Flavanone Naringenin Research Articles

Identification of a Flavanone 2-Hydroxylase Involved in Flavone C-Glycoside Biosynthesis from Camellia sinensis.

Tea contains a variety of flavone C-glycosides, which are important compounds that distinguish tea cultivars and tea categories. However, the biosynthesis pathway of flavone C-glycosides in tea plant remains unknown, and the key enzymes involved have not been characterized. In this study, a liquid chromatography-mass spectrometry method to determine 9 flavone C-glycosides was developed, and the accumulation patterns of 9 flavone C-glycosides in tea plants were examined first. Then, an entry enzyme CsF2H for flavone C-glycoside biosynthesis was identified, which had four cytochrome P450-specific conserved motifs and was targeted to the endoplasmic reticulum. Correlation analysis indicated that the expression level of CsF2H was positively correlated with all contents of 9 flavone C-glycosides. The recombinant CsF2H could convert flavanone (naringenin) into the corresponding 2-hydroxyflavonone (2-hydroxynaringenin), rather than into flavone (apigenin). Heterologous coexpression of CsF2H and CsCGT1 in yeast revealed that the substrate naringenin could be enzymatically converted to flavone mono-C-glycosides vitexin and isovitexin under the catalytic control of CsF2H and CsCGT1 following dehydration. Gene-specific antisense oligonucleotide analysis suggested that suppressing CsF2H significantly reduced the levels of 9 flavone C-glycosides. Together, CsF2H is the first key enzyme that generates flavone C-glycosides through the 2-hydroxyflavanone biosynthesis pathway in tea plants.

Fermentation by Penicillium polonicum improves the functional components and biological effects of orange peel via producing β-glucosidase without the risk of potential mycotoxins

This paper presented the initial investigation into the impact of Penicillium polonicum fermentation on the functional components and bioactivities of navel orange peel. The fermentation process resulted in a notable enhancement of the total flavonoid content (TFC), total phenolic content (TPC), antioxidant capacity, antibacterial activity, and antiglycation activity of orange peel. Eighteen flavonoids were isolated and identified from the ethanolic extract of fermented orange peel (FEE) by employing chromatographic and spectroscopic techniques. The results of the HPLC analysis showed that three flavanones (naringenin, hesperetin, and isosakuranetin) were newly produced and present in high concentrations in FEE, with hesperetin being the most abundant component (39.74 mg/g) in comparison to the ethanolic extract of unfermented orange peel (EE). The TPC, TFC, antioxidant, and antiglycation activities of FEE, as well as the enzymatic activity of β-glucosidase in the fermented orange peels, showed a gradual increase with the progression of fermentation time over a five-month period. HPLC analysis revealed that the fermentation metabolites generated by P. polonicum in rice and orange peel media exhibited distinct profiles, indicating that the fermentation of orange peel by P. polonicum did not result in the production of potential mycotoxins. The findings of this study provided a scientific basis for the high-value utilization of navel orange peels and established a reference point for the potential applications of other peel byproducts via microbial fermentation.

The Citrus flavanone naringenin prolongs the lifespan in C. elegans and slows signs of brain aging in mice

Aging is one of the main risk factors for neurodegenerative disorders, which represent a global burden on healthcare systems. Therefore, identifying new strategies to slow the progression of brain aging is a compelling challenge. In this article, we first assessed the potential anti-aging effects of the Citrus flavanone naringenin (NAR), an activator of the enzyme sirtuin-1 (SIRT1), in a 3R-compliant and short-lived aging model (i.e., the nematode C. elegans). Then, we investigated the preventive effects of a 6-month treatment with NAR (100 mg/kg, orally) against brain aging and studied its mechanism of action in middle-aged mice. We demonstrated that NAR (100 μM) extends lifespan and improves healthspan in C. elegans. In the brain of middle-aged mice, NAR promotes the activity of metabolic enzymes (citrate synthase, cytochrome C oxidase) and increases the expression of the SIRT1 enzyme. Consistently, NAR up-regulates the expression of downstream antioxidant (Foxo3, Nrf2, Ho-1), anti-senescence (p16), and anti-inflammatory (Il-6, Il-18) markers. Our findings support NAR supplementation to slow the signs of brain aging.

