Isolation and purification of salvianolic acid A and salvianolic acid B from Salvia miltiorrhiza by high-speed counter-current chromatography and comparison of their antioxidant activity

Water-soluble salvianolic acid A (Sal A) and salvianolic acid B (Sal B) were successfully isolated and purified from the crude extract of Salvia miltiorrhiza by high-speed counter-current chromatography (HSCCC). The solvent system was n-hexane–ethyl acetate–methanol–water (3:6:6:10, v/v/v/v). 4.27 mg of Sal A and 32.09 mg of Sal B were obtained from 260 mg of the crude sample. The purities of Sal A and Sal B were 96.67% and 97.43%, respectively. Their structures were identified by ¹H NMR and ¹³C NMR. Antioxidant activities of Sal A and Sal B were also evaluated and compared by the methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) radical cation decolourisation assay. Both Sal A and Sal B showed high radical scavenging activities with their EC₅₀ values being 1.43 ± 0.09 and 1.81 ± 0.01 μg/ml in DPPH radical method. The ABTS results showed that Sal A and Sal B exhibited high total antioxidant activities, their EC₅₀ values were 1.35 ± 0.00 and 1.43 ± 0.01 μg/ml, respectively.     

Variation in polyphenolic profile and in vitro antioxidant activity of eastern teaberry (Gaultheria procumbens L.) leaves following foliar development

Seasonal dynamics in the polyphenolic composition, antioxidant activity, and their relationships during plant development were evaluated for eastern teaberry (Gaultheria procumbens L.) leaves, a traditional herbal medicine of North American natives. With the complementary UHPLC-PDA-ESI-MS³, HPLC-PDA-fingerprint, Folin-Ciocalteau, and n-butanol/HCl assays of methanol-water (75:25, v/v) extracts, the dried leaf samples harvested monthly across the growing season under Polish climate conditions were found rich in structurally diverse polyphenols (149.2–210.7 mg/g DW) including the dominating salicylates (64.6–107.5 mg/g DW), proanthocyanidins (53.0–66.8 mg/g DW), and flavonoids (17.3–25.3 mg/g DW), and the accompanying chlorogenic acid isomers (2.4–4.4 mg/g DW) and simple phenolic acids (0.9–1.1 mg/g DW). Among 28 detected analytes, gaultherin (64.6–107.5 mg/g DW), miquelianin (14.6–21.1 mg/g DW), procyanidin A-type trimer (5.5–9.5 mg/g DW), and (–)-epicatechin (5.8–7.8 mg/g DW) were the most abundant. The phenolic levels and antioxidant activity parameters in the DPPH (EC₅₀, 15.0–18.2 μg DW/mL; 0.95–1.16 mmol Trolox equivalents/g DW) and FRAP (2.3–3.4 mmol Fe ²⁺/g DW; 0.86–1.26 mmol Trolox equivalents/g DW) assays showed parallel seasonal trends with maxima in September and October. As the subsequent correlation studies confirmed the determinative impact of polyphenols on the leaf antioxidant activity and its seasonal fluctuations, the Fall season could be recommended as optimal for harvesting the plant material for medicinal purposes and cost-effective production of natural health products.     

Synthesis and radical scavenging activity of phenol–imidazole conjugates

Novel hydroxylated benzylideneamino imidazole derivatives were synthesized and their radical scavenging activity was assessed against DPPH and hydroxyl radicals. In the DPPH assay, most of the synthesized compounds showed an IC₅₀ in the range 3.2 μM ⩽ IC₅₀ ⩽ 8.4 μM, lower than the reference compound trolox (IC₅₀ = 9.5 μM) or the parent aldehydes (5.4 μM ⩽ IC₅₀ ⩽ 11.6 μM). The activity depends mainly on the phenolic subunit (number and position of the hydroxyl groups) and the extent of conjugation with the imidazole ring. In the deoxyribose assay, all the compounds, including parent imidazoles and aldehydes, showed high activity against the hydroxyl radical and the ability to chelate iron ions. At 5 μM concentration, the compounds protected the deoxyribose from degradation by hydroxyl radical between 62% and 38%.     

