Polyphenolic Metabolites Research Articles

Urolithin B protects mice from diet-induced obesity, insulin resistance, and intestinal inflammation by regulating gut microbiota composition.

The increasing prevalence of obesity and type 2 diabetes (T2D) signifies the failure of conventional treatments for these diseases. The gut microbiota has been proposed as a key player in the pathophysiology of diet-induced T2D. Urolithin B (Uro B), a gut microbiota-derived polyphenol metabolite, exerts several beneficial health effects. In this study, we investigated the metabolic effects of Uro B on high-fat/high-sucrose (HFHS)-fed mice and determined whether its antidiabetic effects are related to the modulation of the gut microbiota. C57BL/6J mice were fed either a chow or HFHS diet. HFHS-fed mice were administered daily with either a vehicle (water) or different doses of Uro B (100 or 200 mg kg-1) for eight weeks. The composition of the gut microbiota was assessed by 16S rRNA sequencing. The results showed that Uro B treatment reduced HFHS-induced weight gain and visceral obesity and decreased liver weight and triglyceride accumulation associated with blunted hepatic oxidative stress and inflammation. Furthermore, Uro B administration improved insulin sensitivity as revealed by improved insulin tolerance, a lower homeostasis model assessment of insulin resistance, and decreased glucose-induced hyperinsulinemia during the oral glucose tolerance test. Uro B treatment was found to lower the intestinal triglyceride content and alleviate intestinal inflammation and oxidative stress. Remarkably, Uro B treatment markedly increased the proportion of the mucin-degrading bacterium Akkermansia in metagenomic samples. In conclusion, Uro B exerts beneficial metabolic effects by alleviating HFHS diet-induced features of metabolic syndrome, which is associated with a proportional increase in the population of Akkermansia spp.

Comparative metabolomics analysis of unique yellow hawthorn (Crataegus pinnatifida) and red-skinned cultivars reveals a different polyphenol biosynthesis flux and antioxidative and antidiabetic potential

Abstract Objectives This paper aims to investigate the polyphenol metabolite variation and bioactivities of different-colored hawthorn berries (Crataegus pinnatifida). Materials and Methods Comparative metabolomics analysis between peel and flesh of yellow hawthorn 'Jinruyi' (JRY) and red-skinned ones was carried out by UPLC-MS/MS. Antioxidant activities and α-glucosidase inhibition capacity were also tested among different colored hawthorn samples. Results A total of 453 polyphenols was characterized, among which phenolic acids and flavonoids were abundant, and were closely relevant to the antioxidant capacity of hawthorn fruits. Polyphenol profile showed accession-specific accumulation in peel or flesh of different colored hawthorn. The unique yellow hawthorn was found to have few anthocyanins but showed enhanced flux to synthesize flavones and flavonols, especially flavone C-glycosides and acylated flavonol glycosides. The specific acylation decoration included acetylation, p-coumaroylation, and malonylation. In addition, yellow hawthorn showed excellent α-glucosidase inhibitory effect, which might be associated with the high concentration of 8 polyphenols including 5 phenolic acids, 2 flavone C-glycosides, and an acylated flavonol glycoside, namely, quercetin-7-O-(6ʹʹ-malonyl)glucoside. Such acylated flavonol showed the strongest correlation with the inhibition effect of hawthorn fruits on α-glucosidase, and was predicted to have the lowest binding energy with the enzyme according to molecular docking analysis, indicating its great potential as a strong α-glucosidase inhibitor and an important antidiabetic ingredient in yellow hawthorn. Conclusions The acylated flavonol glycosides and C-glycosyl flavones might be chemotaxonomic markers differentiating varieties and bioactivities of yellow hawthorn from the traditional red-skinned ones. These findings complement the existing knowledge on the metabolite composition and nutritional properties of hawthorn fruits.

