Paper Spray Mass Spectrometry on the Analysis of Phenolic Compounds in Rhynchelytrum repens: A Tropical Grass with Hypoglycemic Activity

Coupling microextraction techniques with substrate spray mass spectrometry, towards a faster analysis of biological samples

Direct coupling sample preparation with mass spectrometry has risen as a reliable analytical strategy in bioanalysis as it provides a high sample throughput. This approach avoids an exhaustive separation step, thus being cost-effective compared to the traditional analytical workflow. The selectivity and sensitivity levels rely on the mass spectrometric analysis and the appropriate selection of the sample preparation. Miniaturized extraction techniques have demonstrated particular utility in this coupling thanks to their ability to pre-concentrate the target analytes while removing many of the matrix components. This article reviews the main developments in combining microextraction techniques with mass spectrometry based on electrospray ionization, a consolidated ionization technique in bioanalysis. The article aims to provide an overview of the potential of these techniques by describing the most significant examples. The different approaches are classified according to the materials or devices used to perform the extraction and analysis.

Structure identification of myricetin-phenylacetaldehyde adducts and their potential biological activities

Our previous research discovered that myricetin could effectively inhibit the formation of heterocyclic aromatic amines (HAAs) in cantonese baked foods by trapping phenylacetaldehyde to form adducts. However, the structure and biological activity of these adducts were still unknown. In this study, we identified two myricetin-phenylacetaldehyde adducts from cantonese mooncakes, BYQ-2 and BYQ-3, using pre-HPLC. These adducts were found to be the products of phenylacetaldehyde addition at the C-8 and C-6 positions of myricetin, followed by cyclization with hydroxyl groups at the C-7 and C-5 positions. Antioxidant assays revealed that BYQ-2 and BYQ-3 have stronger radical scavenging abilities than myricetin in the concentration range of 12.5 ∼ 800 μg/mL in the three samples. Additionally, both adducts showed potential health benefits by inhibiting α-glucosidase and CYP450 1A2, enzymes involved in blood sugar regulation and HAAs metabolism. BYQ-2 exhibited the highest inhibitory potency against α-glucosidase and CYP450 1A2 with IC50 values of 10.32 μg/mL and 5.44 μg/mL, respectively. Theoretical calculations suggested that hydrogen bonding and hydrophobic interactions are the primary forces driving enzyme binding, with BYQ-2 showing the highest binding energies (-7.75 kcal/mol for α-glucosidase and -9.31 kcal/mol for CYP450 1A2). Our findings suggested that myricetin inhibited HAAs in baked foods while also enhancing food safety and providing health benefits through its adduction with small molecule aldehydes. In future research, it is necessary to further evaluate the absorption and metabolic behavior as well as safety of myricetin-HAAs active intermediate adducts at the cellular and animal experimental level.

Evaluation of the Chemical Profile and Antioxidant Capacity of Green, Brown, and Dark Propolis

The chemical composition of propolis varies between different types, due to the specific vegetation found near the hives and the climatic and soil conditions worldwide. Green propolis is exclusive to Brazil, produced by bees, with the resin of the plant Baccharis dracunculifolia. Brown propolis is a specific variety produced mainly in Northeast Brazil from the plant Hyptis divaricata, also known as "maria miraculosa". Dark propolis is a variety of propolis produced by bees from the resin of the plant known as Jurema Preta (Mimosa hostilis benth). In this study, the aqueous extracts of green, brown, and dark propolis were analyzed for their antioxidant capacity using ABTS, FRAP, and DPPH, and their chemical profiles were determined using paper spray mass spectrometry. Among the three extracts, green propolis had the highest content of total phenolic compounds (2741.71 ± 49.53 mg GAE. 100 g-1), followed by brown propolis (1191.55 ± 36.79 mg GAE. 100 g-1), and dark propolis had the lowest content (901.79 ± 27.80 mg GAE. 100 g-1). The three types of propolis showed high antioxidant capacity, with green showing the highest antioxidant capacity for the three methods used. Using paper spray mass spectrometry, it was possible to suggest the presence of 116 substances, including flavonoids (56), phenylpropanoids (30), terpenes (25), carboxylic acids (1), benzoic acid derivatives (1), fatty acids (1), amino acids (1) and alkaloids (1). The compounds in the green, brown, and dark propolis extracts reinforce the bioactive potential for application in these tree extracts' food and pharmaceutical products.

Efficiency of Different Solvents in the Extraction of Bioactive Compounds from Plinia cauliflora and Syzygium cumini Fruits as Evaluated by Paper Spray Mass Spectrometry

Jabuticaba (Plinia cauliflora) and jambolan (Syzygium cumini) fruits are rich in phenolic compounds with antioxidant properties, mostly concentrated in the peel, pulp, and seeds. Among the techniques for identifying these constituents, paper spray mass spectrometry (PS-MS) stands out as a method of ambient ionization of samples for the direct analysis of raw materials. This study aimed to determine the chemical profiles of the peel, pulp, and seeds of jabuticaba and jambolan fruits, as well as to assess the efficiency of using different solvents (water and methanol) in obtaining metabolite fingerprints of different parts of the fruits. Overall, 63 compounds were tentatively identified in the aqueous and methanolic extracts of jabuticaba and jambolan, 28 being in the positive ionization mode and 35 in the negative ionization mode. Flavonoids (40%), followed by benzoic acid derivatives (13%), fatty acids (13%), carotenoids (6%), phenylpropanoids (6%), and tannins (5%) were the groups of substances found in greater numbers, producing different fingerprints according to the parts of the fruit and the different extracting solvents used. Therefore, compounds present in jabuticaba and jambolan reinforce the nutritional and bioactive potential attributed to these fruits, due to the potentially positive effects performed by these metabolites in human health and nutrition.

