iridoids and luteolin-7-glucoside

Olive leaves have become a promising source of phenolic compounds and flavonoids with high added value. Phenolic compounds and flavonoids are important sources of antioxidants and bioactives, and one of the processes used to effectively produce them is extraction via solvents, using aqueous ethanol solutions. To obtain the highest extraction yield per kg of biomass, olive leaves were extracted using a conventional technique (dynamic maceration) and an emerging technology, such as pressurized liquid extraction. Studies of the factors that influence these processes were performed: temperature, leaf moisture content, solvent/solid, and aqueous ethanol concentration were optimized using the central composite and Box-Behnken experiment designs. Pressurized liquid extraction resulted in more efficient oleuropein and luteolin-7-O-glucoside extraction than dynamic maceration. The operational conditions for maximizing the recovery of phenolic compounds and flavonoids and antioxidant capacity were determined to be 190 °C, leaf moisture content of 5%, and aqueous ethanol concentration of 80%.

Topics: Antioxidants; Chromatography, High Pressure Liquid; Flavones; Flavonoids; Glucosides; Iridoid Glucosides; Iridoids; Olea; Phenols; Plant Extracts; Plant Leaves; Solvents; Temperature

Lonicera japonica is one of the most important medicinal plants with applications in traditional Chinese and Japanese medicine for thousands of years. Extensive studies on the constituents of L. japonica extracts have revealed an accumulation of pharmaceutically active metabolite classes, such as chlorogenic acid, luteolin and other flavonoids, and secoiridoids, which impart characteristic medicinal properties. Despite being a rich source of pharmaceutically active metabolites, little is known about the biosynthetic enzymes involved, and their expression profile across different tissues of L. japonica. In this study, we performed de novo transcriptome assembly for L. japonica, representing transcripts from nine different tissues. A total of 22 Gbps clean RNA-seq reads from nine tissues of L. japonica were used, resulting in 243,185 unigenes, with 99,938 unigenes annotated based on a homology search using blastx against the NCBI-nr protein database. Unsupervised principal component analysis and correlation studies using transcript expression data from all nine tissues of L. japonica showed relationships between tissues, explaining their association at different developmental stages. Homologs for all genes associated with chlorogenic acid, luteolin, and secoiridoid biosynthesis pathways were identified in the L. japonica transcriptome assembly. Expression of unigenes associated with chlorogenic acid was enriched in stems and leaf-2, unigenes from luteolin were enriched in stems and flowers, while unigenes from secoiridoid metabolic pathways were enriched in leaf-1 and shoot apex. Our results showed that different tissues of L. japonica are enriched with sets of unigenes associated with specific pharmaceutically important metabolic pathways and, therefore, possess unique medicinal properties. The present study will serve as a resource for future attempts for functional characterization of enzyme coding genes within key metabolic processes.

Topics: Chlorogenic Acid; Glucosides; Iridoids; Lonicera; Luteolin; Plant Leaves; Plants, Medicinal; Transcriptome

The antimicrobial properties of olive leaf extract (OLE) have been well recognized in the Mediterranean traditional medicine. Few studies have investigated the antimicrobial properties of OLE. In this preliminary study, commercial OLE and its major phenolic secondary metabolites were evaluated in vitro for their antimicrobial activities against Escherichia coli and Staphylococcus aureus, both individually and in combination with ampicillin. Besides luteolin 7-O-glucoside, OLE and its major phenolic secondary metabolites were effective against both bacteria, with more activity on S. aureus. In combination with ampicillin, OLE, caffeic acid, verbascoside and oleuropein showed additive effects. Synergistic interaction was observed between ampicillin and hydroxytyrosol. The phenolic composition of OLE and the stability of olive phenols in assay medium were also investigated. While OLE and its phenolic secondary metabolites may not be potent enough as stand-alone antimicrobials, their abilities to boost the activity of co-administered antibiotics constitute an imperative future research area.

Topics: Ampicillin; Anti-Bacterial Agents; Bacteria; Caffeic Acids; Drug Synergism; Escherichia coli; Flavones; Glucosides; Herb-Drug Interactions; Iridoid Glucosides; Iridoids; Medicine, Traditional; Olea; Phenols; Phenylethyl Alcohol; Plant Extracts; Plant Leaves; Staphylococcus aureus

Olive leaves are rich in bioactive compounds, which are beneficial for humans. The objective of this work was to assess the influence of processing conditions (drying and extraction) of olive leaves on the extract's bioaccessibility. Thus, extracts obtained from dried olive leaves (hot air drying at 70 and 120 °C or freeze-drying) by means of conventional or ultrasound-assisted extraction were subjected to in vitro digestion. Antioxidant capacity, total phenolic content, and HPLC-DAD/MS/MS analysis were carried out during digestion. The dehydration treatment used for the olive leaves did not have a meaningful influence on bioaccessibility. The digestion process significantly (p<0.05) affected the composition of the extracts. Oleuropein and verbascoside were quite resistant to gastric digestion but were largely degraded in the intestinal phase. Nevertheless, luteolin-7-O-glucoside was the most stable polyphenol during the in vitro simulation (43% bioaccessibility). Therefore, this compound may be taken into consideration in further studies that focus on the bioactivity of olive leaf extracts.