Exploring polyphenols extraction from Thuja occidentalis L. bark: Optimization, phytochemical profiling, and biological evaluation

Polyphenols were extracted from Thuja occidentalis L. bark and characterized in terms of phytochemical composition and biological activity. The optimization process investigated the impacts of extraction duration, ultrasound amplitude, and ethanol concentration on the total phenolic content in the extract. The antioxidant capacity was examined using DPPH and ABTS assays, and anti-enzyme activity against alpha-glucosidase, alpha-amylase, lipase, acetylcholinesterase, and tyrosinase was determined. The experimental model revealed optimal extraction parameters: a hydroethanolic solvent with 44% v:v ethanol, a 15-minute extraction time, and a 40% ultrasound amplitude. These parameters were validated and confirmed by reaching the target Total Phenolic Content (TPC) predicted by MODDE software. The resulting lyophilized extract exhibited a high polyphenolic content (161.84 ± 23.48 mg GAE/g dry extract) and demonstrated strong antioxidant properties. Notably, it showed significant inhibition of alpha-glucosidase and alpha-amylase, suggesting potential antidiabetic effects, though its inhibition of tyrosinase activity was relatively weak. These findings provide a foundation for further investigations to confirm the qualitative and quantitative presence of specific polyphenolic metabolites in the extract and elucidate the mechanisms underlying its bioactive properties.

Mechanisms of action of tea polyphenols in the modulation of obesity through gut microbiota

Obesity has become an increasingly serious global issue in recent years, leading to a myriad of health concerns for a growing population. Consequently, the quest for rational and safe methods to combat excess body fat has emerged as a mainstream demand among consumers. This paper focuses on tea polyphenols as the primary subject of investigation, employing gut microbiota as a mediator to explore and summarize existing research regarding the anti-obesity effects of tea polyphenols. Current reports suggest that the mechanisms by which tea polyphenols exhibit anti-obesity effects primarily encompass two aspects. Firstly, tea polyphenols can regulate the composition of the gut microbiota, primarily targeting the Firmicutes and Bacteroidetes phyla. This regulation occurs both in their digested state and undigested form, with a greater emphasis on their undigested state. Tea polyphenols primarily function by reducing the abundance of Firmicutes while increasing that of Bacteroidetes, thereby enhancing gut microbiota diversity to exert anti-obesity effects. Secondly, the metabolites of tea polyphenols also play a role in modulating gut microbiota, with phenolic acid compounds being the key metabolites responsible for anti-obesity effects. Compared to the parent tea polyphenols, phenolic acid compounds exhibit higher bioavailability and biological activity.

Targeted metabolomic and transcriptomic reveal the regulation of UV–C on phenolics biosynthesis of peach fruit during storage

Phenolic compounds are important secondary metabolites in peach fruit and play positive roles in plant resilience and human diets. To investigate the regulation of Ultraviolet-C (UV–C) irradiation on phenolics biosynthesis of peach fruit, the targeted metabolomic and transcriptomic were used to analyze polyphenolic metabolites and their gene expression patterns. The metabolomic results showed that a total of 45 phenolics were identified in the peach pulp. Total phenolic content was significantly increased by UV–C irradiation and 35 individual phenolics responded observably to UV–C treatment. In particular, UV–C irradiation dramatically increased the content of 2,6-dihydroxybenzoic acid, luteolin, quercitrin, astragalin, narcissin, nicotiflorin, sorhamnetin-3-O-glucoside and hesperidin. The HCT1, CYP98A1/3, COMT1 and CHS2/3 genes in phenylpropanoid metabolic pathway and the CHI1/3, F3′H1/3, P2′GT1/2/3/4, UFGT3 and DFR2/3 genes in flavonoid metabolic pathway were significantly regulated by UV–C irradiation. Overall, the present study revealed that phenolics biosynthesis is regulated by UV–C irradiation at the level of metabolites and molecule supported by targeted metabolomic and transcriptomic results.

