Fatma Sezer Senol

Acetylcholinesterase, butyrylcholinesterase, and tyrosinase inhibition studies and antioxidant activities of 33 Scutellaria L. taxa from Turkey

The members of Scutellaria L. (Lamiaceae) is known to be rich particularly in flavonoids and among them, S. baicalensis has been recorded to be used for memory-enhancing purpose. Therefore, we initiated a study to screen the methanol extracts prepared from the aerial parts of 33 Turkish Scutellaria species for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, which are the key enzymes taking place in pathogenesis of Alzheimers disease. Besides, the methanol extracts were tested in vitro against another enzyme, tyrosinase, which is associated with melanin hyperpigmentation. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenger effect, ferrous ion-chelating ability, and ferric-reducing antioxidant power (FRAP) of the ethyl acetate and methanol extracts were also determined. AChE, BChE, and tyrosinase inhibition of the extracts were performed on ELISA microplate reader by spectrophotometric method. The extracts showed weak inhibition against AChE and BChE, while the best tyrosinase inhibition was caused by the methanol extract of S. brevibracteata subsp. subvelutina. The extracts had a very high DDPH radical scavenging effect and moderate antioxidant activity in ferrous ion-chelating and FRAP tests.

Antioxidant and anticholinesterase assets and liquid chromatography-mass spectrometry preface of various fresh-water and marine macroalgae.

The ethanol extracts from the fresh-water algae; Chara hispida L., Cladophora glomerata (Dilw.) Kόtz, C. fracta (Dilw.) Kόtz, Spirogyra gratiana Transeau, Mougeotia sp. (C.A. Agardh), Vaucheria sessilis (Vauch.) De Candolle, Geminella mutabilis (Breb.) Wille, the fresh-water plants; Ranunculus rionii Lagger and Ceratophyllum demersum L., as well as the marine algae; Sciniaia furcellata (Turn.) J. Agardh, Dictyota dichotoma (Huds.) Lam., Padina vickersiae Hoyt, Halopteris scoparia (L.) Sauvagau, and the sea grass; Posidonia oceanica (L.) Dell. were assessed in vitro for their antioxidant and anti-acetylcholinesterase (AChE) activities. Antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity test at 0.125, 0.25, 0.5, 1.0, and 2.0 mg ml -1 and ferric-reducing antioxidant power assay (FRAP) at 0.5, 1.0, and 2.0 mg ml −1 concentrations. Total phenolic contents of the extracts were determined using Folin-Ciocalteaus reagent. The extracts were further analyzed qualitatively by LC-DAD-MS. S. gratiana had the best antioxidant activity, followed by R. rionii. LC-DAD-MS showed rich gallic acid and its ethyl ester contents in S. gratiana , while prosperous vitamin C content has been detected in P. oceanica for the first time in this study. S. gratiana possessed the highest inhibition (42.5±2.28%) at 2.0 mg ml −1 against AChE.

Profiling of in vitro neurobiological effects and phenolic acids of selected endemic Salvia species

The ethyl acetate and methanol extracts from 16 Salvia L. species were screened for their inhibitory activity against acetylcholinesterase, butyrylcholinesterase, lipoxygenase, and tyrosinase; the enzymes linked to neurodegeneration. Their antioxidant activity was also tested using DPPH radical scavenging, metal-chelation, and ferric-reducing antioxidant power (FRAP) assays. Total flavonoid content of the extracts was determined by AlCl3 reagent, while HPLC technique was applied for analysis of various phenolic acids in the extracts. The extracts exerted weak cholinesterase and tyrosinase inhibition, and remarkable inhibition against lipoxygenase (13.07±2.73-74.21±5.61%) at 100μgml-1. The methanol extracts showed higher antioxidant activity in DPPH radical scavenging and FRAP assays. The extracts were analyzed for their gallic, protocateuchic, p-hydroxy-benzoic, vanillic, caffeic, chlorogenic, syringic, o- and p-coumaric, ferulic, rosmarinic, and tr-cinnamic acid contents and the methanol extract of Salvia ekimiana (153.50mg100g-1) was revealed to be the richest in terms of rosmarinic acid.

