Varietal classification and antioxidant activity prediction of Osmanthus fragrans Lour. flowers using UPLC–PDA/QTOF–MS and multivariable analysis

Eremophila purpurascens: Anti-oxidant, Anti-hyperglycemic, and Hepatoprotective Potential of Its Polyphenolic Rich Leaf Extract and Its LC-ESI-MS/MS Chemical Characterization and Standardization

The genus Eremophila, despite comprising more than 250 species, has scarce literature studies that could be traced concerning the chemical profile and bioactivity of Eremophila purpurascens. The current study targets the investigation of the in vitro and in vivo anti-oxidant, anti-hyperglycemic, and hepatoprotective potential of the polyphenol-rich leaf extract of E. purpurascens (EP). EP showed promising total anti-oxidant capacity with IC50 values of 106 and 114 μg/mL in 2,2'-azinobis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt (ABTS) and diphenyl-1-picrylhydrazyl (DPPH) assays, respectively, with total anti-oxidant capacities of 331, 245, and 1767 μmol/g in ABTS, DPPH, and ferric reducing anti-oxidant power assays, respectively. In HepG2 cells, pre-treated with CCl4, a dose of 100 μg/mL EP ameliorated the reduced superoxide dismutase and glutathione levels and total anti-oxidant capacity with values of 312.5 U/mL, 15.47 mg/dL, and 1.03 nmol/mL, respectively. In vitro anti-diabetic evaluation using 3T3-L1 adipocyte culture showed that at a dose of 30 μg/mL, the EP extract elicited a 6.3% decrease in the concentration of glucose (22.4 mmol/L), showing significant amelioration with regard to pioglitazone and insulin. EP also demonstrated elevated serum insulin by 77.78% with a marked reduction in fasting blood glucose level by 64.55% relative to the streptozotocin diabetic rats in vivo. EP also relieved the liver stress markers both in vitro in CCl4 and in vivo in tamoxifen (TAM) models. EP markedly decreased TAM toxicity, as demonstrated by the decline in the liver stress markers, ALT and AST, by 36.1 and 51.1%, respectively. It also relieved the oxidative stress triggered by TAM, as revealed by the reduction in the levels of TBARs and TNF-α by 21.4 and 40%, respectively. Liquid chromatography electrospray ionization mass spectrometry of EP revealed a total of twelve peaks belonging to phenylpropanoids, lignans, and phenolics, where verbascoside and pinoresinol-4-O-β-d-glucoside represented the most abundant secondary metabolites. The docking experiment showed that tri-O-galloyl-hexoside had the best fitting within the NADPH oxidase active sites with binding energy (ΔG = -81.12 kcal/mol). Thus, the plant can be of beneficial value in the control of hyperglycemia in diabetic patients, besides its prophylactic potential against hepatic complications.

Phytochemical Profiling by UPLC-ESI-QTOF-MS of Kalaharia uncinata (Schinz) Moldenke, Widely Used in Traditional Medicine in DR Congo

Kalaharia uncinata (Schinz) Moldenke, is a tropical erect bushy shrub or subshrub of the Lamiaceae family. It is an endemic plant species of Southern Africa, widely used in the pharmacopoeia against upper respiratory tract infections. A previously conducted ethnobotanical survey revealed that it is believed to contain bioactive substances. However, no relevant phytochemical information was available. This study aimed to perform a phytochemical characterization of K. uncinata and also to discuss the potential bioactivity of the identified phytochemical constituents based on documented data. Ultra-performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) was used for profiling and identification of the main phytochemical constituents from leaf extracts (MeOH 90 %, DCM, AcOEt, BuOH, hexane and residue) of K.uncinata. Twenty-four constituents, representing mainly flavonoids (14), followed by phenylethanoid glycosides (7), phenolic acids (2), and an iridoid glycoside (1) were tentatively identified. Most of the identified compounds are documented to have antiviral and anti-inflammatory properties, which could possibly be the rationale behind the use of K. uncinata against upper respiratory tract infections.