ANDALIMAN QUERCETIN (ZANTHOXYLUM ACANTHOPODIUM DC.) USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC) METHOD AND ITS ANTIFUNGAL ACTIVITY AGAINST PITYROSPORUM OVALE

People today complain with dandruff accompanied by itching will cause a lack of confidence because of the unpleasant smell and reduce the beauty of the hair. Andaliman is a plant that grows a lot in the Toba Samosir area which is usually used as a spice for cooking. Examination of secondary metabolite compounds contained in these natural materials is the main thing that is important to do. In other studies, andaliman has been studied to provide antimicrobial, antioxidant, and anti-inflammatory effects.
 The test method is carried out using the High Performance Liquid Chromatography (HPLC) Method and the minimum inhibitory concentration test using the diffusion method in order to use paper backups with several variations in test concentration.
 This is related to the content of secondary metabolites such as flavonoids, terpene alkaloids, benzophenthridine alkaloids, pyranoquinoline alkaloids, quaternary isoquinoline alkaloids, aporphyrine alkaloids, essential oils and several types of lignin. Flavonoids are secondary metabolites of polyphenols found in many plants and have a variety of biological effects including antiviral, anti-inflammatory, and antioxidant. Quercetin to derivative active compounds
 The test results of the minimum inhibitory concentration of the extract showed an average inhibitory power of 17.26 mm at a concentration of 80% and EEAD quercetin levels with a concentration of 6.25; 12,5; 25; 50; and 100 ?g/ml contains quercetin percentages of 143.5, 242.15, 395.12, 865.2, and 1134.12 ?g/ml.

Flavonoids from <i>Impatiens grandulifera</i> and Their Antioxidant Activity

Introduction. The genus Impatiens L. includes about 850 species, which are found mainly in tropical and subtropical climate zones. The Indigenous people of Pakistan used pastes and extracts from I. glandulifera for the treatment of joint pain, anxiety and skin allergies [6]. Flowers of I. glandulifera are used in Bach flower remedies, which are used for sedation, relaxation and helping to balance emotional states.Aim. Isolation and structural elucidation of 11 phenolic constituents from the aerial parts of I. glandulifera and the evaluation of their antioxidant activity.Materials and methods. The aerial part of Impatiens glandulifera Royle was collected in the Leningrad region near the village of Orekhovo in 2021. Fractions were analyzed by analytical high performance liquid chromatography (HPLC) using a Prominence LC-20 (Shimadzu, Japan) equipped with a diode array detector. The isolation of individual compounds was carried out by column chromatography on open glass columns with sorbents of different selectivity, as well as by preparative HPLC using a Smartlina (Knauer, Germany) equipped with a spectrophotometric detector. The structure of isolated individual compounds was established by 1D and 2D NMR spectroscopy (Bruker Avance III 400 MHz, Germany). To study the antioxidant activity, we used solutions obtained by dissolving the isolated substances in a mixture of dimethyl sulfoxide and ethanol; an aqueous solution of vitamin C and an alcoholic solution of Trolox (Sigma-Aldrich, Japan).Result and discussion. Phytochemical analysis of the aerial parts of Impatiens glandulifera Royle. resulted in the isolation of 11 polyphenolic secondary metabolites (1-11) and their structures were elucidated. The antioxidant activity of all isolated compounds was evaluated.Conclusion. The maximum RAP values of eriodyctiol (3), kaempferol (1), and quercetin (2) did not differ significantly (p = 0.585) from those of the comparator preparations: vitamin C and Trolox, which indicates that the antioxidant effect of these three isolated compounds is comparable to the well-known antioxidants. However, the semi-effective concentrations of these substances are two or more times lower (p = 2.56 · 10–4) comparted with vitamin C.

Polyphenol and glucosinolate-derived AhR modulators regulate GPR15 expression on human CD4+ T cells

