Chemistry and bioactivity of nobiletin and its metabolites

Flavonoids as Potential Therapeutics Against Neurodegenerative Disorders: Unlocking the Prospects

Neurodegeneration, the decline of nerve cells in the brain, is a common feature of neurodegenerative disorders (NDDs). Oxidative stress, a key factor in NDDs such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease can lead to neuronal cell death, mitochondria impairment, excitotoxicity, and Ca2+ stress. Environmental factors compromising stress response lead to cell damage, necessitating novel therapeutics for preventing or treating brain disorders in older individuals and an aging population. Synthetic medications offer symptomatic benefits but can have adverse effects. This research explores the potential of flavonoids derived from plants in treating NDDs. Flavonoids compounds, have been studied for their potential to enter the brain and treat NDDs. These compounds have diverse biological effects and are currently being explored for their potential in the treatment of central nervous system disorders. Flavonoids have various beneficial effects, including antiviral, anti-allergic, antiplatelet, anti-inflammatory, anti-tumor, anti-apoptotic, and antioxidant properties. Their potential to alleviate symptoms of NDDs is significant.

Nobiletin regulates intracellular Ca2+ levels via IP3R and ameliorates neuroinflammation in Aβ42-induced astrocytes

Astrocytes are the major glial cells in the human brain and provide crucial metabolic and trophic support to neurons. The amyloid-β peptide (Aβ) alter the morphological and functional properties of astrocytes and induce inflammation and calcium dysregulation, contributing to Alzheimer's disease (AD) pathology. Recent studies highlight the role of Toll-like receptor (TLR) 4/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling in inflammation. Reactive oxygen species (ROS) generated due to Aβ, induce apoptosis in the brain cells worsening AD progression. Astrocytic cell surface receptors, such as purinergic receptors (P2Y1 and P2Y2), metabotropic glutamate receptor (mGLUR)5, α7 nicotinic acetylcholine receptor (α7nAChR), and N-methyl-d-aspartate receptors (NMDARs), have been suggested to interact with inositol trisphosphate receptor (IP3R) on the endoplasmic reticulum (ER) to induce Ca2+ movement from ER to cytoplasm, causing Ca2+ dysregulation. We found that the citrus flavonoid nobiletin (NOB) protected primary astrocytes from Aβ42-induced cytotoxicity and inhibited TLR4/NF-κB signaling in Aβ42-induced primary rat astrocytes. NOB was found to regulate Aβ42-induced ROS levels through Keap1-Nrf2 pathway. The receptors P2Y1, P2Y2, mGLUR5, α7nAChR, and NMDARs induced intracellular Ca2+ levels by activating IP3R and NOB regulated them, thereby regulating intracellular Ca2+ levels. Molecular docking analysis revealed a possible interaction between NOB and IP3R in IP3R regulation. Furthermore, RNA sequencing revealed various NOB-mediated biological signaling pathways, such as the AD-presenilin, AD-amyloid secretase, and Wnt signaling pathway, suggesting possible neuroprotective roles of NOB. To conclude, NOB is a promising therapeutic agent for AD and works by modulating AD pathology at various levels in Aβ42-induced primary rat astrocytes.

Elucidation of the composition, antioxidant, and antimicrobial properties of essential oil and extract from Citrus aurantifolia (Christm.) Swingle peel

The most effective methodologies for generating Musa spp. explants involve the utilization of plant tissue culture micropropagation techniques. However, the pervasive challenge of microbial contamination significantly impedes the successful micropropagation of Musa spp. This study examined the antioxidant and antibacterial characteristics of the essential oil (LPO) and extract (LPE) obtained from the peel of Citrus aurantifolia. Additionally, we explored their mechanisms against common microbial contaminants in Musa spp. micropropagation. Using gas chromatography-mass spectrometry, we identified 28 components in LPO, with δ-limonene, β-pinene, citral, trans-citral, β-bisabolene, geranyl acetate, and α-pinene as the primary constituents. Meanwhile, liquid chromatography-mass spectrometry detected 17 components in LPE, highlighting nobiletin, tangeretin, scoparone, sinensetin, tetramethylscutellarein, 5-demethylnobiletin, and pyropheophorbide A as the predominant compounds. Evaluation using the DPPH and ABTS methods revealed the IC50 values for LPE at 0.66 ± 0.009 and 0.92 ± 0.012 mg/mL, respectively, indicating higher antioxidant activity compared to LPO, with IC50 values of 3.03 ± 0.019 and 4.27 ± 0.023 mg/mL using the same methods. Both LPO and LPE exhibited antimicrobial activities against all tested contaminant microorganisms through in vitro assays. Mechanistic investigations employing time-kill analysis, assessment of cell membrane integrity, and scanning electron microscopy (SEM) revealed changes in the morphological characteristics of the tested microbial contaminants, intensifying with increased concentration and exposure duration of LPO and LPE. These alterations led to substantial damage, including cell wall lysis, leakage of intracellular components, and subsequent cell death. Consequently, LPO and LPE emerge as promising alternatives for addressing microbial contamination in banana tissue cultures.

Natural product nobiletin-loaded Pickering emulsion stabilized by bovine serum albumin/carboxymethyl inulin complexes: preparation and digestive characteristics

To expand the application of nobiletin (NOB) in semi-solid functional foods, bovine serum albumin (BSA)/carboxymethyl inulin (CMI) complexes-stabilized Pickering emulsion (BCPE) (φoil = 60%, v/v) was fabricated, and the swallowing index and bioavailability of the NOB-loaded Pickering emulsion was evaluated. Confocal laser scanning microscope (CLSM) and cryo-scanning electron microscopy (cryo-SEM) images revealed that BSA/CMI complexes attached to the oil-water interface. NOB-loaded BCPE exhibited a viscoelastic and shear-thinning behavior. Fork drip test results suggested that the textural value of unloaded and NOB-loaded emulsions was International Dysphagia Diet Standardisation Initiative Level 4, which could be swallowed directly without chewing. The in vitro lipolysis model suggested that NOB had a faster digestive profile and a higher bioaccessibility in the BCPE than in the oil suspension. The in vivo rat model revealed that the oral bioavailability of NOB was increased by 2.07 folds in BCPE compared to its bioavailability in unformulated oil. Moreover, BCPE led to a higher plasma concentration of the major demethylated metabolite of NOB (4'-demethylnobiletin) than the unformulated oil. Accordingly, BCPE enhanced the oral bioavailability of NOB by improving bioaccessibility, absorption, and biotransformation.

Comparative Evaluation of Secondary Metabolite Chemodiversity of Citrus Genebank Collection in Greece: Can the Peel be More than Waste?

