Advances in extraction and purification of citrus flavonoids

Health-Promoting Potential of Mandarin Pomace Extracts Enriched with Phenolic Compounds

The aim of this work was to assess the effect of in vitro human digestion on the chemical composition (carbohydrates and phenolic compounds) and bioactivity of hydro-alcoholic-acid pomace extracts from two mandarin varieties (Clemenule and Ortanique) by measuring their antioxidant, antidiabetic, anti-glycative, hypolipidemic, and anti-inflammatory properties. The phenolic compound profile showed that nobiletin was the main flavonoid found in the extracts and digests of Clemenule pomace and extract, while isosinensetin/sinensetin/tangeretin were the ones in the Ortanique samples. The digests of Clemenule and Ortanique extracts showed Folin reaction values of 9.74 and 9.20 mg gallic acid equivalents (GAE)/g of sample, ABTS values of 83.2 and 91.7 µmol Trolox equivalents (TE)/g of sample, and ORAC-FL values of 142.8 and 891.6 µmol TE/g of sample, respectively. Extracts (50-500 µg/mL) inhibited intracellular reactive oxygen species (ROS) formation in CCD-18Co cells under physiological and oxidative-induced conditions. Clemenule and Ortanique extract digests showed IC50 values of 13.50 and 11.07 mg/mL for α-glucosidase, 28.79 and 69.64 mg/mL for α-amylase, and 16.50 and 12.77 mg/mL for AGEs, and 2.259 ± 0.267 and 0.713 ± 0.065 mg/mL for pancreatic lipase inhibition, respectively. Ortanique extract (250-1000 µg/mL) inhibited the production of nitric oxide in RAW264.7 macrophages under inflammation-induced conditions, and intracellular ROS formation. In conclusion, altogether, the results supported the potential of mandarin extracts to be used as health promoters by reducing the risk of non-communicable chronic diseases.

Optimized Synthesis and Antioxidant Activity of Anthocyanins Delphinidin-3-O-glucoside and Petunidin-3-O-glucoside

The chemical synthesis of anthocyanins, especially delphinidin-3-O-glucoside and petunidin-3-O-glucoside, is preferable due to the challenges associated with their extraction and purification. However, the reported methods for the synthesis are scarce and intricate. Our research focused on exploring a one-step ester-to-ketone process and optimizing the ring formation reaction, simplifying and improving the overall synthesis strategy. Through these attempts, we were able to achieve higher production yields of delphinidin-3-O-glucoside and petunidin-3-O-glucoside. According to the results of DPPH, ABTS, and FRAP, the antioxidant activity of anthocyanins was increased with the number of B ring hydroxyl substituent. Additionally, both delphinidin-3-O-glucoside and petunidin-3-O-glucoside exhibited no cytotoxicity effects, highlighting their potential for safe application in various fields.

Microbial synthesis of anthocyanins and pyranoanthocyanins: current bottlenecks and potential solutions

Anthocyanins (ACNs) are secondary metabolites found in plants. Due to their impressive biological activities, ACNs have gained significant popularity and extensive application within the food, pharmaceutical, and nutraceutical industries. A derivative of ACNs: pyranoanthocyanins (PACNs) possesses more stable properties and interesting biological activities. However, conventional methods for the production of ACNs, including chemical synthesis and plant extraction, involve organic solvents. Microbial synthesis of ACNs from renewable biomass, such as amino acids or flavonoids, is considered a sustainable and environmentally friendly method for large-scale production of ACNs. Recently, the construction of microbial cell factories (MCFs) for the efficient biosynthesis of ACNs and PACNs has attracted much attention. In this review, we summarize the cases of microbial synthesis of ACNs, and analyze the bottlenecks in reconstructing the metabolic pathways for synthesizing PACNs in microorganisms. Consequently, there is an urgent need to investigate the mechanisms behind the development of MCFs for PACNs synthesis. Such research also holds significant promise for advancing the production of food pigments. Meanwhile, we propose potential solutions to the bottleneck problem based on metabolic engineering and enzyme engineering. Finally, the development prospects of natural food and biotechnology are discussed.

Integrated Metabolomic-Transcriptomic Analyses of Flavonoid Accumulation in Citrus Fruit under Exogenous Melatonin Treatment

The flavonoids in citrus fruits are crucial physiological regulators and natural bioactive products of high pharmaceutical value. Melatonin is a pleiotropic hormone that can regulate plant morphogenesis and stress resistance and alter the accumulation of flavonoids in these processes. However, the direct effect of melatonin on citrus flavonoids remains unclear. In this study, nontargeted metabolomics and transcriptomics were utilized to reveal how exogenous melatonin affects flavonoid biosynthesis in "Bingtangcheng" citrus fruits. The melatonin treatment at 0.1 mmol L-1 significantly increased the contents of seven polymethoxylated flavones (PMFs) and up-regulated a series of flavonoid pathway genes, including 4CL (4-coumaroyl CoA ligase), FNS (flavone synthase), and FHs (flavonoid hydroxylases). Meanwhile, CHS (chalcone synthase) was down-regulated, causing a decrease in the content of most flavonoid glycosides. Pearson correlation analysis obtained 21 transcription factors co-expressed with differentially accumulated flavonoids, among which the AP2/EREBP members were the most numerous. Additionally, circadian rhythm and photosynthesis pathways were enriched in the DEG (differentially expressed gene) analysis, suggesting that melatonin might also mediate changes in the flavonoid biosynthesis pathway by affecting the fruit's circadian rhythm. These results provide valuable information for further exploration of the molecular mechanisms through which melatonin regulates citrus fruit metabolism.