Diets high in fruit and vegetables are perceived to be beneficial for intestinal homeostasis, in health as well as in the context of inflammatory bowel diseases (IBDs). Recent breakthroughs in the field of immunology have highlighted the importance of the ligand-activated transcription factor aryl hydrocarbon receptor (AhR) as a critical regulator of mucosal immunity, including the intestinal trafficking of CD4+ helper T cells, an immune cell subset implicated in a wide range of homeostatic and pathogenic processes. Specifically, the AhR has been shown to directly regulate the expression of the chemoattractant receptor G Protein-Coupled Receptor 15 (GPR15) on CD4+ T cells. GPR15 is an important gut homing marker whose expression on CD4+ T cells in the peripheral circulation is elevated in patients suffering from ulcerative colitis, raising the possibility that, in this setting, the beneficial effect of a diet rich in fruits and vegetables may be mediated through the modulation of GPR15 expression. To address this, we screened physiologically-relevant polyphenol and glucosinolate metabolites for their ability to affect both AhR activity and GPR15 expression. Our complementary approach and associated findings suggest that polyphenol and glucosinolate metabolites can regulate GPR15 expression on human CD4+ T cells in an AhR-dependent manner.

Targeted metabolic reveals different part of maize in polyphenolic metabolites during germination and hypoglycemic activity analysis.

In this study, qualitative and quantitative analyses of phenolic compounds in the maize germinating seed embryo, radicle, and germ were performed at 0, 48, and 96h post-germination, followed by the evaluation of their hypoglycemic activity. The results revealed the accumulation of 80 phenolics in different parts of germinated maize, of which 47, 48, and 53 were present in the seed embryo, radicle, and germ. After germination 22, 26, and 34 polyphenols were found to differential accumulate in the seed embryo, radicle, and germ. At 96h post-germination, the content of monomeric phenols in the germ was higher than that in the radicle and seed embryo. Moreover, the inhibitory activity of polyphenols in the germ towards α-glucosidase and α-amylase was higher than that in the radicle and seed embryo. These results indicate that germination can effectively improve the type and content of phenolic compounds in different parts of maize.

Microbial Diversity and Characteristic Quality Formation of Qingzhuan Tea as Revealed by Metagenomic and Metabolomic Analysis during Pile Fermentation.

In order to analyze the changes in the microbial community structure during the pile fermentation of Qingzhuan tea and their correlation with the formation of quality compounds in Qingzhuan tea, this study carried out metagenomic and metabolomic analyses of tea samples during the fermentation process of Qingzhuan tea. The changes in the expression and abundance of microorganisms during the pile fermentation were investigated through metagenomic assays. During the processing of Qingzhuan tea, there is a transition from a bacterial dominated ecosystem to an ecosystem enriched with fungi. The correlation analyses of metagenomics and metabolomics showed that amino acids and polyphenol metabolites with relatively simple structures exhibited a significant negative correlation with target microorganisms, while the structurally complicated B-ring dihydroxy puerin, B-ring trihydroxy galloyl puerlin, and other compounds showed a significant positive correlation with target microorganisms. Aspergillus niger, Aspergillus glaucus, Penicillium in the Aspergillaceae family, and Talaromyces and Rasamsonia emersonii in Trichocomaceae were the key microorganisms involved in the formation of the characteristic qualities of Qingzhuan tea.

Cryopreservation of bioflavonoid-rich plant sources and bioflavonoid-microcapsules: emerging technologies for preserving bioactivity and enhancing nutraceutical applications.

Bioflavonoids are natural polyphenolic secondary metabolites that are medicinal. These compounds possess antitumor, cardioprotective, anti-inflammatory, antimicrobial, antiviral, and anti-psoriasis properties to mention a few. Plant species that contain bioflavonoids should be preserved as such. Also, the bioactivity of the bioflavonoids as neutraceutical compounds is compromised following extraction due to their sensitivity to environmental factors like light, pH, and temperature. In other words, the bioflavonoids' shelf-life is affected. Scientists noticed that bioflavonoids have low solubility properties, poor absorption, and low bioavailability following consumption. Researchers came up with methods to encapsulate bioflavonoids in order to circumvent the challenges above and also to mask the unpleasant order these chemicals may have. Besides, scientists cryopreserve plant species that contain bioflavonoids. In this review, we discuss cryopreservation and bioflavonoid microencapsulation focusing mainly on vitrification, slow freezing, and freeze-drying microencapsulation techniques. In addition, we highlight bioflavonoid extraction techniques, medicinal properties, challenges, and future perspectives of cryopreservation and microencapsulation of bioflavonoids. Regardless of the uniqueness of cryopreservation and microencapsulation as methods to preserve bioflavonoid sources and bioflavonoids' bioactivity, there are challenges reported. Freeze-drying technology is costly. Cryoprotectants damage the integrity of plant cells, to say the least. Researchers are working very hard to overcome these challenges. Encapsulating bioflavonoids via coaxial electrospray and then cryopreserving the micro/nanocapsules produced can be very interesting.