Topics: Agriculture; Antioxidants; Dietary Supplements; Digestion; Food Handling; Glucosides; Humans; Hydrolysis; Industrial Waste; Iridoid Glucosides; Iridoids; Luteolin; Models, Biological; Olea; Phenols; Phytochemicals; Plant Extracts; Plant Leaves; Spain

Olive leaves, an easily available natural low-cost material, constitute a source of extracts with significant antitumor activity that inhibits cell proliferation in several breast-cancer-cell models. In this work, a metabolite-profiling approach has been used to assess the uptake and metabolism of phenolic compounds from an olive-leaf extract in the breast-cancer-cell line SKBR3 to evaluate the compound or compounds responsible for the cytotoxic activity. For this, the extract was firstly characterized quantitatively by high-performance liquid chromatography coupled to electrospray ionization-quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS). Then, SKBR3 cells were incubated with 200 μg/mL of the olive-leaf extract at different times (15 min, 1, 2, 24, and 48 h). A metabolite-profiling approach based on HPLC-ESI-QTOF-MS was used to determine the intracellular phenolic compounds, enabling the identification of 16 intact phenolic compounds from the extract and four metabolites derived from these compounds in the cell cytoplasm. The major compounds found within the cells were oleuropein, luteolin-7-O-glucoside and its metabolites luteolin aglycone and methyl-luteolin glucoside, as well as apigenin, and verbascoside. Neither hydroxytyrosol nor any of its metabolites were found within the cells at any incubation time. It is proposed that the major compounds responsible for the cytotoxic activity of the olive-leaf extract in SKBR3 cells are oleuropein and the flavones luteolin and apigenin, since these compounds showed high uptake and their antitumor activity has been previously reported.

Topics: Apigenin; Breast Neoplasms; Carcinoma; Cell Line, Tumor; Chromatography, High Pressure Liquid; Cytoplasm; Female; Flavones; Glucosides; Humans; Iridoid Glucosides; Iridoids; Luteolin; Olea; Phenols; Plant Extracts; Plant Leaves; Pyrans; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry

Two new iridoid diesters of glucopyranose were isolated from the aerial part of Linaria canadensis (L.) Dum. Eight known flavones, apigenin, diosmetin, genkwanin, luteolin, luteolin 7-O-glucoside, luteolin 7-O-glucuronide, genkwanin 4'-O-rutinoside, and quercetin 7-O-rutinoside were also isolated. The chemical structures of the isolated compounds were elucidated based on the analyses of the spectroscopic data.

Topics: Flavones; Flavonoids; Glucosides; Iridoids; Linaria; Luteolin; Magnetic Resonance Spectroscopy; Molecular Structure; Quercetin

In this article, an efficient method was developed to screen, isolate and identify the major radical scavengers in the leaves of Olea europaea L. by DPPH-HPLC-DAD, HSCCC and NMR. The method of DPPH-HPLC-DAD was used to screen the major radical scavengers. It was found that three major constituents (A, B, C) in the extract of the leaves of O. europaea L. possessed potential antioxidant activities. In order to identify the chemical structures of those compounds, the HSCCC method with a two-phase solvent system composed of petroleum ether-ethyl acetate-water at an optimized volume ratio of 6:600:700 (v/v/v) together with column chromatography was developed to isolate and purify the active compounds. Pure compounds A (225 mg), B (10 mg) and C (12 mg) with purities 92.6, 95.1 and 96.4%, respectively, were obtained from the crude sample (500 mg). Their structures were identified as oleuropein (A), luteolin-7-O-glucoside (B) and verbascoside (C) by (1) H-NMR and (13) C-NMR.

Topics: Acetates; Chromatography, High Pressure Liquid; Flavones; Free Radical Scavengers; Glucosides; Iridoid Glucosides; Iridoids; Olea; Phenols; Plant Extracts; Plant Leaves; Pyrans

To study the chemical constituents of Phlomis younghusbandii.. Column chromatography was used in the isolation procedure. The structures of isolated compounds were elucidated by spectral data. Eight compounds were isolated and their structures were identified as barlerin (1), sesamoside (2), phloyoside II (3), salidroside (4), shanzhiside methyl ester (5), acteoside (6), luteolin-7-O-glucoside (7), daucosterol (8).. Compound 4 is firstly isolated from Phlomis genus. Compound 4 and 6 are obtained from this plant for the first time.

