Inhibitory Effects of Luteolin 7-Methyl Ether Isolated from Wikstroemia ganpi on Tnf-A/Ifn-Γ Mixture-Induced Inflammation in Human Keratinocyte.

Plants of the genus Wikstroemia are traditionally used in China to treat various inflammatory diseases. The purpose of this study was to isolate the components of Wikstroemia ganpi (Siebold & Zucc.) Maxim., to evaluate their anti-atopic activities and to identify candidates with anti-atopic therapeutics. A total of 24 compounds were isolated by bioassay-guided separation, including one novel compound, which was tilianin 5-methyl ether. The anti-atopic activities of the isolated compounds were determined using TNF-α-treated RBL-2H3 cells and HaCaT cells. The mRNA expressions of IL-4, IL-6, GM-CSF, G-CSF and TRPV1 were reduced by luteolin 7-methyl ether. The study shows that the luteolin 7-methyl ether isolated from W. ganpi is a potential therapeutic agent for the treatment of atopic dermatitis.

Mechanism of Yinqin Oral Liquid in the Treatment of Chronic Pharyngitis Based on Network Pharmacology.

BACKGROUND: Yinqin oral liquid (YOL) has curative effect for upper respiratory tract infections, especially for chronic pharyngitis (CP). Since the traditional Chinese herbal formulae are complicated, the pharmacological mechanism of YOL remains unclear. The aim of this work was to explore the active ingredients and mechanisms of YOL against CP. METHODS: First, the profile of putative target of YOL was predicted based on structural and functional similarities of all available YOL components, which were obtained from the Drug Bank database, to the known drugs using TCMSP. The chemical constituents and targets of honeysuckle, scutellaria, bupleurum and cicada were searched by TCMSP, CTD, GeneCards and other databases were used to query the CP-related genes, which were searched by UniProt database. Thereafter, the interactions network between compounds and overlapping genes was constructed, visualized, and analyzed by Cytoscape software. Finally, pathway enrichment analysis of overlapping genes was carried out on Database for Annotation, Visualization, and Integrated Discovery (DAVID) platform. RESULTS: The pathway enrichment analysis showed 55 compounds and 113 corresponding targets in the compound-target network, and the key targets involved PTGS1, ESR2, GSK3ß, NCOA2, ESR1. The PPI core network contained 30 proteins, including VEGFA, IL6, ESR1, RELA and HIF1A. A total of 148 GO items were obtained (p<0.05), 102 entries on biological process (BP), 34 entries on biological process (BP) and 12 entries on cell composition (CC) were included. A total of 46 signaling pathways were obtained by KEGG pathway enrichment screening (p<0.05), involving cancer, PI3K-AKT, hepatitis, proteoglycans, p53, HIF-1 signaling pathways. CONCLUSION: These results collectively indicate YOL (including the main ingredients luteolin and baicalein) as a highly effective therapeutic agent for anti-inflammation, through the NF-kB pathway.

Phytochemical characterization of raw and cooked traditionally consumed alimurgic plants.

In the past, wild edible alimurgic plants became an important alternative food source when poverty, wars or drought made it difficult to access crops. These plants were considered rich in highly nutritional compounds and also frequently used as food-medicine given their health-promoting properties. With the aim of improving our knowledge on the content of beneficial or detrimental compounds in relation with past local dietary and curative traditions, 12 wild food plant species were collected from two study areas selected for their very different degree of industrialization, urbanization, and conservation of local past traditions among the population: the Bologna province (Northern Italy) and the Middle Agri Valley (Southern Italy). Protein, polyphenol flavonoid and biogenic amine (both free and conjugated) contents and antioxidant activity of raw and boiled wild food plant extracts, and of cooking water were analyzed by means of spectrophotometric and high-performance liquid chromatography methods. The results demonstrated that most of the phenolic compounds were released in the cooking water which also showed the highest antioxidant activity. Seventeen different phenolic compounds were identified, of which the health-related luteolin, luteolin-7-glucoside and rutin were the most abundant (e.g., S. pratensis L. and C. intybus L.). On the other hand, biogenic amines were absent or present at very low levels in cooking water of those very same species (e.g., S. pratensis L., T. officinalis Weber, C. vesicaria subsp. taraxacifolia and C. intybus L.) of which traditionally a decoction is used for therapeutic purposes. Free and conjugated spermidine and spermine were generally the most abundant biogenic amines, while none of the known detrimental monoamines (e.g., histamine) was detected. In conclusion, the present results seem to support past local popular traditions which indicated beneficial medical properties of some wild edible plant, as well as of their cooking water.