Optimization of gallic acid-enriched ultrasonic-assisted extraction from mango peels

Abstract Gallic acid is recognized as a notable bioactive compound among secondary polyphenolic metabolites. In the current study, gallic acid-enriched extracts were obtained from mango peels using different solvents (ethanol or water) via ultrasound-assisted extraction, and optimized yields were compared with the conventional extraction technique (decoction). Independent variables for the optimization through response surface methodology were ethanol concentration (0–60%), solvent ratio (10–50 mL/g), temperature (30–60℃), and time (10–30 min) for ethanolic extraction. However, extraction carried out by using water had extraction conditions of pH (2–8), solvent ratio (20–0 mL/g), extraction temperature (40–70℃), and time (30–60 min). The optimized yield of gallic acid obtained through ethanol was 5.75 ± 0.21 mg/g, whereas 3.14 ± 0.24 mg/g of gallic acid was quantified in extraction through water. The results were compared with the aforementioned conventional method of decoction, and it was concluded that the ethanolic extracts of mango peels showed the highest gallic acid yield and total flavonoid contents. The obtained extracts could be a potential source of polyphenolics, especially gallic acid, for use in nutraceuticals as well as in other food applications.

Gut microbial metabolites of dietary polyphenols and their potential role in human health and diseases.

Polyphenols contribute as one of the largest groups of compounds among all the phytochemicals. Common sources of dietary polyphenols are vegetables, fruits, berries, cereals, whole grains, etc. Owing to their original form, they are difficult to get absorbed. Dietary polyphenols after undergoing gut microbial metabolism form bioaccessible and effective metabolites. Polyphenols and derived metabolites are all together a diversified group of compounds exhibiting pharmacological activities against cardiovascular, cancer, oxidative stress, inflammatory, and bacterial diseases. The formed metabolites are sometimes even more bioavailable and efficacious than the parent polyphenols. Studies on gut microbial metabolism of dietary polyphenols have introduced new approach for the use of polyphenol-rich food in the form of supplementary diet. This review provides insights on various aspects including classification of polyphenols, gut microbiota-mediated metabolism of polyphenols, chemistry of polyphenol metabolism, and pharmacological actions of gut microbial metabolites of polyphenols. It also suggests the use of polyphenols from marine source for the microbial metabolism studies. Till date, gut microbial metabolism of polyphenols from terrestrial sources is extensively studied as compared to marine polyphenols. Marine ecosystem is a profound but partially explored source of phytoconstituents. Among them, edible seaweeds contain high concentration of polyphenols, especially phlorotannins. Hence, microbial metabolism studies of seaweeds can unravel the pharmacological potential of marine polyphenol-derived metabolites.

Analytical and Preparative Separation of Softwood Lignans by Supercritical Fluid Chromatography

Lignans are widespread polyphenolic secondary plant metabolites possessing high biological activity. One of the most promising industrial-scale sources of such compounds is coniferous knotwood, containing a large number of polyphenolic compounds. Their use in pharmaceutical and other industries is limited by the difficulty in obtaining high-purity preparations from plant material and the requirement of advanced separation techniques. In this study, supercritical fluid chromatography on polar stationary phases was proposed for the efficient separation and identification of spruce, pine, fir, and larch knotwood extractives. Among the six tested sorbents, the best results were shown by silica with grafted diol and 2-ethylpyridine groups under conditions of gradient elution with a carbon dioxide–methanol mobile phase, which ensured the efficient retention and separation of analytes due to donor–acceptor interactions. Scaling up the method on a DIOL stationary phase provided a semi-preparative separation of extractives within 30 min to obtain 14 individual compounds with a purity of 90–99% and yields from 0.3 to 51% of the dry extract. These included eight lignans (nortrachelogenin, matairesinol, oxomatairesinol, α-conidendrin, 5-hydroxymatairesinol and its isomer, lariciresinol, and secoisolariciresinol), two oligolignans, three stilbenes (pinosylvin and its methyl ester, pterostilbene), and flavonoid taxifolin. The developed approach is distinguished with low operational costs, low consumption of organic solvents, environmental safety, and it is fully consistent with the principles of green chemistry.

