Neuroprotective potential of Laurus nobilis antioxidant polyphenol-enriched leaf extracts.

Oxidative stress has been proposed to be an important factor in the pathogenesis of Alzheimer's disease (AD), playing a central role in amyloid ß-protein (Aß) generation and neuronal apoptosis. Oxidative damage directly correlates with the presence of Aß deposits. Aß and oxidative stress jointly induce neuronal death, Aß deposits, gliosis, and memory impairment in AD. In order to counteract AD neurodegeneration, the inhibition of the vicious cycle of Aß generation and oxidation is an attractive therapeutic strategy, and antiamyloidogenic and antioxidant herbal drugs could represent an alternative and valid approach. In this context, an alcoholic extract from Laurus nobilis leaves (LnM) and seven fractions obtained therefrom were of interest. All extracts prepared through extractive and chromatographic techniques were phytochemically studied by chromatographic techniques including gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS(n)). The potential antioxidant efficacy of the obtained fractions was screened by DPPH(•) and ABTS(•+) assays, as well as specific assay media characterized from the presence of highly reactive ROS and RNS species (ROO(•), OH(•), O2(•-), and NO). In order to evaluate the preparation of safe and nontoxic extracts, MTT, SRB, and LDH assays toward SH-5YSY and SK-N-BE(2)-C human neuronal cell lines, as well as on C6 mouse glial cell line, were performed. The apoptosis-inducing properties by spectroscopic evaluation of the extracts' ability to activate caspase-3 and by a DNA fragmentation assay were also investigated. Data thus obtained allowed us to state the absence of toxic effects induced by phenolic-rich fractions (LnM, LnM-1, LnM-1a, LnM-1b, and LnM-2c), which at the same time exerted significant cytoprotective and antioxidant responses in hydrogen peroxide and Aß(25-35)-fragment-oxidized cell systems. The potential antiamyloidogenic efficacy of Laurus nobilis leaf polar extracts in the Aß(25-35) fragment oxidized cell systems was further analyzed by Congo red staining.

Apolar Laurus nobilis leaf extracts induce cytotoxicity and apoptosis towards three nervous system cell lines.

In the course of a bioactivity screening of Mediterranean plants, the assessment of neuroprotective properties of Laurus nobilis L. was of interest. Dried leaves were extracted by sonication using CHCl3 as solvent. The CHCl3 parental extract (CHCl3-pe) was fractionated to yield CHCl3 (LnC-1), EtOAc (LnC-2), MeOH (LnC-3) fractions. Each fraction underwent an extensive screening towards human neuroblastoma (SK-N-BE(2)-C, and SH-SY5Y) and rat glioma (C6) cell lines. MTT and SRB cytotoxicity tests were performed. The effect on the plasma membrane integrity was evaluated by assessment of LDH release. The caspase-3 activation enzyme and DNA fragmentation were also evaluated. The oxidant/antioxidant ability of all the extracts were evaluated using different methods. Furthermore, a metabolite profiling of the investigated extracts was carried out by GC-EI-MS. CHCl3-pe contained terpenes, allylphenols, and α-tocopherol. Dehydrocostus lactone was the main constituent. As result of the fractionation technique, the LnC-1 extract was mainly composed of α-tocopherol, whereas the LnC-2 fraction was enriched in guaiane and eudesmane terpenes. The most cytotoxic LnC-2 fraction induced apoptosis; it was ineffective in preventing in vitro free radicals production. Overall, the experimental results support a possible role of LnC-2 preparation as a chemopreventive agent for neuronal cells or other cells of the CNS.

Antioxidant properties and cytotoxic effects on human cancer cell lines of aqueous fermented and lipophilic quince (Cydonia oblonga Mill.) preparations.

In the course of a screening program on quince phytochemicals, two complex preparations were in the focus of the present study, i.e., a lipophilic quince wax extract (QWE) and an aqueous fermented one (QAFE). While the phytochemical composition has been described earlier, the intention of the current investigation was to complement these data with an extensive antioxidant screening of these preparations including their radical scavenging and reductive power as well as their antilipoperoxidative properties. The Quince Aqueous Fermented Extract (QAFE) effectively scavenged the radical target species exhibiting ID(50) values equal to 68.8 µg/mL towards DPPH· and 73.7 µg/mL towards the anion superoxide radical. Quince wax extract (QWE) was more effective at preventing the formation of thiobarbituric reactive species than QAFE exhibiting an ID(50) value equal to 48.9 µg/mL. Moreover the cytotoxic effects towards human HepG2, A549, and HeLa cell lines were evaluated. The two preparations exerted a different effect on the proliferation of the three tested cell lines. Noteworthy, QAFE was almost always more active than QWE but, sometimes, its effects seemed to be strongly dependent on exposure time. Data obtained demonstrate clearly that both hydrophilic and lipophilic quince preparations are non-toxic and exert health-promoting properties.