Alternative Approach for Specific Tyrosinase Inhibitor Screening: Uncompetitive Inhibition of Tyrosinase by Moringa oleifera.

Tyrosinase (TYR) is a type III copper oxidase present in fungi, plants and animals. The inhibitor of human TYR plays a vital role in pharmaceutical and cosmetic fields by preventing synthesis of melanin in the skin. To search for an effective TYR inhibitor from various plant extracts, a kinetic study of TYR inhibition was performed with mushroom TYR. Among Panax ginseng, Alpinia galanga, Vitis vinifera and Moringa oleifera, the extracts of V. vinifera seed, A. galanga rhizome and M. oleifera leaf reversibly inhibited TYR diphenolase activity with IC50 values of 94.8 ± 0.2 µg/mL, 105.4 ± 0.2 µg/mL and 121.3 ± 0.4 µg/mL, respectively. Under the same conditions, the IC50 values of the representative TYR inhibitors of ascorbic acid and kojic acid were found at 235.7 ± 1.0 and 192.3 ± 0.4 µg/mL, respectively. An inhibition kinetics study demonstrated mixed-type inhibition of TYR diphenolase by A. galanga and V. vinifera, whereas a rare uncompetitive inhibition pattern was found from M. oleifera with an inhibition constant of Kii 73 µg/mL. Phytochemical investigation by HPLC-MS proposed luteolin as a specific TYR diphenolase ES complex inhibitor, which was confirmed by the inhibition kinetics of luteolin. The results clearly showed that studying TYR inhibition kinetics with plant extract mixtures can be utilized for the screening of specific TYR inhibitors.

Microextraction of Reseda luteola-Dyed Wool and Qualitative Analysis of Its Flavones by UHPLC-UV, NMR and MS.

Detailed knowledge on natural dyes is important for agronomy and quality control as well as the fastness, stability, and analysis of dyed textiles. Weld (Reseda luteola L.), which is a source of flavone-based yellow dye, is the focus of this study. One aim was to reduce the required amount of dyed textile to ≤50 µg for a successful chromatographic analysis. The second aim was to unambiguously confirm the identity of all weld flavones. By carrying out the extraction of 50 µg dyed wool with 25 µL of solvent and analysis by reversed-phase UHPLC at 345 nm, reproducible chromatographic fingerprints could be obtained with good signal to noise ratios. Ten baseline separated peaks with relative areas ≥1% were separated in 6 min. Through repeated polyamide column chromatography and prepHPLC, the compounds corresponding with the fingerprint peaks were purified from dried weld. Each was unequivocally identified, including the position and configuration of attached sugars, by means of 1D and 2D NMR and high-resolution MS. Apigenin-4'-O-glucoside and luteolin-4'-O-glucoside were additionally identified as two trace flavones co-eluting with other flavone glucosides, the former for the first time in weld. The microextraction might be extended to other used dye plants, thus reducing the required amount of precious historical textiles.

Luteolin: a blocker of SARS-CoV-2 cell entry based on relaxed complex scheme, molecular dynamics simulation, and metadynamics.

Natural products have served human life as medications for centuries. During the outbreak of COVID-19, a number of naturally derived compounds and extracts have been tested or used as potential remedies against COVID-19. Tetradenia riparia extract is one of the plant extracts that have been deployed and claimed to manage and control COVID-19 by some communities in Tanzania and other African countries. The active compounds isolated from T. riparia are known to possess various biological properties including antimalarial and antiviral. However, the underlying mechanism of the active compounds against SARS-CoV-2 remains unknown. Results in the present work have been interpreted from the view point of computational methods including molecular dynamics, free energy methods, and metadynamics to establish the related mechanism of action. Among the constituents of T. riparia studied, luteolin inhibited viral cell entry and was thermodynamically stable. The title compound exhibit residence time and unbinding kinetics of 68.86 ms and 0.014 /ms, respectively. The findings suggest that luteolin could be potent blocker of SARS-CoV-2 cell entry. The study shades lights towards identification of bioactive constituents from T. riparia against COVID-19, and thus bioassay can be carried out to further validate such observations.

