji berries.

Nontargeted screening of aldehydes and ketones by chemical isotope labeling combined with ultra-high performance liquid chromatography-high resolution mass spectrometry followed by hybrid filtering of features

Aldehydes and ketones are important carbonyl compounds that are widely present in foodstuffs, biological organisms and human living environment. However, it is still challenging to comprehensively detect and capture them using liquid chromatography – mass spectrometry. In this work, a chemical isotope labeling (CIL) coupled with ultra-high performance liquid chromatography - high resolution mass spectrometry (UHPLC–HRMS) strategy was developed for the capture and detection of this class of compounds. 2,4-Dinitrophenylhydrazine (DNPH) and isotope-labeled DNPH (DNPH-d3) were utilized to selectively label the target analytes. To address the difficulties in processing UHPLC–HRMS data, a post-acquisition data processing method called MSFilter was proposed to facilitate the screening and identification aldehydes and ketones in complex matrices. The MSFilter consists of four independent filters, namely statistical characteristic-based filtering, mass defect filtering, CIL paired peaks filtering, and diagnostic fragmentation ion filtering. These filters can be used individually or in combination to eliminate unrelated interfering MS features and efficiently detect DNPH-labeled aldehydes and ketones. The results of a mixture containing 48 model compounds showed that although all individual filtering methods could significantly reduce more than 95% of the raw MS features with acceptable recall rates above 85%, but they had relatively high false positive ratios of over 90%. In comparison, the hybrid filtering method combining four filters is able to eliminate massive interfering features (> 99.5%) with a high recall rate of 81.25% and a much lower false positive ratio of 15.22%. By implementing the hybrid filtering method in MSFilter, a total of 154 features were identified as potential signals of CCs from the original 45,961 features of real tobacco samples, of which 70 were annotated. We believe that the proposed strategy is promising to analyze the potential CCs in complex samples by UHPLC–HRMS.

In-depth profiling of carbohydrate isomers in biological tissues by chemical derivatization-assisted mass spectrometry imaging

Carbohydrates play crucial regulatory roles in various physiological and pathological processes. However, the low ionization efficiency and the presence of linkage pattern, monosaccharide composition and anomeric configuration isomers make their in-depth analysis very challenging, especially for heterogeneous biological tissues. In this study, we propose a high-sensitive and isomer-specific imaging approach to visualize the spatial distributions of monosaccharide and disaccharide isomers by integrating chemical derivatization and matrix-assisted laser desorption/ionization tandem mass spectrometry imaging (MALDI-MS2I). 2-Pyridinecarbohydrazide (PYD) is developed as a novel derivatization reagent which can not only improves the MS sensitivity of carbohydrates, but also enables the identification and visualization of ketose and aldose monosaccharide isomers, as well as linkage pattern, monosaccharide composition and anomeric configuration disaccharide isomers by mass spectrometry imaging of isomer-specific MS/MS fragment ions. Moreover, we build quantitative MALDI-MS2 and MALDI-MS2I methods for disaccharide isomers based on the diagnostic fragment ions, and good linear relationships could be achieved both in solution and on glass slides. We expect that this study should provide new ideas for in-depth profiling of the spatial signatures of carbohydrates in biological tissues and lay the foundation for a deeper understanding of carbohydrates’ structure.

Metabolic profiling of the flower of Citrus aurantium L. var. amara Engl. in rats using ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry with data mining strategy.