Citrus fruits are among the most economically important crops in the world. In the global market, the Citrus peel is often considered a byproduct but substitutes an important phenotypic characteristic of the fruit and a valuable source of essential oils, flavonoids, carotenoids, and phenolic acids with variable concentrations. The Mediterranean basin is a particularly dense area of autochthonous genotypes of Citrus that are known for being a source of healthy foods, which can be repertoires of valuable genes for molecular breeding with the focus on plant resistance and quality improvement. The scope of this study was to characterize and compare the main phenotypic parameters (i.e., peel thickness, fruit volume, and area) and levels of bioactive compounds in the peel of fruits from the local germplasm of Citrus in Greece, to assess their chemodiversity regarding their polyphenolic, volatile, and carotenoid profiles. A targeted liquid chromatographic approach revealed hesperidin, tangeretin, narirutin, eriocitrin, and quercetin glycosides as the major polyphenolic compounds identified in orange, lemon, and mandarin peels. The content of tangeretin and narirutin followed the tendency mandarin > orange > lemon. Eriocitrin was a predominant metabolite of lemon peel, following its identification in lower amounts in mandarin and at least in the orange peel. For these citrus-specific metabolites, high intra- but also interspecies chemodiversity was monitored. Significant diversity was found in the essential oil content, which varied between 1.2 and 3% in orange, 0.2 and 1.4% in mandarin, and 0.9 and 1.9% in lemon peel. Limonene was the predominant compound in all Citrus species peel essential oils, ranging between 88 and 93% among the orange, 64 and 93% in mandarin, and 55 and 63% in lemon cultivars. Carotenoid analysis revealed different compositions among the Citrus species and accessions studied, with β-cryptoxanthin being the most predominant metabolite. This large-scale metabolic investigation will enhance the knowledge of Citrus peel secondary metabolite chemodiversity supported by the ample availability of Citrus genetic resources to further expand their exploitation in future breeding programs and potential applications in the global functional food and pharmaceutical industries.

Citrus reticulata peel extract mitigates oxidative stress and liver injury induced by abamectin in rats

The prevalent use of abamectin (ABM) has latterly raised safety attention as it has different toxicities to non-target living organisms. Citrus fruits are widely renowned for their nutritional and health-promoting qualities, and their peels are full of phenolic constituents. The purpose of the current study was to evaluate the modulatory effectiveness of Citrus reticulata peel extract (CPE) against abamectin-induced hepatotoxicity and oxidative injury. Rats were distributed into 4 groups as follows: control, CPE (400 mg/kg bw orally for 14 days), ABM (2 mg/kg bw for 5 days), and CPE + ABM at the doses mentioned above. Results revealed that GC-MS analysis of CPE has 19 identified components with significant total phenolic and flavonoid contents. Treatment with ABM in rats displayed significant variations in enzymatic and non-enzymatic antioxidants, oxidative stress markers (MDA, H2O2, PCC), liver and kidney function biomarkers, hematological parameters, lipids, and protein profile as well as histopathological abnormalities, inflammation and apoptosis (TNF-α, Caspase-3, NF-κB, and Bcl-2 genes) in rats' liver. Supplementation of CPE solo dramatically improved the antioxidant state and reduced oxidative stress. C. reticulata peel extract pretreatment alleviated ABM toxicity by modulating most of the tested parameters compared to the ABM group. Conclusively, CPE had potent antioxidant activity and could be used in the modulation of ABM hepatotoxicity presumably due to its antioxidant, anti-inflammatory, and gene-regulating capabilities.

Combination of in silico prediction and convolutional neural network framework for targeted screening of metabolites from LC-HRMS fingerprints: A case study of "Pericarpium Citri Reticulatae - FructusAurantii"

In this study, a novel approach is introduced, merging in silico prediction with a Convolutional Neural Network (CNN) framework for the targeted screening of in vivo metabolites in Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) fingerprints. Initially, three predictive tools, supplemented by literature, identify potential metabolites for target prototypes derived from Traditional Chinese Medicines (TCMs) or functional foods. Subsequently, a CNN is developed to minimize false positives from CWT-based peak detection. The Extracted Ion Chromatogram (EIC) peaks are then annotated using MS-FINDER across three levels of confidence. This methodology focuses on analyzing the metabolic fingerprints of rats administered with "Pericarpium Citri Reticulatae - Fructus Aurantii" (PCR-FA). Consequently, 384 peaks in positive mode and 282 in negative mode were identified as true peaks of probable metabolites. By contrasting these with "blank serum" data, EIC peaks of adequate intensity were chosen for MS/MS fragment analysis. Ultimately, 14 prototypes (including flavonoids and lactones) and 40 metabolites were precisely linked to their corresponding EIC peaks, thereby providing deeper insight into the pharmacological mechanism. This innovative strategy markedly enhances the chemical coverage in the targeted screening of LC-HRMS metabolic fingerprints.

Synergistic effects of flavonoids and paclitaxel in cancer treatment: a systematic review

Paclitaxel is a natural anticancer compound with minimal toxicity, the capacity to stabilize microtubules, and high efficiency that has remained the standard of treatment alongside platinum-based therapy as a remedy for a variety of different malignancies. In contrast, polyphenols such as flavonoids are also efficient antioxidant and anti-inflammatory and have now been shown to possess potent anticancer properties. Therefore, the synergistic effects of paclitaxel and flavonoids against cancer will be of interest. In this review, we use a Boolean query to comprehensively search the well-known Scopus database for literature research taking the advantage of paclitaxel and flavonoids simultaneously while treating various types of cancer. After retrieving and reviewing the intended investigations based on the input keywords, the anticancer mechanisms of flavonoids and paclitaxel and their synergistic effects on different targets raging from cell lines to animal models are discussed in terms of the corresponding involved signaling transduction. Most studies demonstrated that these signaling pathways will induce apoptotic / pro-apoptotic proteins, which in turn may activate several caspases leading to apoptosis. Finally, it can be concluded that the results of this review may be beneficial in serving as a theoretical foundation and reference for future studies of paclitaxel synthesis, anticancer processes, and clinical applications involving different clinical trials.

Citri Reticulatae Pericarpium Limits TLR-4-Triggered Inflammatory Response in Raw264.7 Macrophages by Activating RasGRP3

Inflammation is an important immune response to pathogen invasion, but excessive inflammation leads to tissue injury and even cytokine storm. Therefore, proper response is needed depending on the intensity of the infection. Ras guanine nucleotide releasing protein 3 (RasGRP3) is a regulator of the TLR-mediated response. In low-intensity inflammation, it negatively regulates production of pro-inflammatory cytokines, especially IL-6. Citri Reticulatae Pericarpium, the peel of Citrus reticulata Blanco, is a major medicinal herb in Korean medicine. The present study aims to investigate whether the Citri Reticulatae Pericarpium extract (CRE) has immunomodulatory activity using the Raw264.7 macrophage. Also, we investigated the effect of CRE on RasGRP3 expression. In the present study, CRE reduced IL-6 production in the low-LPS environment (1 ng/mL) and did not in the high-LPS environment (100 ng/mL). The suppression of IL-6 production in the low-LPS environment (1 ng/mL) was abolished after the pretreatment of RasGRP3 siRNA. The reduced RasGRP3 protein content by 100 ng/mL LPS treatment was increased by CRE treatment. Additionally, nobiletin, a major component of CRE showed a suppressive effect on IL-6 production in the low-LPS environment (1 ng/mL). The present results suggest that CRE alleviates inflammatory response via activating RasGRP3 expression in low-intensity inflammation.