Medicago truncatula β-glucosidase 17 contributes to drought and salt tolerance through antioxidant flavonoid accumulation.

Flavonoids are usually present in forms of glucosides in plants, which could be catabolized by β-glucosidase (BGLU) to form their corresponding flavonoid aglycones. In this study, we isolated three abiotic-responsive BGLU genes (MtBGLU17, MtBGLU21and MtBGLU22) from Medicago truncatula, and found only the recombinant MtBGLU17 protein could catalyse the hydrolysis of flavonoid glycosides. The recombinant MtBGLU17 protein is active towards a variety of flavonoid glucosides, including glucosides of flavones (apigenin and luteolin), flavonols (kaempferol and quercetin), isoflavones (genistein and daidzein)and flavanone (naringenin). In particular, the recombinant MtBGLU17 protein preferentially hydrolyses flavonoid-7-O-glucosides over their corresponding 3-O-glucosides. The content of luteoin-7-O-glucoside was reduced in the MtBGLU17 overexpression plants but increased in the Tnt-1 insertional mutant lines, whereas luteoin content was increased in the MtBGLU17 overexpression plants but reduced in the Tnt-1 insertional mutant lines. Under drought and salt (NaCl) treatment, the MtBGLU17 overexpression lines showed relatively higher DPPH content, and higher CAT and SOD activity than the wild type control. These results indicated that overexpression lines of MtBGLU17 possess higher antioxidant activity and thus confer drought and salt tolerance, implying MtBGLU17 could be potentially used as a candidate gene to improve plant abiotic stress tolerance.

Highly Promiscuous Flavonoid Di-O-glycosyltransferases from Carthamus tinctorius L.

Safflower (Carthamus tinctorius L.) has been recognized for its medicinal value, but there have been limited studies on the glycosyltransferases involved in the biosynthesis of flavonoid glycosides from safflower. In this research, we identified two highly efficient flavonoid O-glycosyltransferases, CtOGT1 and CtOGT2, from safflower performing local BLAST alignment. By constructing a prokaryotic expression vector, we conducted in vitro enzymatic reactions and discovered that these enzymes were capable of catalyzing two-step O-glycosylation using substrates such as kaempferol, quercetin, and eriodictyol. Moreover, they exhibited efficient catalytic activity towards various compounds, including flavones (apigenin, scutellarein), dihydrochalcone (phloretin), isoflavones (genistein, daidzein), flavanones (naringenin, glycyrrhizin), and flavanonols (dihydrokaempferol), leading to the formation of O-glycosides. The broad substrate specificity of these enzymes is noteworthy. This study provides valuable insights into the biosynthetic pathways of flavonoid glycosides in safflower. The discovery of CtOGT1 and CtOGT2 enhances our understanding of the enzymatic processes involved in synthesizing flavonoid glycosides in safflower, contributing to the overall comprehension of secondary metabolite biosynthesis in this plant species.

Comparative transcriptomics reveals the mechanism of antibacterial activity of fruit-derived dihydrochalcone flavonoids against Porphyromonas gingivalis.

Porphyromonas gingivalis causes various health issues through oral infections. This study investigates the antibacterial activities of food-derived dihydrochalcone flavonoids against Porphyromonas gingivalis and their mechanisms of antibacterial action through comparative transcriptome profiling. Susceptibility tests showed that two typical dihydrochalcone flavonoids (phloretin and phlorizin) had much lower minimum inhibitory concentrations (12.5 μg mL-1 and 50 μg mL-1, respectively) than the common flavanone naringenin (100 μg mL-1). SEM observations and the LDH activity assay indicated obvious anomalies in cell morphology and increased cell membrane permeability, indicating the destructive effect of those compounds on the cell structure. These compounds might also induce apoptosis in P. gingivalis, as shown by the CLSM fluorescence images. Transcriptomic analysis revealed that the flavonoid treatment impacted DNA function and oxidative damage. These flavonoids may activate antioxidant-related pathways that are lethal to anaerobic bacteria like P. gingivalis. Additionally, the compounds resulted in the silencing of transposition-related genes, potentially inhibiting resistance-gene acquisition and expression. Phloretin regulated fatty acid metabolism pathways, which are related to the construction and maintenance of the cell membrane. This suggests a relationship between the structure and antibacterial activities of the tested compounds that share a flavonoid skeleton but differ in the C-ring and glucose moiety. This is the first report of the antibacterial activities and mechanisms of action of food-derived dihydrochalcone flavonoids at the transcriptome level, offering a promising approach for the development of new antibacterial agents from natural products and enhancing their applicability in treating diseases associated with oral pathogens as a substitute for antibiotics.

