Natural phenolic compounds are rich in cereal and pulse seeds and their dietary functions tend to improve dramatically during germination. This article reviews recent research on the transformation ...of phenolic compounds during seed germination. In particular, it highlights the classification of crude phenolic compounds that can be divided into extractable and non-extractable phenolic compounds based on the biosynthesis process and extraction method. It also recommends grouping resorcinol lipids in the category of extractable phenolic compounds as non-polar solvent extractable phenolic compounds. Moreover, it discusses the variation of the different form of phenolic compounds and proposes a possible metabolic model of these phenolic compounds for seeds germination. This article is crucial for phenolic compounds research, cereal and pulse seeds germination, and food ingredients industry.
Combustion of organic solid wastes releases phenolic compounds which can act as precursors in the formation of environmentally persistent free radicals (EPFRs) in the post-flame, cooling zone of ...waste combustion. The study investigated the generation mechanism of EPFRs from phenolic compounds catalyzed by transition metals in air atmosphere under simulated combustion conditions. Representative combustion-derived phenolic compounds were used, and SiO2 particulates containing different mass ratio of Fe2O3 were synthesized as carriers. EPFRs formed had g-factors between 1.9998 and 2.0066, indicating phenoxyl-, cyclopentadienyl-, and semiquinone-type radicals, along with paramagnetic F-centers. The promotion effect of phenolic compounds on EPFR formation during heating decreased as catechol > hydroquinone > phenol > p-cresol. This trend is related to hydroxyl groups and activation energy. In particular, catechol chemically adsorbed on Fe2O3 at 600 K led to the formation of EPFRs with relatively high spin concentrations (up to 1.28 × 1017 spin/g). Higher Fe2O3 concentrations promoted the transformation of phenoxyl-type radicals into cyclopentadienyl-type and paramagnetic F-centers. However, as the Fe2O3 loading increased from 1.25% to 5%, the density of EPFRs decreased. The findings related to the influence of various precursors and Fe2O3 concentration on EPFR formation provide valuable insights for estimating EPFR generation and associated risk during combustion processes.
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•The underlying links between EPFRs and Phenolic Compounds were clarified.•The electron transfer between Fe2O3 and the precursor was determined by XPS.•A high concentration of Fe2O3 promotes cyclopentadienyl- and paramagnetic F-centers to form.•EPFRs concentration is related to the position of hydroxyl groups in the precursor.
•Notable correlations between pellicle colors and phenolics in kernel without pellicle.•Positive correlations between TPCs of three forms in pellicle and their colors.•Dark walnuts with high contents ...of flavanols, flavones and flavonols in free form.
Although walnut kernels are a rich source of phenolic compounds, little is known about the profiles of phenolic compound forms in various colored-pellicle walnuts, which may be important for product development and utilization. In this work, the free, esterified and bound forms of phenolic compounds in various colored-pellicle walnuts were identified using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry ((UHPLC-MS/MS). The total phenolics (TPCs) in pellicle, kernel without pellicle and whole kernel (with pellicle) were presented in the free form (62.6%) and bound form (1.30 %–12.2 %). Positive correlations were found between the TPCs of three forms in pellicle and the pellicle color, with correlation coefficients of 0.920, 0.990 and 0.940. In addition, the phenolic compounds in free form in the whole kernel (with dark pellicle) demonstrated notable advantages in flavanols, flavones and flavonols contents, particularly (+)-catechin (C) (40.7 μg/g) and epicatechin (EC) (25.8g/g), which were 2–153 times higher than other phenolic compounds in free form. Furthermore, the dark group of esterified phenolic acids showed advantages, particularly ellagic acid (428 μg/g) and gallic acid (130 μg/g).
•Phenolics were extracted from MOLs using customised deep eutectic solvents (DES).•DES-based ultrasonic-assisted extraction (UAE) conditions were optimized by RSM.•DES-based UAE exhibited high ...efficiency for the extraction of the phenolic compounds.•DES-based UAE showed strong antioxidant activities.•Phenolic constituents in the MOLs extracts were analyzed.