Total phenolics,flavonoids and antioxidant properties of three Ceropegia species from Western Ghats of India

The aim of present work was to assess the total phenolic content (TPC), total flavonoid content (TFC), phenolic compounds and antioxidant properties of various extracts of three Ceropegia spp.: Ceropegia spiralis, Ceropegia panchganiensis and Ceropegia evansii from Western Ghats of India. TPC of the samples varied from 0.3 ± 0.2 to 28.5 ± 0.3 mg TAE/g FW, whereas, TFC of the samples ranged between 0.1 ± 0.1 and 15.3 ± 0.3 mg RE/g FW. The major phenolic compounds identified were gallic acid, vanillin, cathechol and ferulic acid. All the extracts possess 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP) as well as metal chelating ability and this was also supported by significant correlation with TPC and TFC. To the best of our knowledge, this is the first paper presenting comprehensive data on TPC, TFC, phenolic profile and antioxidant properties of the Ceropegia spp.     

Enhanced phenolic antioxidants production in submerged cultures of Inonotus obliquus in a ground corn stover medium

The medicinal mushroom Inonotus obliquus has been a folk remedy for a long time in East-European and Asian countries. It is currently ascribed to a number of phenolic compounds as well as triterpenoids and polysaccharides responsible for significant biological and pharmacological properties. A study was conducted to determine the effects of inclusion of lignocellulosic material, in this case corn stover on production and antioxidant activity of extracellular (EPC) and intracellular phenolic compounds (IPC) by Inonotus obliquus in submerged fermentation. The corn stover medium contained 3% ground corn stover and 3.5% corn flour but the control medium contained 5% corn flour without corn stover. All of the other components were same in the two media. Decomposition rates of cellulose, hemicellulose, and lignin in the corn stover substrate were 20.9%, 17.9%, and 19.8% through 288 h of submerged cultivation. Lignocellulose decomposition in the corn stover-containing medium yielded significantly higher EPC (118.9/135.7 mg GAE (gallic acid equivalents)) and IPC (21.2/23.7 mg GAE) than in the control medium (34.7/42.5 mg GAE of EPC and 12.5/13.5 mg GAE of IPC) per liter of culture broth (EPC) and per gram of mycelia (IPC) in shake flask cultures/10 L fermenter runs. Both EPC and IPC from the corn stover medium showed a higher scavenging activity against hydroxyl radicals and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals than those from the control medium during the later fermentation period. In dose-dependent experiments, EPC from the corn stover medium at 216 h demonstrated a significantly stronger free radical scavenger activity against DPPH and hydroxyl radicals, shown as much lower IC50 values, than that from the control medium and IPC from the two media.     

Antioxidant activity of aqueous methanol extracts from the lucanid beetle,Serrognathus platymelus castanicolor Motschulsky (Coleoptera: Lucanidae)

The objective of this study was to evaluate the antioxidant properties of extracts of the lucanid beetle, Serrognathus platymelus castanicolor Motschulsky, obtained at different growth stages. The antioxidant activities of six different extracts were determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), and singlet oxygen (¹O₂). The activity level of pupal methanol extracts (PME) was higher in the DPPH and ABTS radical scavenging assays, whereas that of the water extracts was weaker in all assays. The ¹O₂ quenching ability of the PME was comparable to that of ascorbic acid (effective concentration of 50% ¹O₂ quenching: EC₅₀ = 0.184 mg/ml^-1 and 0.167 mg/ml^-1, respectively). The free radical scavenging antioxidant ability of the extracts significantly altered phenolic contents, important factors in the potency of antioxidant capacity. Our results suggest that these extracts may reduce oxidative stress in living organisms and reduce oxidative damage in insects under unfavorable conditions.     