Novel Flavanone Naringenin Derivative with Anti-Inflammatory Activity

Naringenin is a flavonoid with several biological activities already reported but with few biological applications in the pharmaceutical field. In this work, a new flavanone, called carboxymidamide (DCHA), synthesized through the condensation reaction between naringenin and aminoguanidine is structurally confirmed through spectroscopic analysis of nuclear magnetic resonance, mass spectrometry and Fourier transform infrared. DCHA was not toxic to human fibroblasts and inhibited macrophage activation in vitro. In vivo, it suppressed leukocyte migration in lipopolysaccharide (LPS)-induced peritonitis and reduced zymosan-induced paw edema. Molecular docking simulations of DCHA in the active site of the enzymes inducible nitric oxide synthase, cyclooxygenase-2 and phosphodiesterase type 4 indicate that the anti-inflammatory activity of this new flavanone can be explained by the inhibition of these target enzymes. This is the first work to present the synthesis of a flavonoid derivative with aminoguanidine that showed a high anti-inflammatory potential.

Binding characteristics and conformational changes in alpha-2-macroglobulin by the dietary flavanone naringenin: biophysical and computational approach

In the present study, we investigated the interaction of alpha-2-macroglobulin (α2M) with naringenin using multi-spectroscopic, molecular docking, and molecular simulation approaches to identify the functional changes and structural variations in the α2M structure. Our study suggests that naringenin compromised α2M anti-proteinase activity. The results of absorption spectroscopy and fluorescence measurement showed that naringenin-α2M formed a complex with a binding constant of (kb)∼104, indicative of moderate binding. The value of ΔG° in the binding indicates the process to be spontaneous and the major force responsible to be hydrophobic interaction. The findings of FRET reveal the binding distance between naringenin and the amino acids of α2M was 2.82 nm. The secondary structural analysis of α2M with naringenin using multi-spectroscopic methods like synchronous fluorescence, red-edge excitation shift (REES), FTIR, and CD spectra further confirmed the significant conformational alterations in the protein. Molecular docking approach reveals the interactions between naringenin and α2M to be hydrogen bonds, van der Waals forces, and pi interactions, which considerably favour and stabilise the binding. Molecular dynamics modelling simulations also supported the steady binding with the least RMSD deviations. Our study suggests that naringenin interacts with α2M to alter its confirmation and compromise its activity. Communicated by Ramaswamy H. Sarma

Stepwise changes in flavonoids in spores/pollen contributed to terrestrial adaptation of plants.

Protecting haploid pollen and spores against ultraviolet-B (UV-B) light and high temperature, two major stresses inherent to the terrestrial environment, is critical for plant reproduction and dispersal. Here, we show flavonoids play an indispensable role in this process. Firstly, we identified the flavanone naringenin, which serves to defend against UV-B damage, in the sporopollenin wall of all vascular plants tested. Secondly, we found that flavonols are present in the spore/pollen protoplasm of all euphyllophyte plants tested and that these flavonols scavenge ROS to protect against environmental stresses, particularly heat. Genetic and biochemical analyses showed that these flavonoids are sequentially synthesized in both the tapetum and microspores during pollen ontogeny in Arabidopsis (Arabidopsis thaliana). We show that stepwise increases in the complexity of flavonoids in spores/pollen during plant evolution mirrors their progressive adaptation to terrestrial environments. The close relationship between flavonoid complexity and phylogeny and its strong association with pollen survival phenotypes suggests that flavonoids played a central role in the progression of plants from aquatic environments into progressively dry land habitats.

