Production of hydroxytyrosol rich extract from Olea europaea leaf with enhanced biological activity using immobilized enzyme reactors.

As olive leaves constitute the main by-product of the olive oil industry with important environmental and economic impact, there is an increasing demand for its valorization. In the present work, we report the development and application of immobilized enzyme batch bioreactors for the chemo-enzymatic treatment of an aqueous Olea europaea leaf extract rich in oleuropein to produce an extract enriched in hydroxytyrosol and other oleuropein hydrolysis products. To this end, a robust biocatalyst was developed through the immobilization of ß-glucosidase on chitosan-coated magnetic beads which exhibited high hydrolytic stability after 240 h of incubation at 37 °C. The biocatalyst was successfully used in both a rotating bed-reactor and a stir-tank reactor for the modification of the olive leaf extract leading to high conversion yields of oleuropein (exceeding 90%), while an up to 2.5 times enrichment in hydroxytyrosol was achieved. Over 20 phenolic compounds (from different classes of phytochemicals such as flavonoids, secoiridoids, and their derivatives) were identified, in the extract before and after its modification through various chromatographic and spectroscopic techniques. Finally, the biological activity of both extracts was evaluated. Compared to the non-modified extract, the modified one demonstrated 20% higher antioxidant activity, seven-fold higher antibacterial activity, and enhanced cytotoxicity against leiomyosarcoma cells.

Simultaneous determination of artemisinin and its analogs and flavonoids in Artemisia annua crude extracts with the use of NMR spectroscopy.

Artemisia annua is a promising and potent antimalarial herbal drug. This activity has been ascribed to its component artemisinin, a sesquiterpene lactone. The ability to determine artemisinin and its known analogs in plant extracts is an especially difficult task because the compounds are present in low concentrations, are thermolabile, and lack ultraviolet or fluorescent chromophores. We report herein a facile and rapid 1-D 1 H, 1-D total correlation spectroscopy, 2-D 1 H-13 C heteronuclear single quantum coherence, and 1 H-13 C heteronuclear multiple bond correlation nuclear magnetic resonance techniques for the simultaneous identification and quantification of artemisinin and five of its analogs along with five flavonoids, an aromatic ketone, and camphor (in total, 13 compounds) in crude diethyl ether A. annua extract without the need of laborious isolation of the individual analytes. The above method was validated in terms of precision, linearity, and limit of detection. The analytical results were found to be in excellent agreement with those obtained with the use of the time consuming high-performance liquid chromatography with diode-array detection and liquid chromatography with tandem mass spectrometry for the compounds that standards were available.

Deconvoluting the Dual Antiplatelet Activity of a Plant Extract.

A thorough evaluation of the antiplatelet activity profile of hexane olive leaf extract in human platelets indicated a potent activity accomplished through a two axis inhibition of platelet activation triggered both by ADP and thrombin. To delineate the extract components responsible for this dual activity, an NMR based method was established to determine and quantify the triterpenoid content leading to the characterization of uvaol, erythrodiol, and oleanolic acid. The antiplatelet profile of the total extract and of the 3 determined triterpenoids was evaluated against in vitro platelet aggregation induced by several platelet agonists as also on PAC-1 binding and P-selectin membrane expression both in healthy volunteers and in platelets from patients with an acute coronary syndrome receiving dual antiplatelet therapy with aspirin and ticagrelor. The extract was identified to inhibit ADP-induced platelet activation due to its erythrodiol content and TRAP-induced platelet activation due to the activity of uvaol and oleanolic acid.

Ethyl Acetate Extract of Origanum vulgare L. ssp. hirtum Prevents Streptozotocin-Induced Diabetes in C57BL/6 Mice.