Asiaticoside exerts neuroprotection through targeting NLRP3 inflammasome activation

BACKGROUND

Parkinson's disease (PD), a neurodegenerative disorder, is characterized by motor symptoms due to the progressive loss of dopaminergic neurons in the substantia nigra (SN) and striatum (STR), alongside neuroinflammation. Asiaticoside (AS), a primary active component with anti-inflammatory and neuroprotective properties, is derived from Centella asiatica. However, the precise mechanisms through which AS influences PD associated with inflammation are not yet fully understood.

PURPOSE

This study aimed to explore the protective mechanism of AS in PD.

METHODS

Targets associated with AS and PD were identified from the Swiss Target Prediction, Similarity Ensemble Approach, PharmMapper, and GeneCards database. A protein-protein interaction (PPI) network was constructed to identify potential therapeutic targets. Concurrently, GO and KEGG analyses were performed to predict potential signaling pathways. To validate these mechanisms, the effects of AS on 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD in mice were investigated. Furthermore, neuroinflammation and the activation of the NLRP3 inflammasome were assessed to confirm the anti-inflammatory properties of AS. In vitro experiments in BV2 cells were then performed to investigate the mechanisms of AS in PD. Moreover, CETSA, molecular docking, and molecular dynamics simulations (MDs) were performed for further validation.

RESULTS

Network pharmacology analysis identified 17 potential targets affected by AS in PD. GO and KEGG analyses suggested the biological roles of these targets, demonstrating that AS interacts with 149 pathways in PD. Notably, the NOD-like receptor signaling pathway was identified as a key pathway mediating AS's effect on PD. In vivo studies demonstrated that AS alleviated motor dysfunction and reduced the loss of dopaminergic neurons in MPTP-induced PD mice. In vitro experiments demonstrated that AS substantially decreased IL-1β release in BV2 cells, attributing this to the modulation of the NLRP3 signaling pathway. CETSA and molecular docking studies indicated that AS forms a stable complex with NLRP3. MDs suggested that ARG578 played an important role in the formation of the complex.

CONCLUSION

In this study, we first predicted that the potential target and pathway of AS's effect on PD could be NLRP3 protein and NOD-like receptor signaling pathway by network pharmacology analysis. Further, we demonstrated that AS could alleviate symptoms of PD induced by MPTP through its interaction with the NLRP3 protein for the first time by in vivo and in vitro experiments. By binding to NLRP3, AS effectively inhibits the assembly and activation of the inflammasome. These findings suggest that AS is a promising inhibitor for PD driven by NLRP3 overactivation.

Sustainable control of Microcystis aeruginosa, a harmful cyanobacterium, using Selaginella tamariscina extracts

Eco-friendly reagents derived from plants represent a promising strategy to mitigate the occurrence of toxic cyanobacterial blooms. The use of an amentoflavone-containing Selaginella tamariscina extract (STE) markedly decreased the number of Microcystis aeruginosa cells, thus demonstrating significant anti-cyanobacterial activity. In particular, the Microcystis-killing fraction obtained from pulverized S. tamariscina using hot-water-based extraction at temperatures of 40 °C induced cell disruption in both axenic and xenic M. aeruginosa. Liquid chromatographic analysis was also conducted to measure the concentration of amentoflavone in the STE, thus supporting the potential M. aeruginosa-specific killing effects of STE. Bacterial community analysis revealed that STE treatment led to a reduction in the relative abundance of Microcystis species while also increasing the 16S rRNA gene copy number in both xenic M. aeruginosa NIBR18 and cyanobacterial bloom samples isolated from a freshwater environment. Subsequent testing on bacteria, cyanobacteria, and algae isolated from freshwater revealed that STE was not toxic for other taxa. Furthermore, ecotoxicology assessment involving Aliivibrio fischeri, Daphnia magna, and Danio rerio found that high STE doses immobilized D. magna but did not impact the other organisms, while there was no change in the water quality. Overall, due to its effective Microcystis-killing capability and low ecotoxicity, aqueous STE represents a promising practical alternative for the management of Microcystis blooms.