The flower of Citrus aurantium L. var. amara Engl. (FCAVA), an edible tea and herbal medicine with anti-obesity effect, has attracted great attention in China. The structural elucidation of chemical components in FCAVA has been realized in our previous work. It is well known that metabolic profiling provided a structural basis to discover potential anti-obesity ingredients in FCAVA. Nevertheless, there are no reports about in vivo metabolic profiles of FCAVA. Therefore, it is necessary to comprehensively identify in vivo substances of FCAVA. The identification of in vivo substances of FCAVA remains a challenge due to the strong interference of complex chemical components, biological matrices and metabolite isomers. In this work, ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS) analysis with a data mining strategy was established and applied for the metabolic profiling of FCAVA in rats. The data mining strategy, including diagnostic product ions and neutral loss filtering, improved structural elucidation of xenobiotics in rats after oral administration of FCAVA. A total of 228 xenobiotics, including 80 prototypes (10 unambiguous confirmed with reference standards) and 148 metabolites, were tentatively characterized in rat plasma, urine and fecal samples. Among them, 35 xenobiotics were found in plasma, 124 in urine and 156 in feces. The main biotransformation pathway of FCAVA metabolism was deglycosylation, methylation, glucuronidation and sulfation. The main compounds absorbed into the blood were neohesperidin and naringin, which have been reported to show significant anti-obesity effect. Collectively, this present study would be conducive to the discovery of active ingredients of FCAVA for the treatment of obesity and the development of quality control of FCAVA.

Characterization of unsaturated lipids with high structural specificity by coupling epoxidation with tandem mass spectrometry

Comprehensive characterization of lipid structures is of significance, as they play a key role in numerous biological processes. Mass spectrometry (MS) emerges as a preferred tool for lipid analysis, providing good performance in sensitivity and accuracy. However, characterization of unsaturated lipids still has certain difficulties due to structural diversity. In this work, combining epoxidation and tandem MS was developed for unsaturated lipids analysis with high structural specificity. By using the proposed method, it could simultaneously produce high-abundance diagnostic ions specific to lipid C=C locations and sn-positions, facilitating lipid isomers identification. Determining C=C location and sn-position isomers of lipid in a single spectrum can be achieved, which is valuable for discovery of great structural diversity. The capability of this approach in characterizing unsaturated lipids at high structural level has been illustrated with different standards including a lipid extract from complex biological sample. The relative quantitation capability of C=C location and sn-position isomers was also demonstrated based on diagnostic ion intensities.

Detecting diagnostic features in MS/MS spectra of post-translationally modified peptides

Post-translational modifications are an area of great interest in mass spectrometry-based proteomics, with a surge in methods to detect them in recent years. However, post-translational modifications can introduce complexity into proteomics searches by fragmenting in unexpected ways, ultimately hindering the detection of modified peptides. To address these deficiencies, we present a fully automated method to find diagnostic spectral features for any modification. The features can be incorporated into proteomics search engines to improve modified peptide recovery and localization. We show the utility of this approach by interrogating fragmentation patterns for a cysteine-reactive chemoproteomic probe, RNA-crosslinked peptides, sialic acid-containing glycopeptides, and ADP-ribosylated peptides. We also analyze the interactions between a diagnostic ion’s intensity and its statistical properties. This method has been incorporated into the open-search annotation tool PTM-Shepherd and the FragPipe computational platform.

Targeted characterization and guided isolation of chemical components in Scrophulariae Radix based on LC-MS

How to achieve rapid characterization and efficient isolation of chemical components from traditional Chinese medicines (TCMs) is what the researchers have been exploring. Herein, a strategy integrated diagnostic ion filtering (DIF) and selected ion recording (SIR)-based screen was firstly proposed and successfully applied for targeted characterization and guided isolation of the chemical components from Scrophulariae Radix, one of TCMs. After acquiring the Q-TOF-MS/MS untargeted data, 128 compounds were characterized based on DIF, a self-built database and comparison of the related literatures, in which 38 compounds were reported for the first time. Subsequently, the SIR method of UPLC-QqQ-MS/MS was adopted to guide the isolation of potential new compounds. Finally, three new compounds together with one known compound with the same skeleton were isolated, and unambiguously elucidated by NMR and acid hydrolysis. These results indicated that this integrated analytical approach is effective and reliable in targeted characterizing chemical components and isolating new compounds from the extract of Scrophulariae Radix.