Anti-inflammatory effect of Adelia ricinella L. aerial parts.

OBJECTIVE: To investigate the main chemical components and the anti-inflammatory activity of extracts of Adelia ricinella L. aerial parts. METHODS: Three extracts obtained by soxhlet extraction and ethanol/water mixtures were evaluated in their chemical composition by UPLC-DAD-MS/MS. The in vitro anti-inflammatory activity of the prepared extracts was assessed through three different assays: COX-1 and COX-2 enzymatic inhibition, cell-based COX assays on RAW264.7 macrophages (ATCC) measuring the COX-2 protein expression by Western blot and the measurement of the PGE2 concentration in the supernatants of the culture medium. Also was determinate the effect of the three extracts on the RAW 264.7 cell viability. KEY FINDINGS: Few differences in the phytochemical profile were found between the three prepared extracts, identifying a blend of thirteen flavonoids derived from luteolin and apigenin, with orientin as main constituent. Plant extracts (alcoholic and aqueous) did not affect the macrophage cell viability (IC50 > 256 µg/ml) and significantly reduced COX-1 and COX-2 enzyme activities. Additionally, COX-2 expression and PGE2 release were suppressed after 24 h of LPS stimulation and treatment with plant extracts (8-64 µg/ml). CONCLUSIONS: A. ricinella extracts showed the ability to reduce the inflammatory effect exerted by LPS in murine macrophages. However, further studies should confirm their anti-inflammatory activity.

Natural Product Luteolin Rescues THAP-Induced Pancreatic ß-Cell Dysfunction through HNF4α Pathway.

Endoplasmic reticulum stress (ER stress) plays a main role in pancreatic [Formula: see text]-cell dysfunction and death because of intracellular Ca[Formula: see text] turbulence and inflammation activation. Although several drugs are targeting pancreatic [Formula: see text]-cell to improve [Formula: see text]-cell function, there still lacks agents to alleviate [Formula: see text]-cell ER stress conditions. Therefore we used thapsigargin (THAP) or high glucose (HG) to induce ER stress in [Formula: see text]-cell and aimed to screen natural molecules against ER stress-induced [Formula: see text]-cell dysfunction. Through screening the Traditional Chinese drug library ([Formula: see text] molecules), luteolin was finally discovered to improve [Formula: see text]-cell function. Cellular viability results indicated luteolin reduced the THAP or HG-induced [Formula: see text]-cell death and apoptosis through MTT and flow cytometry assay. Moreover, luteolin improved [Formula: see text]-cell insulin secretion ability under ER stress conditions. Also ER stress-induced intracellular Ca[Formula: see text] turbulence and inflammation activation were inhibited by luteolin treatment. Mechanically, luteolin inhibited HNF4[Formula: see text] signaling, which was induced by ER stress. Moreover, luteolin reduced the transcriptional level of HNF4[Formula: see text] downstream gene, such as Asnk4b and HNF1[Formula: see text]. Conversely HNF4[Formula: see text] knockdown abolished the effect of luteolin on [Formula: see text]-cell using siRNA. These results suggested the protective effect of luteolin on [Formula: see text]-cell was through HNF4[Formula: see text]/Asnk4b pathway. In conclusion, our study discovered that luteolin improved [Formula: see text]-cell function and disclosed the underlying mechanism of luteolin on [Formula: see text]-cell, suggesting luteolin is a promising agent against pancreatic dysfunction.

A strategy based on liquid-liquid-refining extraction and high-speed counter-current chromatography for the bioassay-guided separation of active compound from Taraxacum mongolicum.

The research of natural active substances is facing the problems of low separation efficiency and active component loss due to the complex composition of natural extracts. In this study, a strategy based on liquid-liquid-refining extraction and high-speed counter-current chromatography was established to solve this problem. Separation of an active compound with the α-amylase inhibitory activity from Taraxacum mongolicum Hand. -Mazz. was presented as an example. The ethyl acetate extract (FA) from T. mongolicum exhibited the potential effect on α-amylase and was divided into 8 fractions (FB-FI) by liquid-liquid-refining extraction. The results showed that the activity of FE was higher than the others. According to the results of liquid-liquid-refining extraction, a two-phase solvent system with a slightly higher polarity was selected to separate the fraction by HSCCC, and 110 mg of compound was separated from 900 mg FA using the model of consecutive separation. The compound was identified as luteolin by 1H NMR and 13C NMR. The IC50 of luteolin against α-amylase was 42.33±0.82 µg/mL. Then, molecular docking was introduced to study the relationship between the activity and the structure. The results showed that luteolin enfolded in the catalytic site of α-amylase through hydrogen bonds, van der Waals force and hydrophobic interaction, thus inhibiting the activity of the enzyme.

