Müberra Koşar

In vitro antioxidant properties and phenolic composition of Salvia halophila Hedge from Turkey

An endemic plant of Turkey Salvia halophila Hedge (Lamiaceae) was examined for its antioxidant activity and phenolic compositions. The aerial part of S. halophila was extracted with different solvents in an order of increasing polarity such as hexane, ethyl acetate, methanol, and 50% methanol using a Soxhlet apparatus. Water extract was also prepared from S. halophila by reflux. All solvent fractions were investigated for their total phenolic contents, flavonoids, flavonols, qualitative-quantitative compositions, iron(III) reductive activities, free radical scavenging activities and the effect upon linoleic acid peroxidation activities. The peroxidation level was also determined by the TBA method. The results of activity tests given as IC50 values were estimated from non-linear algorithm and compared with standards via BHT, ascorbic acid, gallic acid. Polar fractions were found more active among the others in free radical activity system whereas non-polar fractions protected the peroxidation of linoleic acid. Rosmarinic acid was the most abundant component, in the extracts.

Inhibitory effects of dietary flavonoids on purified hepatic NADH-cytochrome b5 reductase: Structure-activity relationships

The structure-activity relationships of flavonoids with regard to their inhibitory effects on NADH-cytochrome b5 reductase (E.C. 1.6.2.2), a clinically and toxicologically important enzyme, are not known. In the present study, the inhibitory effects of fourteen selected flavonoids of variable structure on the activity of purified bovine liver cytochrome b5 reductase, which shares a high degree of homology with the human counterpart, were investigated and the relationship between structure and inhibition was examined. Of all the compounds tested, the flavone luteolin was the most potent in inhibiting b5 reductase with an IC50 value of 0.11 μM, whereas naringenin, naringin and chrysin were inactive within the concentration range tested. Most of the remaining flavonoids (morin, quercetin, quercitrin, myricetin, luteolin-7-O-glucoside, (-)-epicatechin, and (+)-catechin) produced a considerable inhibition of enzyme activity with IC50 values ranging from 0.81 to 4.5 μM except apigenin (36 μM), rutin (57 μM) and (+)-taxifolin (IC50 not determined). The magnitude of inhibition was found to be closely related to the chemical structures of flavonoids. Analysis of structure-activity data revealed that flavonoids containing two hydroxyl groups in ring B and a carbonyl group at C-4 in combination with a double bond between C-2 and C-3 produced a much stronger inhibition, whereas substitution of a hydroxyl group at C-3 was associated with a less inhibitory effect. The physiologically relevant IC50 values for most of the flavonoids tested regarding b5 reductase inhibition indicate a potential for significant flavonoid-drug and/or flavonoid-xenobiotic interactions which may have important therapeutic and toxicological outcomes for certain drugs and/or xenobiotics.

In vitro effects of myricetin, morin, apigenin, (+)-taxifolin, (+)-catechin, (−)-epicatechin, naringenin and naringin on cytochrome b5 reduction by purified NADH-cytochrome b5 reductase

The microsomal NADH-dependent electron transport system consisting of cytochrome b5 reductase and cytochrome b5 participates in a number of physiologically important processes including lipid metabolism as well as is involved in the metabolism of various drug and xenobiotics. In the present study, we assessed the inhibitory effects of eight dietary flavonoids representing five distinct chemical classes on cytochrome b5 reduction by purified cytochrome b5 reductase. From the flavonoids tested, myricetin was the most potent in inhibiting cytochrome b5 reduction with an IC50 value of 0.35μM. Myricetin inhibited b5 reductase noncompetitively with a Ki of 0.21μM with respect to cofactor NADH, and exhibited a non-linear relationship indicating non-Michaelis-Menten kinetic binding with respect to cytochrome b5. In contrast to the potent inhibitory activity of myricetin, (+)-taxifolin was found to be a weak inhibitor (IC50=9.8μM). The remaining flavonoids were inactive within the concentration range tested (1-50μM). Analysis of structure-activity data suggested that simultaneous presence of three OH groups in ring B is a primary structural determinant for a potent enzyme inhibition. Our results suggest that inhibition of the activity of this system by myricetin or myricetin containing diets may influence the metabolism of therapeutic drugs as well as detoxification of xenobiotics.

Anti-inflammatory effects of Pelargonium endlicherianum Fenzl. extracts in lipopolysaccharide-stimulated macrophages.

Objectives: This study was designed to investigate the anti-inflammatory effects of Pelargonium endlicherianum Fenzl. and Pelargonium quercetorum Agnew. root extracts compared with the effects of commercial Pelargonium sidoides root extract by production of pro-inflammatory substances and inflammatory signal transduction on LPS-stimulated macrophages. Materials and Methods: To measure the effects of root extracts on pro-inflammatory mediators, we used the following methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (cell viability or cytotoxcicity), enzyme-linked immunosorbent assay (cytokine production, prostoglandin E2 production), reverse transcriptase-polymerase chain reaction (COX-2, iNOS mRNA), Western blotting analysis [MAPK activation and NF-κB (p65) traslocation] and the Griess reaction (NO production). Results: Stimulation of the RAW 264.7 cells with LPS (0.5 µg/mL, 6 hrs treatment) caused an elevated production of pro-inflammatory cytokines (TNF-α and IL-6), increased mRNA expression of COX-2 and inducible NO synthase with release of PGE2 and NO, activated MAPK (phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, P38) signalling pathway, and nuclear translocation of NF-κB (p65), which were markedly inhibited by the pre-treatment with 11% ethanol and 70% methanol root extracts of P. endlicherianum without causing any cytotoxic effects. P. quercetorum root extract only decreased TNF-α production and P. sidoides root extract alleviated P38/MAPK activation and COX-2 mRNA expression with PGE2 production. Conclusion: Our data indicate that especially 11% ethanol root extract of P. endlicherianum targets the inflammatory response of macrophages via inhibition of COX-2, IL-6, and TNF-α through inactivation of the NF-κB signalling pathway, supporting the pharmacologic basis of P. endlicherianum as a traditional herbal medicine for the treatment of inflammation and its associated disorders.

The opium poppy as a symbol of sleep in Bertel Thorvaldsen's relief of 1815

Danish sculptor Bertel Thorvaldsen (1770-1844) is one of the most remarkable representatives of Neoclassicist sculptural art in Europe, which was largely inspired by the classical art and culture of Greek and Roman antiquity. A pair of marble reliefs, Night and Day, exhibited in the Thorvaldsen Museum (Copenhagen), marks the culmination of Thorvaldsens relief art and is of particular interest to the history of sleep medicine. In the first relief, Night, an angel with her neck bent and eyes closed has two babies in her embrace and seems to be floating down in grief, with an owl hovering behind her. Her hair is also twined with opium poppies, the symbol of sleep and death in antiquity. Our findings suggest that this relief not only indicates a mythological association between the opium poppy and sleep but also has a strong connotation with the poppys medicinal use for inducing sleep throughout the centuries.

Quantitative Determination of Gallic acid and Cyanidin-3-O-Glucoside within Sumac Extracts by HPLC-MS/MS

In this study gallic acid and cyanidin-3-O-glucoside contents of Water and MeOH %70 extracts of sumac were investigated using with HPLC ESI/MSMS MRM method. The assay performed in different concentrations of gallic acid and cyanidin-3-O-glucoside chloride as standard solutions. The diagnostic fragmentations of gallic acid and cyanidin-3-O-glucoside were used 168.7/125–79 and 448.7/287–150 respectively for MRM quantitative determination.