Inhibitory potential of the leaves and berries of Myrtus communis L. (myrtle) against enzymes linked to neurodegenerative diseases and their antioxidant actions

The dichloromethane (DCM), acetone, ethyl acetate and methanol extracts of the leaves and berries of Myrtus communis L. were screened against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and tyrosinase (TYRO), the enzymes linked to neurodegenerative diseases, at 200 μg ml− 1. Antioxidant activity was tested using radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and N,N- dimethyl-p-phenylenediamine (DMPD) radicals, metal chelation capacity, ferric-reducing antioxidant power (FRAP) and phosphomolybdenum-reducing antioxidant power (PRAP) assays. Total phenol and flavonoid quantification of the extracts was calculated spectrophotometrically. The extracts showed a moderate AChE (17.49 ± 3.99% to 43.15 ± 1.55%) and TYRO inhibition (4.48 ± 1.50% to 40.53 ± 0.47%). The leaf extracts were ineffective against BChE, while the berry extracts displayed inhibition between 21.83 ± 3.82% and 36.80 ± 2.00%. The polar extracts exerted remarkable scavenging effect against DPPH and DMPD and also in the FRAP assay, where the DCM extract of the berries had the best metal chelation capacity (79.29 ± 1.14%). This is the first study that demonstrates in vitro neuroprotective effects of myrtle.

In Silico Approach to Inhibition of Tyrosinase by Ascorbic Acid Using Molecular Docking Simulations

Current evidence suggests that endogenous dopamine may act as a neurotoxin following its oxidation to an oquinone and reaction with cellular thiols, which are neutoxic, which may occur spontaneously or via reaction with tyrosinase or some other enzymes. Tyrosinase (E.C. 1.14.18.1) with two cupper ions coordinated by three histidines is a bifunctional enzyme that catalyses both the hydroxylation of tyrosine to L-DOPA and the consequent oxidation of the resulting catechol-containing species to an o-quinone. Therefore, tyrosinase may play a role in neuromelanin formation in the brain and could be central to dopamine neurotoxicity by contributing to the neurodegeneration associated with Parkinsons disease. In the present study, inhibitory effect of ascorbic acid against tyrosinase has been investigated and it has shown a remarkable inhibitory effect in in vitro assays. Then, the in silico-based experiments established through molecular docking calculations and scoring, docking search algorithm, and data plotting indicated that ascorbic acid is strong inhibitor of tyrosinase by interacting with four amino acid units (histidine 263, serine 282, phenylalanine 264, and valin 283) in the active site of the enzyme. The compound also had two long distant hydrogen bindings with Cu1 and Cu2 with distances of 3.57 and 3.41 A, respectively, through its O5 atom.

Phytochemical Characterization of Phagnalon graecum Boiss. by HPLC and GC-MS with its Enzyme Inhibitory and Antioxidant Activity Profiling by Spectrophotometric Methods

In the current study, the n-hexane, chloroform, ethyl acetate, methanol, and water extracts of Phagnalon graecum Boiss. (Asteraceae), a spice plant, were investigated for their enzyme inhibitory activity against acetylcholinesterase, butyrylcholinesterase, lipoxygenase, tyrosinase, and antioxidant activities. Antioxidant activity of the extracts was determined by 2,2-diphenyl-1-picrylhydrazyl radical scavenging, ferric ion-chelation activity, and ferric-reducing antioxidant power tests. Total phenol (gallic acid equivalent) and flavonoid (quercetin equivalent) contents were calculated. Essential oil of the plant was analyzed by GC-MS, while the selected phenolic acids were analyzed by HPLC. The extracts had insignificant inhibition against the tested enzymes, whereas they displayed a remarkable antioxidant activity. Therefore, to the best of our knowledge, this study presents the first data on biological activity and phytochemical content of P. graecum and this species could be utilized as potential antioxidant applicable for food preservation.

An in vitro perspective to cholinesterase inhibitory and antioxidant activity of five Gentiana species and Gentianella caucasea.

The dichloromethane (DCM), ethyl acetate (EtOAc), and methanol extracts from the leaves, roots, and flowers of the five species of Gentiana (Gentiana asclepiadea, Gentiana cruciata, Gentiana olivieri, Gentiana septemfida, and Gentiana verna) and Gentianella caucasea were investigated for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and antioxidant effect using 2,2-diphenyl-1-picrylhydrazyl radical scavenging, metal-chelation capacity, and ferric-reducing antioxidant power assays. Total phenol and flavonoid contents of the extracts were determined spectrophotometrically. The presence of some characteristic compounds found in Gentiana species (gentiopicroside, swertiamarin, isoorientin, isovitexin and vitexin) was analyzed in the extracts by thin layer chromatography. The flower DCM extract of G. verna exerted the highest inhibition against AChE (53.65 ± 1.03%), whereas the root EtOAc extract of G. cruciata was the most effective in BChE inhibition assay (50.72 ± 0.75%) at 100 μg ml− 1. The extracts of G. verna were also found to be more active in the antioxidant tests.

