Chemical structures of constituents from the flowers of Osmanthus fragrans var. aurantiacus

Glycolipid-enriched fraction of Osmanthus fragrans inhibits LPS-induced expression of inflammatory genes, COX-2, E-selectin, and Interleukin-8

ETHNOPHARMACOLOGICAL RELEVANCE

Osmanthus fragrans Lour. is a small ornamental tree native to the Southeastern parts of China. It is mainly cultivated because of its characteristic fragrance, and used in the food and perfume industry. Besides, its flowers are used in traditional Chinese medicine to treat a variety of diseases including those related to inflammation.

AIM OF THE STUDY

The aim of the study was to investigate in more detail the anti-inflammatory properties of O. fragrans flowers, and to characterize their active principles and mechanisms of action.

MATERIALS AND METHODS

O. fragrans flowers were successively extracted with n-hexane, dichloromethane and methanol. The extracts were further fractionated by chromatographic separation. COX-2 mRNA expression in PMA-differentiated, LPS-stimulated THP-1 cells was used as lead assay for activity-guided fractionation. The most potent fraction was chemically analyzed by LC-HRMS. The pharmacological activity was also evaluated in other inflammation-related in-vitro models, such as analysis of IL-8 secretion and E-selectin expression in HUVECtert cells and selective inhibition of COX-isoenzymes.

RESULTS

n-Hexane and dichloromethane extracts of O. fragrans flowers significantly inhibited COX-2 (PTGS2) mRNA expression. Additionally, both extracts inhibited COX-2 enzyme activity, whereas COX-1 enzyme activity was affected to a significantly lower extent. Fractionation of the extracts led to a highly active, glycolipid-containing fraction. In total, 10 glycolipids were tentatively annotated by LC-HRMS. This fraction also inhibited LPS-induced COX-2 mRNA expression, IL-8 secretion and E-selectin expression. The effects were limited to LPS-induced inflammation and not observed when inflammatory genes were induced by TNF-α, IL-1β or FSL-1. Since all these inducers of inflammation act via different receptors, it is likely that the fraction interferes with the binding of LPS to the TLR4-receptor, which mediates pro-inflammatory effects of LPS.

CONCLUSION

Taken together, the results demonstrate the anti-inflammatory potential of O. fragrans flower extracts in general, and of the glycolipid-enriched fraction in particular. The effects of glycolipid-enriched fraction are potentially mediated via the inhibition of the TLR4 receptor complex.

Osmanthus Fragrans Loaded NIPAAM Hydrogel Promotes Osteogenic Differentiation of MC3T3-E1

There is an urgent need to find long-acting, natural osteogenesis-promoting drug systems. In this study, first the potential targets and mechanism of osmanthus fragrans (O. fragrans) extract in regulating osteogenic differentiation based on autophagy were analyzed by network pharmacology and molecular docking. Then, osmanthus fragrans was extracted using the ethanol reflux method and an osmanthus fragrans extract loaded Poly N-isopropylacrylamide (OF/NIPAAM) hydrogel was prepared by electron beam radiation. The chemical components of the osmanthus fragrans extract and the microstructure of OF/NIPAAM hydrogels were characterized by ultraviolet-visible spectrophotometry (UV-Vis) and X-ray diffraction (XRD), respectively. Mouse embryonic osteoblast precursor cells MC3T3-E1 were cultured with different concentrations of OF/NIPAAM hydrogel to discover cell proliferation activity by CCK-8 assay. Alkaline phosphatase (ALP) staining and alizarin red staining were used to observe the differentiation and calcification. Through experimental exploration, we found that a total of 11 targets were predicted, which are TP53, CASP3, SIRT1, etc., and osmanthus fragrans had good binding activity to TP53. In vitro, except for proliferation promotion, OF/NIPAAM hydrogel enhanced ALP activity and formation of mineralized nodules of MC3T3-E1 cells at a concentration equal to or less than 62.5 μg/mL (p < 0.05). The addition of autophagy inhibitor 3-methyladenine (3-MA) reduced ALP activity and mineralized nodule formation.

Traditional uses, phytochemical constituents and pharmacological properties of Osmanthus fragrans: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Osmanthus fragrans Lour., is a medicinal plant distributed widely in some Asian countries including Japan and Korea and southwestern China. It has been used traditionally for the treatment of weakened vision, halitosis, panting, asthma, cough, toothache, stomachache, diarrhea, rheumatism, physique pain and hepatitis.