Transcriptomic and metabolomic analysis of autumn leaf color change in Fraxinus angustifolia

Fraxinus angustifolia is a type of street tree and shade tree with ornamental value. It has a beautiful shape and yellow or reddish purple autumn leaves, but its leaf color formation mechanism and molecular regulation network need to be studied. In this study, we integrated the metabolomes and transcriptomes of stage 1 (green leaf) and stage 2 (red-purple leaf) leaves at two different developmental stages to screen differential candidate genes and metabolites related to leaf color variation. The results of stage 1 and stage 2 transcriptome analysis showed that a total of 5,827 genes were differentially expressed, including 2,249 upregulated genes and 3,578 downregulated genes. Through functional enrichment analysis of differentially expressed genes, we found that they were involved in flavonoid biosynthesis, phenylpropanoid biosynthesis, pigment metabolism, carotene metabolism, terpenoid biosynthesis, secondary metabolite biosynthesis, pigment accumulation, and other biological processes. By measuring the metabolites of Fraxinus angustifolia leaves, we found the metabolites closely related to the differentially expressed genes in two different periods of Fraxinus angustifolia, among which flavonoid compounds were the main differential metabolites. Through transcriptome and metabolomics data association analysis, we screened nine differentially expressed genes related to anthocyanins. Transcriptome and qRT-PCR results showed that these nine genes showed significant expression differences in different stages of the sample, and we speculate that they are likely to be the main regulatory factors in the molecular mechanism of leaf coloration. This is the first time that we have analyzed the transcriptome combination metabolome in the process of leaf coloration of Fraxinus angustifolia, which has important guiding significance for directional breeding of colored-leaf Fraxinus species and will also give new insights for enriching the landscape.

Evaluation of Radio Frequency-Assisted Enzymatic Extraction of Non-Anthocyanin Polyphenols from Akebia trifoliata Flowers and Their Biological Activities Using UPLC-PDA-TOF-ESI-MS and Chemometrics

A new radio frequency heating-assisted enzymatic extraction (RF-E) method is applied for the determination of phenolic compounds in Akebia trifoliata flowers, compared with hot water, acidified ethanol (EtOH), and enzymatic-assisted (EA) extractions. Non-anthocyanin polyphenol profiles, antibacterial, angiotensin-converting enzyme (ACE) inhibitory, anti-inflammatory activities, and structures of extracts are evaluated. Results show no significant differences in the extraction of total flavonoid content (15.85-16.63 mg QEs/g) and ACE inhibitory activity (51.30-52.86%) between RF-E and EA extracts. RF-E extract shows the highest anti-inflammatory activities. FTIR and UV spectra reveal that acidified EtOH treatment has a significant effect on the structure of the extract due to its highest flavonoid content (20.33 mg QEs/g), thus it has the highest antibacterial activity against Staphylococcus aureus and Escherichia coli. Sixteen non-anthocyanin polyphenols are identified by UPLC-PDA-TOF-ESI-MS and RF pre-treatment did not cause significant compound degradation. The chemometric analysis shows that enzymatic hydrolysis significantly increased biological activities, and the presence of non-anthocyanin polyphenols correlates well with ACE inhibitory and anti-inflammatory activities. Accordingly, A trifoliata flowers have potential as reagents for the food and pharmaceutical industries due to their abundant polyphenols that could be extracted efficiently using RF-E.

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.

