Search Results (486)

Salt stress is a major abiotic stress that threatens citrus yield and quality. To elucidate the molecular mechanisms underlying differential salt tolerance in citrus rootstocks, we performed an integrative transcriptomic and metabolomic analysis of salt-sensitive trifoliate orange (Poncirus trifoliata) and salt-tolerant Goutoucheng (Citrus aurantium) under 60 mM NaCl treatment for 12 h and 24 h. Physiological observations confirmed that Goutoucheng exhibited less growth inhibition and leaf damage than trifoliate orange. Transcriptome sequencing identified 2081 and 1588 differentially expressed genes (DEGs) in trifoliate orange at 12 h and 24 h, respectively, compared with 1166 and 997 DEGs in Goutoucheng. Metabolome profiling revealed 217 and 173 differentially accumulated metabolites (DAMs) in trifoliate orange versus 162 and 239 DAMs in Goutoucheng at the two time points. KEGG pathway analysis showed that DEGs were mainly enriched in the Mitogen-activated protein kinase (MAPK) signaling pathway—plant, plant hormone signal transduction, and flavonoid biosynthesis—and DAMs were mainly enriched in flavonoid biosynthesis, starch and sucrose metabolism, and glutathione metabolism. Integrative nine-quadrant and two-way orthogonal partial least squares analyses further pinpointed flavonoid biosynthesis as a central hub in salt response. Notably, quercetin derivatives accumulated preferentially in the salt-tolerant rootstock Goutoucheng. Several transcription factor families—including HSF, MYB, NAC, HB-HD-ZIP, C2H2, bHLH, AP2/ERF, and Trihelix—may enhance antioxidant capacity under salt stress by regulating flavonoid accumulation. Collectively, these results indicated that coordinated regulation of flavonoids contributed critically to salt stress adaptation in citrus rootstocks. The identified DEGs, DAMs, and transcription factors provide candidate targets for genetic improvement of salt tolerance in citrus. Full article

Breast cancer remains one of the most frequently diagnosed malignancies and a leading cause of cancer-related mortality among women worldwide. The growing interest in natural bioactive compounds has highlighted plant-derived phytochemicals as promising agents for cancer prevention and adjunctive therapy due to their pleiotropic biological activities and relatively low toxicity. In parallel, increasing attention has been directed toward agro-industrial by-products generated during food processing, which represent abundant and sustainable sources of valuable phytochemicals. This review provides a comprehensive overview of recent advances in the identification, extraction, and biological evaluation of phytochemicals derived from plants and agro-industrial residues, using pomegranate (Punica granatum) peels, onion (Allium cepa) skins, and citrus by-products as representative examples of phytochemical-rich agro-industrial residues. These by-products are rich in polyphenols, flavonoids, and other secondary metabolites—including punicalagins, ellagic acid, quercetin, hesperidin, and naringin—that have demonstrated significant antioxidant, anti-inflammatory, and anticancer properties. Recent in vitro and in vivo studies indicate that these compounds can modulate key molecular pathways involved in breast cancer initiation and progression, such as oxidative stress regulation, apoptosis induction, inhibition of cell proliferation, and suppression of signaling cascades including PI3K/Akt, NF-κB, and MAPK pathways. Furthermore, the valorization of agro-industrial waste offers a sustainable strategy to recover high-value bioactive compounds while reducing environmental impact. Overall, phytochemicals obtained from plant materials and food processing by-products represent promising functional agents for breast cancer prevention and therapy, although further studies are required to improve bioavailability, elucidate mechanisms of action, and validate their clinical potential. Full article

Ougan (Citrus suavissima Hort. et Tanaka) is valued for its distinctive sweet–bitter flavor and nutritional properties; however, tissue-resolved metabolic differences between two cultivar forms (seeded and seedless) of Ougan (C. suavissima) remains poorly understood. In this study, a comprehensive UPLC-MS/MS-based metabolomic analysis was conducted on peel (SP and NP), pulp (SF and NF), segment membrane (SM and NM) and seed tissues (SS, from seeded fruit only) of seeded and seedless Ougan fruits. A total of 1333 metabolites were annotated, with flavonoids (48.53%) and phenolics (12.25%) representing the predominant compound classes. Tissues specificity was the primary determinant of metabolic variation, with peel and segment membrane tissue showing relatively high abundance (fold change ≥ 2, |Log₂FC| ≥ 1) of phenylpropanoid- and flavonoid-derived metabolites. Comparative analysis between seeded and seedless tissues revealed significant modulation of phenylpropanoid biosynthesis, flavonoid biosynthesis, phenylalanine metabolism, and related secondary metabolite pathways. Seeded tissues showed a higher relative abundance of selected flavonol glycosides (6-hydroxykaempferol-3,6-O-diglucoside), hydroxycinnamic acid derivatives, and santhocyanin-related compounds, whereas seedless tissues showed higher relative abundance of selected flavanones and malonylated flavonoid glycosides. Seeds were characterized by high limonin content, consistent with limonoid-associated bitterness chemistry. Overall, our findings provide a tissue-resolved metabolomic framework for understanding quality-associated secondary metabolite variation in mature Ougan fruit. Full article