Quantitative trait loci mapping of polyphenol metabolites from a 'Latham' x 'Glen Moy' red raspberry (Rubus idaeus L) cross.

The objective of this study was to investigate the genetic control of polyphenol accumulation in red raspberry (Rubus idaeus L). The levels of total anthocyanins and 37 individual polyphenol metabolites were measured over three years in a raspberry biparental mapping population. Quantitative trait loci (QTLs) for these traits were mapped onto a high-density SNP linkage map. At least one QTL was detected for each trait, with good consistency among the years. On four linkage groups (LG), there were major QTLs affecting several metabolites. On LG1, a QTL had large effects on anthocyanins and flavonols containing a rutinoside or rhamnose group. On LG4, a QTL had large effects on several flavonols and on LG5 and LG6 QTLs had large effects on ellagic acid derivatives. Smaller QTLs were found on LG2 and LG3. The identification of robust QTLs for key polyphenols in raspberry provides great potential for marker-assisted breeding for improved levels of potentially health beneficial components.

A dietary polyphenol metabolite alters CA1 excitability ex vivo and mildly affects cortico-hippocampal field potential generators in anesthetized animals.

Dietary polyphenols have beneficial effects in situations of impaired cognition in acute models of neurodegeneration. The possibility that they may have a direct effect on the electrical activity of neuronal populations has not been tested. We explored the electrophysiological action of protocatechuic acid (PCA) on CA1 pyramidal cells ex vivo and network activity in anesthetized female rats using pathway-specific field potential (FP) generators obtained from laminar FPs in cortex and hippocampus. Whole-cell recordings from CA1 pyramidal cells revealed increased synaptic potentials, particularly in response to basal dendritic excitation, while the associated evoked firing was significantly reduced. This counterintuitive result was attributed to a marked increase of the rheobase and voltage threshold, indicating a decreased ability to generate spikes in response to depolarizing current. Systemic administration of PCA only slightly altered the ongoing activity of some FP generators, although it produced a striking disengagement of infraslow activities between the cortex and hippocampus on a scale of minutes. To our knowledge, this is the first report showing the direct action of a dietary polyphenol on electrical activity, performing neuromodulatory roles at both the cellular and network levels.

Dietary polyphenols drive dose-dependent behavioral and molecular alterations to repeated morphine

Opioid Use Disorder (OUD) is associated with tremendous morbidity and mortality. Despite this burden, current pharmacotherapies for OUD are ineffective or intolerable for many patients. As such, interventions aimed at promoting resilience against OUD are of immense clinical interest. Treatment with a Bioactive Dietary Polyphenol Preparation (BDPP) promotes resilience and adaptive neuroplasticity in multiple models of neuropsychiatric disease. Here, we assessed effects of BDPP treatment on behavioral and molecular responses to repeated morphine treatment in male mice. BDPP pre-treatment alters responses for both locomotor sensitization and conditioned place preference. Most notably, polyphenol treatment consistently reduced formation of preference at low dose (5 mg/kg) morphine but enhanced it at high dose (15 mg/kg). In parallel, we performed transcriptomic profiling of the nucleus accumbens, which again showed a dose × polyphenol interaction. We also profiled microbiome composition and function, as polyphenols are metabolized by the microbiome and can act as prebiotics. The profile revealed polyphenol treatment markedly altered microbiome composition and function. Finally, we investigated involvement of the SIRT1 deacetylase, and the role of polyphenol metabolites in behavioral responses. These results demonstrate polyphenols have robust dose-dependent effects on behavioral and physiological responses to morphine and lay the foundation for future translational work.