A Combination of Polymethoxyflavones from Citrus sinensis and Prenylflavonoids from Humulus lupulus Counteracts IL-1β-Induced Differentiated Caco-2 Cells Dysfunction via a Modulation of NF-κB/Nrf2 Activation

We here investigated the anti-inflammatory activity of a polymethoxylated flavone-containing fraction (PMFF) from Citrus sinensis and of a prenylflavonoid-containing one (PFF) from Humulus lupulus, either alone or in combination (MIX). To this end, an in vitro model of inflammatory bowel disease (IBD), consisting of differentiated, interleukin (IL)-1β-stimulated Caco-2 cells, was employed. We demonstrated that non-cytotoxic concentrations of either PMFF or PFF or MIX reduced nitric oxide (NO) production while PFF and MIX, but not PMFF, also inhibited prostaglandin E2 release. Coherently, MIX suppressed both inducible NO synthase and cyclooxygenase-2 over-expression besides NF-κB activation. Moreover, MIX increased nuclear factor erythroid 2-related factor 2 (Nrf2) activation, heme oxygenase-1 expression, restoring GSH and reactive oxygen and nitrogen species (RONs) levels. Remarkably, these effects with MIX were stronger than those produced by PMFF or PFF alone. Noteworthy, nobiletin (NOB) and xanthohumol (XTM), two of the most represented phytochemicals in PMFF and PFF, respectively, synergistically inhibited RONs production. Overall, our results demonstrate that MIX enhances the anti-inflammatory and anti-oxidative effects of the individual fractions in a model of IBD, via a mechanism involving modulation of NF-κB and Nrf2 signalling. Synergistic interactions between NOB and XTM emerge as a relevant aspect underlying this evidence.

Preliminary Phytochemical and Biological Evaluation of Rudbeckia hirta Flowers

Black-eyed Susan (Rudbeckia hirta L.), a flowering plant with various traditional medicinal uses, has recently garnered interest for its therapeutic properties. However, little is known about the potential therapeutic activities of the plant species. The current study focused on conducting a comprehensive investigation into the chemical composition and bioactivity of black-eyed Susan cultivated in Romania. Untargeted metabolite profiling and UHPLC-HR-MS phytochemical analysis of the studied extract revealed the presence of more than 250 compounds pertaining to different classes, including sesquiterpene lactones, polyphenolic acids, flavonoids, amino acids, and fatty acids. The tested extract exhibited inhibitory activity against Gram-positive bacteria and showed promising antifungal activity. It also demonstrated potent antioxidant properties through iron chelation and 15-LOX inhibition capacities, as well as inhibition of cell growth, particularly on the MCF-7 cell line, suggesting potential anticancer effects. Therefore, current research provides valuable information on the antioxidant, antimicrobial, and antitumor potential of Rudbeckia hirta flowers. Implicitly, the discovery of such a wide range of biosubstances, together with the biological activity observed for the studied extract in these preliminary in vitro studies, paves the way for future investigation of the potential application of the plant in the pharmaceutical and nutraceutical sectors.

Bioactive Chemical Constituents and Pharmacological Activities of Ponciri Fructus

Ponciri Fructus is a crude drug obtained from the dried immature fruits of Poncirus trifoliata (L). Raf. (Syn. Citrus trifoliata L.). This study aims to compile and analyze the ethnomedicinal uses, bioactive constituents, and pharmacological activities of Ponciri Fructus. Various online bibliographic databases namely, SciFinder, PubMed, Google Scholar, and Web of Science were used for collecting information on traditional uses, biological activities, and bioactive constituents. Concerning ethnomedicinal uses, Ponciri Fructus is extensively used in traditional Korean, Chinese, and Kampo medicines to mitigate allergic reactions, inflammation, edema, digestive complications, respiratory problems, spleen-related problems, liver complications, neuronal pain, hyperlipidemia, rheumatoid arthritis, cardiovascular problems, hernia, sinusitis, and insomnia. Several studies have shown that Ponciri Fructus is a major source of diverse classes of bioactive compounds namely flavonoids, terpenoids, coumarins, phytosterols, and alkaloids. Several in vivo and in vitro pharmacological activity evaluations such as antidiabetic, anti-obesity, anti-inflammatory, antiallergic, antimelanogenic, gastroprotective, anticancer, and neuroprotective effects have been conducted from Ponciri Fructus. However, scientific investigations focusing on bioassay-guided isolation and identification of specific bioactive constituents are limited. Therefore, an in-depth scientific investigation of Ponciri Fructus focusing on bioassay-guided isolation, mechanism based pharmacological studies, pharmacokinetic studies, and evaluation of possible toxicities is necessary in the future.

The Chemistry and the Anti-Inflammatory Activity of Polymethoxyflavonoids from Citrus Genus

Polymethoxyflavonoids (PMFs) are a large group of compounds belonging to the more general class of flavonoids that possess a flavan carbon framework decorated with a variable number of methoxy groups. Hydroxylated polymethoxyflavonoids (HPMFs), instead, are characterized by the presence of both hydroxyl and methoxy groups in their structural unities. Some of these compounds are the aglycone part in a glycoside structure in which the glycosidic linkage can involve the -OH at various positions. These compounds are particular to Citrus genus plants, especially in fruits, and they are present mainly in the peel. A considerable number of PMFs and HPMFs have shown promising biological activities and they are considered to be important nutraceuticals, responsible for some of the known beneficial effects on health associated with a regular consumption of Citrus fruits. Among their several actions on human health, it is notable that the relevant contribution in controlling the intracellular redox imbalance is associated with the inflammation processes. In this work, we aim to describe the status concerning the chemical identification and the anti-inflammatory activity of both PMFs and HPMFs. In particular, all of the chemical entities unambiguously identified by isolation and complete NMR analysis, and for which a biochemical evaluation on the pure compound was performed, are included in this paper.

Polymethoxyflavones from citrus peel: advances in extraction methods, biological properties, and potential applications

Citrus peel, as an effective component of citrus by-products, contains a large number of natural active components, including pectin, vitamins, dietary fiber, essential oil, phenolic compounds, flavonoids, and so on. With the development of the circular economy, citrus peel has attracted extensive concern in the food industry. The exploitation of citrus peel would assist in excavating potential properties and alleviating the environmental burden. Polymethoxyflavones (PMFs) exist almost in citrus peel, which have remarkable biological activities including antioxidant, anti-inflammatory, anti-cancer, and anti-obesity. Therefore, PMFs from citrus peel have the potential to develop as dietary supplements in the near future. Collectively, it is essential to take action to optimize the extraction conditions of PMFs and make the most of the extracts. This review mainly compiles several extraction methods and bioactivities of PMFs from citrus peel and introduces different applications including food processing, pharmaceutical industry, and plant rhizosphere to develop better utilization of citrus PMFs.

Evaluation of flavonoids as potential inhibitors of the SARS-CoV-2 main protease and spike RBD: Molecular docking, ADMET evaluation and molecular dynamics simulations

The 3CLpro main protease and the RDB spike (s) protein of SARS-CoV-2 are critical targets in the treatment of coronavirus 19 disease (COVID-19), as they are responsible for the COVID-19 replication and infection. With this in mind, Molecular docking of 26 natural compounds belonging to the flavonoid family with the 3CLpro and RBD sites of SARS-CoV-2 has been performed. The docking results revealed that the ligands Silibinin, Tomentin A, Tomentin B, 4′-O-methyldiplacone, Hesperidin Amentoflavone and Bilobetin act as a potential inhibitor of SARS-CoV-2 3CLpro, and that the ligands Herbacetin, Morin, Silibinin, Tomentin E, Amentoflavone, Bilobetin, Baicalein and Quercetin can be potential inhibitors of SARS-CoV-2 RBD. It has been noticed that three ligands can inhibit both sites of SARS-CoV-2, indicating a great potential of these compounds to combat COVID-19. Moreover, molecular docking has been validated by a new validation method based on visual inspiration. Evaluation of ADMET pharmacokinetic properties and the drug likeness in silico revealed that six compounds could be effective drugs against COVID-19. Finally, the docking results were verified by molecular dynamics simulations and MM-GBSA calculation to confirm the stability of hydrogen bonding interactions with crucial residues, which are essential to overcome SARS-CoV-2. These results could direct researchers toward plant-derived compounds that could be further investigated as therapeutic targets against COVID-19 replication and infection.

