Signals of diagnostic ions in the product ion spectra of [M - H]- ions of methoxylated flavonoids

Comment on the "Does saponin in quinoa really embody the source of its bitterness?"

Saponins are considered the main source of the bitter taste of quinoa, however, it has not been confirmed by Song et al. (2024). These authors suggested that saponin extracts contribute to the umami taste, however, the stronger source of the bitter taste may be the flavonoids contained in the extracts. It is an interesting finding in view of the flavonoids role in the field of food sciences. The UPLC-MS results showed that besides saponins, also polyphenols were present in the analyzed samples. However, the presented results of UPLC-MS analysis should be substantially improved, mainly with respect to the reported accurate masses and retention times, as described in details in this comment.

Teaching mass spectrometry: A compilation of approaches to teaching theory and practice of mass spectrometry

The areas of mass spectrometry applications seem to be much larger than those of any other analytical techniques. They extend from the determination of molecular mass in organic chemistry, through the analytical applications in forensic, environmental and omics sciences, the application in extra-terrestrial exploration and many others. Mass spectrometry, usually coupled with chromatographic techniques, has also found wide application in the pharmaceutical industry, forensic laboratories, laboratories of sanitary inspection or environmental inspection, etc. The growing areas of applications give rise to the demand for the comprehensive mass spectrometry education of undergraduates. This overview covers the body of literature describing various interesting ideas that can be successfully used for teaching mass spectrometry. Since mass spectrometry is a multidisciplinary field, old but dynamically developing, teaching mass spectrometry may be more problematic in comparison to teaching other analytical techniques, for example, there is the problem of position of mass spectrometry in the chemistry curriculum. On the other hand, it is obvious that the mass spectrometry community, besides difficult scientific work, does great and admirable teaching work, in order to perfectly educate undergraduates in the field of mass spectrometry and to make learning mass spectrometry as attractive as possible.

Comment on Villalva et al. Antioxidant, Anti-Inflammatory, and Antibacterial Properties of an Achillea millefolium L. Extract and Its Fractions Obtained by Supercritical Anti-Solvent Fractionation against Helicobacter pylori. Antioxidants 2022, 11, 1849

Villalva et al. evaluated the potential utility of an Achillea millefolium (yarrow) extract in the control of H. pylori infection. The agar-well diffusions bioassay was applied to determine the antimicrobial activity of yarrow extracts. The supercritical anti-solvent fractionation process of yarrow extract was made to give two different fractions with polar phenolic compounds and monoterpenes and sesquiterpenes, respectively. Phenolic compounds were identified by HPLC-ESIMS by using the accurate masses of [M-H]^- ions and the characteristic product ions. However, some of the reported product ions seem to be disputable, as described below.

The Potential Therapeutic Properties of Prunetin against Human Health Complications: A Review of Medicinal Importance and Pharmacological Activities

BACKGROUND

Flavonoids are polyphenolic compounds found to be present in nature and abundant in flowers and fruits. Flavonoidal class phytochemicals have gained interest in the scientific field because of their important pharmacological activities. Several scientific studies have revealed anti-bacterial, anti-oxidant, anti-fungal, analgesic, anti-viral, anti-inflammatory, anti-tumor, anti-parasitic and anti-allergic activities of flavonoidal class phytochemicals. Prunetin is an O-methylated isoflavone that belongs to the phytochemical phytoestrogen class, found to be present in licorice, red cherry, soybean and legumes.

METHODS

Biological potential and pharmacological activities of prunetin have been investigated in the present work through scientific data analysis of numerous scientific research works. Numerous literature databases have been searched in order to collect the scientific information on prunetin in the present work. Pharmacological activities of prunetin have been investigated in the present work through literature data analysis of different scientific research works. Scientific data have been collected from Google Scholar, Google, PubMed, Science Direct and Scopus. Analytical data on prunetin has been collected from literature sources and analyzed in the present work.