The Combination of Natural Molecules Naringenin, Hesperetin, Curcumin, Polydatin and Quercetin Synergistically Decreases SEMA3E Expression Levels and DPPIV Activity in In Vitro Models of Insulin Resistance.

Type 2 diabetes mellitus (T2DM) is a disease characterized by a prolonged hyperglycemic condition caused by insulin resistance mechanisms in muscle and liver, reduced insulin production by pancreatic β cells, and a chronic inflammatory state with increased levels of the pro-inflammatory marker semaphorin 3E. Phytochemicals present in several foods have been used to complement oral hypoglycemic drugs for the management of T2DM. Notably, dipeptidyl peptidase IV (DPPIV) inhibitors have demonstrated efficacy in the treatment of T2DM. Our study aimed to investigate, in in vitro models of insulin resistance, the ability of the flavanones naringenin and hesperetin, used alone and in combination with the anti-inflammatory natural molecules curcumin, polydatin, and quercetin, to counteract the insulin resistance and pro-inflammatory molecular mechanisms that are involved in T2DM development. Our results show for the first time that the combination of naringenin, hesperetin, curcumin, polydatin, and quercetin (that mirror the nutraceutical formulation GliceFen®, Mivell, Italy) synergistically decreases expression levels of the pro-inflammatory gene SEMA3E in insulin-resistant HepG2 cells and synergistically decreases DPPIV activity in insulin-resistant Hep3B cells, indicating that the combination of these five phytochemicals is able to inhibit pro-inflammatory and insulin resistance molecular mechanisms and could represent an effective innovative complementary approach to T2DM pharmacological treatment.

Simultaneous Determination of Steroidal Alkaloids and Polyphenol Group from Eight Varieties of Siberian Solanum tuberosum L. through Tandem Mass Spectrometry

The purpose of this work was a comparative metabolomic study of extracts of from Siberian breeds of the Solanum tuberosum L.: Tuleevsky, Kuznechanka, Memory of Antoshkina, Tomichka, Hybrid 15/F-2-13, Hybrid 22103-10, Hybrid 17-5/6-11, and Sinilga from the collection of Siberian Federal Scientific Centre of Agrobiotechnology of the Russian Academy of Sciences. HPLC was used in combination with ion trap to identify target analytes in extracts of tuber part of a potato. The results showed the presence of 87 target analytes corresponding to S. tuberosum. In addition to the reported metabolites, a number of metabolites were newly annotated in S. tuberosum. There were essential amino acid L-Tryptophan, L-glutamate, L-lysine, Nordenine; flavones Ampelopsin; Chrysoeriol, Diosmetin, Diosmin, Myricetin; flavanones Naringenin and Eriodictyol-7-O-glucoside; dihydrochalcone Phlorizin; oligomeric proanthocyanidin (Epi)afzelechin-(epi)afzelechin; Shikimic acid; Hydroxyphenyllactic acid; Fraxidin; Myristoleic acid; flavan-3-ols Epicatechin, Gallocatechin, Gibberellic acid, etc.

Citrus × paradisi L. Fruit Waste: The Impact of Eco-Friendly Extraction Techniques on the Phytochemical and Antioxidant Potential