Symptom-oriented network pharmacology revealed the mechanism of HuangQi-DanShen herb pair against cerebral ischemia coupled with comprehensive chemical characterization

Ethnopharmacological relevanceIn the clinical practice of traditional Chinese medicine, HuangQi-DanShen (HD) is an important drug pair for the treatment of cerebral ischemia (CI). Aim of the studyElucidate the mechanism of HD against CI based on symptom-oriented network pharmacology coupled with comprehensive chemical characterization. Materials and methodsUHPLC-Q-Exactive Orbitrap-MS technology was firstly used to obtain the chemical profile of HD constituents. A comprehensive strategy combining in-house library, diagnostic ions, Compound Discover software and network databases was then established to identify its chemical constitutes. Symptomatic treatment is a treatment aimed at relieving or eliminating symptoms which is often characterized as a stop-gap measure due to its inability to cure the disease fundamentally. Nevertheless, symptomatic treatment is an indispensable part of clinical practice and has an important place in medical therapeutics. Therefore, network pharmacology technique were used to elucidate molecular mechanisms from the symptoms of CI. Finally, some literatures were further mined to support our conclusions. ResultsA total of 190 ingredients were identified in HD. Symptom-oriented network pharmacology analysis indicated that compounds of HD relieved “blood” through the regulation of ADORA2A, ADORA1, PTPN11, MMP9 and EGFR, relieved “qi” via the regulation of ADORA2A, EGFR, MMP9 and CA2. The therapeutic effect of HD on “faint” was linked to PTPN11 and MMP9, while the regulation of “dyskinesia” was related to ADORA2A and EGFR, and ADORA1, PTPN11 and MMP9 were associated withe its effect on “speech disorder”. ADORA1, ADORA2A and MMP9 were key to the HD component in treating “visual disturbance”. ConclusionThe approach of symptom-oriented network pharmacology coupled with comprehensive chemical characterization proposed a further orientation for exploring the mechanisms of HD against CI.

Rapid characterization and identification of non-volatile constituents in Pogostemonis Herba by UPLC-Q-TOF-MS combined with UNIFI and an in-house library

This study aimed to characterize and identify the non-volatile components in Pogostemonis Herba by using ultra-perfor-mance liquid chromatography-quadrupole-time of flight-mass spectrometry(UPLC-Q-TOF-MS) combined with UNIFI and an in-house library. The chemical components in 50% methanol extract of Pogostemonis Herba were detected by UPLC-Q-TOF-MS in both positive and negative MS~E continuum modes. Then, the MS data were processed in UNIFI combined with an in-house library to automatically characterize the metabolites. Based on the multiple adduct ions, exact mass, diagnostic fragment ions, and peak intensity of compounds and the fragmentation pathways and retention behaviors of reference substances, the structures identified by UNIFI were further verified and those of the unidentified compounds were tentatively elucidated. A total of 120 compound structures were identified or tentatively identified, including flavonoids, phenylpropanoids, phenolic acids, terpenes, fatty acids, alkaloids, and phenylethanoid glycosides. Sixteen of them were accurately identified by comparison with reference substances, and 53 compounds were reported the first time for Pogostemonis Herba. This study systematically characterized and identified the non-volatile compounds in Pogostemonis Herba for the first time. The findings provide a scientific basis for revealing the pharmacodynamic material basis, establishing a quality control system, and developing products of Pogostemonis Herba.