Transcriptomics, molecular docking, and cross-resistance profiling of nobiletin in cancer cells and synergistic interaction with doxorubicin upon SOX5 transfection

BACKGROUND

Nobiletin is a polymethoxylated flavone from citrus fruit peels. Among other bioactivities, it acts antioxidative, anti-inflammatory, neuroprotective, and cardiovascular-protective. Nobiletin exerts profound anticancer activity in vitro and in vivo but the underlying mechanisms are not well understood.

PURPOSE

The aim was to unravel the multiple modes of action against cancer cells by bioinformatic and transcriptomic techniques and their verification by molecular pharmacological methods.

METHODS

The in silico methods used were COMPARE analysis of transcriptomic data, signaling pathway analysis, transcription factor binding motif analysis in promoter sequences of target genes, and molecular docking. The in vitro methods used were resazurin assay, isobologram analysis, generation of stably SOX5-tranfected cells, and Western blotting.

RESULTS

Nobiletin was cytotoxic against a wide range of cell lines from different tumor types, including diverse phenotypes to established anticancer drugs (e.g., P-glycoprotein, ABCB5, p53, EGFR). Cross-resistance profiling with 83 standard anticancer drugs revealed a correlation to antihormonal anticancer drugs, which can be explained by the phytoestrogenic features of nobiletin. Transcriptomic analysis showed that the responsiveness of tumor cells was predictable by their specific mRNA expression profile. Nobiletin bound to the transcription factor SOX5 in silico. SOX5 conferred resistance to the control drug doxorubicin but collateral sensitivity to nobiletin in HEK293 cells transfected with a lentiviral GFP-tagged pLOCORF-SOX5 vector. The combination of nobiletin and doxorubicin synergistically killed HEK293-SOX5 cells in isobologram analyses, implying attractive new treatment options.

CONCLUSION

Nobiletin represents an interesting candidate for cancer therapy with broad-spectrum activity and multiple modes of action. The identification of novel targets (i.e., SOX5) may allow its use for targeted tumor therapy in individualized treatment protocols.

Effect of Fibril Entanglement on Pickering Emulsions Stabilized by Whey Protein Fibrils for Nobiletin Delivery

The aim of the study was to investigate the effects of whey protein isolate (WPI) fibrils entanglement on the stability and loading capacity of WPI fibrils-stabilized Pickering emulsion. The results of rheology and small-angle X-ray scattering (SAXS) showed the overlap concentration (C*) of WPI fibrils was around 0.5 wt.%. When the concentration was higher than C*, the fibrils became compact and entangled in solution due to a small cross-sectional radius of gyration value (1.18 nm). The interfacial behavior was evaluated by interfacial adsorption and confocal laser scanning microscopy (CLSM). As the fibril concentration increased from 0.1 wt.% to 1.25 wt.%, faster adsorption kinetics (from 0.13 to 0.21) and lower interfacial tension (from 11.85 mN/m to 10.34 mN/m) were achieved. CLSM results showed that WPI fibrils can effectively absorb on the surface of oil droplets. Finally, the microstructure and in vitro lipolysis were used to evaluate the effect of fibrils entanglement on the stability of emulsion and bioaccessibility of nobiletin. At C* concentration, WPI fibrils-stabilized Pickering emulsions exhibited excellent long-term stability and were also stable at various pHs (2.0–7.0) and ionic strengths (0–200 mM). WPI fibrils-stabilized Pickering emulsions after loading nobiletin remained stable, and in vitro digestion showed that these Pickering emulsions could significantly improve the extent of lipolysis (from 36% to 49%) and nobiletin bioaccessibility (21.9% to 62.5%). This study could provide new insight into the fabrication of food-grade Pickering emulsion with good nutraceutical protection.

Citrus Peels as a Source of Bioactive Compounds with Industrial and Therapeutic Applications

Agriculture wastes are considered a good starting point to discover for new drugs all over the world. In this context, Agriculture wastes contain millions of compounds to be screened to find bioactive compounds responsible for the activity to be used in drugs. Citrus agriculture is one of the most important commercial and industrial agricultural activities in the world. The peel waste of Citrus species is a rich source of bioactive compounds such as essential oils, flavones, polyphenols, and pigment. Citrus peel has been widely used in the medicine industry. The waste peel of citrus consider a rich source of pharmacologically active metabolites with antioxidant activities.

Genome-Wide Association Study of Healthful Flavonoids among Diverse Mandarin Accessions

Mandarins have many unique flavonoids with documented health benefits and that help to prevent chronic human diseases. Flavonoids are difficult to measure and cannot be phenotyped without the use of specialized equipment; consequently, citrus breeders have not used flavonoid contents as selection criteria to develop cultivars with increased benefits for human health or increased tolerance to diseases. In this study, peel, pulp, and seed samples collected from many mandarin accessions and their hybrids were analyzed for the presence of selected flavonoids with documented human health benefits. A genome-wide association study (GWAS) was used to identify SNPs associated with biosynthesis of flavonoids in these mandarin accessions, and there were 420 significant SNPs were found to be associated with 28 compounds in peel, pulp, or seed samples. Four candidate genes involved in flavonoid biosynthesis were identified by enrichment analysis. SNPs that were found to be associated with compounds in pulp samples have the potential to be used as markers to select mandarins with improved phytonutrient content to benefit human health. Mandarin cultivars bred with increased flavonoid content may provide value to growers and consumers.

Citrus depressa Hayata Peel Ameliorates Nonalcoholic Fatty Liver and Modulates the Hepatic Drug-metabolizing Enzymes and Transporters in Rats Fed a High-fat Diet

Citrus depressa Hayata is a small, green citrus fruit native to Taiwan and Japan. The citrus peel contains polymethoxylated flavones, including nobiletin and tangeretin, and might have strong antioxidant and...

Nobiletin mitigates NAFLD via lipophagy and inflammation

Nonalcoholic fatty liver disease (NAFLD), an increasingly serious health issue in the world, was characterized as lipid metabolic disorder without a satisfactory treatment. Nobiletin (NOB), a citrus flavonoid, was considered...

Biotransformation and Quantification of Sinensetin and Its Metabolites in Plasma, Urine, and Feces of Rats

As one of the major polymethoxyflavones in citrus peels, sinensetin (Sin) has been reported to possess numerous bioactivities. However, its detailed in vivo metabolic fate has not been uncovered yet. In the present study, the possible metabolites of Sin were synthesized, and all five mono-demethylated metabolites were successfully identified via ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis in rats fed with 100 mg/(kg·bw) Sin. The excretion and pharmacokinetic studies were then carried out to quantitatively investigate their variation in content with time in urine, feces, and plasma samples. Results showed that 4'-demethylsinensetin, 6-demethylsinensetin, and 3'-demethylsinensetin were the three most abundant metabolites generated in the above-mentioned biological samples. In addition, the total amount of Sin with its metabolites showed a significantly higher content in urine than in feces, indicating that Sin may be easily absorbed in the small intestine.

