Biophenols: Enzymes (β-secretase, Cholinesterases, histone deacetylase and tyrosinase) inhibitors from olive (Olea europaea L.)

The focus of this study was on inhibition of enzymes involved in the pathogenesis Alzheimer's disease (AD) including prime amyloid beta (Aβ) producing enzyme (β-secretase: BACE-1) and disease progression enzymes including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), histone deacetylase (HDAC), and tyrosinase along with the catecholamine L-DOPA, by using olive biophenols. Here we report the strongest inhibition of BACE-1 from rutin (IC50: 3.8 nM) followed by verbascoside (IC50: 6.3 nM) and olive fruit extract (IC50: 18 ng), respectively. Olive biophenol, quercetin exhibited strongest enzyme inhibitory activity against tyrosinase (IC50: 10.73 μM), BChE (IC50: 19.08 μM), AChE (IC50: 55.44 μM), and HDAC (IC50: 105.1 μM) enzymes. Furthermore, olive biophenol verbascoside (IC50: 188.6 μM), and hydroxytyrosol extreme extract (IC50: 66.22 μg) were showed the highest levels of inhibition against the HDAC enzyme. Neuroprotective capacity against levodopa-induced toxicity in neuroblastoma (SH-SY5Y) cells of olive biophenols were assessed, where rutin indicated the highest neuroprotection (74%), followed by caffeic acid (73%), and extract hydroxytyrosol extreme (97%), respectively. To the best of our knowledge, this is the first in vitro report on the enzymes inhibitory activity of olive biophenols. Taken together, our in vitro results data suggest that olive biophenols could be a promising natural inhibitor, which may reduce the enzyme-induced toxicity associated with the oxidative stress involved in the progression of AD. Chemical compounds used in the study: Acetylthiocholine iodide (PubChem CID: 74629); S-Butyrylthiocholine chloride (PubChem CID: 3015121); Caffeic acid (PubChem CID: 689043); Dimethyl sulfoxide (DMSO) (PubChem: 679); L-3,4-Dihydroxyphenylalanine (L-DOPA) (PubChem CID: 6047); 5,5′-Dithiobis (2-nitrobenzoic acid) (DTNB) (PubChem CID: 6254); Epigallocatechin gallate (EGCG) (PubChem CID: 65064); Ethylenediamine tetraacetic acid (EDTA) (PubChem CID: 6049); Galantamine hydrobromide (PubChem CID: 121587); L-Glutamine (PubChem CID: 5961); Hydroxytyrosol (PubChem CID: 82755); Kojic acid (PubChem CID: 3840); Luteolin (PubChem CID: 5280445); Oleuropein (PubChem CID: 5281544); Penicillin-streptomycin (PubChem CID: 131715954); Quercetin (PubChem CID: 5280343); Rutin (PubChem CID: 5280805); Tris-HCl buffer (PubChem: 93573); Trypan blue (PubChem: 9562061)

Olive biophenols: A Natural β-secretase (BACE-1) Inhibitor

Globally growing public health concern, Alzheimer disease (AD) affecting a high percentage of people over age 65 years including Australia. The exact cause of the AD is still unknown but the evidence suggests that the ageing and family history. Currently, there is no treatment and cure for AD but the symptomatic relief drug will delay the disease progression. According to the most accepted amyloid hypothesis, the extracellular deposits of amyloid beta peptide (Aβ) which is produced from sequential endoproteolytic cleavage of amyloid precursor protein (APP) by β- and γ-secretases. Biophenols are the naturally accruing secondary phenol content metabolites of ubiquitous presence in the plant kingdom. Studies have been showed that the biophenols regulate Aβ production and clearance, it has been suggested that a few biophenols act by directly inhibiting β-secretase (BACE-1) activity. In the present study, we have investigated the direct inhibitory effects of olive biophenols including flavonoids (quercetin, rutin, luteolin), non-flavonoids (oleuropein, hydroxytyrosol, verbascoside, caffeic acid) and commercial extracts (olive leaf and fruit extract). Mostly of the olive biophenols significantly inhibited in vitro BACE-1 activity measured by using fluorometer with an excitation wavelengths of 335-345 nm and emission wavelengths of 485-510 nm). The flavonoid biophenol, rutin showing the highest BACE-1 inhibition (IC50 3.8nM) followed by non-flavonoid biophenol verbascoside (IC50 6.3nM)). The major biophenol among the olive leaf and fruit, oleuropein showed inhibition (IC50 2.76µM) followed by another major compound hydroxytyrosol (IC50 35nM). The commercial olive extracts also showed significant inhibition, olive fruit extract showed the highest (IC50 18ng) followed by hydroxytyrosol extreme extract ((IC50 0.26µg). Taken together, our data suggested that the olive biophenols could be promising compound against Aβ production in the development of Alzheimer’s disease. Further, animal and human studies are required to confirm the efficiency of olive biophenols to assess their safety and bioavailability in AD

Olive (Olea europaea L.) biophenols: A nutriceutical against Oxidative Stress in SH-SY5Y Cells