Background: Ensuring authenticity and verifying the floral origin of honey are persistent and critical issues in the quality control of bee products; in particular, the characteristic components and practical authenticity evaluation standards of several specialty fruit monofloral honeys are still insufficiently defined. Methods: To address this, we conducted a comparative analysis of five fruit monofloral honey (loquat, pomegranate, citrus, apple, and blueberry) phytochemicals using high-performance liquid chromatography (HPLC), liquid chromatography–mass spectrometry (LC-MS), and the Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine (TCM). Results: Based on the currently available literature and databases, eleven identified phytochemicals appear to be reported in honey for the first time, including quinic acid derivatives, phenolamides, and flavonoid glycosides. Characteristic components with high species dependence were identified in distinct honey samples: anisic acid in loquat honey; methyl syringate in pomegranate honey; caffeine in citrus honey; cinnamic acid and methyl syringate in apple honey; and phaseic acid, methyl syringate, isorhamnetin-3-O-neohesperidoside, and callunene in blueberry honey. Twenty-three commercial samples were collected from the retail market to assess authenticity using HPLC fingerprints and quantitative thresholds for characteristic components. Authenticity was assessed based on both chromatographic fingerprint similarity and the content thresholds of characteristic phytochemicals specific to each monofloral honey type. The results indicated that 19 commercial samples satisfied the proposed authenticity criteria, whereas four commercial samples showed inconsistencies in characteristic phytochemical profiles or fingerprint similarity. Conclusions: This research establishes reliable chemical markers and a quantitative method to assess the authentication of five monofloral honeys, supporting high-value product development. Full article

The rising threat of antimicrobial resistance necessitates the search for novel bioactive molecules from natural sources. This study investigated the phytochemical composition, antibacterial potency, and molecular docking interactions of Citrus aurantium peel ethanol extract against Escherichia coli outer-membrane and topoisomerase proteins and Staphylococcus aureus toxins as drug target proteins. Qualitative and quantitative phytochemical compositions were examined using standard analytical methods, chemical compounds were evaluated and qualified using Gas Chromatography–Mass Spectrometry (GC-MS), and antibacterial effects were investigated in silico and validated in vitro. Qualitative and quantitative analyses revealed high concentrations of flavonoids (4.54 ± 0.11%), alkaloids (1.6 ± 0.03%), terpenoids (1.35 ± 0.01%), tannins (1.02 ± 0.05%), phenols (0.97 ± 0.07%), and saponins (0.80 ± 0.01%). GC–MS profiling identified several dominant compounds, including β-D-glucopyranose, neo-inositol, 8-(2,3-dihydroxy-3-methylbutyl)-7-methoxy-2H-chromen-2-one, and D-allose. In silico docking studies against bacterial druggable proteins (PDB IDs: 4C56 and 3MFG, which are S. aureus toxins; 1BXW and 3FV5, which are E. coli outer-membrane and topoisomerase proteins) revealed strong binding affinities (−6.477 to −8.774 kcal/mol), comparable to standard antibiotics. ADMET predictions confirmed favorable pharmacokinetic and safety profiles, with most lead compounds displaying high intestinal absorption, low hepatotoxicity, and compliance with Lipinski’s rule of five. The extract exhibited stronger antibacterial activity, producing inhibition zones of 25.11 ± 0.017 and 23.04 ± 0.25 mm against clinical isolates of S. aureus and E. coli, respectively, at a concentration of 10 mg/mL, comparable to ciprofloxacin (30.35 ± 0.26 mm). These findings highlight C. aurantium peel phytoconstituents as promising scaffolds for antibacterial drug development and justify further in vivo validation for combating multidrug-resistant pathogens. Full article

