Corn tassel (CT) is a waste part of the corn plant. It is a good co-product and rich in terms of bioactive compounds and phytochemicals. This research tried to show the phenolic profile, antioxidants, anticholinergic activities, and antibacterial properties of CT ethanol extract. The phenolic content analysis of the CT was determined quantitatively by LC-MS/MS, and the antioxidant capacity was measured using ABTS, DPPH, Cu(2+)-Cu(+), and Fe(3+)-Fe(2+) reducing methods. The anticholinergic measurements of CT were detected by inhibition of acetylcholinesterase (AChE). The antibacterial activity was determined by MIC and disc diffusion methods. Many phenolic compounds such as vanillic acid, caffeic acid, fumaric acid, acetohydroxamic acid, butein, myricetin, resveratrol, catechin hydrate, and 4-hydroxybenzoic acid were detected in ethanol extract of CT. The obtained plant ethanol extract had a 7.04% DPPH value, while it showed ABTS activity at 9.45%. Moreover, it had a 0.10 mg/mL inhibition effect on the AChE in terms of IC(50) values. The ethanol extract of the CT had an antibacterial property on the investigated bacteria at different ratios. In conclusion, this research aims to consider CT as a source of phenolic compounds and to reveal its bioactive properties and its effects on the treatment of some diseases.
Title: Anticholinergic, antioxidant, and antibacterial properties of Vitex agnus-castus L. seed extract : Assessment of its phenolic content by LC-MS/MS Kavaz A, Isik M, Dikici E, Yuksel M Ref: Chem Biodivers, :, 2022 : PubMed
In this current study, Vitex agnus-castus seed ethanol extracts were analyzed for their phytochemical component content, anticholinergic and antioxidant activities, and antibacterial properties. The phenolic compound composition of these seeds was determined by using LC-MS/MS. Antioxidant activity of the seeds was examined by the DPPH, ABTS, Fe 3+ -Fe 2+ reducing, and CUPRAC. Also, the anticholinergic activity was measured by the inhibition of acetylcholinesterase (AChE). The antibacterial activity was performed by disc diffusion and minimum inhibitory concentration methods. The main phenolic compound was vanillic acid (22812.05 microg/L ) and followed by luteolin, fumaric acid, quercetin, caffeic acid, 4-hydroxybenzoic acid, salicylic acid, kaempferol, btein, ellagic acid, resveratrol, catechin hydrate, phloridzin dehydrate, naringenin, respectively. The DPPH free radical scavenging value of ethanol extract of plant seeds was 9.41%, while the ABTS radical scavenging activity was determined as 12.66%. The ethanol extract of the seeds exhibited antibacterial activity on Escherichia coli, Staphylococcus aureus , and Salmonella Typhimurium, differently. S. aureus was found to be more susceptible to the extract than other bacteria. Also, the inhibition effect of seed ethanolic extract on the AChE with IC 50 values were 36.34+/-5,6 microg/mL. From the results, V. agnus-castus seed can be suggested as a promising natural antioxidant and antibacterial candidate for the preservation of foods.
Title: Toluidine blue O attenuates tau phosphorylation in N2a-APPSwe cells Onder S, Biberoglu K, Yuksel M, Tacal O Ref: Chemico-Biological Interactions, 366:110126, 2022 : PubMed
Alzheimer's disease (AD) is characterized by extracellular amyloid plaques composed of amyloid-beta peptide (Abeta), intracellular neurofibrillary tangles containing hyperphosphorylated tau protein and neuronal loss. Most of the FDA-approved AD drugs currently on the market are cholinesterase inhibitors, which are only effective in relieving the symptoms of AD. However, recent studies in AD drug discovery focus on multi-targeted strategies, including anti-amyloid and anti-tau therapy. In the current study, we have investigated the effects of toluidine blue O (TBO), a cholinesterase inhibitor, on amyloid precursor protein (APP) processing, tau phosphorylation, and tau kinases/phosphatase in N2a mouse neuroblastoma cells stably expressing the Swedish mutation of human APP695 (N2a-APPSwe). The results demonstrated that TBO reduces Abeta40/42 levels by decreasing expression levels of beta-secretase 1 (BACE1), presenilin 1 (PS1) and total APP without causing cytotoxic effects in N2a-APPSwe cells. TBO also decreased the levels of both total tau and phosphorylated tau at residues Ser202/Thr205, Thr181, Ser396 and Ser 396/Ser404. Moreover, when the possible mechanisms underlying its effects on tau pathology were explored, TBO was found to decrease tau phosphorylation at those sites by reducing the expression levels of Akt, GSK-3beta, Cdk5, inactive p-PP2A and increasing the expression levels of p-Akt Ser473 and inactive p-GSK-3beta Ser9. Our new data support the idea that TBO may be a promising multi-target drug candidate for the treatment of AD.