RESULTS

Scientific data analysis revealed the biological importance of prunetin in medicine. Prunetin was found to be present in the pea, peach, Oregon cherry, skimmed cheese, cheese, cow kefir and goat kefir. Prunetin is also present in the Prunus avium, Andira surinamensis, Butea superba, Dalbergia sympathetica, Ficus nervosa, Pterospartum tridentatum and Pycnanthus angolensis. Pharmacological data analysis revealed the biological importance of prunetin on bone disorders, cancers, especially hepatocellular carcinoma, urinary bladder cancer, gastric cancer, ovarian cancer, human airway, gut health and enzymes. Scientific data analysis revealed biological effectiveness of prunetin for their angiogenic effects, anti-inflammatory, anti-oxidant, antimicrobial, estrogenic and vasorelaxant potential. Analytical data revealed the importance of modern analytical techniques for qualitative and quantitative analysis of prunetin in the scientific fields.

CONCLUSION

Scientific data analysis in the present investigation revealed the biological importance and pharmacological activities of prunetin in medicine.

Sensitized photoreduction of selected benzophenones. Mass spectrometry studies of radical cross-coupling reactions

The hydrogen atom transfer reaction (HAT) between selected benzophenones (benzophenone BP, 3-carboxybenzophenone 3CB, and 4-carboxybenzophenone 4CB) and 2-propanol was reinvestigated focusing on stable product analysis. As expected, the primary species of these HAT's are the respective diphenyl and dimethyl ketyl radicals that eventually undergo several radical coupling reactions leading to stable photoproducts. However, the mechanisms of these free radical reactions remain unclear and open to question. In this report, we focus on the detailed analysis of the stable photoproducts of these reactions using liquid chromatography coupled with high-resolution mass spectrometry (LC-ESI-QTOF-MS/MS). Products of photopinacolization (benzpinacol and two diastereoisomers of 4CB and 3CB dimers) and isomeric radical cross-coupling adducts of respective diphenyl and dimethyl ketyl radicals were separated chromatographically, and their structures were determined by high-resolution MS/MS, and the mechanisms of the reactions are discussed.

Antioxidant and Cytotoxic Activities of Kudzu Roots and Soy Molasses against Pediatric Tumors and Phytochemical Analysis of Isoflavones Using HPLC-DAD-ESI-HRMS

Pediatric solid tumors (PSTs) are life-threatening and can lead to high morbidity and mortality rates in children. Developing novel remedies to treat these tumors, such as glioblastoma multiforme and sarcomas, such as osteosarcoma, and rhabdomyosarcoma, is challenging, despite immense attempts with chemotherapeutic or radiotherapeutic interventions. Soy (Glycine max) and kudzu roots (KR) (Pueraria spp.) are well-known phytoestrogenic botanical sources that contain high amounts of naturally occurring isoflavones. In the present study, we investigated the antioxidant and cytotoxic effects of the extracts of KR and soy molasses (SM) against PSTs. The green extraction of isoflavones from KR and SM was performed using natural deep eutectic solvents. The extracts were subsequently analyzed by high-performance liquid chromatography (HPLC)-diode array detector (DAD) coupled with high-resolution (HR) mass spectrometry (MS), which identified 10 isoflavones in KR extracts and 3 isoflavones in the SM extracts. Antioxidant and cytotoxic activities of KR and SM extracts were assessed against glioblastoma multiforme (A-172), osteosarcoma (HOS), and rhabdomyosarcoma (Rd) cancer cell lines. The KR and SM extracts showed satisfactory cytotoxic effects (IC₅₀) against the cancer cell lines tested, particularly against Rd cancer cell lines, in a dose-dependent manner. Antioxidant activity was found to be significantly (p ≤ 0.05) higher in KR than in SM, which was consistent with the results of the cytotoxic activity observed with KR and SM extracts against glioblastoma and osteosarcoma cells. The total flavonoid content and antioxidant activities of the extracts were remarkably attributed to the isoflavone content in the KR and SM extracts. This study provides experimental evidence that HPLC-ESI-HRMS is a suitable analytical approach to identify isoflavones that exhibit potent antioxidant and anticancer potential against tumor cells, and that KR and SM, containing many isoflavones, can be a potential alternative for health care in the food and pharmaceutical industries.