Citrus flavonoid intake is associated with beneficial effects on endothelial function. Our previous randomized control trial demonstrated that the concentration of Hesperetin-7-O-glucuronide (H7G) was positively correlated with the improvement in endothelial function in overweight and obese participants following blood orange juice consumption. To explore the underlying mechanism by which H7G improves endothelial function, we investigated the regulation of H7G on endothelial function in a permanent human endothelial cell line (EA. hy926 cells) under normal and oxidative conditions treated with high-oxidation low-density lipoprotein. The results indicated that H7G improved the expression of nitric oxide synthase 3 (NOS3), heme oxygenase 1 (HMOX1) ad glutamate cysteine ligase catalytic (GCLC), and inhibited the expression of endothelin-1 (EDN1), through the upregulation of miR-660-5p and inhibition of miR-21-5p. In summary, H7G improves endothelial cell function via the upregulation of miR-660-5p and the inhibition of miR-21-5p. Full article

Huanglongbing (HLB), primarily caused by ‘Candidatus Liberibacter asiaticus’ (CLas), threatens global citrus production. Deciphering the molecular interplay between citrus and CLas is crucial for successful control. This review synthesizes current understanding of the molecular mechanisms underlying citrus-CLas interactions, providing a comprehensive overview that spans immune signaling, hormonal and metabolic reprogramming, non-coding RNA-mediated regulation, pathogen effector biology, and emerging biotechnological interventions. We detail the hierarchical host response: initial immune recognition via pattern recognition receptors, triggering reactive oxygen species bursts and calcium signaling. Moreover, hormonal network reprogramming and their complex interplay in defense/susceptibility are examined. Transcriptomic studies have revealed key features of metabolic reprogramming, including suppression of photosynthesis and impairment of phloem function. Additionally, long-term strategies like cell wall reinforcement, accumulation of defensive compounds such as flavonoids and terpenoids, and roles of post-transcriptional regulation of microRNAs are discussed. Conversely, CLas counter-defense, notably effector-mediated immunity suppression and host metabolism manipulation, is also considered. Comparative transcriptomics between tolerant and susceptible varieties identifies tolerance or resistance genes/pathways for breeding and engineering. Despite this progress, critical knowledge gaps remain, particularly regarding the precise molecular mechanisms of CLas immune evasion and effector-mediated suppression, the genetic basis of natural tolerance, and the field-level efficacy of defense priming strategies. Future research directions should integrate single-cell omics, CRISPR/Cas9 editing, nano-enabled delivery, and microbiome engineering to bridge these gaps and accelerate HLB-tolerant/resistant citrus development. This review synthesizes how molecular profiling advances understanding of citrus defense mechanisms against HLB, and underscores the imperative for interdisciplinary research and global collaboration. Full article

The development of novel multifunctional emulsifiers using protein–polyphenol interactions is a common strategy. Previously, we investigated the emulsifying properties of the four citrus flavonoids alone. This study investigated how complexing lysozyme (LY) with four citrus-derived flavonoids affects emulsifying properties. Results demonstrated that the emulsification performance was enhanced when flavonoids were complexed with LY, following the order: hesperidin (Hpd) > neohesperidin dihydrochalcone (Neohpddic) > neohesperidin (Neohpd) > hesperetin (Hpt). This enhancement was positively correlated with the intrinsic emulsification abilities of the flavonoids, suggesting that the synergistic effect should not overlook the emulsifying capacity of the flavonoids themselves. The Hpd-LY mixture increased the three-phase contact angle (to near 90°) compared to Hpd alone (51.16° ± 0.58), which helped form high internal phase emulsion (HIPE) gels. Stable HIPEs were achieved at an oil phase fraction φ = 80%, mixture concentration w ≥ 0.8%, and Hpd-to-LY ratio k ≥ 1:1. Droplet size decreased as w increased from 0.6% to 1.2%, but increased with higher φ and k, while gel strength improved. In addition, these HIPEs protected encapsulated lutein and suppressed lipid oxidation. The findings show that flavonoid–protein complexes, especially Hpd-LY, can build stable and functional HIPEs for protecting bioactive compounds. Full article