Integration of Transcriptome and Metabolome Provides New Insights to Flavonoids Biosynthesis in Dendrobium huoshanense

Dendrobium huoshanense is both a traditional herbal medicine and a plant of high ornamental and medicinal value. We used transcriptomics and metabolomics to investigate the effects of growth year on the secondary metabolites of D. huoshanense stems obtained from four different years of cultivation. In this study, a total of 428 differentially accumulated metabolites (DAMs) and 1802 differentially expressed genes (DEGs) were identified. The KEGG enrichment analysis of DEGs and DAMs revealed significant differences in "Flavonoid biosynthesis", "Phenylpropanoid biosynthesis" and "Flavone and flavonol biosynthesis". We summarize the biosynthesis pathway of flavonoids in D. huoshanense, providing new insights into the biosynthesis and regulation mechanisms of flavonoids in D. huoshanense. Additionally, we identified two candidate genes, FLS (LOC110107557) and F3'H (LOC110095936), which are highly involved in flavonoid biosynthesis pathway, by WGCNA analysis. The aim of this study is to investigate the effects of growth year on secondarily metabolites in the plant and provide a theoretical basis for determining a reasonable harvesting period for D. huoshanense.

Spatial variation of volatile organic compounds and antioxidant activity of turmeric (Curcuma longa L.) essential oils harvested from four provinces of China

The objective of this study was to investigate the spatial variation of volatile organic compounds and antioxidant activity of turmeric essential oils (TEOs) harvested from four provinces of China. The major chemical components of these TEOs were analyzed using headspace solid-phase micro-extraction gas chromatography-mass spectrometry. More than forty volatile organic compounds in TEOs were identified, which accounted for 82.09–93.64% of the oil components. The relative abundances of the main volatile organic compounds in TEOs at the genus level were visualized by a heat map. The antioxidant activity of the TEOs of five different origins was characterized by the DPPH free radical scavenging activity, in which the antioxidant activity of the TEOs from Guangxi was superior to those of other sources. Furthermore, the IC₅₀ values of the antioxidants TEOs collected from Guangxi, Sichuan, Yunnan, Changting, and Liancheng were 33.30, 42.5, 35.22, 63.27, and 39.96 mg/mL, respectively, which indicated the excellent free radical scavenging activity of those TEOs. Therefore, the TEOs might be considered as a natural antioxidant with potential applications in food and pharmaceutical industries.

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Turmeric essential oils stemmed from four provinces of China were investigated.

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Multivariate analysis of volatile organic compounds in TEOs was performed.

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The major components of volatile organic compounds exhibited a spatial variation.

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Antioxidant activity of turmeric essential oils demonstrated a spatial variation.

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TEOs of Guangxi had a superior antioxidant activity to those of other origins.

Bioactivity-Guided Extract Optimization of Osmanthus fragrans var. aurantiacus Leaves and Anti-Inflammatory Activities of Phillyrin

The aim of this study was to identify the optimal extraction conditions for leaves of Osmanthus fragrans var. aurantiacus. Inhibitory effects of various extracts on NO production were compared. Antioxidant evaluations for total phenol and flavonoid contents were carried out using various extracts of O. fragrans var. aurantiacus leaves obtained under optimal extraction conditions that showed the greatest effect on NO production. The optimal method for extracting O. fragrans var. aurantiacus leaves resulted in an extract named OP OFLE. OP OFLE showed DPPH and ABTS radical scavenging activities in a concentration-dependent manner. Phillyrin (PH) was isolated as a major compound from OP OFLE by HPLC/DAD analysis. OP OFLE and PH reduced inducible nitric oxide (iNOS) and cyclooxygenase (COX)-2 protein expression and downregulated proinflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in LPS-stimulated RAW 264.7 and HT-29 cells. To determine the signal pathway involved in the inhibition of NO production, a Western blot analysis was performed. Results showed that OP OFLE decreased phosphorylation of extracellular regulated kinase (pERK) 1/2 and the expression of nuclear factor-kappa B (NF-κB). Our results suggest that extracts of O. fragrans var. aurantiacus leaves and its major components have biological activities such as antioxidative and anti-inflammatory properties.