Fast gas chromatography-tandem mass spectrometry under milder electron ionization conditions for the assay of vitamin D metabolites in human serum

The proposed research was focused on the development of a gas chromatography-tandem mass spectrometry (GC-QqQ-MS) method under milder electron ionization (EI) conditions for the assay of vitamin D metabolites in human serum. Efficiency of three different silylation agents was evaluated for the conversion of vitamin D species into trimethylsilyl (TMS) derivatives, among which N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA) proved to be the most effective. Indeed, the MSTFA reagent was able to convert in TMS ether even the 25-hydroxyl vitamin D derivative that, as known, possesses steric hindrance problems. The separation of vitamin D compounds was obtained in about 11.5 min using a narrow-bore column of dimensions 30 m × 0.25 mm ID × 0.10 μm df with a poly(5% diphenyl/95% dimethyl siloxane) stationary phase. The mass spectrometry ionization of the silylated derivatives was performed under milder EI conditions (20-eV energy) that, respect to common 70-eV energy, generated scan mass spectra with higher relative and absolute intensities of high-mass diagnostic ions, along with a reduced abundance of the low-mass. The signals of the ionized compounds were acquired in multi-reaction-monitoring (MRM) mode, thus enabling the obtainment of highly-sensitive and selective quantitative data. The developed method was validated in term of linearity, accuracy, limits of detection (LoD) and quantification (LoQ). In detail, regression coefficients of the calibration curves were between 0.9959 and 0.9999; LoDs ranged from 0.06 ng mL−1 to 0.73 ng mL−1 and LoQs from 0.16 ng mL−1 to 2.45 ng mL−1. With respect to accuracy, the serum SRM 972a certified reference material (Vitamin D metabolites in frozen human serum) (Levels 1–4) was analyzed.

Differentiation of the Aziridine Functionality from Related Functional Groups in Protonated Analytes by Using Selective Ion-Molecule Reactions Followed by Collision-Activated Dissociation in a Linear Quadrupole Ion Trap Mass Spectrometer.

Aziridines are commonly used as reagents for the synthesis of drug substances although they are potentially mutagenic and genotoxic. Therefore, their unambiguous detection is critically important. Unfortunately, tandem mass spectrometry (MS2) based on collision-activated dissociation (CAD), a powerful method used for the identification of many unknown compounds in complex mixtures, does not provide diagnostic fragmentation patterns for ionized aziridines. Therefore, a different mass spectrometry approach based on MS3 experiments is presented here for the identification of the aziridine functionalities. This approach is based on selective gas-phase ion-molecule reactions of protonated analytes with tris(dimethylamino)borane (TDMAB) followed by diagnostic CAD reactions in a modified linear quadrupole ion trap (LQIT) mass spectrometer. TDMAB reacts with protonated aziridines by forming adduct ions that have lost a dimethylamine (DMA) molecule ([M + H + TDMAB - HN(CH3)2]+). CAD on these product ions generated diagnostic fragment ions with m/z-values 25- and 43-units lower than those of the ion-molecule reaction product ions. None of the ion-molecule reaction product ions formed from other, structurally related, protonated analytes produced related fragment ions. Quantum chemical calculations were employed to explore the mechanisms of the observed reactions.

PE, or not PE, that is the question: The case of overlooked lyso-N-acylphosphatidylethanolamines.

Lyso derivatives of N-acyl-1,2-diacylglycero-3-phosphoethanolamines (L-NAPEs) are a lipid class mostly expressed in vegetables during stress and tissue damage that is involved in the synthesis of the lipid mediator N-acylethanolamines. L-NAPEs can be challenging to distinguish from isomeric phosphatidylethanolamines (PEs), especially in extracted complex samples where they could be confused with abundant PEs. In this study, hydrophilic interaction liquid chromatography with electrospray ionization hyphenated with (tandem) mass spectrometry (MS) was proposed to distinguish L-NAPEs and PEs as deprotonated molecules, [M - H]─ , using both high-resolution/accuracy Fourier transform MS and low-resolution linear ion trap (LIT) mass analyzers. MS3 experiments of [M - H - KE]─ as precursor ions (KE, ketene loss) using the LIT instrument allowed us to distinguish between isomeric L-NAPE and PE species. Regiochemical rules were proposed working on enzymatically synthesized L-NAPEs. A few key differences in MS/MS spectra, including abnormal intensity of acyl chain losses as fatty acids, the presence of N-acylphosphoethanolamine ions, and diagnostic ions of the polar head, were disclosed. Additionally, MS3 spectra of [M - H - KE]─ as precursor ions allowed us to confirm the identification of L-NAPE species. The proposed rules were applied to samples extracted from tomato by-products including stems and leaves. Overall, our methodology is demonstrated as a robust approach to recognizing L-NAPEs in complex samples. L-NAPEs 18:2-N-18:2, 18:2-N-18:3, 18:3-N-18:2, and 18:2-N-18:1 were the prevailing compounds in the analyzed tomato samples, accounting for more than 90%. In summary, a reliable method for identifying L-NAPEs in complex samples is described. The proposed method could prevent overlooking L-NAPEs and overestimating isomeric PE species in future lipid analyses.