This study investigated the fermentation kinetics, microbial community succession, and potential functional metabolite formation in Symbiotic culture of bacteria and yeast (SCOBY)-mediated fermentation using pomelo peel substrates. Pomelo peel substrates were prepared using 1% and 6% (w/w) SCOBY combined with 10 g and 25 g pomelo peel and fermented at 30 °C for 25 days. The results showed that higher SCOBY inoculum significantly accelerated acid production, resulting in a rapid decrease in pH and an increase in titratable acidity. Total soluble solids continuously decreased due to microbial utilization of sugars. The highest lactic acid bacteria count (6.04 log CFU/mL) and total viable count (7.23 log CFU/mL) were observed in S6-P25 at day 25. Bioactive compound analysis revealed that total flavonoid content reached its maximum in S6-P25 at day 20 (15.34 ± 0.70 mg RE/g dry weight, DW), while the highest total phenolic content was found in S1-P25 (151.5 ± 1.29 mg GAE/g DW), suggesting that a lower SCOBY level may favor polyphenol production. Antioxidant activity (DPPH and TEAC) increased with fermentation time and was highest in S6-P25. Microbiome analysis demonstrated that Firmicutes was the dominant phylum, with Apilactobacillus ozensis accounting for 99% of the relative abundance, indicating strong microbial selection and its potential role in acid production and fermentation ability. This microbial structure was consistent with the improved fermentation performance and enhanced bioactive properties observed in the pomelo peel substrates. These findings highlight SCOBY fermentation as a promising biotechnological strategy for converting citrus processing by-products into fermented ingredients for food applications. Full article

Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive stage of metabolic dysfunction-associated steatotic liver disease characterized by lipid dysregulation, oxidative stress, inflammation, and fibrosis. Because these processes occur simultaneously, compounds targeting multiple pathways may offer therapeutic benefit. Naringin, a citrus-derived flavonoid, has reported antioxidant and anti-inflammatory properties, but its integrated effects in MASH remain unclear. In this study, the effects of naringin were evaluated using combined in silico analysis and in vivo experiments. Network pharmacology and molecular docking predicted targets related to lipid metabolism, oxidative stress, inflammation, and fibrosis, which were validated in a methionine- and choline-deficient diet-induced mouse model. Naringin reduced hepatic lipid accumulation and improved serum AST and ALT levels. It modulated oxidative stress-related genes, attenuated inflammatory responses, and reduced fibrogenic markers. Naringin also decreased Ly6Chigh inflammatory monocytes and Kupffer cell activation, and reduced hypothalamic microglial activation. These findings suggest that naringin exerts multi-target effects across hepatic, systemic, and central pathways, supporting its potential as a therapeutic candidate for MASH. Full article

Hesperidin, a flavonoid abundantly found in citrus fruits, has demonstrated a substantial role in the management of various pathogeneses. Furthermore, the wide range of health-promoting properties of hesperidin, including antioxidant, anti-inflammatory, anti-cancerous, hepatoprotective, neuroprotective, nephroprotective, and cardioprotective effects, has been well documented. Additionally, persuasive evidence from both in vivo and in vitro studies highlights its substantial roles in combating obesity, protecting the kidneys, liver, and lung tissue architecture, promoting wound healing, and modulating immune responses. This flavonoid acts as an effective antimicrobial agent against a wide range of microorganisms by inhibiting biofilm formation and disrupting the cell membrane. This review aims to deliver comprehensive insights into the therapeutic potential of hesperidin across different pathogenesis through distinct mechanisms. Moreover, it provides up-to-date evidence on the synergistic properties of this compound with other drugs as well as compounds, and emerging plans to enhance its efficiency in health management through various nanoformulation approaches. Despite its considerable therapeutic potential, the clinical application of hesperidin remains constrained by poor bioavailability, rapid degradation, and dosage-related limitations. Addressing these challenges will require extensive further research to clarify its mechanisms of action, safety profile, and therapeutic efficacy in managing underlying pathogenic conditions. Full article

Cover crops are crucial in conservation agriculture for preventing soil erosion. For Citrus unshiu production, rattail fescue (Vulpia myuros (L.) C.C. Gmel) is a popular cover crop because its growth season differs from the citrus season, minimizing nutrient competition. However, no studies have examined its effects on the seasonal concentrations of flavonoids and monoterpenes in citrus peels, which are often used as medical ingredients. In this study, our aim is to determine the effects of cover crops on the sugar content and medicinal properties of unripe citrus fruit during the growing season. Samples collected in 2022 were examined for the effects of cover crops on the sugar concentration of fresh pulp. In addition, samples were taken from three randomly selected trees in each cover crop treatment (0, 50, and 100% area coverage) at the thinning (July, August, and September) of 2023 and 2024 to analyze hesperidin and d-limonene concentrations using standard methods. The results showed that cover crops reduced the sugar concentration of fresh pulp but had no impact on hesperidin concentrations across all thinning events and had inconsistent effects on the d-limonene concentration. Hence, while the use of rattail fescue might negatively affect the sugar concentration of mature Citrus unshiu, the use of premature fruits for medical ingredients could compensate for this loss. Full article