Evaluation of Amyloid Polypeptide Aggregation Inhibition and Disaggregation Activity of A-Type Procyanidins

The number of people worldwide suffering from Alzheimer’s disease (AD) and type 2 diabetes (T2D) is on the rise. Amyloid polypeptides are thought to be associated with the onset of both diseases. Amyloid-β (Aβ) that aggregates in the brain and human islet amyloid polypeptide (hIAPP) that aggregates in the pancreas are considered cytotoxic and the cause of the development of AD and T2D, respectively. Thus, inhibiting amyloid polypeptide aggregation and disaggregation existing amyloid aggregates are promising approaches in the therapy and prevention against both diseases. Therefore, in this research, we evaluated the Aβ/hIAPP anti-aggregation and disaggregation activities of A-type procyanidins 1–7 and their substructures 8 and 9, by conducting structure–activity relationship studies and identified the active site. The thioflavin-T (Th-T) assay, which quantifies the degree of aggregation of amyloid polypeptides based on fluorescence intensity, and transmission electron microscopy (TEM), employed to directly observe amyloid polypeptides, were used to evaluate the activity. The results showed that catechol-containing compounds 1–6 exhibited Aβ/hIAPP anti-aggregation and disaggregation activities, while compound 7, without catechol, showed no activity. This suggests that the presence of catechol is important for both activities. Daily intake of foods containing A-type procyanidins may be effective in the prevention and treatment of both diseases.

Nobiletin-loaded composite penetration enhancer vesicles restore the normal miRNA expression and the chief defence antioxidant levels in skin cancer

Skin cancer is one of the most dangerous diseases, leading to massive losses and high death rates worldwide. Topical delivery of nutraceuticals is considered a suitable approach for efficient and safe treatment of skin cancer. Nobiletin; a flavone occurring in citrus fruits has been reported to inhibit proliferation of carcinogenesis since 1990s, is a promising candidate in this regard. Nobiletin was loaded in various vesicular systems to improve its cytotoxicity against skin cancer. Vesicles were prepared using the thin film hydration method, and characterized for particle size, zeta potential, entrapment efficiency, TEM, ex-vivo skin deposition and physical stability. Nobiletin-loaded composite penetration enhancer vesicles (PEVs) and composite transfersomes exhibited particle size 126.70 ± 11.80 nm, 110.10 ± 0.90 nm, zeta potential + 6.10 ± 0.40 mV, + 9.80 ± 2.60 mV, entrapment efficiency 93.50% ± 3.60, 95.60% ± 1.50 and total skin deposition 95.30% ± 3.40, 100.00% ± 2.80, respectively. These formulations were selected for cytotoxicity study on epidermoid carcinoma cell line (A431). Nobiletin-loaded composite PEVs displayed the lowest IC50 value, thus was selected for the in vivo study, where it restored skin condition in DMBA induced skin carcinogenesis mice, as delineated by histological and immuno-histochemical analysis, biochemical assessment of skin oxidative stress biomarkers, in addition to miRNA21 and miRNA29A. The outcomes confirmed that nobiletin- loaded composite PEVs is an efficient delivery system combating skin cancer.

Bioactive compounds analysis in ethanolic extracts of Citrus maxima and Citrus sinensis exocarp and mesocarp

The composition of phenolic compounds of ethanolic extract taken from mesocarp and exocarp parts of Citrus maxima and Citrus sinensis peels cultivated in Iran have been identified. The Phenolic compounds in ethanolic extracts were quantified using HPLC-DAD. Different amounts of phenolic compounds were detected in the samples including hesperidin, t-ferulic acid, catechin, sinapic acid, vanillin, chlorogenic acid and caffeic acid. The most represented compound in both plants was hesperidin. It was the main phenolic compound detected in both exocarp and mesocarp parts of both species, with the maximum amount belonging to mesocarp of C. sinensis. The average amount of hesperidin detected in mesocarp and exocarp of C. maxima was 15.04 and 7.42 mg g^-1 dry weight, while it was 17.34 and 7.63 mg g^-1 dry weight for C. sinensis.

Nobiletin-induced partial abrogation of deleterious effects of AKT inhibition on preimplantation bovine embryo development in vitro

During preimplantational embryo development, PI3K/AKT regulates cell proliferation and differentiation and nobiletin modulates this pathway to promote cell survival. Therefore, we aimed to establish whether, when the AKT cascade is inhibited using inhibitors III and IV, nobiletin supplementation to in vitro culture media during the minor (2 to 8-cell stage, MNEGA) or major (8 to 16-cell stage, MJEGA) phases of EGA is able to modulate the development and quality of bovine embryos. In vitro zygotes were cultured during MNEGA or MJEGA phase in SOF + 5% FCS or supplemented with: 15 μM AKT-InhIII; 10 μM AKT-InhIV; 10 μM nobiletin; nobiletin+AKT-InhIII; nobiletin+AKT-InhIV; 0.03% DMSO. Embryo development was lower in treatments with AKT inhibitors, while combination of nobiletin with AKT inhibitors was able to recover their adverse developmental effect and also increase blastocyst cell number. The mRNA abundance of GPX1, NFE2L2, and POU5F1 was partially increased in 8- and 16-cell embryos from nobiletin with AKT inhibitors. Besides, nobiletin increased the p-rpS6 level whether or not AKT inhibitors were present. In conclusion, nobiletin promotes bovine embryo development and quality and partially recovers the adverse developmental effect of AKT inhibitors which infers that nobiletin probably uses another signalling cascade that PI3K/AKT during early embryo development in bovine.

Bidirectional interaction of nobiletin and gut microbiota in mice fed with a high-fat diet

Nobiletin is abundant in citrus peels and demonstrates good anti-obesity bioactivity. However, its anti-obesity mechanisms still remain unclear. This study aims to explore the bidirectional interaction between nobiletin and gut microbiota in mice fed with a high-fat diet. For the colonic bioconversion, more demethylated metabolites with higher biological activity were found in feces than nobiletin in the 48 h excretion study and 8 week consecutive dosing study. Moreover, long-term oral intake of nobiletin would modify the gut microbiota with improved demethylation ability and enhanced production of short chain fatty acids. The comparison of metabolite profiles in mouse liver and feces indicated that gut microbiota might have a higher biotransformation activity on nobiletin than the host. Two bacteria at the genus level, Allobaculum and Roseburia, remained enriched by nobiletin after the 4- and 8-week feedings. They might correlate with the enhanced nobiletin biotransformation and actively contribute to the health benefits of nobiletin in vivo. These results suggested that the bidirectional interaction of nobiletin and gut microbiota played an important role on the anti-obesity effect of nobiletin.

An Up-to-Date Review on Citrus Flavonoids: Chemistry and Benefits in Health and Diseases

Flavonoids, the main class of polyphenols, are characterized by the presence of 2-phenyl-benzo-pyrane nucleus. They are found in rich quantities in citrus fruits. Citrus flavonoids are classified into flavanones, flavones, flavonols, polymethoxyflavones and anthocyanins (found only in blood oranges). Flavanones are the most abundant flavonoids in citrus fruits. In many situations, there are structure-function relationships. Due to their especial structures and presence of many hydroxyls, polymethoxies and glycoside moiety, the flavonoids have an array of multiple biological and pharmacological activities. This article provides an updated overview of the differences in chemical structures of the classes and members of citrus flavonoids and their benefits in health and diseases. The review article also sheds light on the mechanisms of actions of citrus flavonoids in the treatment of different diseases, including arthritis, diabetes mellitus, cancer and neurodegenerative disorders as well as liver, kidney and heart diseases. The accumulated and updated knowledge in this review may provide useful information and ideas in the discovery of new strategies for the use of citrus flavonoids in the protection, prevention and therapy of diseases.