Systemic chemical characterization of Lemna minor by UHPLC-Q-Exactive Orbitrap MS coupled with parallel reaction monitoring.

Lemna minor L. (LM) has been used for measles opacity, rubella itching, edema, and oliguria, and the main active ingredients were flavonoids, namely, apigenin, apigenin-7-O-glucoside, and luteolin-7-O-glucoside. However, few systematic analyses of their constituents have been performed; thus, it was necessary to establish a fast and efficient method to identify the chemical composition of LM. In this study, the UHPLC-Q-Exactive Orbitrap mass spectrometry coupled with parallel reaction monitoring was established. Finally, a total of 112 constituents, including 30 dipeptides, 28 nucleosides, 11 amino acids, 10 organic acids, 10 flavonoids, and 23 other compounds, were identified by MS, diagnostic fragment ions, and retention time. One hundred one of those chemicals were first found in LM, which was very beneficial for the further development and utilization of nutriments and the medicinal use of LM.

Rapid imaging of unsaturated lipids at isomer level using photoepoxidation

Unsaturated lipids play an essential role in living organisms, and their different isomers show significant functional differences. Therefore, in situ characterization of unsaturated lipids in tissues needs to be extended to isomer level. However, the exposure of tissue sections to an open environment for a long time may cause cell autolysis or corruption, and current unsaturated lipid imaging methods still face challenges in efficiency. This paper proposes an imaging method based on photoepoxidation coupled with air-flow-assisted desorption electrospray ionization mass spectrometry (AFADESI-MS) to rapidly realize the spatial characterization of unsaturated lipids at the isomer level. The technique has a fast response speed, high epoxide yield (>80%), and high diagnostic ion abundance. After 0.5 min of photoepoxidation, the derivation product yield ratio reached 24.6%. This method rapidly identified six glycerophospholipid isomers containing an 18:1 acyl chain in normal rat liver tissue. Then the imaging method was applied in nude mice lung cancer tissue and human thyroid cancer tissue, with only 3 min photoepoxidation. Results successfully characterized the location and range of unsaturated lipid isomers and revealed their enrichment in tumor tissue. In addition, the experiment shows that the variational trend of the ratio of unsaturated lipid isomers in different types of tumor samples is different. Based on the advantages of efficiency and convenience, this method is prospective for screening unsaturated lipid markers and pathological research of related diseases.

Characteristic fragmentation of polyunsaturated fatty acids with allylic vicinal diols in positive-ion LC/ESI-MS/MS

A characteristic fragmentation was observed for PUFAs that contain allylic vicinal diol groups (resolvin D1, D2, D4, E3, lipoxin A4, B4, and maresin 2), which were derivatized with N,N-dimethylethylenediamine (DMED), in positive-ion ESI-MS/MS. The findings indicate that when these compounds contain an allylic hydroxyl group that is located distal to the terminal DMED moiety in the case of resolvin D1, D4, and lipoxin A4, an aldehyde (-CH=O) is predominately formed, which arises from the breakdown in between vicinal diols, whereas, in the case of an allylic hydroxyl group that is located proximal to the DMED moiety, as in resolvin D2, E3, lipoxin B4, and maresin 2, an allylic carbene (-CH=CH-CH:) is formed. These specific fragmentations could be used as diagnostic ions for characterizing the above seven PUFAs. As a result, it was possible to detect resolvin D1, D2, E3, lipoxin A4, and B4 in sera (20 μl) obtained from healthy volunteers by multiple-reaction monitoring using LC/ESI-MS/MS.