UHPLC-HRMS Spectrometric Analysis: Method Validation and Plasma and Urinary Metabolite Identification after Mango Pulp Intake.

After an acute intake of 300 g of mango purée by 10 subjects, 0 and 24 h urine and plasma samples were analyzed by high-performance liquid chromatography-high-resolution mass spectrometry. The method was first validated for 44 reference polyphenols in terms of linearity, specificity, limits of detection and quantification, intra-day and inter-day precision, recovery, and matrix effects in two biological matrices. After method validation, a total of 94 microbial-derived phenolic catabolites, including 15 cinnamic acids, 3 phenylhydracrylic acids, 14 phenylpropanoic acids, 12 phenylacetic acids, 28 benzoic acids, 2 mandelic acids, 15 hydroxybenzenes, and 5 hippuric acid derivatives, were identified or tentatively identified in urine and/or plasma. These results establish the value of the UHPLC-HRMS protocol and the use of authentic standards to obtain a detailed and accurate picture of mango polyphenol metabolites, together with their phase II conjugated metabolites, in human bioavailability studies.

Microbial phenolic metabolites 3-(3′,4′-dihydroxyphenyl)propanoic acid and 3′,4′-dihydroxyphenylacetic acid prevent obesity in mice fed with high-fat diet

Obesity is associated with numerous metabolic disorders, and dietary polyphenols have been confirmed to have beneficial effects on the metabolism in obesity. However, the effect of 3-(3′,4′-dihydroxyphenyl)propanoic acid (DHPA) and 3′,4′-dihydroxyphenylacetic acid (DHAA), two main metabolites of dietary polyphenols, on obesity remains poorly understood. In this study, DHPA and DHAA were found to alleviate obesity, as well as regulate insulin resistance, lipid metabolism, and oxidative stress response in high-fat diet (HFD) mice. Surprisingly, the 16S rRNA sequencing and UHPLC-Q-TOF/MS demonstrated that DHPA and DHAA only slightly disturbed the intestinal microbiome, but significantly altered the urine metabolome of HFD mice mainly by regulating pentose and glucuronate interconversion, tyrosine metabolism, pentose phosphate and tricarboxylic acid (TCA) cycle as indicated by metabolic pathway analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Correlation analysis revealed that the differential metabolites are strongly associated with body weight, blood glucose, insulin level, and superoxide dismutase (SOD) enzyme activity. Our results revealed that DHPA and DHAA exert their anti-obesity effect by regulating important metabolites in the glucose, lipid and tyrosine metabolism pathways.

Optimization of Gallic Acid-Rich Extract from Mango (Mangifera indica) Seed Kernels through Ultrasound-Assisted Extraction

Different types of agro-waste provide potential substrates for the extraction of bioactive compounds. Mango waste (e.g., peels and seeds) is one such example and may serve as a source of gallic acid, a well-known bioactive compound classified as a secondary polyphenolic metabolite. Here, we explored the efficacy of ultrasound-assisted extraction (UAE) in extracting gallic acid from mango seed kernels using different solvent concentrations (0–60%), solvent-to-sample ratios (10–50 mL/g), temperatures (30–60 °C), and times (10–30 min). The maximum yield of gallic acid (6.1 ± 0.09 mg/g) was obtained when using a 19.4% solvent concentration, a 29.32 mL/g solvent-to-sample ratio, and the extraction was conducted at 38.47 °C for 21.4 min, similar to the values predicted by the model equation. As compared to the conventional extraction procedure, the extract obtained by the optimized method was found to be significantly different in total phenolic content, total flavonoid content, and radical scavenging activity. Non-significant differences were observed in antimicrobial activity. The results indicate that mango seed kernels may be a good source of phenolics, and those phenolics can be effectively obtained through an optimized UAE method. Hence, mango seed kernels may be utilized as a suitable source of extracting phenolics in nutraceutical and food applications.