Citrus fruits have been the subject of extensive research over the years due to their impressive antioxidant properties, the health benefits of flavanones, and their potential use in the prevention and treatment of chronic diseases. Grapefruit have been shown in studies to improve overall health, with numerous potential benefits, including improved heart health, reduced risk of certain cancers, improved digestive health, and improved immune system function. The development of cyclodextrin complexes is an exciting approach to increasing the content of flavanones such as naringin and naringenin in the extraction medium while improving the profile of beneficial phenolic compounds and the antioxidant profile. This research aims to optimize the extraction conditions of the flavanones naringin and naringenin with additional compounds to increase their yield from different parts of grapefruit (Citrus × paradisi L.) fruits, such as albedo and segmental membranes. In addition, the total content of phenolic compounds, flavonoids, and the antioxidant activity of ethanolic extracts produced conventionally and with -cyclodextrin was examined and compared. In addition, antioxidant activity was measured using the radical scavenging activity assay (ABTS), radical scavenging activity assay (DPPH), and ferric reducing antioxidant power (FRAP) methods. The yield of naringin increased from 10.53 ± 0.52 mg/g to 45.56 ± 5.06 mg/g to 51.11 ± 7.63 mg/g of the segmental membrane when cyclodextrins (α, β-CD) were used; naringenin increased from 65.85 ± 10.96 μg/g to 91.19 ± 15.19 μg/g of the segmental membrane when cyclodextrins (α, β-CD) were used. Furthermore, the results showed that cyclodextrin-assisted extraction had a significant impact in significantly increasing the yield of flavanones from grapefruit. In addition, the process was more efficient and less expensive, resulting in higher yields of flavanones with a lower concentration of ethanol and effort. This shows that cyclodextrin-assisted extraction is an excellent method for extracting valuable compounds from grapefruit.

Acidity constants of hydroxyl groups placed in several flavonoids: Two flavanones, two flavones and five flavonols

Acidity constants (pKa) of nine flavonoids have been spectrophotometrically determined and the obtained values carefully contrasted with those derived from various experimental approaches given in literature, as well as with the ones predicted by Percepta and SPARC programs. To obtain robust pKa values, titrations in both pH ways, from acid to base and vice-versa, have been performed. The well-known instability of most flavonoids in basic media originates some discrepancies between obtained pKa by both titration ways and also with those coming from different experimental approaches previously published. This study tries to overcome the mentioned lack of integrity of several flavonoids avoiding measurements at high pH values or designing titrations at higher speed, which are able to cover the whole pH range with a minimum damage of studied compound. Suitable spectrophotometric titrations in pure water and, for instance, in methanol/water mixtures have been carried out. Achieved results allow the pKa assignation to hydroxyl groups belonging to two flavanones (Hesperetin and Naringenin), two flavones (Apigenin and Crysin) and five flavonols (Fisetin, Galangin, Kaempherol, Morin and Quercetin).

Metabolomic characterization of the chemical compositions of Dracocephalum rupestre Hance

Maojian tea (MJT) is a traditional Chinese herbal tea beverage manufactured from the leaves of the Dracocephalum rupestre Hance plant. In this study, a nontargeted metabolomics approach combined with absolute quantifications was applied to comprehensively investigate the chemical compositions of MJT and to determine the effects of the processing methods on compounds. Flavones (apigenin and luteolin, 0.06–1.35 mg/g), flavanones (eriodictyol and naringenin, 0.1–2.3 mg/g), flavone 7-O-glycosides (0.15–5.98 mg/g), flavanone 7-O-glycosides (0.28–19.41 mg/g), and triterpenoids were presumed to be characteristic components of MJT. Applying imitative green and black tea processing methods to MJT led to increases in flavone/flavanone aglycones, lipids, and triterpenoids and decreases in flavone/flavanone glycosides, amino acids, organic acids, and most phenolic acids. This study offers novel insights into the chemical compositions and the influences of processing methods on MJT and will be utilized for the quality control of MJT.

Complexations of β-cyclodextrins with naringenin, naringin and catechin: thermodynamic parameters and regulation of mitochondrial functions in vitro