Aqueous and ethanolic extracts of Galinsoga parviflora and Galinsoga ciliata. Investigations of caffeic acid derivatives and flavonoids by HPTLC and HPLC-DAD-MS methods

Galinsoga ciliata Raf. Blake like Galinsoga parviflora Cav., comes from the Andes region. The chemical composition, activity and use are similar for both species. Galinsoga species are used in folk medicine as anti-inflammatory agents and accelerators for wound healing. Extracts are applied topically onto the skin to treat dermatological diseases, eczemas, lichens and hard-healing-wounds, and also to treat snakebites. Orally they used to cure flu and colds.In the studies using HPTLC method, different stationary phases, including unmodified silica gel, silica gels modified with CN, NH₂, DIOL and RP18 groups were tried. The best separation of the tested compounds was achieved on silica gel plates, when as mobile phases mixtures – ethyl acetate–acetic acid–formic acid–water (100:11:11:26, v/v/v/v), ethyl acetate–methanol–formic acid–water (50:3:4:6, v/v/v/v) and ethyl acetate–methyl ethyl ketone–formic acid–water (30:9:3:3, v/v/v/v) – were used. Using reference substances, in the examined extracts the presence of flavonoids: patulitrin, quercimeritrin, quercitagetrin, and phenolic acids – caffeic and chlorogenic acids was found.HPLC analyses of extracts were carried out on a reversed-phase Zorbax SB column (150 mm × 2.1 mm, 1.9 μm). The mobile phase (A) was water/acetonitrile/formic acid (95:5:0.1, v/v/v) and the mobile phase (B) was acetonitrile/formic acid (100:0.1, v/v). A linear gradient system was used: 0–30 min, 1–30% B. Application of HPLC-DAD-MS method confirmed the results obtained by HPTLC method. Moreover, in the tested extracts the presence of caffeoylglucaric acids as dominating compounds was detected.     

Two-step acid and alkaline ethanolysis/alkaline peroxide fractionation of sugarcane bagasse and rice straw for production of polylactic acid precursor

Sugarcane bagasse and rice straw were subjected to acid and alkaline ethanolysis and sequential enzymatic hydrolysis to produce glucose for lactic acid production. Influence of physico-chemical treatments using ultrasonic bath and ultrasonic probe was studied compared with mechanical stirring. The results showed that the highest glucose yield with least contamination of xylose was obtained from acid ethanolysis fractionation (5 N H₂SO₄ + 50%, v/v ethanol) when stirred at 90 °C for 4 h. Alkaline ethanolysis accomplished high amount of both glucose and xylose released, however it was not favorable substrate for homofermentative lactic acid bacteria. In order to enhance enzymatic hydrolysis of acid ethanolysis fractionated samples, lignin was subsequently removed by the second step alkaline/peroxide delignification. The maximum lactic acid was obtained at 23.6 ± 0.2 g/L from Lactobacillus casei fermentation after 72 h when hydrolysate from two-step acid hydrolysis and alkaline/peroxide fractionated sugarcane bagasse containing 24.6 g/L initial glucose concentration was used as substrate.     

Effects of salt stress on volatile compounds,total phenolic content and antioxidant activities of Salvia mirzayanii

Salvia mirzayanii is a medicinal and aromatic plant belonging to the Lamiaceae family, which is an endemic plant in Iran. In this study, the effects of different salt concentrations on total phenolic content, antioxidant activities and volatile components of the aerial parts of S. mirzayanii were studied. The results showed that total phenolic content increased with the increase in salt concentration. The increase was more pronounced under moderate salinity (3.8 mg GAE g^− 1 DW at 6.8 dS m^− 1 NaCl). Plants grown at 6.8 dS m^− 1 NaCl displayed the highest DPPH˚ scavenging activity with the lowest IC₅₀ value (2.13 mg ml^− 1) compared to the control. The volatile components were identified and analyzed by HS (headspace)-GC–MS using the Combi PAL System technique. The main components of control plants were α-terpinyl acetate, 1,8-cineole and bicyclogermacrene. The proportions of these main compounds were differently affected by salinity stress. The results showed that the synthesis of both total phenolic and some important volatile components was induced by moderate salinity.     