Polyphenols synergistic drugs to ameliorate non-alcoholic fatty liver disease via signal pathway and gut microbiota: A review

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disease with an increasing incidence worldwide. Single drug therapy may have toxic side effects and disrupt gut microbiota balance. Polyphenols are widely used in disease intervention due to their distinctive nutritional properties and medicinal value, which a potential gut microbiota modulator. However, there is a lack of comprehensive review to explore the efficacy and mechanism of combined therapy with drugs and polyphenols for NAFLD.

AIM OF REVIEW

Based on this, this review firstly discusses the link between NAFLD and gut microbiota, and outlines the effects of polyphenols and drugs on gut microbiota. Secondly, it examined recent advances in the treatment and intervention of NAFLD with drugs and polyphenols and the therapeutic effect of the combination of the two. Finally, we highlight the underlying mechanisms of polyphenol combined drug therapy in NAFLD. This is mainly in terms of signaling pathways (NF-κB, AMPK, Nrf2, JAK/STAT, PPAR, SREBP-1c, PI3K/Akt and TLR) and gut microbiota. Furthermore, some emerging mechanisms such as microRNA potential biomarker therapies may provide therapeutic avenues for NAFLD.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Drawing inspiration from combination drug strategies, the use of active substances in combination with drugs for NAFLD intervention holds transformative and prospective potential, both improve NAFLD and restore gut microbiota balance while reducing the required drug dosage. This review systematically discusses the bidirectional interactions between gut microbiota and NAFLD, and summarizes the potential mechanisms of polyphenol synergistic drugs in the treatment of NAFLD by modulating signaling pathways and gut microbiota. Future researches should develop multi-omics technology to identify patients who benefit from polyphenols combination drugs and devising individualized treatment plans to enhance its therapeutic effect.

Sea Buckthorn Flavonoid Extracted by High Hydrostatic Pressure Inhibited IgE-Stimulated Mast Cell Activation through the Mitogen-Activated Protein Kinase Signaling Pathway

Sea buckthorn (Hippophaë rhamnoides L.), as one of the Elaeagnaceae family, has the significant function of anti-tumor, anti-inflammation, anti-oxidation, and other physiological activities. High hydrostatic pressure (HHP) extraction has the advantages of being easy and efficient, while maintaining biological activity. In this study, sea buckthorn flavonoid (SBF) was extracted with HHP and purified sea buckthorn flavonoid (PSBF) was isolated by AB-8 macroporous resin column. HPLC analysis was used to quantified them. In addition, the effect of anti-allergy in RBL-2H3 cells by SBF, PSBF, and their flavonoid compounds was evaluated. The results demonstrate the conditions for obtaining the maximum flavonoid amount of SBF: 415 MPa for 10 min, 72% ethanol concentration, and a liquid to solid ratio of 40 mL/g, which increased the purity from 1.46% to 13.26%. Both SBF and PSBF included rutin, quercitrin, quercetin, isorhamnetin, and kaempferol. In addition, quercitrin, kaempferol, and SBF could regulate Th1/Th2 cytokine balance. Moreover, extracellular Ca2+ influx was reduced by quercitrin and PSBF. Furthermore, rutin, quercetin, iso-rhamnetin, and SBF could also inhibit P-p38 and P-JNK expression, thereby suppressing the phosphorylation of the MAPK signaling pathways. Overall, SBF is effective for relieving food allergy and might be a promising anti-allergic therapeutic agent.

Phenolics and Terpenoids Profiling in Diverse Loquat Fruit Varieties and Systematic Assessment of Their Mitigation of Alcohol-Induced Oxidative Stress

To compare and investigate the phenolic compounds in the peel and flesh of loquat (Eriobotrya japonica) and evaluate their ability to protect against alcohol-induced liver oxidative stress, we employed a combination of ultra-performance liquid chromatography (UPLC) and high-resolution mass spectrometry (HRMS) to qualitatively and quantitatively analyze 22 phenolics and 2 terpenoid compounds in loquat peel and flesh extracts (extraction with 95% ethanol). Among these, six compounds were identified for the first time in loquat, revealing distinct distribution patterns based on variety and tissue. Various chemical models, such as DPPH, FRAP, ORAC, and ABTS, were used to assess free radical scavenging and metal ion reduction capabilities. The results indicate that peel extracts exhibited higher antioxidant capacity compared with flesh extracts. Using a normal mouse liver cell line, AML-12, we explored the protective effects of loquat extracts and individual compounds against ethanol-induced oxidative stress. The findings demonstrate the enhanced cell viability and the induction of antioxidant enzyme activity through the modulation of Nrf2 and Keap1 gene expression. In a C57/BL6 mouse model of alcohol-induced liver damage, loquat extract was found to alleviate liver injury induced by alcohol. The restoration of perturbed serum liver health indicators underscored the efficacy of loquat extract in reclaiming equilibrium. The culmination of these findings significantly bolsters the foundational knowledge necessary to explore the utilization of loquat fruit extract in the creation of health-focused products.