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Concept: Osmanthus fragrans

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The 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway is responsible for the biosynthesis of many crucial secondary metabolites, such as carotenoids, monoterpenes, plastoquinone, and tocopherols. In this study, we isolated and identified 10 MEP pathway genes in the important aromatic plant sweet osmanthus (Osmanthus fragrans). Multiple sequence alignments revealed that 10 MEP pathway genes shared high identities with other reported proteins. The genes showed distinctive expression profiles in various tissues, or at different flower stages and diel time points. The qRT-PCR results demonstrated that these genes were highly expressed in inflorescences, which suggested a tissue-specific transcript pattern. Our results also showed that OfDXS1, OfDXS2, and OfHDR1 had a clear diurnal oscillation pattern. The isolation and expression analysis provides a strong foundation for further research on the MEP pathway involved in gene function and molecular evolution, and improves our understanding of the molecular mechanism underlying this pathway in plants.

Concepts: DNA, Gene, Gene expression, Transcription, Molecular biology, Metabolism, Osmanthus fragrans, Osmanthus

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Acteoside and salidroside are major phenylethanoid glycosides (PhGs) in Osmanthus fragrans Lour. flowers with extensive pharmacological activities and poor oral bioavailability. The absorption mechanisms of these two compounds remain unclear. This study aimed to investigate the bioaccessibility of these compounds using an in vitro gastro-intestinal digestion model, and to examine the absorption and transport mechanisms of PhGs using the Caco-2 cell model. The in vitro digestion model revealed that the bioaccessibility of salidroside (98.7±1.35%) was higher than that of acteoside (50.1±3.04%), and the superior bioaccessibility of salidroside can be attributed to its stability. The absorption percentages of total phenylethanoid glycoside, salidroside and acteoside were 1.42-1.54%, 2.10-2.68% and 0.461-0.698% in the Caco-2 model, respectively. Salidroside permeated Caco-2 cell monolayers through passive diffusion. At the concentration of 200 μg/mL, the apparent permeability ( Papp) of salidroside in the basolateral (BL)-to-apical (AP) direction was 23.7±1.33 × 10-7 cm/s, which was 1.09-fold of that in the AP-to-BL direction (21.7±1.38 × 10 -7 cm/s). Acteoside was poorly absorbed with low Papp (AP to BL) (4.75±0.251 × 10 -7 cm/s), and its permeation mechanism was passive diffusion with active efflux mediated by P-glycoprotein (P-gp). This study clarified the bioaccessibility, absorption and transport mechanisms of PhGs. It also demonstrated that the low bioavailability of acteoside might be attributed to its poor bioaccessibility, low absorption and P-gp efflux transporter.

Concepts: Protein, Digestive system, Absorption, Pharmacokinetics, Digestion, Bioavailability, Glycosides, Osmanthus fragrans

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Osmanthus fragrans has been used as folk medicine for thousands of years. The extracts of Osmanthus fragrans flowers were reported to have various bioactivities including free radical scavenging, anti-inflammation, neuroprotection and antitumor effects. However, there is still lack of knowledge about its essential oil.

Concepts: DNA, Radical, Osmanthus fragrans, Osmanthus

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Ripe O. fragrans fruit is composed of purple peels, green pulps and light brown seeds. Since the biological effects such as antioxidative activities and platelet-aggregation inhibition are related to the phenolic compounds and flavonoids in O. fragrans fruits, these components have a great potential as functional food ingredient. In the work, active components in O. fragrans fruits extraction were investigated by HPLC-ESI-MS/MS. A total of twenty-eight compounds were identified and sixteen components were first discovered in O. fragrans fruits, most of which were a series of phenylethanoid glucosides. These compounds are assigned as methyloleoside neonuezhenide and possible fragmentation pathway of mass spectrometry is first elucidated. Additionally, sensitive HPLC-ESI-MS/MS method for five phenylethanoid glycosides of salidroside, acteoside, isoacteoside, neonuezhenide and nuezhenide and two triterpenes of oleanolic acid and ursolic acid has been established for the quality of O. fragrans fruits comprehensively.

Concepts: Mass spectrometry, Fruit, Glycoside, Terpenes and terpenoids, Ursolic acid, Oleanolic acid, Osmanthus fragrans

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Microwave-assisted and ultrasound-assisted extraction assays were used to isolate total flavonoids (TF) from Osmanthus fragrans flowers. The effects of the solid-liquid ratio, ethanol concentration, microwave power, microwave extraction time, ultrasonic power and ultrasonic extraction time on the yield of TF were studied. A sequential combination of microwave- and ultrasound-assisted extraction (SC-MUAE) methods was developed, which was subsequently optimized by Box-Behnken design-response surface methodology (BBD-RSM). The interaction effects of the ethanol concentration (40-60%), microwave extraction time (5-7 min), ultrasonic extraction time (8-12 min) and ultrasonic power (210-430 W) on the yield of TF were investigated. The optimum operating parameters for the extraction of TF were determined to be as follows: ethanol concentration (48.15%), microwave extraction time (6.43 min), ultrasonic extraction time (10.09 min) and ultrasonic power (370.9 W). Under these conditions, the extraction yield of TF was 7.86 mg/g.

