Neuroprotective Potential of Laurus nobilis Antioxidant Polyphenol-Enriched Leaf Extracts

Abstract

Oxidative stress has been proposed to be an important factor in the pathogenesis of Alzheimer's disease (AD), playing a central role in amyloid β-protein (Aβ) generation and neuronal apoptosis. Oxidative damage directly correlates with the presence of Aβ deposits. Aβ and oxidative stress jointly induce neuronal death, Aβ deposits, gliosis, and memory impairment in AD. In order to counteract AD neurodegeneration, the inhibition of the vicious cycle of Aβ 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 Aβ(25-35)-fragment-oxidized cell systems. The potential antiamyloidogenic efficacy of Laurus nobilis leaf polar extracts in the Aβ(25-35) fragment oxidized cell systems was further analyzed by Congo red staining.

Red-fleshed Apples: Old Autochthonous Fruits as a Novel Source of Anthocyanin Antioxidants

“…For the ORAC assay final concentration levels of each extract were 3.9, 7.8, 15.62, 31.25, and 62.5 μg/mL. Spectrophotometric measurements were carried out on a Shimadzu UV-1700 spectrophotometer, spectrofluorimetric ones using a Tecan SpectraFluor fluorescence and absorbance reader [15,16]. Tests were carried out performing 3 replicate measurements for three samples (n=3) of each extract (in total, 3×3 measurements).…”

“…SH-SY5Y, SK-N-BE(2)-C, HepG2, A549 and HeLa cell lines, grown as previously described [17,18], were seeded in 96-multiwell plates at a density of 1.0×10 4 cells/well. After 24 h of incubation, cells were treated with apple extracts at five final dose levels (15.62, 31.25, 62.50, 125.0 and 250.0 μg/mL).…”

“…After 24 h of incubation, cells were co-treated with apple extracts (125.0 μg/mL, final concentration levels) and H 2 O 2 (400 μM) for 24 h. After the treatment period, cell viability (CV) was assessed by MTT assay [18].…”

Reactivity of phenolic compounds towards free radicals under in vitro conditions

“…The protective effects of diets, rich in vegetables, fruits and cereals against various forms of cancer and cardiovascular diseases (De Ancos et al 2000;Nicodemus et al 2001) have been attributed, in large to the antioxidant nutrients and plant phenolics such as flavonoids, benzoic acid derivatives and phenylpropanoids (Lin et al 2014;Pacifico et al 2014;Hermann 1989). In addition to t2he free radical scavenging capacity (Lucini et al 2015;Heo et al 2014) plant phenolics have multiple biological activities including vasodilatory, anticarcinogenic, anti-inflammatory, antibacterial, immune stimulating, anti-allergic, antiviral and estrogenic effects (Heo et al 2014;Crozier et al 2009;Kumbulainen and Salonen 1999).…”

Biologically Active Substances of the Laurus Nobilis Leaves

“…Pacifico с соавторами из метанольного извлече-ния листьев лавра, собранных в Италии, выделили и идентифицировали [51] Сравнительное изучение культивируемых и ди-корастущих образцов листьев лавра, осуществленное в Португалии [52], идентифицировало присутствие гексозида эпикатехина (51) D.B. Muñiz-Márquez с коллегами [53] обнаружи-ли в извлечениях из листьев лавра присутствие двух фенольных кислот -кумаровой (61) и 2-гидрокси-циннамовой (62).…”