Plant biophenols have been shown to be effective in the modulation of Alzheimer's disease (AD) pathology resulting from free radical-induced oxidative stress and imbalance of the redox chemistry of transition metal ions (e.g., iron and copper). On the basis of earlier reported pharmacological activities, olive biophenols would also be expected to have anti-Alzheimer's activity. In the present study, the antioxidant activity of individual olive biophenols (viz. caffeic acid, hydroxytyrosol, oleuropein, verbascoside, quercetin, rutin and luteolin) were evaluated using superoxide radical scavenging activity (SOR), hydrogen peroxide (H2O2) scavenging activity, and ferric reducing ability of plasma (FRAP) assays. The identification and antioxidant activities in four commercial olive extracts-Olive leaf extractTM (OLE), Olive fruit extractTM (OFE), Hydroxytyrosol ExtremeTM (HTE), and Olivenol plusTM (OLP)-were evaluated using an on-line HPLC-ABTS+ assay, and HPLC-DAD-MS analysis. Oleuropein and hydroxytyrosol were the predominant biophenols in all the extracts. Among the single compounds examined, quercetin (EC50: 93.97 M) and verbascoside (EC50: 0.66 mM) were the most potent SOR and H2O2 scavengers respectively. However, OLE and HTE were the highest SOR (EC50: 1.89 μg/mL) and H2O2 (EC50: 115.8 μg/mL) scavengers among the biophenol extracts. The neuroprotection of the biophenols was evaluated against H2O2-induced oxidative stress and copper (Cu)-induced toxicity in neuroblastoma (SH-SY5Y) cells. The highest neuroprotection values (98% and 92%) against H2O2-induced and Cu-induced toxicities were shown by the commercial extract HTETM. These were followed by the individual biophenols, caffeic acid (77% and 64%) and verbascoside (71% and 72%). Our results suggest that olive biophenols potentially serve as agents for the prevention of neurodegenerative diseases such as AD, and other neurodegenerative ailments that are caused by oxidative stress

Phenolic compounds with antioxidant properties from canola meal extracts inhibit adipogenesis

The extraction of phenolic compounds from canola meal produces functional health products and renders the canola meal a more digestible animal feed. The extracted phenolics may have novel bioactivity worth investigation. In this study, several solvents were evaluated for their ability to extract phenolic compounds from canola meal: Water (WE) and various 80% organic solvent/water mixtures of methanol (ME), acetone (AE), ethanol (EE), butanol (BE), chloroform (CE) and hexane (HE). The in vitro antioxidant and anti-obesity properties of various extracts were investigated. Anti-obesity properties were studied using adipogenic differentiation inhibition of a murine mesenchymal stem cell line (C3H10T1/2) and a pancreatic lipase inhibition assay. AE, ME, and BE showed significant (p < 0.05) adipogenesis and pancreatic lipase inhibitory activities and may have more pharmacological properties. AE down-regulated the gene expression of the major adipogenic transcription factor, peroxisome proliferator-activated receptor gamma (PPAR), correlating to phenolic content in a dose-dependent manner. The chemical characterization of AE revealed the presence of sinapic acid, ferulic acid, and kaempferol derivatives as main bioactive phenols. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Characterization of bioactive and nutraceutical compounds occurring in olive oil processing wastes

Rationale Several bioactive compounds, including phenolic acids and secoiridoids, are transferred from olive drupes to olive oil during the first stage of production. Here, the characterization of these low molecular weight (LMW) compounds in olive oil and in closely related processing materials, like olive leaves (OL) and olive mill wastewaters (OMW), was faced up, for the first time, by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF MS). Methods A novel binary matrix composed of 1,8-bis(tetramethylguanidino)naphthalene (TMGN) and 9-aminoacridine (9AA) (1:1 molar ratio), displaying excellent ionization properties at low levels of laser energy, was employed in reflectron negative ion mode by a MALDI TOF/TOF system equipped with a neodymium-doped yttrium lithium fluoride (Nd:YLF) laser (345 nm). MS/MS experiments were performed by using ambient air as the collision gas. Results Four major secoiridoids typically present in olive oil, i.e., the aglycones of oleuropein and ligstroside, and oleacein and olecanthal at m/z 377.1, 361.1, 319.1 and 303.1, respectively, were detected in virgin olive oil (VOO) extracts, along with some of their chemical/enzymatic hydrolysis by-products, such as elenolic (m/z 241.1), decarboxymethyl-elenolic acids (m/z 183.1) and hydroxytyrosol (m/z 153.1). Besides oleuropein aglycone and oleacein, hydroxylated derivatives of decarboxymethyl-elenolic acid and hydroxytyrosol were evidenced in OMW. Conclusions While oleuropein was confirmed in OL extracts, several interesting phenolic compounds, including hydroxytyrosol, were recognized in OMW. The proposed approach based on the use of a novel binary matrix for MALDI MS/MS analyses of LMW bioactive compounds can be considered a promising analytical tool for a rapid screening of the phenolic fraction in olive oils and related processing wastes