Effect of mandarin peel extract on experimentally induced arthritis in male rats

BACKGROUND

Rheumatoid arthritis (RA) is associated with joint damage. For treatment, non-steroidal anti-inflammatory drugs (NSAIDs), steroidal agents, and immune-suppressants are used. Their side-effects require a safe and effective natural alternative.

ANIMALS AND METHODS

Thirty-six male albino rats, half kept under observation for 1 week (group I) and others for 2 weeks (group II) were used. Each group was subdivided into: normal (A), RA (B), and oral mandarin-peel extract (MPE) treated (C). Ankle diameter, serum levels of RF, interleukin (IL)-1β, TNFα, IL-4, IL-10, liver homogenates malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and nitric oxide (NO) were measured together with the histopathological examination.

RESULTS

MPE treatment was associated with increased serum IL-4, IL-10, liver homogenates GSH, and SOD, and decreased ankle diameter, serum RF, IL-1β, TNFα, liver homogenates MDA, NO, inflammatory cell infiltrate, and necrosis. Two weeks' treatment was better.

CONCLUSIONS

MPE has useful effects in alleviating the disturbed ankle diameter, serum pro- and anti-inflammatory mediators, oxidative stress, and ankle joint histopathology in rheumatic rats.

Physiological effects of tangeretin and heptamethoxyflavone on obese C57BL/6J mice fed a high-fat diet and analyses of the metabolites originating from these two polymethoxylated flavones

Two compounds from citrus peel, tangeretin (TAN) and 3',4',3,5,6,7,8-heptamethoxyflavone (HMF), were investigated for their abilities to repair metabolic damages caused by an high-fat diet (HFD) in C57BL/6J mice. In the first 4 weeks, mice were fed either a standard diet (11% kcal from fat) for the control group, or a HFD (45% kcal from fat) to establish obesity in three experimental groups. In the following 4 weeks, two groups receiving the HFD were supplemented with either TAN or HMF at daily doses of 100 mg/kg body weight, while the two remaining groups continued to receive the standard healthy diet or the nonsupplemented HFD. Four weeks of supplementation with TAN and HMF resulted in intermediate levels of blood serum glucose, leptin, resistin, and insulin resistance compared with the healthy control and the nonsupplemented HFD groups. Blood serum peroxidation (TBARS) levels were significantly lower in the TAN and HMF groups compared with the nonsupplemented HFD group. Several differences occurred in the physiological effects of HMF versus TAN. TAN, but not HMF, reduced adipocyte size in the mice with pre-existent obesity, while HMF, but not TAN, decreased fat accumulation in the liver and also significantly increased the levels of an anti-inflammatory cytokine, IL-10. In an analysis of the metabolites of TAN and HMF, several main classes occurred, including a new set of methylglucuronide conjugates. It is suggested that contrasts between the observed physiological effects of TAN and HMF may be attributable to the differences in numbers and chemical structures of TAN and HMF metabolites.

Assessment of Oral Bioavailability and Biotransformation of Emulsified Nobiletin Using In Vitro and In Vivo Models

Nobiletin has received much attention for its promising biological activities. Owing to its limited solubility, various encapsulation strategies have been developed to enhance nobiletin bioavailability. However, the understanding of the bioavailability and biotransformation of nobiletin in vivo and the correlation between in vitro and in vivo data remains limited. This study developed a high-loading nobiletin (1%) emulsion. The in vitro models, which combined pH-stat lipolysis with a Franz cell, showed very good correlation with in vivo data for the relative bioavailability. Rat studies showed that nobiletin had a high absolute bioavailability (≈20% for oil suspension). Besides, the emulsification improved the amount of bioavailable nobiletin and its major metabolite in the blood by about two times, as compared to an oil suspension. This work provides scientific insights into a rapid screening method for delivery systems and a better understanding of the biological fate of nobiletin in vivo.

Comparative Analyses of Bioavailability, Biotransformation, and Excretion of Nobiletin in Lean and Obese Rats

Nobiletin, one of the prevalent polymethoxyflavones in citrus peels, was reported to possess various health benefits. We conducted the excretion study and pharmacokinetics study of nobiletin via oral administration and intravenous injection and 15 day consecutive dosing study using the high fat diet-induced obese rats and their lean counterparts. By comparing the demethylated metabolite profiles in the urine and feces, gut microbiota demonstrated greater biotransformation activity on nobiletin than the host. The absolute oral bioavailability of nobiletin in lean (22.37% ± 4.52%) and obese (18.67% ± 4.80%) rats has a negligible statistically significant difference (P > 0.05). However, a higher extent of demethylated metabolites was found in the feces and plasma of obese rats than lean rats (P < 0.05). Moreover, the consecutive dosing of nobiletin might lead to a higher extent of demethylated metabolites in the plasma and in feces. These results suggested that gut microbiota played important roles in nobiletin metabolism.

Simultaneous determination of 14 bioactive citrus flavonoids using thin-layer chromatography combined with surface enhanced Raman spectroscopy

Citrus flavonoids consist of diverse analogs and possess various health-promoting effects dramatically depending on their chemical structures. Since different flavonoids usually co-exist in real samples, it's necessary to develop rapid and efficient methods for simultaneous determination of multiple flavonoids. Thin layer chromatography combined with surface enhanced Raman spectroscopy (TLC-SERS) was established to simultaneously separate and detect 14 citrus flavonoids for the first time. These target compounds could be characterized and discriminated when paired with SERS at 6-500 times greater the sensitivity than TLC alone. TLC-SERS exhibited high recovery rates (91.5-121.7%) with relative standard deviation lower than 20.8%. Moreover, the established TLC-SERS method was successfully used to simultaneously detect multiple flavonoids in real samples, which exhibited comparable accuracy to high performance liquid chromatography with shorter analytical time (10 vs 45 min). All the results demonstrated that this could be a promising method for simultaneous, rapid, sensitive and accurate detection of flavonoids.

Beneficial Regulatory Effects of Polymethoxyflavone-Rich Fraction from Ougan (Citrus reticulata cv. Suavissima) Fruit on Gut Microbiota and Identification of Its Intestinal Metabolites in Mice

Polymethoxyflavones (PMFs) are special flavonoids in citrus fruits that have been suggested to be beneficial to human health. However, whether PMFs in citrus fruit alter human gut microbiota is not well understood. The aim of the present study was to investigate the effects of PMF-rich fraction from Ougan (Citrus reticulata cv. Suavissima) on gut microbiota and evaluate the intestinal metabolic profile of PMFs in Institute of Cancer Research mice. The main components of the PMF-rich fraction were nobiletin, tangeretin, and 5-demethylnobiletin. The composition of the gut microbiota was analyzed using 16S ribosomal DNA sequencing. The results showed that after oral administration, the composition of mice gut microbiota was significantly altered. The relative abundance of two probiotics, Lactobacillus and Bifidobacterium, were found to increase significantly. A total of 21 metabolites of PMFs were detected in mice intestinal content by high performance liquid chromatography electrospray ionization tandem mass spectrometry, and they were generated through demethylation, demethoxylation, hydroxylation, and glucuronidation. Our results provided evidence that PMFs have potential beneficial regulatory effects on gut microbiota that in turn metabolize PMFs, which warrants further investigation in human clinical trials.