Chemical Constituents of Salix babylonica L. and Their Antibacterial Activity Against Gram-Positive and Gram-Negative Animal Bacteria.

The principle of animal wellbeing, which states that animals should be free from pain, injury, and disease, is difficult to maintain, because microorganisms are most frequently found to be resistant or multi-resistant to drugs. The secondary metabolites of plants are an alternative for the treatment of these microorganisms. The aim of this work was to determine the antibacterial effect of Salix babylonica L. hydroalcoholic extract (SBHE) against Escherichia coli, Staphylococcus aureus and Listeria monocytogenes, and identify the compounds associated with the activity. The SBHE showed activity against the three strains, and was subjected to a bipartition, obtaining aqueous fraction (ASB) with moderate activity and organic fraction (ACSB) with good activity against the three strains. The chromatographic separation of ACSB, allowed us to obtain ten fractions (F1AC to F10AC), and only three showed activity (F7AC, F8AC and F10AC). In F7AC, five compounds were identified preliminary by GC-MS, in F8AC and F10AC were identified luteolin (1) and luteolin 7-O-glucoside (2) by HPLC, respectively. The best antibacterial activity was obtained with F7AC (Listeria monocytogenes; MIC: 0.78 mg/mL, MBC: 0.78 mg/mL) and F8AC (Staphylococcus aureus; MIC: 0.39 mg/mL; MBC: 0.78 mg/mL). The results indicated that the compounds obtained from SBHE can be used as an alternative treatment against these microorganisms and, by this mechanism, contribute to animal and human health.

Agro food by-products and essential oil constituents curtail virulence and biofilm of Vibrio harveyi.

Vibrio harveyi causes severe loss to the aquaculture industry due to its virulence, which is mediated by Quorum sensing (QS) and biofilm formation. In the current study, we have explored the anti-virulent properties and biofilm disruption ability of luteolin (extracted from coconut shell) and linalool against this important aquaculture pathogen. HPLC analysis of the methanolic extract of coconut shells revealed a single major peak which matched to the standard luteolin which was further elucidated by NMR studies. Further, luteolin and linalool were screened for their ability to inhibit biofilms and various quorum sensing mediated virulence factors of V. harveyi. The Minimum Inhibitory Concentration (MIC) of the two compounds was determined and the sub-inhibitory concentrations of the compounds were able to inhibit biofilm formation. Both the compounds disrupted about 60-70% mature biofilms, which was also visually observed by light microscopy. Both linalool and luteolin exhibited a significant reduction in the production of EPS and alginate in the biofilms matrix of V. harveyi which was confirmed by Scanning Electron Microscopy (SEM). Both compounds inhibited the swarming and swimming motility, the crucial quorum sensing (QS) mediated virulence of V. harveyi. The present study shows the presence of valuable polyphenolic compound like luteolin in coconut shells that are discarded as a waste. From the present study we envisage that luteolin and linalool can serve as potent anti-virulent agents to combat QS mediated infections against aquaculture pathogens.

Chemical and Biological insights of Ouratea hexasperma (A. St.-Hil.) Baill.: a source of bioactive compounds with multifunctional properties.

The study aimed to evaluate in vitro antioxidant, anticholinesterase and antidiabetic properties of Ouratea hexasperma (A. St.-Hil.) Baill. The inflorescence methanol extract and the ethyl acetate fraction of leaves and stems reported the highest Relative Antioxidant Capacity Index (RACI), whereas the dichloromethane fraction of leaves was the best inhibitor of α-amylase and α-glucosidase. Trans-3-O-methyl-resveratrol-2-C-ß-glucoside, lithospermoside, 2,5-dimethoxy-p-benzoquinone, lup-20(30)-ene-3ß,28-diol, 7-O-methylgenistein, apigenin and luteolin and amentoflavone were isolated from O. hexasperma. Resveratrol derivative was isolated for the first time in Ochnaceae family. Luteolin, followed by apigenin, reported the highest Relative Antioxidant Capacity Index and they were also the best inhibitors of α-glucosidase enzyme.