Variation in phenolic compounds and antioxidant activity in apple seeds of seven cultivars

Polyphenols are the predominant ingredients in apple seeds. However, few data are available on the phenolic profile or antioxidant activity in apple seeds in previous researches. In this study, low-molecular-weight phenolic compounds and antioxidant activity in seeds, peels, and flesh of seven apple cultivars grown in northwest China were measured and analyzed using HPLC and FRAP, DPPH, ABTS assays, respectively. HPLC analysis revealed phloridzin as the dominant phenolic compound in the seeds with its contents being 240.45–864.42 mg/100 gDW. Total phenolic content (TPC) measured by the Folin–Ciocalteu assay in apple seed extracts of seven cultivars ranged from 5.74 (Golden Delicious) to 17.44 (Honeycrisp) mgGAE/gDW. Apple seeds showed higher antioxidant activity than peels or flesh; antioxidant activity in seeds varied from 57.59 to 397.70 μM Trolox equivalents (TE)/g FW for FRAP, from 37.56 to 64.31 μM TE/g FW for DPPH, and from 220.52 to 708.02 μM TE/g FW for ABTS. TPC in apple seeds was significantly correlated with all three assays. Principal component analysis (PCA) indicated that Honeycrisp was characterized with high contents of total polyphenols and phloridzin. Our findings suggest that phenolic extracts from apple seeds have good commercial potential as a promising antioxidant for use in food or cosmetics.     

Antioxidative,antimicrobial and cytotoxic effects of the phenolics of Leea indica leaf extract

This study investigated the phytochemical, antioxidative, antimicrobial and cytotoxic effects of Leea indica leaf ethanol extract. Phytochemical values namely total phenolic and flavonoid contents, total antioxidant capacity, DPPH radical scavenging effect, FeCl₃ reducing power, DMSO superoxide scavenging effect and Iron chelating effects were studied by established methods. Antibacterial, antifungal and cytotoxic effects were screened by disk diffusion technique, food poison technique and brine shrimp bioassay, respectively. Results showed the total phenolic content 24.00 ± 0.81 g GAE/100 g, total flavonoid content 194.68 ± 2.43 g quercetin/100 g and total antioxidant capacity 106.61 ± 1.84 g AA/100 g dry extract. Significant (P < 0.05) IC₅₀ values compared to respective standards were recorded in DPPH radical scavenging (139.83 ± 1.40 μg/ml), FeCl₃ reduction (16.48 ± 0.64 μg/ml), DMSO superoxide scavenging (676.08 ± 5.80 μg/ml) and Iron chelating (519.33 ± 16.96 μg/ml) methods. In antibacterial screening, the extract showed significant (P < 0.05) zone of inhibitions compared to positive controls Ampicillin and Tetracycline against Gram positive Bacillus subtilis, Bacillus cereus, Bacillus megaterium, and Staphylococcus aureus and Gram negative Salmonella typhi, Salmonella paratyphi, Pseudomonas aeroginosa, Shigella dysenteriae, Vibrio cholerae, and Escherichia coli. Significant minimum inhibitory concentrations compared to tetracycline were obtained against the above organisms. In antifungal assay, the extract inhibited the growth of Aspergillus flavus, Candida albicans and Fusarium equisetii by 38.09 ± 0.59, 22.58 ± 2.22, and 22.58 ± 2.22%, respectively. The extract showed a significant LC₅₀ value compared to vincristine sulfate in cytotoxic assay. The results evidenced the potential antioxidative, antimicrobial and cytotoxic capacities of Leea inidica leaf extract to be processed for pharmaceutical use.     