ABSTRACT Flavonoids are exogenous phytochemicals with high antioxidative potential. The present work provides the mechanism of the complexations of low water-soluble flavanone naringenin, its glycosylated form naringin, and water-soluble flavan-3-ol catechin with β-cyclodextrin (βCD) and hydroxypropyl-β-cyclodextrin (HPβCD). The flavonoids studied showed high affinity in the interactions with HPβCD (the association constants K and the stoichiometry N were equal to 8500 ± 950 М−1 and 0.85 ± 0.05, 9400 ± 1200 М−1 and 1.7 ± 0.10, 7550 ± 600 M−1 and 1.25 ± 0.05 in the case of naringenin, naringin and catechin, respectively). The formations of the complexes with β-cyclodextrins markedly increased the water solubility of naringenin and naringin. The flavonoid–HPβСD complexations were exothermic (ΔH ˂ 0) and spontaneous (ΔG ˂ 0). The naringenin and naringin complexations with HPβCD were entropy-driven, and the catechin complexation was enthalpy-driven. Flavonoid molecules dispersed in the HPβCD structure during complexations. The flavonoid–HPβCD associations demonstrated enthalpy–entropy compensation. Naringenin (5–50 μM) and, to a lesser extent, catechin inhibited the respiration of isolated rat liver mitochondria. Naringenin, naringin and catechin (5–25 μM) increased the rate of Ca2+-induced mitochondrial permeability transition. The complexations with HPβCD did not significantly influence the effects of the flavonoids on respiration and enhanced the effects on mitochondrial permeability transition.

Naringenin and Phytoestrogen 8-Prenylnaringenin Protect against Islet Dysfunction and Inhibit Apoptotic Signaling in Insulin-Deficient Diabetic Mice.

It has been shown that citrus flavanone naringenin and its prenyl derivative 8-prenylnaringenin (8-PN) possess various pharmacological activities in in vitro and in vivo models. Interestingly, it has been proposed that prenylation can enhance biological potentials, including the estrogen-like activities of flavonoids. The objective of this study was to investigate the anti-diabetic potential and molecular mechanism of 8-PN in streptozotocin (STZ)-induced insulin-deficient diabetic mice in comparison with naringenin reported to exhibit hypoglycemic effects. The oral administration of naringenin and 8-PN ameliorated impaired glucose homeostasis and islet dysfunction induced by STZ treatment. These protective effects were associated with the suppression of pancreatic β-cell apoptosis and inflammatory responses in mice. Moreover, both naringenin and 8-PN normalized STZ-induced insulin-signaling defects in skeletal muscles and apoptotic protein expression in the liver. Importantly, 8-PN increased the protein expression levels of estrogen receptor-α (ERα) in the pancreas and liver and of fibroblast growth factor 21 in the liver, suggesting that 8-PN could act as an ERα agonist in the regulation of glucose homeostasis. This study provides novel insights into the mechanisms underlying preventive effects of naringenin and 8-PN on the impairment of glucose homeostasis in insulin-deficient diabetic mice.

Phytochemical Characterization of Citrus-Based Products Supporting Their Antioxidant Effect and Sensory Quality.

The increasing attention on the impact of food on human and environmental health has led to a greater awareness about nutrition, food processing, and food waste. In this perspective, the present work deals with the investigation of the chemical non-volatile and volatile profiles of two Citrus-based products, produced through a conscious process, using Citrus peels as natural gelling agents. Moreover, the total polyphenol content (TPC) and the antioxidant properties were evaluated, as well as their sensorial properties. Chemical and antioxidant results were compared with those of Citrus fresh fruits (C. reticulata, C. sinensis, and C. limon). Concerning the non-volatile fingerprint, the two samples showed a very similar composition, characterized by flavanones (naringenin, hesperetin, and eriodyctiol O-glycosides), flavones (diosmetin and apigenin C-glucosides), and limonoids (limonin, nomilinic acid, and its glucoside). The amount of both flavonoids and limonoids was higher in the Lemon product than in the Mixed Citrus one, as well as the TPC and the antioxidant activity. The aroma composition of the two samples was characterized by monoterpene hydrocarbons as the main chemical class, mainly represented by limonene. The sensorial analysis, finally, evidenced a good quality of both the products. These results showed that the most representative components of Citrus fruits persist even after the transformation process, and the aroma and sensorial properties endow an added value to Citrus preparations.

OsSPLs Regulate Male Fertility in Response to Different Temperatures by Flavonoid Biosynthesis and Tapetum PCD in PTGMS Rice.