Title: Phytochemicals Analysis and Some Bioactive Properties of Erica manipuliflora Salisb. (EMS); Antibacterial, Antiradical and Anti-lipid Peroxidation Yuksel AK, Dikici E, Yuksel M, Isik M, Tozoglu F, Koksal E Ref: Iran J Pharm Res, 20:422, 2021 : PubMed
In the present study, the phenolic content by using LC MS/MS method, anticholinergic, antioxidant (metal reduction, radical and removal of lipid peroxidation), and antibacterial activities of Erica manipuliflora Salisb. (EMS) extract were determined. The amount of vanillic acid, fumaric acid, catechin hydrate, quercetin, and phloridzin dihydrate were found higher than other compounds. The ethanol extract of the EMS showed an inhibition effect on the Acetylcholinesterase (AChE) enzyme with IC(50) value of 0.124 +/- 0.008 mg mL(-1). Also, this extract of the EMS indicated radical (DPPH and ABTS) scavenging activity (about 20%) and the reducing capacity for Cu(II) and Fe(III) close to trolox, and inhibited the oxidation of linoleic acid with 40.5% at 20 microg mL(-1). Antibacterial activity of the extracts was investigated against Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium using agar disc diffusion and minimum inhibitory concentration (MIC) methods. The EMS extract was found to be effective when used at least 312 mg mL(-1) concentration on the pathogenic microorganisms. Consequently, it has an important non-synthetic natural content that can be used in the treatment of many diseases due to its many bioactivities such as anticholinergic, antioxidant (radical removal, lipid peroxidation prevention, etc.) and antibacterial.
Title: Azure B affects amyloid precursor protein metabolism in PS70cells Biberoglu K, Yuksel M, Tacal O Ref: Chemico-Biological Interactions, 299:88, 2019 : PubMed
Alzheimer's disease (AD), the most common form of dementia, is characterized by abundant deposition of amyloid-beta (Abeta) peptide that is the result of sequential cleavage of amyloid precursor protein (APP) by beta-secretase and gamma-secretase. Several studies have documented that inhibition of Abeta peptide synthesis or facilitating its degradation is one of the attractive therapeutic strategies in AD. Methylene blue (MethB), which has recently been investigated in Phase II clinical trials, is a prominent inhibitor in reducing Abeta oligomers. Herein, we wonder whether the mitigating effects of MethB on amyloid metabolism are related to the activity of its major metabolite, azure B. The goal of this study was to investigate the effects of azure B, which is also a cholinesterase inhibitor, on APP processing by using Chinese hamster ovary cells stably expressing human wild-type APP and presenilin 1 (PS70). Azure B significantly decreased the levels of secreted APPalpha (sAPPalpha) and Abeta40/42 in culture medium with a dose-dependent manner. A significant decrease was also observed in the levels of intracellular APP without affecting the cell viability. In parallel with the decrease of APP and APP metabolites, the activity of beta-secretase 1 (BACE1) was significantly attenuated compared to control. Overall, our results show that azure B has a large contribution for the pharmacological profile of MethB in APP metabolism.