AIM OF THE REVIEW

Recent advances in traditional uses, botanical characteristics, distribution, taxonomy, phytochemical constituents, biological effects as well as the toxicities of O. fragrans are comprehensively presented and critically evaluated, and the underlying mechanism associated with the bioactivities of extracts, essential oil and components from this plant is also well summarized. In order to provide comprehensive scientific basis for the medical application and help interested researchers discover food and medicinal natural products from O. fragrans.

MATERIALS AND METHODS

All information was systematically gathered from globally accepted scientific databases by Internet databases, including Elsevier, ScienceDirect, PubMed, Web of Science, Wiley, Springer, SciFinder, ACS Publications, CNKI, WanFang, Google Scholar, Baidu Scholar, The Plant List Database, and other literature sources (Ph.D. and MSc dissertations). All published contributions on O. fragrans different languages were included and cited. The chemical structures of all isolated compounds were drawn by using ChemBioDraw Ultra 14.0 software.

RESULTS

To date, more than 183 compounds were isolated and structurally identified from different plant parts of O. fragrans. Among them, ionone, ionol, flavonoids, polyphenols and iridoids, as the major bioactive substances, have been extensively studied and displayed the best bioactivity. Pharmacological studies demonstrated that O. fragrans and its active components had a wide range of biological activities, such as antioxidant, antitumor, anti-inflammatory, anti-hyperglycemic, anti-thrombotic, anti-melanogenesis, neuroprotective, and hepatoprotective activities, etc. CONCLUSION: O. fragrans, as a food and medicinal resource, has a good health care function and important edible and medicinal value, and thus has good prospects for utilization. However, many studies on biological activities were mainly based on extracts and the bioactive ingredients of this plant, and the mechanism responsible for these extracts and ingredients have not been well identified and there is a gap in research regarding clinical effect and safety. Therefore, the detail in vitro and in vivo studies on the mechanisms of action of the pure bioactive compounds and more clinical studies are encouraged to be conducted to ensure safety and effectiveness of the plant for human use.

Exploration of Osmanthus fragrans Lour.'s composition, nutraceutical functions and applications

Osmanthus fragrans (Thunb.) Lour. has been cultivated in China for over 2500 years. Due to the unique and strong fragrance, O. fragrans flowers have long been added into food, tea, and beverages. Not only the O. fragrans flowers, but also leaves, barks, roots, and fruits possess some beneficial effects such as relieving pain and alleviating cough in Traditional Chinese Medicine. Modern pharmacological researches demonstrated that O. fragrans possesses a broad spectrum of biological activities including antioxidant, neuroprotective, antidiabetic and anticancer activities etc. A large number of phytochemicals identified in O. fragrans are responsible for its health promoting and disease preventing effects. The components of volatile compounds in O. fragrans are complex but the content is less abundant. The present review mainly focuses on the bioactive ingredients identified from O. fragrans, the therapeutic effects of O. fragrans and its applications in food, cosmetics and medicines.

Microencapsulation of Osmanthus essential oil by interfacial polymerization: Optimization, characterization, release kinetics, and storage stability of essential oil from microcapsules

In this paper, the interface polymerization method was used to prepare Osmanthus essential oil microcapsules. The optimal preparation process of Osmanthus essential oil microcapsules was explored as follows: the dosage ratio of Osmanthus essential oil to N100 was 6:1, the reaction temperature was 70°C, and the reaction time was 2 h. The encapsulation efficiency of Osmanthus essential oil microcapsules could reach 80.31%. The particle size distribution, morphology, chemical structure, and thermal stability of the obtained microcapsules were characterized by laser particle size analyzer, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The release kinetics and storage stability experiments of the microcapsules were studied. The results showed that the average volume diameter of the microcapsules was 101.2 µm. The microcapsules were in the shape of full spheres, with a smooth surface, low viscosity, and high elasticity. Microencapsulation improved the thermal stability of Osmanthus essential oil and promoted the slow release of essential oil. The synthesized microcapsules showed good storage stability under refrigerated and dark conditions, which indicated that microcapsules had broad application prospects in food, medicine, and other fields. PRACTICAL APPLICATION: In this study, we prepared a polyurea membrane to encapsulate Osmanthus essential oil microcapsules by interfacial polymerization. The encapsulation conditions of the microcapsules were optimized and the structure of the microcapsules was characterized in this study. The results showed that microcapsules had a full spherical shape with a smooth surface, high elasticity, good sustained-release ability, good thermal stability, and storage stability. These properties indicated that microcapsules have good application prospects and can be used as a high-quality flavor with a long residual effect and high thermal stability for food and cosmetic scope.