Identification of Xanthomicrol as a Major Metabolite of 5-Demethyltangeretin in Mouse Gastrointestinal Tract and Its Inhibitory Effects on Colon Cancer Cells

5-Demethyltangeretin (5DT) is a unique polymethoxyflavone mainly found in the peel of citrus, and has shown potent suppressive effects on multiple human cancer cells. Biotransformation plays a critical role in the biological activities of dietary bioactive components because their metabolites may exert significant bioactivities. In the present study, the metabolic fate of 5DT in mouse gastrointestinal (GI) tract after long-term oral intake and the anti-cancer effects of its major metabolite were determined. It was found that 5DT underwent extensive biotransformation after oral ingestion in mice. A major demethylated metabolite was produced via phase I metabolism, while conjugates (glucuronide and sulfate) were generated via phase II metabolism. Specifically, 4'-position on the B ring of 5DT was the major site for demethylation reaction, which led to the production of xanthomicrol (XAN) as a major metabolite. More importantly, the level of XAN in the colon was significantly higher than that of 5DT in 5DT-fed mice. Thus, we further determined the suppressive effects of XAN on human colon cancer HCT116 cells. We found that XAN effectively inhibited the proliferation of HCT116 cells by arresting cell cycle and inducing cellular apoptosis, which was further evidenced by upregulated p53 and p21 and downregulated cyclin D and CDK4/6 level. In conclusion, this study identified XAN as a major metabolite of 5DT in mouse GI tract, and demonstrated its suppressive effects on HCT116 colon cancer cells.

Nobiletin Protects against Acute Liver Injury via Targeting c-Jun N-Terminal Kinase (JNK)-Induced Apoptosis of Hepatocytes

Acute liver injury resulting from several factors such as medication, food toxins, and herbal supplementation often leads to a severe health condition and makes treatment difficult; thereby, the prevention of acute liver injury remains a critical issue and is of great importance. In this study, we investigated the preventive effects of nobiletin (NOB) on a mouse model of concanavalin A (ConA)-induced acute liver injury. We observed that NOB (10 mg/kg) pretreatment of ConA-treated mice significantly lowered the levels of liver enzymes including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), decreased the intracellular generation of reactive oxygen species (ROS), and suppressed the release of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). Pathological data suggested that pretreatment with NOB ameliorated ConA-induced liver damage by promoting proliferation and alleviating apoptosis of hepatocytes. Furthermore, significant suppression of the c-Jun-activating kinase (JNK) signal was also observed in NOB-pretreated liver tissues compared with that of ConA treatment only. In addition, an in vitro mechanism study confirmed that the addition of NOB protected hepatocytes via inhibition of JNK activation, manifesting that alleviation of JNK-induced apoptosis of hepatocytes is correlated with NOB protection in acute liver injury.

Apoptosis Exerts a Vital Role in the Treatment of Colitis-Associated Cancer by Herbal Medicine

Colitis-associated cancer (CAC) is known as inflammatory bowel disease (IBD)-developed colorectal cancer, the pathogenesis of which involves the occurrence of apoptosis. Western drugs clinically applied to CAC are often single-targeted and exert many adverse reactions after long-term administration, so it is urgent to develop new drugs for the treatment of CAC. Herbal medicines commonly have multiple components with multiple targets, and most of them are low-toxicity. Some herbal medicines have been reported to ameliorate CAC through inducing apoptosis, but there is still a lack of systematic review. In this work, we reviewed articles published in Sci Finder, Web of Science, PubMed, Google Scholar, CNKI, and other databases in recent years by setting the keywords as apoptosis in combination with colitis-associated cancer. We summarized the herbal medicine extracts or their compounds that can prevent CAC by modulating apoptosis and analyzed the mechanism of action. The results show the following. (1) Herbal medicines regulate both the mitochondrial apoptosis pathway and death receptor apoptosis pathway. (2) Herbal medicines modulate the above two apoptotic pathways by affecting signal transductions of IL-6/STAT3, MAPK/NF-κ B, Oxidative stress, Non-canonical TGF-β1, WNT/β-catenin, and Cell cycle, thereby ameliorating CAC. We conclude that following. (1) Studies on the role of herbal medicine in regulating apoptosis through the Ras/Raf/ERK, WNT/β-catenin, and Cell cycle pathways have not yet been carried out in sufficient depth. (2) The active constituents of reported anti-CAC herbal medicine mainly include polyphenols, terpenoids, and saccharide. Also, we identified other herbal medicines with the constituents mentioned above as their main components, aiming to provide a reference for the clinical use of herbal medicine in the treatment of CAC. (3) New dosage forms can be utilized to elevate the targeting and reduce the toxicity of herbal medicine.

Nobiletin Attenuates DSS-Induced Intestinal Barrier Damage through the HNF4α-Claudin-7 Signaling Pathway

The intestinal epithelium barrier functions to protect human bodies from damages such as harmful microorganisms, antigens, and toxins. In this study, we evaluated the protective effect and molecular mechanism of a dominant polymethoxyflavone nobiletin (NOB) from tangerine peels on intestinal epithelial integrity. The results from transepithelial electrical resistance (TEER) suggested that NOB pretreatment counteracts epithelial injury induced by inflammatory cytokines (TEER value in 48 h: vehicle, 135.6 ± 3.9 Ω/cm²; TNF-α + IL-1β, 90.7 ± 0.5 Ω/cm²; 10 μM NOB + TNF-α + IL-1β, 126.1 ± 0.8 Ω/cm²; 100 μM NOB + TNF-α + IL-1β, 125.3 ± 0.5 Ω/cm². P < 0.001). Clinical and pathological test results suggested that administration of NOB effectively alleviates intestinal barrier injury induced by dextran sulfate sodium (DSS) as evidenced by the length of colon villi on day 7 (control, 253.7 ± 4.8 μm, DSS 131.6 ± 4.6 μm, NOB + DSS, 234.5 ± 5.1 μm. P < 0.001). Interestingly, when screening tight junction molecules for intestinal barrier integrity, we observed that independent treatment with NOB sharply increased claudin-7 levels (ratio of claudin-7 over GAPDH: control, 1.0 ± 0.06; DSS, 0.02 ± 0.001; NOB + DSS, 0.3 ± 0.07. P < 0.001), which was previously suppressed upon DSS stimulation. Furthermore, hepatocyte nuclear factor 4α (HNF-4α) transcriptional regulation of claudin-7 contributed to intestinal barrier homeostasis. Therefore, our study suggests potential intestinal protective strategies based on polymethoxyflavones of aged tangerine peels.

In-vivo biotransformation of citrus functional components and their effects on health

Citrus, one of the most popular fruits worldwide, contains various functional components, including flavonoids, dietary fibers (DFs), essential oils (EOs), synephrines, limonoids, and carotenoids. The functional components of citrus attract special attention due to their health-promoting effects. Food components undergo complex biotransformation by host itself and the gut microbiota after oral intake, which alters their bioaccessibility, bioavailability, and bioactivity in the host body. To better understand the health effects of citrus fruits, it is important to understand the in-vivo biotransformation of citrus functional components. We reviewed the biotransformation of citrus functional components (flavonoids, DFs, EOs, synephrines, limonoids, and carotenoids) in the body from their intake to excretion. In addition, we described the importance of biotransformation in terms of health effects. This review would facilitate mechanistic understanding of the health-promoting effect of citrus and its functional components, and also provide guidance for the development of health-promoting foods based on citrus and its functional components.