Citrus genomes as storehouses of genetic information of immense commercial utility remain untapped for the improvement of fruit quality traits and other production-related stresses. With the rapid expansion of transcriptomic datasets, integrative meta-analysis has further aided in uncovering interspecies molecular mechanisms associated with fruit quality development. In this study, we performed a cross-project RNA-Seq meta-analysis, integrating multiple publicly available BioProjects encompassing diverse citrus species, viz., Citrus sinensis, C. reticulata, C. maxima, C. clementina, C. japonica, and C. papeda, known to dominate the morphogenetic evolution of the citrus industry. High-throughput RNA-Seq data were processed using various bioinformatics tools. A total of 15 interspecies comparisons identified 676 unique DEGs, enriched in pathways related to secondary juice yield and processing quality traits. We also established that domestication aided in metabolism, oxidative stress responses, phenylpropanoid and flavonoid biosynthesis, and hormone-mediated signaling. Multivariate analyses (PCA and heatmap visualization) highlighted distinct yet overlapping expression patterns across these citrus species. By combining differential expression, co-expression network analysis and QTL-GWAS integration, we identified 19 high-confidence candidate genes responsible for transcriptomic variation associated with measurable fruit quality traits. Genes such as LOC102612823 and LOC102607495, which co-localized with seed number QTLs on chromosome 1, represented strong candidates regulating reproductive development and seed formation, the traits that directly influence fruit texture and market acceptability. Genes linked to juice content QTLs, including LOC102611137 and LOC102612553 on chromosome 5, suggested their roles in metabolic regulations behind juice accumulation. These loci provided definitive breeding clues for enhancing the reshaping of citrus fruit transcriptomes while retaining key ancestral regulatory components. Full article

Background/Objectives: Citrus peels are widely utilized as functional ingredients in health foods; however, their functional value is often assumed based on botanical classification rather than verified chemical composition. Bushukan (Citrus medica var. sarcodactylis) was selected as it lacks developed edible pulp; consequently, the usable portion consists almost entirely of peel tissue, making it a suitable model for evaluating peel-specific functional components. This commentary highlights the importance of species- and origin-specific evaluation through a case study of Bushukan (Citrus medica var. sarcodactylis) whole fruit powder cultivated in Japan. Methods: Dried whole-fruit powder samples of bushukan, prepared by freeze-drying and hot-air drying at 50 °C, were analyzed, and the contents of hesperidin and nobiletin were quantified using high-performance liquid chromatography (HPLC) following methanol reflux extraction. Results: Hesperidin was detected at 75 mg/100 g under both drying conditions, whereas nobiletin was below the practical limit of quantification (approximately 1 mg/100 g). No reduction in hesperidin content was observed after drying at 50 °C. These levels were markedly lower than those reported for commonly used citrus peels, such as satsuma mandarin, in previous studies. Conclusions: This commentary demonstrates that Japanese-grown bushukan samples do not necessarily provide substantial levels of commonly expected citrus flavonoids. These findings underscore the need for species- and origin-specific compositional verification before the use of citrus peels as raw materials for health food applications, illustrating this need through a practical, cautionary case study. Full article

Excessive acidity restricts the utilization of citrus pulp, a major by-product of the dried tangerine peel industry. To overcome this bottleneck, a functional microbial consortium (BsHpMrF) comprising Bacillus subtilis L4, Hanseniaspora pseudoguilliermondii B4, and Monascus ruber CGMCC 10910 was constructed for efficient biological deacidification. The consortium exhibited a synergistic effect, achieving an 88.23% reduction in total acidity and converting the acidic pulp into a neutral, bio-stabilized substrate. Untargeted metabolomics analysis revealed that this efficiency was driven by the concurrent activation of the TCA cycle and glyoxylate shunt for organic acid mineralization, coupled with membrane lipid remodeling (increased unsaturation) to enhance acid tolerance. Notably, the fermentation process functioned as a “metabolic factory”, significantly enriching the matrix with bioactive lipids (e.g., 10-HDA, nervonic acid) and indole-3-acetic acid (IAA, 414.28 mg/L). Application assays demonstrated that the fermentation products acted as a potent biostimulant for soybean sprouts, significantly promoting lateral roots and eliciting the accumulation of antioxidant phenolics and flavonoids. This study provides a sustainable “waste-to-treasure” strategy, valorizing acidic citrus pulp into a functional biostimulant for high-quality edible sprout production, thereby achieving a sustainable “waste-to-food” circular loop. Full article