HPLC Analysis and Antioxidant Evaluation of Acteoside-Rich Osmanthus fragrans Extracts

A method for the separation and quantification of acteoside by reverse-phase high-performance liquid chromatography (HPLC) was developed and validated. Hot water and ethanolic extracts of Osmanthus fragrans leaves and flowers were analyzed for acteoside content. Excellent linearity was obtained, with an r2 higher than 0.999. The precision, specificity, and accuracy of our method were excellent, suggesting that it can be conveniently used for the quantification of acteoside in the crude extract of O. fragrans. The hot water and ethanol extracts were analyzed, and their biological activities were tested. The extraction yields, marker (acteoside) contents, and antioxidant activities of the leaf and flower extracts were analyzed. The antioxidant activity was confirmed by measuring the 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity, reducing power, and total phenolic content. The acteoside content tended to be higher in the 100% ethanol extract of O. fragrans compared to those with the other extraction conditions tested. Overall, almost all extracts prepared with ethanolic solvents tended to produce better antioxidant activity than those prepared with hot water. These results suggest that the ethanolic extract of O. fragrans could serve as a potential antioxidant and anti-inflammatory pharmaceutical source, and our validated method would be useful for the quality control of O. fragrans extracts.

Identification and quantification of the bioactive components in Osmanthus fragrans roots by HPLC-MS/MS

The roots of O. fragrans are also a valuable resource in addition to its flowers and fruits. In this study, the HPLC-MS/MS method used for analyzing the chemical constituents in O. fragrans roots extract was developed, which showed high sensitivity for both qualitative and quantitative analyses. Thirty-two compounds were first discovered in O. fragrans roots, one compound of which was reported for the first time. The simultaneous determination method for acteoside, isoacteoside, oleuropein and phillyrin was validated to be sensitive and accurate. Then it was applied to determine the content of bioactive components in O. fragrans roots from different cultivars. The content of oleuropein and phillyrin in the twelve batches was relatively stable, while the content of acteoside and isoacteoside varied greatly. Moreover, the therapeutic material basis and mechanism of O. fragrans roots exerting its traditional pharmacodynamics were analyzed by network pharmacology. The results showed that O. fragrans roots might be effective for the treatment of inflammation, cardiovascular diseases, cancer, and rheumatoid arthritis, which is consistent with the traditional pharmacodynamics of O. fragrans roots. This work can provide an analytical method for the comprehensive development of O. fragrans roots.

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36 compounds were identified and 32 components were firstly discovered in O. fragrans roots.

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Network pharmacology was used for analysis of therapeutic material basis.

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Simple, effective and sensitive HPLC-MS/MS was developed.

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Bioactive components in O. fragrans roots was elucidated by MS/MS.

Structure-Odor Relationship Study on Geraniol, Nerol, and Their Synthesized Oxygenated Derivatives

Despite being isomers having the same citrus-like, floral odor, geraniol, 1, and nerol, 3, show different odor thresholds. To date, no systematic studies are at hand elucidating the structural features required for their specific odor properties. Therefore, starting from these two basic structures and their corresponding esters, namely, geranyl acetate, 2, and neryl acetate, 4, a total of 12 oxygenated compounds were synthesized and characterized regarding retention indices (RI), mass spectrometric (MS), and nuclear magnetic resonance (NMR) data. All compounds were individually tested for their odor qualities and odor thresholds in air (OT). Geraniol, the Z-isomer, with an OT of 14 ng/L, was found to be more potent than its E-isomer, nerol, which has an OT of 60 ng/L. However, 8-oxoneryl acetate was the most potent derivative within this study, exhibiting an OT of 8.8 ng/L, whereas 8-oxonerol was the least potent with an OT of 493 ng/L. Interestingly, the 8-oxo derivatives smell musty and fatty, whereas the 8-hydroxy derivatives show odor impressions similar to those of 1 and 3. 8-Carboxygeraniol was found to be odorless, whereas its E-isomer, 8-carboxynerol, showed fatty, waxy, and greasy impressions. Overall, we observed that oxygenation on C-8 affects mainly the odor quality, whereas the E/ Z position of the functional group on C-1 affects the odor potency.

Oleanane-type Triterpenes with Highly-Substituted Oxygen Functional Groups from the Flower Buds of Camellia sinensis and Their Inhibitory Effects against NO Production and HSV-1

Acylated oleanane-type triterpenes named chakasapogenins I (1), II (2), and III (3) were isolated from the hydrolysis product of the extract obtained from the flower buds of Camellia sinensis. The chemical structures of new triterpenes were elucidated on the basis of chemical and physicochemical evidence. chakasapogenin III (3) inhibited nitric oxide (NO) production in lipopolysaccharide- (LPS) activated RAW264.7 macrophages. In addition, R1-barrigenol (7) showed antiviral effect at 10μM against herpes simplex virus type-1 (HSV-1).