Heart structure, serum cholesterol, and adiposity of rats treated with a hypercaloric diet: effectiveness of Citrus sinensis (L.) Osbeck and swimming

Abstract This study evaluated the effects of the herbal medicine red orange (Citrus sinensis (L.) Osbeck) and swimming for 84 days on the animal, heart, and abdominal fat weight and the histomorphometric aspects of heart and total cholesterol of Wistar rats. The rats were divided into seven experimental groups of 12 animals each, consisting of a normocaloric diet (Dn), hypercaloric diet (Dh), normocaloric diet and herbal medicine (DnH), hypercaloric diet and herbal medicine (DhH), normocaloric diet and swimming (DnS), hypercaloric diet and swimming (DhS), and hypercaloric diet, swimming, and herbal medicine (DhSH). The data were analyzed statistically by the Tukey test and considered significant when p<0.05. Groups treated with the normocaloric diet had lower abdominal fat weight. The normocaloric diet and herbal medicine (DnH) provided the smallest thickness of the right ventricle. The hypercaloric diet (Dh) reduced the number of cardiomyocytes and the perimeter of cardiac muscle fibers. Swimming and the red orange extract acted synergistically by reducing the deleterious effects of the hypercaloric diet and increasing the thickness of the cardiac chambers and the number of cardiomyocytes. Only the supplementation with the red orange extract did not reduce abdominal fat in rats treated with a hypercaloric diet. Therefore, red orange alone did not promote beneficial changes in the studied data, but its association with swimming increased the number of cardiomyocytes and thickness of muscle fibers, which could contribute to preventing cardiovascular diseases and maintaining health, as well as the regular swimming and a normocaloric diet, which provided less adiposity.

Integrating Pharmacology and Gut Microbiota Analysis to Explore the Mechanism of Citri Reticulatae Pericarpium Against Reserpine-Induced Spleen Deficiency in Rats

Citri Reticulatae Pericarpium (CRP), dried peels of Citrus reticulata Blanco and its cultivars, is an important traditional Chinese medicine for the treatment of spleen deficiency-related diseases. To date, the mechanism of CRP alleviating spleen deficiency has not been well investigated. This study aimed to explore corresponding mechanisms with integrating pharmacology and gut microbiota analysis. Firstly, the therapeutic effects of CRP against spleen deficiency were evaluated in reserpine-treated rats. CRP was found to effectively relieve the typical symptoms of spleen deficiency, including poor digestion and absorption capacity, and disorder in gastrointestinal hormones, immune cytokines and oxidative stress. Secondly, high throughput 16S rRNA gene sequencing revealed that CRP could not only up-regulate some short-chain fatty acids producing and anti-inflammatory bacteria but also down-regulate certain spleen deficiency aggravated related bacteria, eventually led to the rebalance of gut microbiota in spleen deficiency rats. In addition, a total of 49 compounds derived from CRP were identified in rat urine using ultra-high performance liquid chromatography-quadrupole- time of flight tandem mass spectrometry. Network pharmacology analysis showed that apigenin, luteolin, naringenin, hesperidin, hesperetin, homoeriodictyol, dihydroxy-tetramethoxyflavone, and monohydroxy-tetramethoxyflavone were the core bioactive components for CRP against spleen deficiency. Further Gene Ontology analysis and pathway enrichment suggested that therapeutic effects of CRP against spleen deficiency involved multiple pathways such as tumor necrosis factor signaling, hypoxia-inducible factor-1 signaling and Toll-like receptor signaling pathway. These results would help to understand the mechanism of CRP alleviating spleen deficiency and provide a reference for further studies.

Aged citrus peel (chenpi) extract causes dynamic alteration of colonic microbiota in high-fat diet induced obese mice

Aged citrus peels (chenpi) have been used as a dietary supplement for gastrointestinal health maintenance in China.

Transdermal delivery of nobiletin using ionic liquids

Nobiletin (NOB), a flavonoid, has extremely low water solubility and low oral bioavailability; however, despite these problems, various physiological effects have been investigated in vitro. In the present study, we investigated the transdermal delivery of NOB using choline and geranic acid (CAGE), which is a biocompatible material that has been reported to be a promising transdermal delivery approach. The feasibility was evaluated by a set of in vitro and in vivo tests. A solubility evaluation demonstrated that CAGE induced excellent solubility of NOB induced by multipoint hydrogen bonding between NOB and CAGE. In vitro transdermal tests using a Franz diffusion cell showed that CAGE was effective in enhancing transdermal absorption of NOB, compared to other penetration enhancers. Subsequent in vivo tests demonstrated that CAGE significantly improved area under the concentration-time curve of NOB in vivo and NOB/CAGE sample showed 20-times higher bioavailability than oral administration of NOB crystal. Furthermore, NOB/CAGE sample also showed significant drops of the blood glucose level in rats derived from hypoglycemic activity of NOB. Thus, transdermal administration of NOB using CAGE was shown to be feasible, which indicates that the use of CAGE may be adapted for other flavonoids that also show both low water solubility and low permeability.

Characterization of polymethoxyflavone demethylation during drying processes of citrus peels

Polymethoxyflavones (PMFs) are found almost exclusively in citrus peel and have attracted much attention due to their potential health benefits. Dried citrus peel is an important ingredient for applications in food and traditional Chinese medicine. However, the structural changes of PMFs during drying processes of citrus peel remain unknown. In this study, for the first time we discovered that four major permethoxylated PMFs, i.e. sinensetin, nobiletin, heptamethoxyflavone and tangeretin, underwent demethylation at the 5-position on the A ring of their flavonoid structures to yield corresponding 5-demethylated PMFs during the drying process of citrus peel. Our results further demonstrated that the aforementioned PMF demethylation was through two mechanisms: acid hydrolysis and enzyme-mediated catalysis. PMF demethylation in citrus peels was systematically characterized during hot-air drying (HAD), vacuum-freeze drying (VFD) and sun drying (SD). The highest PMF demethylation was obtained in SD followed by HAD and VFD. This study provided a solid scientific basis for rational control of PMF demethylation in citrus peels, which could facilitate the production of high-quality citrus peel and related products.

Nanoparticle Encapsulation Strategy: Leveraging Plant Exine Capsules Used as Secondary Capping for Oral Delivery

Protein-based nanoparticles (NPs) with favorable properties including enhanced absorptivity and low toxicity still suffer a major challenge for rapid nutraceutical or drug release after oral administration. Hence, we introduced a secondary encapsulation for unstable factor to attain a controlled-release effect in a gastrointestinal environment. In this work, assembled nanoparticles engineered by nobiletin (NOB), zein, and tannin acid (TA) were first reported for drug delivery systems. The TA added was capable of obtaining further assembly to stabilize nobiletin in comparison with NOB-loaded zein NPs only. Sunflower pollens (SPGs) were selected as carriers for further oral delivery, while zein was chosen as a coating material for capping SPGs absolutely. As a result, the NOB/zein/TA NPs (NZT NPs) obtained had a stable size of 100 nm after 48 h. Besides, they could improve the chemical stability of NOB for at least 120 days at 4 °C compared with zein NPs (ZT NPs). Owing to the secondary capping by SPGs, the final system was able to release selectively via an oral route, that is, achieving no release in a gastric environment and slow release in an intestine environment. Generally, our research proposed a secondary protection model to prevent drug-loaded NPs from resolving after oral administration, which provided a new perspective for nutraceutical or drug encapsulation and controlled-release delivery.