Rapid characterization of the potential active metabolites of diacerein in rat plasma based on UHPLC-Q-exactive orbitrap mass spectrometry and molecular docking

Diacerein, a competently semisynthetic diacetyl derivative of anthraquinone, is a nonsteroidal anti-inflammatory drug, which has been used for treating osteoarthritis and preventing vascular diseases. However, previous investigation indicated that diacerein metabolites and its metabolic pathway in vivo was still unclear. In this research, an effective method was established based on ultra-high-performance liquid chromatography coupled with Q-Exactive-Orbitrap mass spectrometer and molecular docking to screen and detect the potential active metabolites of diacerein in rat plasma after oral administration. The data acquisition and processing methods including Full MS-ddMS2 combined with parallel reaction monitoring mode, extracted ion chromatogram and diagnostic fragment ions were adopted to detect and identify more infinitesimal and unknown diacerein metabolites in vivo. As a result, a total of 32 metabolites were detected and identified in rat plasma according to retention times, accurate mass, diagnostic fragment ions, and relevant drug biotransformation knowledge, among 31 metabolites were firstly reported in this study. Then, the relevant reactions in vivo such as deacetylation, hydroxylation, methylation, sulfate conjugation, glucuronidation, and their composite reactions, were all detected. Ultimately, the results of molecular docking showed that the metabolites of diacerein might have good affinity with IL-1 receptor in vivo. Among them, the metabolites M21 and M1 have the strongest binding affinity with IL-1 receptors, and could be considered as potential active metabolites of diacerein, which have an efficient effect on exerting pharmacological effects of diacerein in vivo. In conclusion, the study of diacerein metabolites in rat plasma expanded our understanding about the metabolism of diacerein in vivo and provided the significant foundation for further drug efficacy studies.

Advanced data post-processing method for rapid identification and classification of the major triterpenoids of Alismatis rhizoma by ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry.

Alismatis rhizoma (AR), a distinguished diuretic traditional Chinese herbal medicine, is widely used for the treatment of diarrhea, edema, nephropathy, hyperlipidemia, and tumors in clinical settings. Most beneficial effects of AR are attributed to the major triterpenoids, whose contents are relatively high in AR. To date, only 25 triterpenoids in AR have been characterized by LC-MS because the low-mass diagnostic ions are hardly triggered in MS, impeding structural identification. Herein, we developed an advanced data post-processing method with abundant characteristic fragments (CFs) and neutral losses (NLs) for rapid identification and classification of the major triterpenoids in AR by UPLC-Q-TOF-MSE . We aimed to establish a systematic method for rapid identification and classification of the major triterpenoids of AR. UPLC-Q-TOF-MSE coupled with an advanced data post-processing method was established to characterize the major triterpenoids of AR. The abundant CFs and NLs of different types of triterpenoids were discovered and systematically summarized. The rapid identification and classification of the major triterpenoids of AR were realized by processing the data and comparing with information described in the literature. In this study, a total of 44 triterpenoids were identified from AR, including three potentially new compounds and 41 known ones, which were classified into six types. The newly established approach is suitable for the chemical profiling of the major triterpenoids in AR, which could provide useful information about chemical constituents and a basis for further exploration of its active ingredients in vivo.

GC-MS of some Amaryllidaceae alkaloids of homolycorine type.