In this study, an ultrasonic-assisted extraction (UAE) procedure with selected deep eutectic solvents (DES) as solvent was first designed to simultaneously optimize the total phenolic/flavonoid content (TPC/TFC) and antioxidant activities of Moringa oleifera L. leaves (MOLs) by using response surface methodology (RSM). The key factors for RSM were selected based on the design of the experimental results along with a three-factors-five-level, central composite design (CCD), including 20 experimental runs. The analysis of variance (ANOVA) results revealed that the water content in DES had a significant influence on all responses, while the ultrasonic time and the ratio of liquid to solid had no statistically significant effects on the total phenolic content. The optimal conditions of the combination of TPC/TFC and antioxidant activities were obtained as follows: 37% water content in DES, 144 W ultrasonic power, and 40 °C ultrasonic temperature. The measured parameters corresponded with the predicted results. Moreover, a comparative study confirmed that the optimized DES-based UAE yielded further higher TPC, TFC, and antioxidant activities than other extraction methods. The results of HPLC analysis in optimized conditions verified that the MOLs extracts with DES-based UAE included 14 phenolic compounds with high concentrations of vicenin-2 (17.6 mg/g) and orientin (23.6 mg/g). The present study supplied a green and high-efficient method for extracting high levels of anti-oxidative phenolic compounds from MOLs.
Bound phenolic compounds have rarely been reported in vegetable oils and this may be due to little research about the extraction. Deep eutectic solvents (DESs), recently applied in the extraction of ...phenolic compounds as alternatives to organic solvents, were adopted in the extraction of free and bound phenolic compounds from tea seed oil in this work. First, the phenolic compounds were analyzed by ultra‐high‐performance liquid chromatography with quadrupole‐time‐of‐flight and triple‐quadrupole tandem mass spectrometry (UHPLC‐Q‐TOF‐MS/MS) for characterization and UHPLC‐QqQ‐MS/MS for quantification and 25 phenolic compounds were found to exist in both free and bound forms. Then, DESs were screened for extraction of free and bound phenolic compounds from tea seed oil as the pretreatment for analysis and the results showed that hydrogen bond donors (HBDs) and temperature significantly affected the extraction efficiency of DESs. Finally, free phenolic compounds (83.91 µg/g) and bound phenolic compounds (25.71 µg/g), extracted by the DES with glycerol as HBD at 50 °C, were 51.0% and 93.2% higher than those extracted by methanol/water (60%, v/v), respectively. This work not only advanced the basic data of phenolic compounds in tea seed oil but also explored an efficient extraction method for scientific analysis of free and bound phenolic compounds.
Schematic representation of the possible formation processes of hydrochars from lignocellulosic biomass via hydrothermal carbonization. Display omitted
► HTC allowed rapid conversion of biomass into ...a carbon-rich and lignite-like product. ► Carbonization involved in dehydration, decarboxylation, and demethanation processes. ► Solid residue and liquid product contained many value-added materials. ► Phenolic compounds and furan derivatives were analyzed by GC–MS.
Hydrothermal carbonization (HTC) is a novel thermochemical conversion process to convert lignocellulosic biomass into value-added products. HTC processes were studied using two different biomass feedstocks: corn stalk and Tamarix ramosissima. The treatment brought an increase of the higher heating values up to 29.2 and 28.4MJ/kg for corn stalk and T. ramosissima, respectively, corresponding to an increase of 66.8% and 58.3% as compared to those for the raw materials. The resulting lignite-like solid products contained mainly lignin with a high degree of aromatization and a large amount of oxygen-containing groups. Liquid products extracted with ethyl acetate were analyzed by gas chromatography–mass spectrometry. The identified degradation products were phenolic compounds and furan derivatives, which may be desirable feedstocks for biodiesel and chemical production. Based on these results, HTC is considered to be a potential treatment in a lignocellulosic biomass refinery.