Metabolomic and Confocal Laser Scanning Microscopy (CLSM) Analyses Reveal the Important Function of Flavonoids in Amygdalus pedunculata Pall Leaves With Temporal Changes

Amygdalus pedunculata Pall [Rosaceae, Prunus, Prunus pedunculata (Pall.) Maxim.] belongs to the Rosaceae family and is resistant to cold and drought. Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry and metabolomics were used to track the changes in bioactive metabolites during several stages of Amygdalus pedunculata Pall growth. A total of 827 different metabolites were detected, including 169 flavonoids, 68 organic acids, 35 terpenoids and 2 tannins. Flavonoid biosynthesis and flavone and flavonol biosynthesis were the main synthetic sources of flavonoids. Quercetin, isoquercitrin, and epicatechin as biomarkers related to growth and development were found. Quercetin connects the biosynthesis of flavonoids and the biosynthesis of flavones and flavonols. The contents of isoquercitrin and epicatechin increased uniformly during the whole growth process from the flowering stage to the fruit ripening stage, indicating that play key roles in the fruit growth and ripening stages of this plant. The tissue location and quantitative analysis of flavonoids in leaves at different stages were performed by confocal laser scanning microscopy. The flavonoids were mainly distributed in the palisade tissue and spongy tissue, indicating the need for protection of these sensitive tissues in particular. Through comprehensive and systematic analysis, the temporal distribution of flavonoids in the process of their leaves growth was determined. These results clarify the important role of flavonoids in the developmental process of Amygdalus pedunculata Pall.

A review on the structure and pharmacological activity of phenylethanoid glycosides

Phenylethanoid glycosides (PhGs) are compounds made of phenylethyl alcohol, caffeic acid and glycosyl moieties. The first published references about phenylethanoid glycosides concerned the isolation of echinacoside from Echinaceu ungustifolia (Asteraceae) in 1950 and verbascoside from Verbascum sinuatum (Scrophulariaceae) in 1963. Over the past 60 years, many compounds with these structural characteristics have been isolated from natural sources, and most of these compounds possess significant bioactivities, including antibacterial, antitumor, antiviral, anti-inflammatory, neuro-protective, antioxidant, hepatoprotective, and immunomodulatory activities, among others. In this review, we will summarize the phenylethanoid glycosides described in recent papers and list all the compounds that have been isolated over the past few decades. We will also attempt to present and assess recent studies about the separation, extraction, determination, and pharmacological activity of the excellent natural components, phenylethanoid glycosides.

Prediction of Soluble Solids Content in Green Plum by Using a Sparse Autoencoder

The soluble solids content (SSC) affects the flavor of green plums and is an important parameter during processing. In recent years, the hyperspectral technology has been widely used in the nondestructive testing of fruit ingredients. However, the prediction accuracy of most models can hardly be improved further. The rapid development of deep learning technology has established the foundation for the improvement of building models. A new hyperspectral imaging system aimed at measuring the green plum SSC is developed, and a sparse autoencoder (SAE)–partial least squares regression (PLSR) model is combined to further improve the accuracy of component prediction. The results of the experiment show that the SAE–PLSR model, which has a correlation coefficient of 0.938 and root mean square error of 0.654 for the prediction set, can achieve better performance for the SSC prediction of green plums than the three traditional methods. In this paper, integration approaches have combined three different pretreatment methods with PLSR to predict the SSC in green plums. The SAE–PLSR model has shown good prediction performance, indicating that the proposed SAE–PLSR model can effectively detect the SSC in green plums.