Gas chromatography-mass spectrometry (GC-MS) is the most frequently applied technique for analysis of Amaryllidaceae alkaloids in plant extracts. These compounds, known for their potent bioactivities, are a distinctive chemotaxonomic feature of the Amaryllidoideae subfamily (Amaryllidaceae). The Amaryllidaceae alkaloids of homolycorine type with a C3-C4 double bond generally show molecular and diagnostic ions at the high mass region with low intensity in EIMS mode leading to problematic identification in complex plant extracts. Eleven standard homolycorine-type alkaloids (isolated and identified by 1D and 2D nuclear magnetic resonance) were subjected to separation with gas chromatography and studied with electron impact mass spectrometry including single quadropole (GC-EIMS), tandem (GC-EIMS/MS), and high resolution (GC-HR-EIMS) detectors, as well as with chemical ionisation mass spectrometry (GC-CIMS). Alkaloid fractions from two Hippeastrum species and Clivia miniata were subjected to GC-EIMS and GC-CIMS for alkaloid identification. GC-EIMS in combination with GC-CIMS provided significant structural information for homolycorine-type alkaloids with C3-C4 double bond facilitating their unambiguous identification. Based on the obtained typical fragmentation, other eleven homolycorine-type compounds were identified in extracts from two Hippeastrum species by parallel GC-EIMS, GC-CIMS and LC-ESI/ToF/MS and in extracts from Clivia miniata by GC-EIMS. GC-MS can be successfully applied for identification of new and known homolycorine-type alkaloids, as well as for chemotaxonomical and chemoecological studies, among others within the Amaryllidoideae subfamily.

PO-02-126 DEEP PHENOTYPING OF DSP-ENCODED DESMOPLAKIN CARRYING GENOTYPE POSITIVE UKBB SUBJECTS REVEALS ECG CHANGES AS A POSSIBLE EARLY DIAGNOSTIC MARKER OF DISEASE

Arrhythmogenic cardiomyopathy (ACM) is defined by fibrofatty replacement of the ventricular myocardium with loss of myocytes that can result in arrhythmias, sudden cardiac death, and heart failure, especially in young patients. DSP-encoded desmoplakin is a structural protein integral to the cardiac desmosome. Pathogenic variants in DSP are implicated with ACM and renders carriers uniquely susceptible to inflammation which can mimic myocarditis. Thus, there is a need to identify diagnostically informative markers which can help identify individuals with pathogenic DSP variants and ACM. The study aims to use the UK Biobank (UKBB) to describe clinical markers associated with individuals who host DSP variants that can help identify individuals with ACM predisposition. UKBB participants who had undergone whole exome sequencing, ECG, and cardiovascular MRI were selected for study. DSP variants were identified by ClinVar, InterVar, and predicted loss of function in silico modeling, and interpreted manually using ACMG criteria. Variants were matched by age and sex with controls that were genotype negative (G-) for diagnostic cardiomyopathy and ion channelopathy variants. Quantitative ECG and MRI analyses were used with ICD codes to deep phenotype participants. In 122 putative pathogenic DSP carriers (55.52 ± 7.66 years), 11 (9.0%) had atrial fibrillation and/or flutter on ECG analysis compared to 18 (4.9%) in 366 G- controls (55.52 ± 7.64 years). ECG analysis identified smaller S-wave peak amplitude in lead III (192.95 ± 298.66 vs. 287.11 ± 359.35; p=0.009), and in lead aVF (121.87 ± 199.19 vs. 169.00 ± 237.67; p=0.049) among DSP G+ vs. G- participants. Further, T-wave inversion in anterolateral leads was seen in 13 (10.7%) vs. 20 (5.5%) and in inferior leads in 20 (16.4%) vs. 37 (10.1%) in DSP G+ vs. G- controls, respectively. Individuals who host putatively pathogenic DSP variants have distinct ECG markers that may suggest early stages of ACM development, and thus may aid in guiding prognostication. Future steps include stratifying risk by pathogenicity of DSP variants by ACMG criteria to ascertain a more concrete association of likely-pathogenic variants in DSP with atrial fibrillation and/or flutter. Ongoing studies also include further characterization of DSP variants with more detailed MRI analyses with RV/LV characteristics.