Comparative antioxidant activity appraisal of traditional Sudanese kisra prepared from two sorghum cultivars

The effect of fermentation and heating on the antioxidant activity of the fermented and fermented baked (kisra) dough prepared from two Sorghum cultivars (Tabat and Wad Ahmed) was evaluated. Kisra prepared from Tabat cultivar showed higher DPPH (1,1-diphenyl-2-picrylhydrazyl radical) scavenging and ferric reducing/antioxidant power (FRAP) than that of the Wad Ahmed cultivar. Baking improves the DPPH and FRAP of the kisra prepared from two cultivars. Baking caused a variable effect on the total phenol, tannins and flavonoids content across different periods of fermentation where an increase was mainly observed for samples subjected to longer periods of fermentation. A positive high correlation between the total phenol and antioxidant activity, using the DPPH and FRAP assays, was obtained for kisra prepared from both cultivars. The same observation was obtained for tannin content. In conclusion, fermentation and heating improve the antioxidant capacity of the sorghum grains from Tabat and Wad Ahmed cultivars.

Assessment of antimicrobial, insecticidal and genotoxic effects of Melia azedarach L. (chinaberry) naturalized in Anatolia.

In this study, antibacterial, antifungal, insecticidal and genotoxic activities of the fruit and leaf extracts of Melia azedarach of Turkish origin were evaluated for the first time. The antimicrobial activity was assessed against Gram (+) and ( − ) bacteria, four Candida species and three dermatophytic fungus (Trichophyton rubrum, Epidermophyton floccosum and Microsporum gypseum). The insecticidal activity of the methanolic fruit extract was performed against the larvae of Aedes aegpyti, Culex pipiens and Culex quinquefasciatus. The genotoxicity of this extract was evaluated against Drosophila melanogaster by somatic mutation and recombination test. The extracts showed higher antibacterial effect against Gram ( − ) strains (16–32 μg ml− 1 of minimal inhibition concentration, MIC), while the leaf extracts were more effective on Candida albicans (32 μg ml− 1 of MIC). The extracts did not exhibit insecticidal activity and genotoxicity. Total phenol and flavonoid contents of the extracts were determined spectrophotometrically, and the ethyl acetate extract of the leaves was the richest in total flavonoids.

In vitro cholinesterase inhibitory and antioxidant effect of selected coniferous tree species.

OBJECTIVE To explore cholinesterase inhibitory and antioxidant effect of six coniferous trees (Abies bornmulleriana, Picea pungens, Juniperus communis, Cedrus libani, Taxus baccata, and Cupressus sempervirens var. horizantalis). METHODS Acetone (Ace), ethyl acetate (EtOAc), and ethanol (EtOH) extracts prepared from the needles and shoots of the six coniferous trees were screened for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity at 100 μg/mL. Antioxidant activity of the extracts was tested using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and N,N-dimethyl-p-phenylendiamine (DMPD) radical scavenging, metal-chelation capacity, ferric-(FRAP) and phosphomolibdenum-reducing antioxidant power (PRAP) assays. All of the assays were performed in ELISA microplate reader. Total phenol and flavonoid amounts in the extracts were determined spectrophotometrically. RESULTS Among thirty-six extracts in total, the shoot-Ace extract of Cupressus sempervirens var. horizantalis exerted the highest inhibition against AChE [(54.84±2.51)%], while the needle-Ace extract of Cedrus libani was the most effective in inhibiting BChE [(67.54±0.30)%]. The highest DPPH radical scavenging effect, FRAP and PRAP was observed in the shoot-Ace and EtOAc extracts from Taxus baccata, whereas all the extracts showed a variable degree of scavenging effect against DPMD radical. The shoot-EtOAc extract of Cedrus libani had the highest metal-chelation capacity [(58.04±0.70)%]. The shoot extracts of Taxus baccata were determined to have the richest total phenol content, which may contribute to its marked antioxidant activity. CONCLUSIONS The conifer species screened in this study may contain cholinesterase-inhibiting and antioxidant properties, which might be useful against Alzheimers disease.