E. I. Chernyak

Deaminated UV filter 3-hydroxykynurenine O-β-d-glucoside is found in cataractous human lenses

Analysis of UV filter levels in 48 cataractous human lenses was performed with the use of HPLC. A new chromophore with the absorption maximum at 410nm and molecular mass of 369Da was detected and assigned as deaminated 3-hydroxykynurenine O-beta-D-glucoside (3OHCKAG). Cataractous lenses are characterized by the wide range of the UV filter concentrations and remarkably lower levels of UV filters and glutathione than published for the normal lenses. No correlation between the lens age and the level of UV filters has been found in cataractous lenses.

Asynchrony between Host Plant and Insects-Defoliator within a Tritrophic System: The Role of Herbivore Innate Immunity.

The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects’ fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon. However, the spreading of this phenomenon through the food chain, and especially those mechanisms operating this spreading, are still unclear. In this paper, we study the effect of seasonally declined leafquality (estimated in terms of phenolics and nitrogen content) on herbivore fitness, immune parameters and resistance against pathogen by using the silver birch Betula pendula—gypsy moth Lymantria dispar—nucleopolyhedrovirus as the tritrophic system. We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph. In addition, the larval susceptibility to exogenous nucleopolyhydrovirus infection as well as covert virus activation were both enhanced due to the phenological mismatch. The observed effects of phenological mismatch on insect-baculovirus interaction may partially explain the strong and fast fluctuations in the population dynamics of the gypsy moth that is often observed in the studied part of the defoliator area. This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.

Leaf Surface Lipophilic Compounds as One of the Factors of Silver Birch Chemical Defense against Larvae of Gypsy Moth

Plant chemical defense against herbivores is a complex process which involves a number of secondary compounds. It is known that the concentration of leaf surface lipophilic compounds (SLCs), particularly those of flavonoid aglycones are increased with the defoliation treatment of silver birch Betula pendula. In this study we investigated how the alteration of SLCs concentration in the food affects the fitness and innate immunity of the gypsy moth Lymantria dispar. We found that a low SLCs concentrations in consumed leaves led to a rapid larval development and increased females’ pupae weight (= fecundity) compared to larvae fed with leaves with high SLCs content. Inversely, increasing the compounds concentration in an artificial diet produced the reverse effects: decreases in both larval weight and larval survival. Low SLCs concentrations in tree leaves differently affected larval innate immunity parameters. For both sexes, total hemocytes count in the hemolymph increased, while the activity of plasma phenoloxidase decreased when larvae consume leaves with reduced content of SLCs. Our results clearly demonstrate that the concentration of SLCs in silver birch leaves affects not only gypsy moth fitness but also their innate immune status which might alter the potential resistance of insects against infections and/or parasitoids.

Synthesis of spin-labeled amides of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox)

Reaction of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) with 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 3-amino-2,2,5,5-tetramethylpyrrolidine-1-oxyl, and 3-aminomethyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl synthesized the corresponding spin-labeled amides. The synthesized compounds exhibited antioxidant potential and were promising for application in biomedical studies using magnetic-resonance imaging (MRI).

Use of the Mannich Reaction to Synthesize Spin-Labeled Derivatives of the Natural Flavonoid Dihydroquercetin

Mono-substituted spin-labeled compounds were synthesized from Mannich reactions of dihydroquercetin with 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 3-amino-2,2,5,5-tetramethylpyrrolidine-1-oxyl, and 3-aminomethyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl. According to preliminary data, the compounds possessed antioxidant activity and selective cytotoxicity against various tumor cells and were promising for biomedical tests including magnetic resonance tomography.

Dynamics of Biologically Active Compound Contents from Betula pendula Leaves During Early Leaf Development

The individual group compositions of hydroxycinnamic acid derivatives, flavonoids, terpenoids, fatty acids, and hydrocarbons from Betula pendula leaves during early leaf development were studied using GC-MS and HPLC. The contents of biologically active compounds varied considerably during observation for 20 d after leaf emergence. It was shown that the dynamics of antifeedant triterpenoid contents correlated with the dynamics of L. dispar caterpillar deaths during the study period. The dynamics of the contents of total phenols, slightly oxidized phenols, and soluble proanthocyanidins were studied using spectrophotometry.