Type 1 diabetes (T1D) is an autoimmune disease that develops as a consequence of pancreatic ß-cell death induced by proinflammatory mediators. Because Origanum vulgare L. ssp. hirtum (Greek oregano) contains antiinflammatory molecules, we hypothesized that it might be beneficial for the treatment of T1D. An ethyl acetate extract of oregano (EAO) was prepared from the leaves by a polar extraction method. Phytochemical composition was determined by liquid chromatography-UV diode array coupled to ion-trap mass spectrometry with electrospray ionization interface (LC/DAD/ESI-MS(n) ). In vitro immunomodulatory effect of EAO was estimated by measuring proliferation (MTT) or cytokine secretion (ELISA) from immune cells. Diabetes was induced by multiple low doses of streptozotocin (MLDS) in male C57BL/6 mice and EAO was administered intraperitoneally for 10 d. Determination of cellular composition (flow cytometry) and cytokine production (ELISA) was performed on 12th d after diabetes induction. EAO suppressed the function of both macrophages and lymphocytes in vitro. In vivo, EAO treatment significantly preserved pancreatic islets and reduced diabetes incidence in MLDS-challenged mice. Besides down-modulatory effect on macrophages, EAO reduced the number of total CD4(+) and activated CD4(+) CD25(+) T cells. Furthermore, EAO affected the number of T helper 1 (Th1) and T helper 17 (Th17) cells through downregulation of their key transcription factors T-bet and RORγT. Because EAO treatment protects mice from development of hyperglycemia by reducing proinflammatory macrophage/Th1/Th17 response, this plant extract could represent a basis for future diabetes therapy.

Rosemary tea consumption results to anxiolytic- and anti-depressant-like behavior of adult male mice and inhibits all cerebral area and liver cholinesterase activity; phytochemical investigation and in silico studies.

Our aim was to investigate the possible effects of regular drinking of Rosmarinus officinalis L. leaf infusion on behavior and on AChE activity of mice. Rosemary tea (2% w/w) phytochemical profile was investigated through LC/DAD/ESI-MS(n). Adult male mice were randomly divided into two groups: "Rosemary-treated" that received orally the rosemary tea for 4weeks and "control" that received drinking water. The effects of regular drinking of rosemary tea on behavioral parameters were assessed by passive avoidance, elevated plus maze and forced swimming tests. Moreover, its effects on cerebral and liver cholinesterase (ChE) isoforms activity were examined colorimetricaly. Phytochemical analysis revealed the presence of diterpenes, flavonoids and hydroxycinnamic derivatives in rosemary tea; the major compounds were quantitatively determined. Its consumption rigorously affected anxiety/fear and depression-like behavior of mice, though memory/learning was unaffected. ChE isoforms activity was significantly decreased in brain and liver of "rosemary treated" mice. In order to explain the tissue ChE inhibition, principal component analysis, pharmacophore alignment and molecular docking were used to explore a possible relationship between main identified compounds of rosemary tea, i.e. rosmarinic acid, luteolin-7-O-glucuronide, caffeic acid and known AChE inhibitors. Results revealed potential common pharmacophores of the phenolic components with the inhibitors. Our findings suggest that rosemary tea administration exerts anxiolytic and antidepressant effects on mice and inhibits ChE activity; its main phytochemicals may function in a similar way as inhibitors.

Methanolic extract of Origanum vulgare ameliorates type 1 diabetes through antioxidant, anti-inflammatory and anti-apoptotic activity.

Type 1 diabetes (T1D), an autoimmune inflammatory disorder, develops as a consequence of pancreatic ß-cell destruction and results in hyperglycaemia. Since current T1D therapy mainly involves insulin replacement, the aim of the present study was to evaluate the therapeutic potential of Origanum vulgare L. ssp. hirtum (Greek oregano) leaf extract rich in biophenols for the treatment of T1D. The phytochemical profile of methanolic oregano extract (MOE) and aqueous oregano extract (AOE) was determined by liquid chromatography/electrospray ion-trap tandem MS (LC/DAD/ESI-MSn), while their main compounds were quantified by HPLC with diode array detection. After establishing their potent in vitro antioxidant activity, the extracts were administered to C57BL/6 mice treated with multiple low doses of streptozotocin for diabetes induction. While prophylactic AOE therapy had no impact on diabetes induction, MOE reduced diabetes incidence and preserved normal insulin secretion. In addition, MOE scavenged reactive oxygen and nitrogen species and, therefore, alleviated the need for the up-regulation of antioxidant enzymes. MOE treatment specifically attenuated the pro-inflammatory response mediated by T helper 17 cells and enhanced anti-inflammatory T helper 2 and T regulatory cells through the impact on specific signalling pathways and transcription factors. Importantly, MOE preserved ß-cells from in vitro apoptosis via blockade of caspase 3. Finally, rosmarinic acid, a predominant compound in MOE, exhibited only partial protection from diabetes induction. In conclusion, acting as an antioxidant, immunomodulator and in an anti-apoptotic manner, MOE protected mice from diabetes development. Seemingly, there is more than one compound responsible for the beneficial effect of MOE.