Chemical Structure of an Acylated Oleanane-type Triterpene Oligoglycoside and Anti-inflammatory Constituents from the Flower Buds of Camellia sinensis

A new acylated oleanane-type triterpene oligoglycoside, floratheasaponin K (1), was isolated together with 11 known compounds including floratheasaponins D (2)–G (5), and I (6), chakasaponin V (7), and assamsaponin E (8) from the flower buds of Camellia sinensis cultivated in India. The chemical structure of floratheasaponin K (1) was elucidated on the basis of chemical and physicochemical evidence. In addition, chakasaponins V (7) and I (13) significantly inhibited nitric oxide (NO) production in lipopolysaccharide- (LPS) activated RAW264.7 cells without cytotoxicity.

Hydroxycinnamoyl derivatives and secoiridoid glycoside derivatives from Syringa vulgaris flowers and their effects on the pro-inflammatory responses of human neutrophils

Thirteen new compounds including caffeoyl-glucaric and p-coumaroyl-altraric acid derivatives, one monoterpenoid glucoside, four secoiridoid glycosides, and three hydroxycinnamoyl phenylpropanoid glycosides esterified with an oleoside 11-methyl ester along with fifteen known compounds were isolated from flowers of Syringa vulgaris L. (Oleaceae). Their structures were elucidated by high-resolution spectroscopic methods. The tested compounds were able to decrease the production of reactive oxygen species. Moreover, oleoechinacoside (13), demethylhydroxyoleonuezhenide (14), demethyloleonuezhenide (15), syringaoleoacteoside (25) and oleoacteoside (26) at the concentration of 50μM, moderately suppressed the LPS-stimulated release of pro-inflammatory chemokine IL-8 and TNF-α from human neutrophils. Moreover, oleonuezhenide (12), oleoside 11-methyl ester (16) and oleoacteoside (26) at the concentration of 50μM were able to induce the surface expression of interleukin 10 receptor, which is suppressed by the incubation of monocyte/macrophage cells with LPS.

Structures of Aromatic Glycosides from the Seeds of Cassia auriculata

A new benzocoumarin glycoside, cassiaglycoside I (1), a new naphthol glycoside, cassiaglycoside II (2), a new chromon glycoside, cassiaglycoside III (3), a new phenylethyl glycoside, cassiaglycoside IV (4), were isolated from the seeds of Cassia auriculata, together with seven known constituents. The chemical structures of four new constituents were characterized on the basis of chemical and physicochemical evidence.

Structure of a Coumaric Acid Analogue with a Monoterpene Moiety from the Flowers of Osmanthus fragrans var. aurantiacus and Evaluation of Cinnamic Acid Analogues as Nitric Oxide Production and Degranulation Inhibitors

A coumaric acid analogue with a monoterpene moiety named floraosmanol A (1) was isolated from the flowers of Osmanthus fragrans var. aurantiacus. The chemical structure was elucidated on the basis of chemical and physicochemical evidence. Floraosmanol A (1) significantly inhibited nitric oxide (NO) production in lipopolysaccharide- (LPS) activated RAW264.7 macrophages and the release of β-hexosaminidase as a marker of degranulation from rat basophile leukemia (RBL-2H3) cells. In addition, several cinnamic acid analogues were conjugated with geraniol and 3-methyl-2-buten-1-ol through an ester linkage. The inhibitory effects on NO production and the release of β-hexosaminidase of the synthesized compounds were examined for structure-activity relationships.

Phenylethanoid Glycoside Profiles and Antioxidant Activities of Osmanthus fragrans Lour. Flowers by UPLC/PDA/MS and Simulated Digestion Model

Variations of phenylethanoid glycoside profiles and antioxidant activities in Osmanthus fragrans flowers through the digestive tract were evaluated by a simulated digestion model and UPLC/PDA/MS. Major phenylethanoid glycosides and phenolic acids, namely, salidroside, acteoside, isoacteoside, chlorogenic acid, and caffeic acid, were identified in four cultivars of O. fragrans flowers, and the concentration of acteoside was the highest, being up to 71.79 mg/g dry weight. After simulated digestion, total phenylethanoid glycoside contents and antioxidant activities were significantly decreased. Acteoside was identified as decomposing into caffeic acid, whereas salidroside was found to be stable during simulated digestion. According to Pearson's correlation analysis, acteoside contents showed good correlations with antioxidant activities during simulated digestion (R(2) = 0.994, P < 0.01). In conclusion, acteoside was the major contributor to the antioxidant activity of O. fragrans flowers, and salidroside was considered as the major antioxidant compound of O. fragrans flowers in vivo.