Comparative Metabolomic Analysis Reveals Distinct Flavonoid Biosynthesis Regulation for Leaf Color Development of Cymbidium sinense 'Red Sun'

The colorful leaf is an important ornamental character of Cymbidium sinense (C. sinense), especially the red leaf, which has always been attracted by breeders and consumers. However, little is documented on the formation mechanism of the red leaf of C. sinense. In this study, the changing patterns of flavonoid-related metabolites, corresponding enzyme activities and genes expression in the leaves of C. sinense ‘Red Sun’ from red to yellow and finally to green was investigated. A total of 196 flavonoid-related metabolites including 11 anthocyanins metabolites were identified using UPLC-MS/MS-based approach. In the process of leaf color change, 42 metabolites were identified as having significantly different contents and the content of 28 differential metabolites turned to zero. In anthocyanin biosynthetic pathway, content of all 15 identified metabolites showed downregulation trend in the process of leaf color change. Among the 15 metabolites, the contents of Naringenin chalcone, Pelargonidin O-acetylhexoside and Anthocyanin 3-O-beta-d-glucoside decreased to zero in the green leaf stage. The changing pattern of enzyme activity of 10 enzymes involved in the anthocyanin biosynthetic pathway showed different trends from red leaves that have turned yellow and finally green, while the expression of genes encoding these enzymes was all down-regulated in the process of leaf color change. The results of this study revealed the types of flavonoid-related metabolites and the comprehensive analysis of metabolites content, enzyme activities and genes expression providing a new reference for breeders to improve the leaf color of C. sinense ‘Red Sun’.

Genome-Wide Identification of the Auxin Response Factor (ARF) Gene Family and Their Expression Analysis during Flower Development of Osmanthus fragrans

Auxins have long been implicated in many aspects of plant growth and development. Auxin response factors (ARFs) are important proteins in auxin-mediated pathways and they play key roles in plant physiological and biochemical processes, including flower development. Endogenous indoleacetic acid (IAA) levels were measured and ARFs were studied in the flowers during the developmental stages in order to further elucidate the role of auxin in flower development of Osmanthus fragrans. A systematic analysis of OfARFs was conducted by carrying out a genome-wide search of ARFs. A total of 50 ARF genes (OfARFs) were detected and validated from the Osmanthus fragrans genome. Furthermore, a comprehensive overview of the OfARFs was undertaken, including phylogenetic relationship, gene structures, conserved domains, motifs, promoters, chromosome locations, gene duplications, and subcellular locations of the gene product. Finally, expression profiling, while using transcriptome sequencing from a previous study and quantitative real-time PCR (qRT-PCR), revealed that many OfARF genes have different expression levels in various tissues and flower developmental stages. By comparing the expression profiles among the flower developmental stages, and the relationship between ARFs and endogenous IAA levels, it can be supposed that OfARFs function in flower development of O. fragrans in an auxin-mediated pathway.

Chemical profiling and total quality assessment of Isodon japonica using data-independent acquisition mode combined with superimposed multiple product ion UHPLC-Q-TOF-MS and chemometric analysis

In this paper, an analytical strategy combined data acquisition with a practical mining strategy aimed at rapid characterization and quantitation of ent-kaurane diterpenoids in Isodon japonica using ultra high-performance liquid chromatography-triple time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS). First, an effective self-built filter template based on drug phase I/II metabolic reaction theory and a components library data set were established. Second, the mass spectra of ent-kaurane diterpenoid standards were studied and their mass spectrum cleavage pathways were summarized. Next, the methanol extract of this herb was studied by data-independent acquisition mode (DIA). With the aid of a self-built filter template, the peaks of ent-kaurane diterpenoids were easily picked out and rapidly classified as ent-kaurane diterpenoids from a complex matrix. A total of 24 ent-kaurane diterpenoids were structurally identified. Meanwhile, the self-built filter template provided a convenient and fast method for the structural characterization and Isodon japonica was used to illustrate this approach for the first time. Furthermore, eight major bioactive diterpenoids were simultaneously quantified by a newly developed superimposed multiple product ion (SMPI) with UPLC-Q-TOF-MS/MS method. Principal component analysis (PCA) revealed significant differences in different batches of samples. These combined qualitative and quantitative methods were used to provide a potential approach for the holistic quality evaluation of traditional Chinese medicine (TCM) and its preparations.