Phytoecdysteroids from the Aerial Part of Silene colpophylla

The genus Silene L. includes about 700 species according to current data [1] and represents the richest source of ecdysteroids. Greater than 100 species of this genus have now been found to produce ecdysteroids [2]. Greater than 80 of the 476 identified ecdysteroids are synthesized by Silene species [3, 4]. The goal of the present work was to study the chemical composition of ecdysteroids from the aerial part of S. colpophylla Wrigley, which we recommend for the first time as a source of ecdysteroids. Ecdysteroids were isolated from the aerial part of S. colpophylla collected during flowering in 2009–2012. Starting extracts were obtained by exhaustive extraction of ground air-dried raw material by EtOH (70%). Lipophilic substances were removed by hexane. Subsequent multiple extraction by n-BuOH extracted terpenoid and phenolic compounds. The concentrated residual was fractionated successively using CHCl3–EtOH (9:1), EtOH (70%), and H2O. The CHCl3–EtOH fraction of the BuOH extract was separated by repeated chromatography over columns of silica gel. A total of 17 ecdysteroids were isolated from S. colpophylla for the first time. Six of these were identified by various physicochemical analytical methods (UV, HPLC, MS, NMR). HPLC-MS analysis was carried out on an Agilent 1200 LC with a diode-matrix detector, a hybrid quadrupole–timeof-flight micrOTOF-Q mass spectrometer (Bruker), and a Zorbax SB-C18 column (2.1 50 mm) using HCOOH–MeOH 2% eluent (linear gradient AcN content from 10 to 90% over 0–20 min) at flow rate 0.2 mL/min. The mass detector operated in chemical ionization and electrospray modes at atmospheric pressure (APCI pos. and API-ES). Positive and negative ions were scanned in the range m/z 100–3000. The drying gas (N2) flow rate was 4 mL/min at 220°C. HPLC-UV analysis was carried out on an Agilent 1100 LC with a diode-matrix detector and a Zorbax Eclipse XDB C8 chromatography column (4.6 150 mm, 5 m) using MeOH–TFA (0.1%) eluent (gradient from 2 to 100% MeOH) at flow rate 0.8 mL/min. The analytical wavelength for detecting phytoecdysteroids was max 254 nm. The principal compounds in chromatograms of the CHCl3–EtOH fraction had absorption maxima in the range 244– 252 nm and corresponded to ecdysteroids from plants of the genus Silene [2–4], the structural features of which included an , -unsaturated ketone. The following ecdysteroids were isolated for the first time. Compound 1, tR 14.00 min. UV spectrum (MeOH, max, nm): 248. Mass spectrum, m/z 497 [MH] +, 479, 461, 443, 425; 541 [M + HCOO]–, identified as integristerone A; C27H44O8 [2, 3]. Compound 2, tR 16.15 min. UV spectrum (MeOH, max, nm): 246. Mass spectrum, m/z 481 [MH] +, 463, 445, 427, 409; 525 [M + HCOO]–, identified as 20-hydroxyecdysone; C27H44O7 [2, 4]. Compound 3, tR 16.49 min. UV spectrum (MeOH, max, nm): 250. Mass spectrum, m/z 497 [MH] +, 481, 463, 445, 427; 541 [M + HCOO]–, identified as polipodine B; C27H44O8 [2, 3]. Compound 4, tR 19.08 min. UV spectrum (MeOH, max, nm): 248. Mass spectrum, m/z 465 [MH] +, 447, 429, 411; 509 [M + HCOO]–, identified as ecdysone; C27H44O6 [2, 3]. Compound 5, tR 20.03 min. UV spectrum (MeOH, max, nm): 246. Mass spectrum, m/z 465 [MH] +, 447, 429, 411, 393; 509 [M + HCOO]–, identified as 2-deoxy-20-hydroxyecdysone; C27H44O6 [3, 4].

First Spin-Labeled α-Tocopherol and Trolox Succinyl Derivatives

Spin-labeled α-tocopherol succinyl derivatives were synthesized by the reaction of α-tocopherol succinate with 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 3-aminomethyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl, and 3-amino-2,2,5,5-tetramethylpyrrolidine-1-oxyl. Acylation of spin-labeled trolox amides by succinic anhydride produced the corresponding spin-labeled trolox amide succinyl derivatives.

Kinetics and mechanism of thermal decomposition of kynurenines and biomolecular conjugates: Ramifications for the modification of mammalian eye lens proteins

Thermal degradation reactions of kynurenine (KN), 3-hydroxykynurenine (3OHKN), and several adducts of KN, to amino acids and reduced glutathione (GSH) have been studied at physiological temperature. These compounds are all implicated in age-related mammalian eye lens cataract formation at the molecular level. The main reaction pathway for both KN and 3OHKN is deamination via beta-elimination to carboxyketoalkenes CKA and 3OHCKA. These reactions show a weak pH dependence below pH values of approximately 8, and a strong pH dependence above this value. The 3OHKN structure deaminates at a faster rate than KN. A mechanism for the deamination reaction is proposed, involving an aryl carbonyl enol/enolate ion, that is strongly supported by the structural, kinetic, and pH data. The degradation of Lys, His, Cys and GSH adducts of the CKA moieties was also studied. The Lys adduct was found to be relatively stable over 200 h at 37 degrees C, while significant degradation was observed for the other adducts. The results are discussed in terms of known post-translational modification reactions of the lens proteins and compared to incubation studies involving KN and related compounds in the presence of proteins.

Antioxidants Based on Covalently and Ionically Bound Trolox Conjugates

Three types of trolox dimers (bis-trolox derivatives), two of which were pairs of trolox molecules bound symmetrically through an ethylenediamine linker with covalent or ionic bonds and one of which was an asymmetric ionic–covalent conjugate, were synthesized. The water-solubility and antioxidant activity were measured for the synthesized compounds.