Topics: Flavones; Glucosides; Iridoids; Magnetic Resonance Spectroscopy; Molecular Structure; Phenols; Phlomis; Plant Roots; Plants, Medicinal; Pyrans

A continuous approach assisted by ultrasound for direct enrichment of edible oils (olive, sunflower, and soya) with the main phenols in olive leaves (i.e., oleuropein, verbascoside, apigenin-7-glucoside, and luteolin-7-glucoside) has been developed. Multivariate methodology was used to carry out a detailed optimization of the enrichment, and quantitation of the transferred compounds was based on LC-MS-MS in multiple reaction monitoring optimizing the most sensitive transition for each biophenol. Under the optimal working conditions, only 20 min is necessary to enrich the edible oils with 14.45-9.92 microg/mL oleuropein, 2.29-2.12 microg/mL verbascoside, 1.91-1.51 microg/mL apigenin-7-glucoside, and 1.60-1.42 microg/mL luteolin-7-glucoside. The enrichment method is carried out at room temperature and is organic-solvent-free; thus, the healthy properties of the edible oils improve as does their quality. Also, the low acquisition and maintenance costs of an ultrasound source and its application in a dynamic system make advisable the industrial implementation of the proposed method.

Topics: Apigenin; Dietary Fats, Unsaturated; Food, Fortified; Glucosides; Iridoid Glucosides; Iridoids; Luteolin; Olea; Phenols; Plant Leaves; Pyrans; Ultrasonics

This study presents a new HPLC method for the simultaneous determination of seven major components, namely chlorogenic acid, caffeic acid, loganin, sweroside, secoxyloganin, rutin and luteolin 7-O-glucoside in Caulis Lonicerae Japonicae, a commonly used traditional Chinese medicinal herb derived from the caulis of Lonicera japonica Thunb. These seven compounds, belonging to the chemical types of phenolic acids, iridoids and flavonoids, were separated on a C18 column (250 x 4.6 mm, 5.0 microm) with the column temperature at 30 degrees C. The mobile phase was composed of (A) aqueous acetic acid (0.4%, v/v) and (B) acetonitrile using a gradient elution of 10% B at 0-12 min, 10-17% B at 12-25 min and 17% B at 25-35 min. The flow rate was 1.0 mL/min and detection wavelength was set at 245 nm. The limit of detection (S/N = 3) ranged from 0.10 to 0.23 microg/mL and the limit of quantification (S/N = 10) ranged from 0.69 to 3.56 microg/mL. All calibration curves showed good linear regression (r2 > 0.9990) within the test ranges. The intra- and inter-day precisions as determined from sample solutions were below 1.24 and 2.28%, respectively. The recoveries for seven compounds were found to range from 94.2 to 103.6%. This verified method has been successfully applied to evaluation of commercial samples of Caulis Lonicerae Japonicae from different markets in China.

Topics: Caffeic Acids; Chlorogenic Acid; Chromatography, High Pressure Liquid; Drugs, Chinese Herbal; Flavonoids; Glucosides; Hydroxybenzoates; Iridoid Glucosides; Iridoids; Linear Models; Lonicera; Luteolin; Molecular Structure; Reproducibility of Results; Rutin; Sensitivity and Specificity; Spectrophotometry, Ultraviolet

To study the chemical constituents of Phlomis younghusbandii.. Compounds were isolated from the ethanolic extract by silica gel column chromatography, and their structures were identified by physical and chemical evidences and spectral methods.. Eight compounds were isolated and identified respectively as 8-acetylshanzhiside methyl ester (1), shanzhiside methyl ester (2), phlomiol (3), 2-butoxy-2-(hydroxymthyl) tetrahydro-2H-3,4,5-pyrantriol (4), sesamoside (5), pulchelloside-I (6), luteolin-7-O-beta-D-glucopyranoside (7) and daucosterol (8).. All the compounds were isolated from the plant for the first time.

Topics: Glucosides; Iridoid Glucosides; Iridoids; Lamiaceae; Luteolin; Molecular Structure; Plants, Medicinal; Pyrans; Sitosterols; Tibet

Oleuropein and other healthy olive biophenols (OBPs) such as verbacoside, apigenin-7-glucoside and luteolin-7-glucoside have been extracted from olive leaves by using superheated liquids and a static-dynamic approach. Multivariate methodology has been used to carry out a detailed optimisation of the extraction. Under the optimal working conditions, complete removal without degradation of the target analytes was achieved in 13 min. The extract was injected into a chromatograph-photodiode array detector assembly for individual separation-quantification. The proposed approach - which provides more concentrated extracts than previous alternatives - is very useful to study matrix-extractant analytes partition. In addition, the efficacy of superheated liquids to extract OBPs, the simplicity of the experimental setup, its easy automation and low acquisition and maintenance costs make the industrial implementation of the proposed method advisable.

Topics: Analytic Sample Preparation Methods; Apigenin; Glucosides; Hot Temperature; Hydrogen-Ion Concentration; Iridoid Glucosides; Iridoids; Luteolin; Olea; Phenols; Plant Leaves; Pyrans; Reproducibility of Results