Antioxidant activity and mineral composition of three Mediterranean common seaweeds from Abu-Qir Bay,Egypt

Antioxidant activity and mineral composition were evaluated seasonally from spring to autumn 2010 in the three common seaweeds Ulva lactuca Linnaeus (Chlorophyta), Jania rubens (Linnaeus) J.V. Lamouroux and Pterocladia capillacea (S.G. Gmelin) Bornet (Rhodophyta). The antioxidant activity was measured with β-carotene, total phenol content and DPPH (2,2-diphenyl-1-picrylhydrazyl). Seaweeds were collected from the rocky site near Boughaz El-Maadya Abu-Qir Bay of Alexandria, Egypt. The results showed maximum increase of β-carotene in P. capillacea during summer. A significant increase in total phenolic content at P ⩽ 0.05 was found in the red alga (J. rubens) during summer. Also, U. lactuca showed the maximum antioxidant scavenging activity especially during summer. Minerals in all investigated samples were higher than those in conventional edible vegetables. Na/K ratio ranged between 0.78 and 2.4 mg/100 g, which is a favorable value. All trace metals exceeded the recommended doses by Reference Nutrient Intake (RNI). During summer season, it was found that Cu = 2.02 ± 0.13 and Cr = 0.46 ± 0.14 mg/100 g in U. lactuca and Fe had a suitable concentration (18.37 ± 0.5 mg/100 g) in P. capillacea. The studied species were rich in carotenoids, phenolic compounds, DPPH free radicals and minerals, therefore, they can be used as potential source of health food in human diets and may be of use to food industry.     

Identification of novel acetylcholinesterase inhibitors: Indolopyrazoline derivatives and molecular docking studies

The synthesis of novel indolopyrazoline derivatives (P1-P4 and Q1-Q4) has been characterized and evaluated as potential anti-Alzheimer agents through in vitro Acetylcholinesterase (AChE) inhibition and radical scavenging activity (antioxidant) studies. Specifically, Q3 shows AChE inhibition (IC₅₀: 0.68 ± 0.13 μM) with strong DPPH and ABTS radical scavenging activity (IC₅₀: 13.77 ± 0.25 μM and IC₅₀: 12.59 ± 0.21 μM), respectively. While P3 exhibited as the second most potent compound with AChE inhibition (IC₅₀: 0.74 ± 0.09 μM) and with DPPH and ABTS radical scavenging activity (IC₅₀: 13.52 ± 0.62 μM and IC₅₀: 13.13 ± 0.85 μM), respectively. Finally, molecular docking studies provided prospective evidence to identify key interactions between the active inhibitors and the AChE that furthermore led us to the identification of plausible binding mode of novel indolopyrazoline derivatives. Additionally, in-silico ADME prediction using QikProp shows that these derivatives fulfilled all the properties of CNS acting drugs. This study confirms the first time reporting of indolopyrazoline derivatives as potential anti-Alzheimer agents.     

Alkaline lipase from a novel strain Burkholderia multivorans: Statistical medium optimization and production in a bioreactor

An alkaline lipase from Burkholderia multivorans was produced within 15 h of growth in a 14 L bioreactor. An overall 12-fold enhanced production (58 U mL⁻¹ and 36 U mg⁻¹ protein) was achieved after medium optimization following the “one-variable-at-a-time” and the statistical approaches. The optimal composition of the lipase production medium was determined to be (% w/v or v/v): KH₂PO₄ 0.1; K₂HPO₄ 0.3; NH₄Cl 0.5; MgSO₄·7H₂O 0.01; yeast extract 0.36; glucose 0.1; olive oil 3.0; CaCl₂ 0.4 mM; pH 7.0; inoculum density 3% (v/v) and incubation time 36 h in shake flasks. Lipase production was maximally influenced by olive oil/oleic acid as the inducer and yeast extract as the additive nitrogen. Plackett–Burman screening suggested catabolite repression by glucose. Amongst the divalent cations, Ca²⁺ was a positive signal while Mg²⁺ was a negative signal for lipase production. RSM predicted that incubation time, inoculum density and oil were required at their higher levels (36 h, 3% (v/v) and 3% (v/v), respectively) while glucose and yeast extract were required at their minimal levels for maximum lipase production in shake flasks. The production conditions were validated in a 14 L bioreactor where the incubation time was reduced to 15 h.     