1H-NMR as a structural and analytical tool of intra- and intermolecular hydrogen bonds of phenol-containing natural products and model compounds.

Experimental parameters that influence the resolution of 1H-NMR phenol OH signals are critically evaluated with emphasis on the effects of pH, temperature and nature of the solvents. Extremely sharp peaks (Δν1/2≤2 Hz) can be obtained under optimized experimental conditions which allow the application of 1H-13C HMBC-NMR experiments to reveal long range coupling constants of hydroxyl protons and, thus, to provide unequivocal assignment of the OH signals even in cases of complex polyphenol natural products. Intramolecular and intermolecular hydrogen bonds have a very significant effect on 1H OH chemical shifts which cover a region from 4.5 up to 19 ppm. Solvent effects on -OH proton chemical shifts, temperature coefficients (Δδ/ΔT), OH diffusion coefficients, and nJ(13C, O1H) coupling constants are evaluated as indicators of hydrogen bonding and solvation state of phenol -OH groups. Accurate 1H chemical shifts of the OH groups can be calculated using a combination of DFT and discrete solute-solvent hydrogen bond interaction at relatively inexpensive levels of theory, namely, DFT/B3LYP/6-311++G (2d,p). Excellent correlations between experimental 1H chemical shifts and those calculated at the ab initio level can provide a method of primary interest in order to obtain structural and conformational description of solute-solvent interactions at a molecular level. The use of the high resolution phenol hydroxyl group 1H-NMR spectral region provides a general method for the analysis of complex plant extracts without the need for the isolation of the individual components.

Olive leaf extracts are a natural source of advanced glycation end product inhibitors.

Advanced glycation end products (AGEs), which are readily formed and accumulated with sustained hyperglycemia, contribute to the development of diabetic complications. As a consequence, inhibition of AGE formation constitutes an attractive therapeutic/preventive target. In the current study, we explored the phytochemical composition and the in vitro effect of two different olive leaf extracts (an aqueous and a methanolic) on AGE formation. The methanolic olive leaf extract inhibited fluorescent AGE formation in a bovine serum albumin (BSA)-ribose system, whereas the aqueous extract had no effect in both BSA-fructose and BSA-ribose systems. The phytochemical profile was investigated with liquid chromatography-ultraviolet-visible (UV-Vis) diode array coupled to electrospray ionization multistage mass spectrometry (LC/DAD/ESI-MS(n)). Quantification of the major phenolic compounds was performed with high performance liquid chromatography with UV-Vis diode array detection and nuclear magnetic resonance spectroscopy. Among the major phenolic components (luteolin, hydroxytyrosol, luteolin-4'-O-ß-D-glucopyranoside, luteolin-7-O-ß-D-glucopyranoside, and oleuropein), luteolin and luteolin-4'-O-ß-D-glucopyranoside were assigned as potent inhibitors of AGE formation. The extraction procedure greatly affects the composition and therefore the anti-glycation potential of olive leaves.

Phytochemical composition of "mountain tea" from Sideritis clandestina subsp. clandestina and evaluation of its behavioral and oxidant/antioxidant effects on adult mice.

PURPOSE: The goals of this study were to monitor the effect of drinking of herbal tea from Sideritis clandestina subsp. clandestina for 6 weeks on behavioral and oxidant/antioxidant parameters of adult male mice and also to evaluate its phytochemical composition. METHODS: The phytochemical profile of the Sideritis tea was determined by liquid chromatography-UV diode array coupled to ion-trap mass spectrometry with electrospray ionization interface. The effects of two doses of the herbal infusion (2 and 4% w/v, daily) intake on anxiety-like state in mice were studied by the assessment of their thigmotactic behavior. The oxidant/antioxidant status of brain (-Ce), liver and heart of adult male Balb-c mice following the consumption of Sideritis tea was also evaluated via the measurement of malondialdehyde (MDA) and reduced glutathione (GSH) levels using fluorometric assays. Our study was further extended to determine the antioxidant effects of the herbal tea on specific brain regions (cerebral cortex, cerebellum and midbrain). RESULTS: The identified compounds were classified into several natural product classes: quinic acid derivatives, iridoids, phenylethanol glycosides and flavonoids. Our results showed that only the 4% Sideritis tea exhibited anxiolytic-like properties as evidenced by statistically significant (p < 0.05) decrease in the thigmotaxis time and increase in the number of entries to the central zone in comparison with the control group. Consumption of both tea doses (2 and 4% w/v) elevated GSH (12 and 28%, respectively, p < 0.05) and decreased MDA (16 and 29%, p < 0.05) levels in brain (-Ce), while liver and heart remained unaffected. In regard to the effect of herbal tea drinking (2 and 4% w/v) on specific brain regions, it caused a significant increase in GSH of cerebellum (13 and 36%, respectively, p < 0.05) and midbrain (17 and 36%, p < 0.05). Similarly, MDA levels were decreased in cerebellum (45 and 79%, respectively, p < 0.05) and midbrain (50 and 63%, respectively, p < 0.05), whereas cerebral cortex remained unaffected. CONCLUSIONS: Mountain tea drinking prevents anxiety-related behaviors and confers antioxidant protection to rodent's tissues in a region-specific, dose-dependent manner, and its phytochemical constituents are shown for the first time.