Photoperiod and thermo-sensitive genic male sterile (PTGMS) rice is an important resource for two line hybrid rice production. The SQUAMOSA–promoter binding, such as the (SPL) gene family, encode the plant specific transcription factors that regulate development and defense responses in plants. However, the reports about SPLs participating in male fertility regulation are limited. Here, we identified 19 OsSPL family members and investigated their involvement in the fertility regulation of the PTGMS rice lines, PA2364S and PA2864S, with different fertility transition temperatures. The results demonstrated that OsSPL2, OsSPL4, OsSPL16 and OsSPL17 affect male fertility in response to temperature changes through the MiR156-SPL module. WGCNA (weighted gene co-expression network analysis) revealed that CHI and APX1 were co-expressed with OsSPL17. Targeted metabolite and flavonoid biosynthetic gene expression analysis revealed that OsSPL17 regulates the expression of flavonoid biosynthesis genes CHI, and the up regulation of flavanones (eriodictvol and naringenin) and flavones (apigenin and luteolin) content contributed to plant fertility. Meanwhile, OsSPL17 negatively regulates APX1 to affect APX (ascorbate peroxidase) activity, thereby regulating ROS (reactive oxygen species) content in the tapetum, controlling the PCD (programmed cell death) process and regulating male fertility in rice. Overall, this report highlights the potential role of OsSPL for the regulation of male fertility in rice and provides a new insight for the further understanding of fertility molecular mechanisms in PTGMS rice.

INVESTIGATION OF SUPERCRITICAL CO2-EXTRACTS OF WILD LEDUM PALUSTRE L. (RHODODENDRON TO-MENTOSUM HARMAJA) AND IDENTIFICATION OF ITS METABOLITES BY TANDEM MASS SPECTROMETRY

The purpose of this research is to investigate and identify polyphenolic complexes and other biologically active compounds by tandem mass spectrometry, presented in the leaves and stems of Ledum palustre L. Carbon dioxide, compressed to a supercritical state, was used for the most environmentally friendly extraction of polyphenolic complexes and other biologically active compounds of Ledum palustre L. The most effective extraction characteristics (pressure 350 bar; temperature 60 °С; extraction time 1-hour, co-solvent MeOH 3.5%) supercritical CO2-extraction of L. palustre were obtained empirically. To identify target analytes in supercritical extracts, High Performance Liquid Chromatography (HPLC) was used in combination with a BRUKER DALTONIKS ion trap. The results showed the presence of 61 biologically active compounds corresponding to the rhododendron species, of which 32 were identified for the first time in L. palustre. These are flavanols dihydrokaempferol, quercetin arabinoside, myricetin galactoside; flavones: diosmetin, nevadensin, cirsimaritin; flavanone naringenin; anthocyanins delphinidin, petunidin, cyanidin pentoside, delphinidin pentoside, peonidin 3-(6-O-acetyl) glucoside, peonidin-3-O-malonylglucoside, cyanidin-3-rutinoside, peonidin 3-O-glucoside; ellagic acid; lignan medioresinol; a type A procyanidin dimer; sterols fucosterol and avenasterol, etc.

Insights into the biosynthesis pathway of phenolic compounds in microalgae

Among the most relevant bioactive molecules family, phenolic compounds (PCs) are well known in higher plants, while their knowledge in microalgae is still scarce. Microalgae represent a novel and promising source of human health benefit compounds to be involved, for instance, in nutraceutical composition. This study aims to investigate the PCs biosynthetic pathway in the microalgal realm, exploring its potential variability over the microalgal biodiversity axis. A multistep in silico analysis was carried out using a selection of core enzymes from the pathway described in land plants. This study explores their presence in ten groups of prokaryotic and eukaryotic microalgae.. Analyses were carried out taking into account a wide selection of algal protein homologs, functional annotation of conserved domains and motifs, and maximum-likelihood tree construction. Results showed that a conserved core of the pathway for PCs biosynthesis is shared horizontally in all microalgae. Conversely, the ability to synthesize some subclasses of phenolics may be restricted to only some microalgal groups (i.e., Chlorophyta) depending on featured enzymes, such as the flavanone naringenin and other related chalcone isomerase dependent compounds.