Bioaccessibility and Absorption Mechanism of Phenylethanoid Glycosides Using Simulated Digestion/Caco-2 Intestinal Cell Models

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 gastrointestinal 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 ( P_app) 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 P_app (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.

Identification and Quantitation of the Bioactive Components in Osmanthus fragrans Fruits by HPLC-ESI-MS/MS

Information on the chemical composition of Osmanthus fragrans fruits is still limited because there are many compounds present in low concentrations in the plant. In this work, the bioactive components in O. fragrans fruit extract were investigated by a new high-performance liquid chromatography electrospray ionization tandem mass spectrometry method, which allows sensitive analysis both in identification and quantitation. A total of 28 compounds were tentatively identified, and 16 components were discovered in O. fragrans fruits for the first time. The validated quantitative methods for the determination of the bioactive components were subsequently applied to analyze batches of O. fragrans fruits from different cultivars, which is beneficial for the comprehensive utilization of O. fragrans fruits.

Fabrication and evaluation of magnetic phosphodiesterase-5 linked nanoparticles as adsorbent for magnetic dispersive solid-phase extraction of inhibitors from Chinese herbal medicine prior to ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis

In the present study, the preparation of the magnetic phosphodiesterase-5 linked Fe₃O₄@ SiO₂ nanoparticles was successfully achieved by amide reaction and the magnetic phosphodiesterase-5 linked Fe₃O₄@SiO₂ nanoparticles were evaluated as a new adsorbent for magnetic dispersive solid-phase extraction of ligands from medicinal plant samples before the analysis by UHPLC-Q-TOF/MS. The prepared phosphodiesterase-5 linked Fe₃O₄@SiO₂ nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, vibration sample magnetometer and potential laser particle size analyzer. The effects of EDC concentration, incubation time and bead-protein ratio on the amount of immobilized protein were studied. The main experimental parameters affect extraction efficiency of ligands, such as wash times, wash solvents, incubation pH, ion strength and incubation temperature, were investigated and optimized by using echinacoside as a model compound. The absolute recovery of echinacoside was ranged from 98.36%-102.16% in Cistanche tubulosa sample under the optimal extraction conditions. Good linearity was observed in the investigated concentration range of 0.006 mgmL^-1-0.97 mgmL^-1(R² = 0.9999). The limit of detection was 0.002 mgmL^-1. The RSDs of within-day and between-day precision were less than 2.3%. Due to the excellent magnetic behavior of Fe₃O₄@SiO₂ nanoparticles, the proposed method was shown to be simple and rapid. Remarkably, the magnetic phosphodiesterase-5 linked Fe₃O₄@SiO₂ nanoparticles could be recycled for ten times with loss of 10% activity.

Degradation of phenylethanoid glycosides in Osmanthus fragrans Lour. flowers and its effect on anti-hypoxia activity

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.

Antioxidant synergistic effects of Osmanthus fragrans flowers with green tea and their major contributed antioxidant compounds

The antioxidant synergistic effects of Osmanthus fragrans flowers with green tea were evaluated, and their major antioxidant compounds contributed to the total amount of synergy were determined. The antioxidant compounds in O. fragrans flowers with green tea were identified by LC-MS and quantified by UPLC-PDA. The synergistic antioxidant interactions between O. fragrans flowers with green tea and their antioxidant compounds were tested using the Prieto’s model after the simulated digestion. The main antioxidant compounds in O. fragrans flowers were acteoside and salideroside, whereas the main antioxidant compounds in green tea were caffeine, gallic acid, and L-epicatechin. The significant synergistic effect between O. fragrans flowers and green tea was observed and among nearly all of the combinations of their antioxidant compounds. Among the combinations, acteoside and gallic acid contributed most to the antioxidant synergy between O. fragrans flowers and green tea. However, the simulated digestion decreased this antioxidant synergy because it reduced the contents and the antioxidant capacities of their compounds, as well as the antioxidant synergy among the compounds.