Phytochemical profile of Rosmarinus officinalis and Salvia officinalis extracts and correlation to their antioxidant and anti-proliferative activity.

The goal of this study was to monitor the anti-proliferative activity of Rosmarinus officinalis and Salvia officinalis extracts against cancer cells and to correlate this activity with their phytochemical profiles using liquid chromatography/diode array detection/electrospray ion trap tandem mass spectrometry (LC/DAD/ESI-MS(n)). For the quantitative estimation of triterpenic acids in the crude extracts an NMR based methodology was used and compared with the HPLC measurements, both applied for the first time, for the case of betulinic acid. Both extracts exerted cytotoxic activity through dose-dependent impairment of viability and mitochondrial activity of rat insulinoma m5F (RINm5F) cells. Decrease of RINm5F viability was mediated by nitric oxide (NO)-induced apoptosis. Importantly, these extracts potentiated NO and TNF-α release from macrophages therefore enhancing their cytocidal action. The rosemary extract developed more pronounced antioxidant, cytotoxic and immunomodifying activities, probably due to the presence of betulinic acid and a higher concentration of carnosic acid in its phytochemical profile.

Phenolic compounds and antioxidant activity of olive leaf extracts.

The total phenolic content and antioxidant activities of olive leaf extracts were determined. Plant material was extracted with methanol and fractionated with solvents of increasing polarity, giving certain extracts. The qualitative changes in the composition of the extracts were determined after the storage of leaves for 22 h at 37°C, before the extraction. Total polyphenol contents in extracts were determined by the Folin-Ciocalteu procedure. They were also analysed by liquid chromatography-mass spectrometry. Their antioxidant activities were evaluated using the diphenyl picrylhydrazyl method and the ß-carotene linoleate model assay. Moreover, the effects of different crude olive leaf extracts on the oxidative stability of sunflower oil at 40°C and sunflower oil-in-water emulsions (10% o/w) at 37°C, at a final concentration of crude extract 200 mg kg(-1) oil, were tested and compared with butylated hydroxyl toluene.

Rapid and novel discrimination and quantification of oleanolic and ursolic acids in complex plant extracts using two-dimensional nuclear magnetic resonance spectroscopy-Comparison with HPLC methods.

A novel strategy for NMR analysis of mixtures of oleanolic and ursolic acids that occur in natural products is described. These important phytochemicals have similar structure and their discrimination and quantification is rather difficult. We report herein the combined use of proton-carbon heteronuclear single-quantum coherence ((1)H-(13)C HSQC) and proton-carbon heteronuclear multiple-bond correlation ((1)H-(13)C HMBC) NMR spectroscopy, in the identification and quantitation of oleanolic acid (OA) and ursolic acid (UA)in plant extracts of the Lamiaceae and Oleaceae family. The combination of (1)H-(13)C HSQC and (1)H-(13)C HMBC techniques allows the connection of the proton and carbon-13 spins across the molecular backbone resulting in the identification and, thus, discrimination of oleanolic and ursolic acid without resorting to physicochemical separation of the components. The quantitative results provided by 2D (1)H-(13)C HSQC NMR data were obtained within a short period of time ( approximately 14min) and are in excellent agreement with those obtained by HPLC, which support the efficiency of the suggested methodology.