Hickory is an abundant source of phenolic compounds that exhibit a diverse range of bioactivities. In this study, phenolic compounds were extracted and purified from hickory green husk (HG), hickory ...nutshell (HN), and hickory seed coat (HS) using solid-phase extraction and ultrasonication (SPE-US). The effects of the SPE-US treatment on the structure and properties of the phenolic compounds were then investigated, including their composition, antioxidant activity, and antimicrobial activity. The dominant phenolic substances in the different extracts after SPE-US treatment were: ellagic acid and trans ferulic acid (HS); ellagic acid and sinapic acid (HN); and rutin (HG). The HS-SPE-US1 extract exhibited the highest total polyphenol content (416 ± 11 mg GAE/g DW), total flavonoid content (47.51 ± 0.68 mg RE/g DW), Fe3+ reduction ability (74.2 ± 1.0 mmol Fe2+/g DW), radical (DPPH and ABTS) scavenging ability, and antimicrobial activity against Staphylococcus aureus.
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•The hickory phenolic compounds were purified by solid phase extraction-sonication.•The purified phenolic compounds were mainly ellagic acid and rutin.•The highest antibacterial activity was contained in seed coat extract.
Avocado ripening entails intricate physicochemical transformations resulting in desirable characteristics for consumption; however, its impact on specific metabolites and its cultivar dependence ...remains largely unexplored. This study employed LC-MS to quantitatively monitor 30 avocado pulp metabolites, including phenolic compounds, amino acids, nucleosides, vitamins, phytohormones, and related compounds, from unripe to overripe stages, in three commercial varieties (Hass, Fuerte, and Bacon). Multivariate statistical analysis revealed significant metabolic variations between cultivars, leading to the identification of potential varietal markers. Most monitored metabolites exhibited dynamic quantitative changes. Although phenolic compounds generally increased during ripening, exceptions such as epicatechin and chlorogenic acid were noted. Amino acids and derivatives displayed a highly cultivar-dependent evolution, with Fuerte demonstrating the highest concentrations and most pronounced fluctuations. In contrast to penstemide, uridine and abscisic acid levels consistently increased during ripening. Several compounds characteristic of the Bacon variety were delineated but require further research for identification and role elucidation.
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•30 compounds were quantitatively monitored over ripening in avocados from 3 varieties.•Metabolic differences were noted between unripe/ripe fruits and tested cultivars.•Phenolic compounds concentration exhibited an increase during the softening process.•The evolution of amino acids and derivatives was highly cultivar-dependent.•Abscisic acid, uridine, and penstemide displayed consistent trends for all varieties.
The objective of this work was to study the non-targeted metabolite profiling of potato leaves using high performance liquid chromatography coupled to quadrupole-time of flight mass spectrometry ...(HPLC-ESI-QTOF-MS). The mass accuracy, true isotopic pattern in both MS and MS/MS spectra provided by QTOF-MS made possible the tentative identification of 109 compounds present in potato leaves, including organic acids, amino acids and derivatives, phenolic acids, flavonoids, iridoids, oxylipins and other polar and semi-polar compounds. Among them, 32 compounds have been found for the first time in potato leaf and in the Solanaceae family. Quinic acid and its derivatives represented more than 45% of the bioactive compounds quantified in the extract. Derivatives of hydroxybenzoic acid and gentisic acid were also founded at considerable concentrations.
This study shed light on the composition of potato leaf extract and will serve as a base for further research into activities of the various compounds found in this matrix which has demonstrated a potential use as functional ingredients.
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•Non-targeted metabolite profiling of potato leaves using HPLC-ESI-QTOF-MS.•Identification of 108 compounds in potato leaves from 7 different families.•32 compounds found for the first time in potato leaf and in the Solanaceae family.•Quinic acid and its derivatives represented more than 45% of the bioactive compounds.