In-depth phytochemical and biological studies on potential AChE inhibitors in red and zigzag clover dry extracts using reversed-phase liquid chromatography (RP-LC) coupled with photodiode array (PDA) and electron spray ionization-quadrupole/time of flight-mass spectrometric (ESI-QToF/MS-MS) detection and thin-layer chromatography-bioautography

In the study, Trifolium medium L. and T. pratense L. were used to obtain lyophilisates which were named as TML and TPL, respectively. The former clover taxon represents a little explored species, while the latter one is often found in dietary supplements and functional foods due to the content of isoflavones that alleviate various menopausal symptoms. Detailed phytochemical profiles of both lyophilisates were examined and compared using coupled chromatographic (RP-LC) and spectroscopic PDA/ESI-QToF/MS-MS methods. A total of 54 and 55 compounds were identified in TML and TPL, respectively. Close chemotaxonomic similarities were confirmed for both clover taxa examined, especially in terms of the most abundant isoflavones and hydroxycinnamates. For the first time, neurotropic polyphenols (AChE inhibitors) were identified in clover extracts using TLC-bioautography. In this group, caffeoylmalic acid exhibited significant AChE inhibitory effect confirming the potential of TPL and TML to support physiological functions of the endocrine and nervous systems.

UHPLC-MS/MS Analysis on Flavonoids Composition in Astragalus membranaceus and Their Antioxidant Activity

Astragalus membranaceus is a valuable medicinal plant species widely distributed in Asia. Its root is the main medicinal tissue rich in methoxylated flavonoids. Origin can highly influence the chemical composition and bioactivity. To characterize the principal chemicals influenced by origin and provide more information about their antioxidant profile, the extracts of A. membranaceus roots from four origins were analysed by UHPLC-MS/MS. Thirty-four flavonoids, including thirteen methoxylated flavonoids, fifteen flavonoid glycosides and six flavonols, were identified. By principal component analysis, eighteen identified compounds were considered to be principal compounds. They could be used to differentiate A. membranaceus from Shanxi, Inner Mongolia, Heilongjiang and Gansu. The antioxidant activity was analysed by ORAC assay, DPPH radical scavenging activity assay and cell antioxidant activity assay. 'Inner Mongolia' extract showed the highest antioxidant activity. These results were helpful to understand how origin influenced the quality of A. membranaceus.

LC-Q-TOF-MS/MS detection of food flavonoids: principle, methodology, and applications

Flavonoids have been attracting increasing research interest because of their multiple health promoting effects. However, many flavonoids with similar structures are present in foods, often at low concentrations, which increases the difficulty of their separation and identification. Liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-Q-TOF-MS/MS) has become one of the most widely used techniques for flavonoid detection. LC-Q-TOF-MS/MS can achieve highly efficient separation by LC; it also provides structural information regarding flavonoids by Q-TOF-MS/MS. This review presents a comprehensive summary of the scientific principles and detailed methodologies (e.g., qualitative determination, quantitative determination, and data processing) of LC-Q-TOF-MS/MS specifically for food flavonoids. It also discusses the recent applications of LC-Q-TOF-MS/MS in determination of flavonoid types and contents in agricultural products, changes in their structures and contents during food processing, and metabolism in vivo after consumption. Moreover, it proposes necessary technological improvements and potential applications. This review would facilitate the scientific understanding of theory and technique of LC-Q-TOF-MS/MS for flavonoid detection, and promote its applications in food and health industry.

Advanced Analytical Approaches for the Analysis of Polyphenols in Plants Matrices—A Review

Phenolic compounds are plants’ bioactive metabolites that have been studied for their ability to confer extensive benefits to human health. As currently there is an increased interest in natural compounds identification and characterization, new analytical methods based on advanced technologies have been developed. This paper summarizes current advances in the state of the art for polyphenols identification and quantification. Analytical techniques ranging from high-pressure liquid chromatography to hyphenated spectrometric methods are discussed. The topic of high-resolution mass spectrometry, from targeted quantification to untargeted comprehensive chemical profiling, is particularly addressed. Structure elucidation is one of the important steps for natural products research. Mass spectral data handling approaches, including acquisition mode selection, accurate mass measurements, elemental composition, mass spectral library search algorithms and structure confirmation through mass fragmentation pathways, are discussed.