NMR-based metabolic profiling and in vitro antioxidant and hepatotoxic assessment of partially purified fractions from Golden germander (Teucrium polium L.) methanolic extract.

Golden germander (Teucrium polium L.) is a Mediterranean shrub of the Labiatae family, used in traditional medicine for its diuretic, antipyretic, diaphoretic, antispasmodic, tonic, anti-inflammatory, antihypertensive, anorexic, analgesic, antibacterial and antidiabetic effects. Like other plants of the Teucrium genus, it was widely popular because of its hypoglycemic and hypolipidemic properties but various cases of T. polium-induced hepatitis have been reported. neo-Clerodane diterpenoids, considered chemotaxonomic markers for the Teucrium genus, are believed to be responsible for the observed hepatotoxicity. The plant also produces flavonoids and phenylethanoid glycosides to which the antioxidant and cytoprotective therapeutic properties of its preparations can be traced back. In order to establish a herbal formula that preserves the plant beneficial properties, T. polium leaf drug has been subjected to a bio-guided fractionation. The different phytocomplexes obtained were analyzed by means of an extensive antioxidant screening and hepatotoxicity evaluation against HepG2, a human hepatoblastoma cell line. The cytotoxicity of the fractions was also evaluated against HeLa and A549 cell lines. In order to identify the substances responsible for the bioactivities, NMR-based metabolic profiling techniques of all the phytocomplexes were performed. Data obtained highlighted the possibility of preparing strong antioxidant extracts, useful as food additives, such as MeOH-2, and MeOH-3, completely devoid of hepatotoxic components.

Structure elucidation and hepatotoxicity evaluation against HepG2 human cells of neo-clerodane diterpenes from Teucrium polium L.

Seven neo-clerodanes (teupolins VI-XII) and eleven known compounds were isolated and characterized from leaf extracts of Teucrium polium L., a medicinal plant used in traditional and herbal medicine for its hypolipidemic, hypoglycemic, antioxidant and antiproliferative properties. The structures of these compounds were elucidated by 1D (1H, 13C and DEPT) and 2D (COSY, TOCSY, HSQC, HMBC) NMR experiments and by mass spectrometry analysis. The complete stereostructure of each compound was defined with a NOESY experiment. Because the overexploitation of herbal remedies containing T. polium extracts has resulted in several cases of hepatitis, the hepatotoxic activity of pure metabolites against the human hepatoblastoma cancer cell line HepG2 was assessed by the MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) test. All of the compounds showed low toxicity values at the highest concentration tested (200 µM).

Metabolic profiling of strawberry grape ( Vitis × labruscana cv. 'Isabella') components by nuclear magnetic resonance (NMR) and evaluation of their antioxidant and antiproliferative properties.

In the assessment of the antioxidant properties of edible plants, the widely consumed Vitis × labruscana cv. 'Isabella', known in Italy as "fragola" (strawberry) grape, was of interest. Phenol and flavonoid contents of the methanolic extracts of peel, pulp, seed, leaf, and stalk components of the plant were determined. The metabolic profile of the extracts was performed by 1D and 2D NMR. Quantitative analysis, obtained in the presence of 0.01% of internal standard trimethylsilyl propionate, evidenced the presence of catechins in both stalk and seed extracts, whereas caffeic acid and quercetin were the main metabolites of the leaf extract. Furthermore, the extracts were tested for their radical scavenging and reducing capacities by measuring their capacity to scavenge DPPH(•) and ABTS(•+) and to reduce Fe(III) and Mo(VI) salts. The antioxidant efficacy of the extracts in cell-free systems and their antiproliferative activity toward HepG2 and A549 cells were also evaluated. Seed and stalk components are able to reduce by 39.6 and 40.6%, respectively, the amount of the metabolically active HepG2 cells after only 24 h of exposure.

Spectroscopic characterization and antiproliferative activity on HepG2 human hepatoblastoma cells of flavonoid C-glycosides from Petrorhagia velutina.

Eight flavonoid C-glycosides, including three new analogues, have been isolated from leaf and root methanolic extracts of Petrorhagia velutina, a Mediterranean herbaceous plant. The antiproliferative activity against human hepatoblastoma cancer cell line HepG2 has been analyzed by the MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) test. Isoorientin (4) significantly reduces the proliferation of HepG2 cells as determined by the complete conversion of the tetrazolium probe into formazan after 48 h of exposure.