Scrophularia lucida L. as a valuable source of bioactive compounds for pharmaceutical applications: In vitro antioxidant, anti-inflammatory, enzyme inhibitory properties, in silico studies, and HPLC profiles.

The genus Scrophularia has received much interest with regards to its traditional uses against eczema, psoriasis, and mastitis. Yet, the medicinal properties of some species still need to be scientifically validated. The present study was designed to investigate into the biological properties of various solvent extracts (ethyl acetate, methanol, and aqueous) of the roots and aerial parts of Scrophularia lucida based on its antioxidant, anti-inflammatory, and enzyme inhibitory activities together with phytochemical screening. Our results revealed that the solvent extracts differed in their biological effectiveness. The root ethyl acetate extract showed the highest ABTS scavenging, FRAP, CUPRAC, and inhibitory activity against AChE and α-glucosidase. The ethyl acetate extract of the aerial parts displayed the highest BChE and α-amylase inhibition and antioxidant effect in the phosphomolybdenum assay, while the methanol extracts of both parts were the most effective DPPH• scavengers and tyrosinase inhibitors. The methanol extracts of the root and aerial parts also inhibited NO production in lipopolysaccharide (LPS)-stimulated murine leukemic monocyte-macrophage cell (4.99% and 10.77%, respectively), at 31.25 µg/mL concentration. The highest TPC (34.98 mg GAE/g extract) and TFC (48.33 mg RE/g extract) were observed in the ethyl acetate extract of the root and aerial parts, respectively. The most abundant compounds in the root ethyl acetate extract were luteolin (852 µg/g extract), rosmarinic acid (522 µg/g extract), and hesperidin (394 µg/g extract) while kaempferol was most abundant in the ethyl acetate extract of the aerial parts (628 µg/g extract). In silico experiments were conducted on tyrosinase and the higher docking values were observed for rosmarinic acid and hesperidin. The present findings provide base line information which tend to support the potential use of S. lucida in the management of several chronic diseases, including Alzheimer's disease and diabetes mellitus.

Isolation, identification of secondary metabolites from Salvia absconditiflora and evaluation of their antioxidative properties.

Salvia absconditiflora Greuter & Burdet (Synonym Salvia cryptantha Montbret & Aucher ex Benth) has been used extensively for traditional medicine. The aerial of plant material was boiled in water then filtrated. The filtrate was partitioned with ethyl acetate and n-butanol sequentially to yield the ethyl acetate and n-butanol extract. A sample of water was lyophilized to yield the water extract. Ethyl acetate extract revealed the highest antioxidant activity and included the most phenolic compounds among the extracts. Hence, ethyl acetate extract was subjected to chromatographic techniques. Ursolic acid (1), crismaritin (2), luteolin (3), rosmarinic acid methyl ester (4), 3,4-dihydroxyl benzaldehyde (protocatechuic aldehyde) (5), caffeic acid (6), apigenin-7-O-ß-glucoside (7), rosmarinic acid (8) and luteolin-7-O-ß-glucoside (9) were isolated and the structures were elucidated by spectroscopic methods including 1D, 2D NMR, and LC-TOF/MS. Cirsimaritin (2), luteolin (3), rosmarinic acid methyl ester (4), rosmarinic acid (8), luteolin-7-O-ß-glucoside (9) displayed the considerable antioxidant activity.

7-Methoxy-luteolin-8-C-ß-6-deoxy-xylo-pyranos-3-uloside exactly (mLU8C-PU) isolated from Arthraxon hispidus inhibits migratory and invasive responses mediated via downregulation of MMP-9 and IL-8 expression in MCF-7 breast cancer cells.