Concepts: Interaction, Sequence, Osmanthus fragrans, Osmanthus

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In a greenhouse experiment, five ornamental plants, Osmanthus fragrans (OF), Ligustrum vicaryi L. (LV), Cinnamomum camphora (CC), Loropetalum chinense var. rubrum (LC), and Euonymus japonicas cv. Aureo-mar (EJ), were studied for the ability to phytostabilization for Cd-contaminated soil. The results showed that these five ornamental plants can grow normally when the soil Cd content is less than 24.6 mg·kg(-1). Cd was mainly deposited in the roots of OF, LV, LC and EJ which have grown in Cd-contaminated soils, and the maximum Cd contents reached 15.76, 19.09, 20.59 and 32.91 mg·kg(-1), respectively. For CC, Cd was mainly distributed in the shoots and the maximum Cd content in stems and leaves were 12.5 and 10.71 mg·kg(-1), however, the total amount of Cd in stems and leaves was similar with the other ornamental plants. The enzymatic activities in Cd-contaminated soil were benefited from the five tested ornamental plants remediation. Soil urease and sucrase activities were improved, while dehydrogenase activity was depressed. Meanwhile, the soil microbial community was slightly influenced when soil Cd content is less than 24.6 mg·kg(-1) under five ornamental plants remediation. The results further suggested that ornamental plants could be promising candidates for phytostabilization of Cd-contaminated soil.

Concepts: Photosynthesis, Soil, Zinc, Tree, Shrub, Osmanthus fragrans, Cinnamomum camphora, Loropetalum chinense

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Colonoscopy can be painful and uncomfortable. Aromatherapy is often used for the relief of anxiety or discomfort. Recently, it has been reported that olfactory stimulation induces various physiological effects. We investigated the effects of aromatherapy on anxiety and abdominal discomfort during colonoscopy.

Concepts: Anxiety, Grapefruit, Aromatherapy, Osmanthus fragrans

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This study was aimed at investigating the chemical stability (the thermal, light and pH stability) of phenylethanoid glycosides (PhGs) in Osmanthus fragrans Lour. flowers, identifying the degradation products of acteoside and salidroside (major PhGs in O. fragrans flowers) by UPLC-QTOF-MS and studying the anti-hypoxia activity of PhGs after degradation. The degradation of PhGs followed first-order reaction kinetics, and the rate constant of acteoside (4.3 to 203.4 × 10(-3) day(-1)) was higher than that of salidroside (3.9 to 33.3 × 10(-3) day(-1)) in O. fragrans flowers. Salidroside was mainly hydrolyzed to tyrosol during storage, and the degradation products of acteoside were verbasoside, caffeic acid, isoacteoside, etc. In a model of cobalt chloride (CoCl2)-induced hypoxia in PC12 cells, the anti-hypoxia ability of PhGs decreased after degradation, which resulted from the reduction of PhGs contents. Particularly, caffeic acid exhibited stronger anti-hypoxia ability than acteoside and could slightly increase the anti-hypoxia ability of degraded acteoside. The results revealed that high temperature, high pH and light exposure caused PhGs degradation, and thus the anti-hypoxia ability of PhGs reduced.

Concepts: Acid, PH, Sodium hydroxide, Chemical kinetics, Rate equation, Base, Reaction rate, Osmanthus fragrans

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Oxidative stress can stimulate the secretion of pro-inflammatory cytokines. Interleukin-8 (IL-8) has been implicated in the pathogenesis of inflammatory bowel disease and the metastatic spread of colorectal cancer. The flowers of Osmanthus fragrans (sweet olive) are used to alleviate dysentery with blood in the bowel, as well as stomach ache and diarrhea. However, the evidence of their therapeutic effects on these symptoms remains unclear. In the present study, the protective effects of sweet olive flower ethanolic extract (OFE) against oxidative stress in WiDr cells was assessed by evaluating its 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. In addition, cellular IL-8 secretion was evaluated. Notably, high-performance liquid chromatography showed verbascoside to be the primary constituent in OFE; it exhibited a DPPH scavenging activity with an IC50 of 8.23 μg/mL. Moreover, OFE (1 to 100 μg/mL) showed a potent, dose-dependent inhibitory effect on H2 O2 -induced IL-8 secretion in WiDr cells. Nine compounds were isolated from OFE based on a protective effect-guided purification process. Of these compounds, 5 phenolic compounds-verbascoside, phillygenin, tyrosol, methyl 4-hydroxycinnamate, and eutigoside A-reduced IL-8 secretion at 10 μg/mL treatment concentrations. Further analysis showed that the anti-inflammatory effects of OFE likely occurred via nuclear factor-κB pathway inhibition, which attenuates IL-8 secretion in cells. Collectively, these data suggest that OFE could be developed as an agent that suppresses IL-8 secretion to treat chronic inflammatory diseases.

Concepts: Inflammation, Colorectal cancer, Ulcerative colitis, Crohn's disease, Chromatography, Adenocarcinoma, Anti-inflammatory, Osmanthus fragrans

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Osmanthus fragrans are well-known for their fragrance, but it is wasteful if to discard O. fragrans flower after extracting their essential oils. In this paper, we found that O. fragrans flower residues were rich in flavonoids. Six flavonoids and one phenylethanoid glycoside were isolated from the ethanol extract of O. fragrans flower residues, identified as quercetin (1), rutin (2), verbascoside (3), genistin (4), kaempferol (5), isorhamnetin (6) and naringin (7). In bioactivity study, kaempferol (IC50 = 1.43 μg/mL) showed the best anti-inflammatory activity. Isorhamnetin, quercetin, kaempferol, verbascoside and rutin (the values of IC50 were 18.30, 11.05, 16.88, 20.21 and 22.76 μg/mL, respectively) showed excellent DPPH free radical scavenging activity. Verbascoside performed relatively well at inhibiting the growth of both CT26 colonic carcinoma cells (IC50 = 46.87 μg/mL) and HepG2 hepatocarcinoma cells (IC50 = 30.58 μg/mL). In addition, quercetin and kaempferol showed strong anti-proliferation activity against HepG2 cells.

Concepts: Quercetin, Flavonoid, Glycoside, Essential oil, Oil, Flavonols, Rutin, Osmanthus fragrans