Optimization protocol for the extraction of antioxidant components from Origanum vulgare leaves using response surface methodology

In the present work, the response surface methodology (RSM) based on a central composite rotatable design (CCRD), was used to determine optimum conditions for the extraction of antioxidant compounds from Origanum vulgare leaves. Four process variables were evaluated at three levels (31 experimental designs): methanol (70%, 80%, and 90%), the solute:solvent ratio (1:5, 1:12.5, 1:20), the extraction time (4, 10, 16 h), and the solute particle size (20, 65, 110 micron). Using RSM, a quadratic polynomial equation was obtained by multiple regression analysis for predicting optimization of the extraction protocol. Analysis of variance (ANOVA) was applied and the significant effect of the factors and their interactions were tested at 95% confidence interval. The antioxidant extract (AE) yield was significantly influenced by solvent composition, solute to solvent ratio, and time. The maximum AE was obtained at methanol (70%), liquid solid ratio (20), time (16 h), and particle size (20 micron). Predicted values thus obtained were closer to the experimental value indicating suitability of the model. Run 25 (methanol:water 70:30; solute:solvent 1:20; extraction time 16 h and solute particle size 20) showed highest TP contents (18.75 mg/g of dry material, measured as gallic acid equivalents) and DPPH radical scavenging activity (IC₅₀ 5.04 μg/mL). Results of the present study indicated good correlation between TP contents and DPPH radical scavenging activity. Results of the study indicated that phenolic compounds are powerful scavengers of free radical as demonstrated by a good correlation between TP contents and DPPH radical scavenging activity.     

Isolation of antioxidant constituents from Combretum apiculatum subsp. apiculatum

Species of the family Combretaceae are used extensively in traditional medicine against inflammation and infections, and although antibacterial activity has been reported in non-polar extracts, further rationale for the widespread use of the Combretaceae is expected to exist. Methanol extracts of leaves of ten different Combretum species were evaluated for antioxidant activity by spraying TLC chromatograms of each leaf extract with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Compounds with antioxidant activity were detected by bleaching of the purple DPPH colour. Leaf extracts of Combretum apiculatum subsp. apiculatum had the most antioxidant compounds. This species was consequently selected for phytochemical investigation. A DPPH assay-directed fractionation of the leaf extracts of C. apiculatum led to the isolation of four antioxidant compounds from the ethyl acetate and butanol soluble fractions. The structures of the compounds were determined by spectroscopic analyses (¹H-NMR, ¹³C-NMR and MS) and identified as: cardamonin (1), pinocembrin (2), quercetrin (3) and kaempferol (4). In a quantitative antioxidant assay, the more polar fractions (ethyl acetate and butanol) obtained by solvent–solvent fractionation had the highest antioxidant activity among the solvent fractions obtained from C. apiculatum, with EC₅₀ values of 3.91 ± 0.02 and 2.44 ± 0.02 μg/ml respectively. Of the four isolated compounds, quercetrin (4) and kaempferol (3) had the strongest antioxidant activity, with EC₅₀ values of 11.81 ± 85 and 47.36 ± 0.03 μM respectively. Cardamonin (1) and pinocembrin (2) did not demonstrate strong activity. L-ascorbic acid was used as standard antioxidant agent (EC₅₀ = 13.37 ± 0.20 μM or 2.35 μg/ml). The cytotoxicity of cardamonin and pinocembrin was evaluated on Vero kidney cells using the MTT (3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide) assay with berberine as positive control. At concentrations higher than 50 μg/ml of cardamonin or pinocembrin, the cells were not viable. Cardamonin was more toxic (LC₅₀ = 1.97 μg/ml) than pinocembrin (LC₅₀ = 29.47 μg/ml) and even the positive control, berberine (LC₅₀ = 12.35 μg/ml).     