7-Methoxy-luteolin-8-C-ß-6-deoxy-xylo-pyranos-3-uloside (mLU8C-PU) is a glycosylflavone of luteolin isolated from Arthraxon hispidus (Thunb.). Luteolin is known to exert anti-migratory and anti-invasive effects on tumor cells. However, there are no reports on the effects of mLU8C-PU on tumor invasiveness and associated signaling pathways. In this study, we demonstrated the anti-migratory and anti-invasive effects of mLU8C-PU in 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated MCF-7 breast cancer cells. We also investigated the effect of mLU8C-PU on invasion- related signal transducers, including protein kinase Cα (PKCα), c-Jun N terminal kinase (JNK), activator protein-1 (AP-1), and nuclear factor-kappa B (NF-ĸB). TPA-induced membrane translocation of PKCα, phosphorylation of JNK, and the nuclear translocations of AP-1 and NF-κB were downregulated by mLU8C-PU in MCF-7 cells. In addition, mLU8C-PU also inhibited matrix metalloproteinase-9 (MMP-9) and interleukin-8 (IL-8) expression. These results indicate that mLU8C-PU inhibits migratory and invasive responses in MCF-7 breast cancer cells by suppressing MMP-9 and IL-8 expression through mitigating TPA-induced PKCα, JNK activation, and the nuclear translocation of AP-1 and NF-κB. These results suggest that mLU8C-PU may be used as an anti-metastatic agent.

Cytotoxic, proapoptotic and antioxidative potential of flavonoids isolated from propolis against colon (HCT-116) and breast (MDA-MB-231) cancer cell lines.

Isolated and structurally confirmed, eleven flavonoids from propolis were examined for their cytotoxicity toward human colon cancer and human breast cancer cells. Their effect on induction of apoptosis and their antioxidative activities were also evaluated. Six flavonoids induced cytotoxic effects in both cell lines. Luteolin had a marked effect on both cell lines, especially on HCT-116 cells (IC50 72h, 66.86µM). Also, luteolin was observed to have the highest apoptotic potential after 72h treatment of examined cell lines (27.13% and 37.09%, respectively). Myricetin exhibited selective inhibition of cell growth (IC50 114.75µM) and induced apoptosis in MDA-MB-231 cells only. Luteolin and galangin exhibited prooxidative properties 24h after the treatment in HCT-116 cells, while myricetin induced prooxidative effects in MDA-MB-231 cells. On the other hand, selected flavonoids exhibited antioxidative properties 72h after the treatment, decreasing superoxide anion radical and nitrite levels in both cell lines. Cytotoxic and proapoptotic effects on colon and breast cancer cell lines and the influence on their redox status make tested flavonoids good candidates for developing new anticancer drugs.

LC-MS/MS method for the simultaneous quantification of luteolin, wedelolactone and apigenin in mice plasma using hansen solubility parameters for liquid-liquid extraction: Application to pharmacokinetics of Eclipta alba chloroform fraction.

Eclipta alba (Bhringraj) in ayurveda has been widely used as a traditional medicine for its multi-therapeutic properties for ages. Luteolin (LTL), wedelolactone (WDL) and apigenin (APG) are the three main bioactive phytochemicals present in Eclipta alba extract. However there was a lack of sensitive bioanalytical method for the pharmacokinetics of these free compounds in plasma which majorly contributes for their activities after oral administration of Eclipta alba. The present study aims to develop a sensitive, rapid and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous estimation of mice plasma concentrations of LTL, WDL and APG using quercetin as an internal standard for the pharmacokinetic analysis. Analytes were separated on Phenomenex Luna C18 (150 × 4.6 mm, 3.0 µm) column with mobile phase containing methanol: acetonitrile (90: 10, v/v) and 0.1% formic acid in 10 mM ammonium formate buffer in the ratio of 70: 30 (v/v) in isocratic mode. Liquid-liquid extraction was optimized using Hansen solubility parameters and diethyl ether finalized as an extraction solvent for the recovery ranging from 61 to 76% for all analytes in mice plasma. The validated method has an accuracy and precision over the linearity range of 0.1-200 ng/mL with a correlation coefficient (r2) of ≥0.997. The intra and inter-day assay accuracy was between 98.17 and 107% and 95.83-107.89% respectively and the intra and inter day assay precision ranged from 0.37-6.05% and 1.85-10.76%, respectively for all the analytes. This validated method can be used for future clinical investigation studies of Eclipta alba extracts.

Flavonoids from Trollius europaeus flowers and evaluation of their biological activity.