Title: Toluidine blue O modifies hippocampal amyloid pathology in a transgenic mouse model of Alzheimer's disease Yuksel M, Biberoglu K, Onder S, Akbulut KG, Tacal O Ref: Biochimie, 146:105, 2018 : PubMed
Recently, we have demonstrated that toluidine blue O (TBO), a phenothiazine dye, shows inhibitory effects on both cholinesterases and amyloid pathology in Alzheimer's disease (AD) cellular model. In the present study, we aimed to determine the effects of TBO (in a purity of 85%) on amyloid and tau pathologies in a triple transgenic mouse model of AD (3xTg-AD). Beginning at 7.5 (mild pathology) or 13 (severe pathology) months of age, 3xTg-AD mice were treated intraperitoneally with 4mg/kg TBO or vehicle daily for 30 days. TBO treatment significantly reduced the levels of insoluble Abeta40 and Abeta42 in the hippocampi of mild and severe pathology groups compared to vehicle-treated counterparts. When the levels of full-length amyloid precursor protein (APP) and beta-site APP-cleaving enzyme 1 (BACE1) were assessed in 3xTg-AD mice at late pathological stage, no significant changes were observed after TBO treatment. Similarly, TBO did not recover hyperphosphorylation of tau at residues Thr181 and Ser202/Thr205 significantly in soluble and insoluble hippocampal fractions of 3xTg-AD mice. Taken together, the current study is the first in vivo report, to our knowledge, demonstrating that TBO mitigates amyloid pathology in 3xTg-AD mice with no apparent change on tau phosphorylation. Overall, the preliminary data presented here support the possible use of TBO as a disease-modifying drug for AD treatment.
Title: Effects of phenothiazine-structured compounds on APP processing in Alzheimer's disease cellular model Yuksel M, Biberoglu K, Onder S, Akbulut KG, Tacal O Ref: Biochimie, 138:82, 2017 : PubMed
The excess accumulation of amyloid-beta (Abeta) peptides derived from the sequential cleavage of amyloid precursor protein (APP) by secretases, is one of the toxic key events leading to neuronal loss in Alzheimer's disease (AD). Studies have shown that cholinergic activity may also be involved in the regulation of APP metabolism. In the current study, we have investigated the roles of toluidine blue O (TBO) and thionine (TH), newly recognized phenothiazine-derived cholinesterase inhibitors, on the metabolism of APP in Chinese hamster ovary cells stably expressing human APP751 and presenilin 1 (PS70 cells). We assessed the effects of both compounds on the levels of Abeta, soluble APP-alpha (sAPPalpha), intracellular APP and beta-site APP-cleaving enzyme 1 (BACE1). After treatment of PS70 cells with TBO or TH without any side effect on cell viability, the levels of secreted Abeta40, Abeta42 and sAPPalpha were assayed by specific sandwich ELISAs while APP and BACE1 in cell lysates were analyzed using Western blot. The secreted Abeta40, Abeta42 and sAPPalpha in TBO- and TH-treated cells were found to be reduced in a dose-dependent manner compared to vehicle-treated cells. Results suggest that TH mitigated the Abeta pathology by lowering APP levels whereas reduced Abeta caused by TBO treatment seems to be the outcome of both less substrate availability and amyloidogenic APP processing. Taken together, our results represent the first report demonstrating that TBO and TH can affect amyloid metabolism in vitro.
The "cholinergic anti-inflammatory pathway" provides neurological modulation of cytokine synthesis to limit the magnitude of the immune response. This study aimed to evaluate the impact of the cholinergic anti-inflammatory pathway on the extent of tissue integrity, oxidant-antioxidant status and neutrophil infiltration to the inflamed organ in a rat model of acetic acid-induced colitis. Colitis was induced by intrarectal administration of 5% acetic acid (1ml) to Sprague-Dawley rats (200-250g; n=7-8 per group). Control group received an equal volume of saline intrarectally. The rats were treated with either nicotine (1mg/kg/day) or huperzine A (0.1mg/kg/day) intraperitoneally for 3 days. After decapitation, the distal colon was scored macroscopically and microscopically. Tissue samples were used for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, and myeloperoxidase (MPO) activity. Formation of reactive oxygen species was monitored by using chemiluminescence (CL). Nuclear factor (NF)-kappaB expression was evaluated in colonic samples via immunohistochemical analysis. Trunk blood was collected for the assessment of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-10, resistin and visfatin levels. Both nicotine and huperzine A reduced the extent of colonic lesions, increased colonic MDA level, high MPO activity and NF-kappaB expression in the colitis group. Elevation of serum IL-1beta level due to colitis was also attenuated by both treatments. Additionally, huperzine A was effective to reverse colitis-induced high lucigenin-enhanced CL values and serum TNF-alpha levels. Colitis group revealed decreased serum visfatin levels compared to control group which was completely reversed by nicotine. In conclusion, modulation of the cholinergic system either by nicotine or ACh esterase inhibition improved acetic acid-induced colonic inflammation as confirmed by macroscopic and microscopic examination and biochemical assays.