Influence of Harvest Time on the Chemical Profile of Pereskia aculeate Mill. Using Paper Spray Mass Spectrometry

This study evaluated the physicochemical characteristics and the production of bioactive compounds of Pereskia aculeata Mill. at different harvest times. Here, we performed a qualitative evaluation of the chemical profile by paper spray mass spectrometry (PSMS), the phenolic acid and flavonoid profile by high-performance liquid chromatography (HPLC), antioxidant activity, total carotenoids, total phenolic compounds, total flavonoids, total anthocyanins, color characteristics, total soluble solids (TSS), total solids (TS), pH, and total titratable acidity (TTA). The chemical profile was not affected, with the exception of 4,5-dimethyl-2,6-octadiene and azelaic acid, which was only identified in the leaves harvested during the winter. The content of four phenolic acids and three flavonoids were analyzed; out of these, no significant amounts of ellagic acid and quercetin were detected. There was no difference in production of bioactive compounds between seasons, reflecting the antioxidant activity, which also did not differ. Brightness, chroma, and leaf pH were the only physicochemical characteristics that did not vary between seasons.

Applications of ambient ionization mass spectrometry in 2021: An annual review

Ambient ionization mass spectrometry (AIMS) has revolutionized the field of analytical chemistry, enabling the rapid, direct analysis of samples in their native state. Since the inception of AIMS almost 20 years ago, the analytical community has driven the further development of this suite of techniques, motivated by the plentiful advantages offered in addition to traditional mass spectrometry. Workflows can be simplified through the elimination of sample preparation, analysis times can be significantly reduced and analysis remote from the traditional laboratory space has become a real possibility. As such, the interest in AIMS has rapidly spread through analytical communities worldwide, and AIMS techniques are increasingly being integrated with standard laboratory operations. This annual review covers applications of AIMS techniques throughout 2021, with a specific focus on AIMS applications in a number of key fields of research including disease diagnostics, forensics and security, food safety testing and environmental sciences. While some new techniques are introduced, the focus in AIMS research is increasingly shifting from the development of novel techniques toward efforts to improve existing AIMS techniques, particularly in terms of reproducibility, quantification and ease-of-use.

Phytochemicals of Avocado Residues as Potential Acetylcholinesterase Inhibitors, Antioxidants, and Neuroprotective Agents

Avocado (Persea americana) is a widely consumed fruit and a rich source of nutrients and phytochemicals. Its industrial processing generates peels and seeds which represent 30% of the fruit. Environmental issues related to these wastes are rapidly increasing and likely to double, according to expected avocado production. Therefore, this work aimed to evaluate the potential of hexane and ethanolic peel (PEL-H, PEL-ET) and seed (SED-H, SED-ET) extracts from avocado as sources of neuroprotective compounds. Minerals, total phenol (TPC), total flavonoid (TF), and lipid contents were determined by absorption spectroscopy and gas chromatography. In addition, phytochemicals were putatively identified by paper spray mass spectrometry (PSMS). The extracts were good sources of Ca, Mg, Fe, Zn, ω-6 linoleic acid, and flavonoids. Moreover, fifty-five metabolites were detected in the extracts, consisting mainly of phenolic acids, flavonoids, and alkaloids. The in vitro antioxidant capacity (FRAP and DPPH), acetylcholinesterase inhibition, and in vivo neuroprotective capacity were evaluated. PEL-ET was the best acetylcholinesterase inhibitor, with no significant difference (p > 0.05) compared to the control eserine, and it showed neither preventive nor regenerative effect in the neuroprotection assay. SED-ET demonstrated a significant protective effect compared to the control, suggesting neuroprotection against rotenone-induced neurological damage.

Physicochemical Characterization and Paper Spray Mass Spectrometry Analysis of Myrciaria Floribunda (H. West ex Willd.) O. Berg Accessions

Myrciaria floribunda, also known as rumberry, is a tree native to the Brazilian Atlantic Forest, where its fruits have the potential for commercial use. This study evaluates the antioxidant potential, determines the phytochemical profile, and chemically characterizes the rumberry fruit. Accessions were sampled from the Rumberry Active Germplasm Bank of the Federal University of Alagoas, Brazil. Physical characteristics, chemical characteristics, and phenolic compound content were analyzed. Chemical profile characterization was carried out using PSMS. Accessions had an average weight of 0.86 g. Accession AC137 presented a higher pulp yield (1.12 g). AC132 and AC156 had larger fruits, AC137 showed greater firmness (5.93 N), and AC160 had a higher and total phenolic content ratio (279.01 ± 11.11). Orange-colored accessions scored higher in evaluated parameters, except for AC160 for phenolic content. Thirty-two compounds were identified on positive ionization mode and 42 compounds on negative ionization mode using PSMS. Flavonoids, followed by the derivatives of benzoic acid, sugars, and phenylpropanoids, were the most prominent. Myricitrin, quercitrin, and catechin stand out as flavonoids that have been reported in previous studies with antioxidant and antimicrobial properties, in addition to health and therapeutical benefits, demonstrating the potential of the rumberry fruit.