Ethanol and furfural production from corn stover using a hybrid fractionation process with zinc chloride and simultaneous saccharification and fermentation (SSF)

A two-stage hybrid fractionation process was investigated to produce cellulosic ethanol and furfural from corn stover. In the first stage, zinc chloride (ZnCl₂) was used to selectively solubilize hemicellulose. During the second stage, the remaining treated solids were converted into ethanol using commercial cellulase and Saccharomyces cerevisiae or recombinant Escherichia coli, KO11. This hybrid fractionation process recovered 93.8% of glucan, 89.7% of xylan, 71.1% of arabinan, and 74.9% of lignin under optimal reaction conditions (1st stage: 5% acidified ZnCl₂, 7.5 ml/min, 150 °C (10 min) and 170 °C (10 min); 2nd stage: simultaneous saccharification and fermentation (SSF) using S. cerevisiae). The furfural yield from the hemicellulose hydrolysates was 58%. The SSF of the treated solids resulted in 69–98% of the theoretical maximum ethanol yields based on the glucan content in the treated solids. After fermentation, the solid residues contained primarily lignin. Based on the total lignin in untreated corn stover, the lignin recovery yield was 74.9%.     

Zinc protects Ceratophyllum demersum L. (free-floating hydrophyte) against reactive oxygen species induced by cadmium

Evidence for Zn protection against Cd-induced reactive oxygen species in the free-floating hydrophyte Ceratophyllum demersum L. is presented in this paper. Metal treatments of 10 μmol/L Cd, 10 Cd μmol/L supplemented with Zn (10, 50, 100 and 200 μmol/L) and Zn-alone treatments of the same concentrations were used. Using 5,5 dimethyl pyrroline-N-oxide as the spin-probe, electron spin resonance spectra indicated a drastic increase in hydroxyl radicals (OH) in Cd-10 μmol/L treatments, which was closely correlating with the enhanced formation of hydrogen peroxide (H₂O₂) and generation of superoxide radical (O₂^?) triggered by the oxidation of NADPH. The supplementation of adding Zn (10–200 μmol/L) to the Cd-10 μmol/L treatments significantly decreased the production of free radicals especially by eliminating the precursors of OH through inhibition of NADPH oxidation. Cd-enhanced ROS production which substantially increased the oxidative products of proteins measured as carbonyls was effectively inhibited by Zn supplementation.     

Validated liquid chromatography–tandem mass spectrometry method for quantitative determination of dauricine in human plasma and its application to pharmacokinetic study

A highly sensitive and selective LC–MS/MS method was developed and validated for the determination of dauricine in human plasma, using protopine as internal standard (IS). The analyte and IS were extracted by liquid–liquid extraction and analyzed by LC–MS/MS. Chromatographic separation was performed on Agilent TC-C₁₈ column with a mobile phase of methanol–water–glacial acetic acid (60:40:0.8, v/v/v) at a flow rate of 0.7 mL/min. Detection was performed on a triple quadrupole tandem mass spectrum by multiple reaction monitoring (MRM) mode using the electrospray ionization technique in positive mode. The method was linear over the concentration range of 1–200 ng/mL. The lower limit of quantification (LLOQ) was 1 ng/mL in human plasma with acceptable precision and accuracy. The intra- and inter-day precision was less than 5.9% determined from quality control (QC) samples at concentrations of 2.0, 20.0 and 160 ng/mL, and the accuracy was within ±9.9%. This method was successfully applied for the evaluation of pharmacokinetics of dauricine after oral doses of 100, 300 and 600 mg phenolic alkaloids of menispermum dauricum tablet (PAMDT) to 12 Chinese healthy volunteers.     

A convenient preparation of pentaaquanitrosylchromium(2+) sulfate: The crystal structure revisited

The complex pentaaquanitrolsylchromium(2+) sulfate, [Cr(OH₂)₅(NO)]SO₄ has been prepared in a high yield by the hydrolysis of [Cr(NCCH₃)₅(NO)](BF₄)₂ in dilute sulfuric acid. Crystals of [Cr(OH₂)₅(NO)]SO₄ · H₂O have been grown and characterized by X-ray crystallography. Continuous photolysis of [Cr(NCCH₃)₅(NO)]²⁺ in acetonitrile solution with 404 nm light results in a release of NO with the quantum yield Φ = 0.55 mol einstein⁻¹ at 298 K with the resulting solvated Cr²⁺ ion being trapped by molecular dioxygen present in the solution.