OBJECTIVES: This article describes the flavonoid composition of the flowers of Trollius europaeus and the method of isolation thereof and provides an attempt at investigating the antioxidant activity of the isolated flavonoids and the antityrosinase activity of the extracts from the investigated material. METHODS: The compositional data were acquired by combining results of nuclear magnetic resonance, ultraviolet spectroscopy, electrospray ionisation-tandem mass spectrometry (ESI-MS/MS) analyses and those of an analysis of the products of acid hydrolysis of the compounds. The antioxidant activity of the extracts was studied using the 2,2'-diphenyl-1-picrylhydrazyl assay and the tyrosinase inhibitory activity - with the use of mushroom tyrosinase. KEY FINDINGS: Ten flavonoid derivatives of luteolin and apigenin were isolated from the flowers of T. europaeus and identified. The investigation into the antioxidant activity revealed that orientin 2″-O-α-arabinopyranoside (4) and orientin 2″-O-ß glucopyranoside (5) had a significant antioxidant effect. CONCLUSIONS: The studies conducted led to the development of a method of isolating flavonoid, potentially antioxidant, compounds from T. europaeus. They allowed to determine which of the investigated flavonoids demonstrated significant antioxidant activity and could be used as natural antioxidants.

Absorption Properties of Luteolin and Apigenin in Genkwa Flos Using In Situ Single-Pass Intestinal Perfusion System in the Rat.

The flower bud of Daphne genkwa (Genkwa Flos) is a commonly used herbal medicine in Asian countries. Luteolin and apigenin are two recognized active flavonoids in Genkwa Flos. The aim of this study was to investigate the intestinal absorption mechanisms of Genkwa Flos flavonoids using in situ single-pass intestinal perfusion rat model. Using HPLC, we determined its major effective flavonoids luteolin, apigenin, as well as, hydroxygenkwanin and genkwanin in biological samples. The intestinal absorption mechanisms of the total flavonoids in Genkwa Flos (TFG) were investigated using in situ single-pass intestinal perfusion rat model. Comparing the TFG absorption rate in different intestinal segments, data showed that the small intestine absorption was significantly higher than that of the colon ([Formula: see text]). Compared with duodenum and ileum, the jejunum was the best small intestinal site for TFG absorption. The high TFG concentration (61.48[Formula: see text][Formula: see text]g/ml) yielded the highest permeability ([Formula: see text]). Subsequently, three membrane protein inhibitors (verapamil, pantoprazole and probenecid) were used to explore the TFG absorption pathways. Data showed probenecid, a multidrug resistance protein (or MRP) inhibitor, effectively enhanced the TFG absorption ([Formula: see text]). Furthermore, by comparing commonly used natural absorption enhancers on TFG, it was observed that camphor was the most effective. In Situ single-pass intestinal perfusion experiment shows that TFG absorption is much higher in the small intestine than in the colon, and the TFG is absorbed mainly via an active transport pathway with MRP-mediated efflux mechanism. Camphor obviously enhanced the TFG absorption, and this could be an effective TFG formulation preparation method to increase clinical effectiveness after Genkwa Flos administration. Our study elucidated the TFG absorption mechanisms, and provided new information for its formulation preparation.

Homogenate-assisted Vacuum-powered Bubble Extraction of Moso Bamboo Flavonoids for On-line Scavenging Free Radical Capacity Analysis.

A homogenate-assisted vacuum-powered bubble extraction (HVBE) method using ethanol was applied for extraction of flavonoids from Phyllostachys pubescens (P. pubescens) leaves. The mechanisms of homogenate-assisted extraction and vacuum-powered bubble generation were discussed in detail. Furthermore, a method for the rapid determination of flavonoids by HPLC was established. HVBE followed by HPLC was successfully applied for the extraction and quantification of four flavonoids in P. pubescens, including orientin, isoorientin, vitexin, and isovitexin. This method provides a fast and effective means for the preparation and determination of plant active components. Moreover, the on-line antioxidant capacity, including scavenging positive ion and negative ion free radical capacity of different fractions from the bamboo flavonoid extract was evaluated. Results showed that the scavenging DPPH˙ free radical capacity of vitexin and isovitexin was larger than that of isoorientin and orientin. On the contrary, the scavenging ABTS⁺˙free radical capacity of isoorientin and orientin was larger than that of vitexin and isovitexin.