Comparison of the Polyphenolic Profile of Medicago sativa L. and Trifolium pratense L. Sprouts in Different Germination Stages Using the UHPLC-Q Exactive Hybrid Quadrupole Orbitrap High-Resolution Mass Spectrometry

Identification and quantification of polyphenols in plant material are of great interest since they make a significant contribution to its total bioactivity. In the present study, an UPLC-Orbitrap-MS/MS approach using the variable data acquisition mode (vDIA) was developed and applied for rapid separation, identification, and quantification of the main polyphenolic compounds in Medicago sativa L. and Trifolium pratense L. sprouts in different germination stages. Based on accurate MS data and fragment ions identification strategy, a total of 29 compounds were identified by comparing their accurate masses, fragment ions, retention times, and literatures. Additionally, a number of 30 compounds were quantified by comparing to the reference standards. Data were statistically analysed. For both plant species, the sprouts of the third germination day are valuable sources of bioactive compounds and could be used in phytotherapy and nutrition. Although Trifolium pratense L. (Red Clover) is considered to be a reference for natural remedies in relieving menopause disorders, alfalfa also showed a high level of biological active compounds with estrogenic activity.

Comment on the published data concerning the identification of biochanin A and prunetin by LC/ESI-MS

Biochanin A is one of the most common phytoestrogens, occurring in high concentrations in soy and red clover, for instance, which shows a wide spectrum of biological activity. Prunetin is an isomer of biochanin A, and even though it is not very common, its structural relationship to the latter makes it interesting, regarding its biological activity. Nowadays, LC/ESI-MS methods are widely used for identification of natural compounds, including biochanin A and prunetin. However, we found that the published data concerning the identification of biochanin A and prunetin are sometimes disputable. Namely, the identification is based on the product ions which cannot be regarded as characteristic of biochanin A or prunetin. The reported retention times sometimes may be also disputable.

Structural characterization of bioactive compounds in Cotula cinerea extracts by ultra-high-performance liquid chromatography with photodiode array and high-resolution time-of-flight mass spectrometry detectors

RATIONALE

Cotula cinerea of the Asteraceae family is a traditional Moroccan plant with various biological activities such as analgesic, cytotoxic and antioxidant effects which are often related to the presence of secondary metabolites. The present work aims to screen and identify the main phytochemicals compounds of Cotula cinerea extracts.

METHODS

A method was developed that coupled a rapid and simple ultra-high-performance liquid chromatography system with both photodiode array and high-resolution time-of-flight mass spectrometry detectors (UHPLC-PDA/TOF-HRMS) for the identification of the main secondary metabolites of three investigated extracts (hexane, AcOEt and n-BuOH).

RESULTS

A total of 30 phytocomponents pertaining to phenolic compounds and terpenoids have been detected, identified and quantified. Among these were previously reported free and conjugated coumaric and caffeic acids along with free and conjugated flavones and flavonols with kaempferol, quercetin, luteolin and apigenin aglycones. In addition, sulfated flavonoids were identified in the investigated extracts and are reported in this work for the first time in Cotula cinerea. The obtained results have been discussed in relation to the biological activities of the corresponding extracts.

CONCLUSIONS

This study proposed a practical strategy for rapidly screening and identifying secondary metabolites of Cotula cinerea and provided new information on the phytochemicals of this Saharan plant. This work has therefore provided useful results for further pharmacological studies and the design of new drugs based on this species and will facilitate the utilization of Cotula cinerea in the clinic and its safety evaluation. It is also hoped that the information presented here might stimulate further studies that will possibly lead to development of therapeutic agents from this plant.