Single-step chromatography for simultaneous purification of C-phycocyanin and allophycocyanin with high purity and recovery from <Emphasis Type="Italic">Spirulina</Emphasis> (<Emphasis Type="Italic">Arthrospira</Emphasis>) <Emphasis Type="Italic">platensis</Emphasis>

The cyanobacterium Spirulina (Arthrospira) platensis is a good source of phycobiliprotein purification. C-phycocyanin (C-PC) is the major phycobiliprotein, while allophycocyanin (APC) is less abundant in S. platensis. Previously reported methods for C-PC purification are only able to offer either high purity or high efficiency. This paper describes one-step anion exchange chromatography method with continuous pH gradient elution for simultaneous purification of C-PC and APC with high purity and high recovery. Crude C-PC and APC were extracted and concentrated by ammonium sulfate fractionation at saturation of 25% and 60%, then purified on a DEAE-Sepharose Fast Flow chromatography column with continuous pH gradient elution from pH 5.0 to 3.6. After this single-step chromatography, C-PC and APC with high purity and recovery were simultaneously obtained. The purity ratios of C-PC and APC reached 5.59 (A₆₂₀/A₂₈₀) and 5.19 (A₆₅₀/A₂₈₀), respectively. Their purity was further demonstrated by electrophoresis and fluorescence emission spectroscopy. Moreover, the total recovery yield of pure C-PC and APC were 67.04% and 80.0%, representing 111.83 and 29.28 mg·g⁻¹ lyophilized weight, respectively. The obtained C-PC and APC remained stable over a pH range of 4–9. This purification method for high purity and recovery of C-PC and APC proved to be fairly efficient compared with previously reported methods.     

别藻蓝蛋白藻蓝胆素发色团分子构象研究

主要研究了蓝绿藻污棕席藻(Phormidium luridum)别藻蓝蛋白在不同 pH值条件下的吸收光谱和共振拉曼光谱.发现低聚化的结果导致了三聚体别藻蓝蛋白 650nm 特征吸收峰的消失和一些共振拉曼带强度和位置的移动.结果表明在低 pH 值作用下的低聚化的别藻蓝蛋白中藻蓝胆素发色团分子的构象和自由胆素分子类似,比三聚体的别藻蓝蛋白的发色团分子更趋于卷曲,折叠的构象态.而三聚体的别藻蓝蛋白,主要的拉曼带 1645cm^-1是其发色团分子构象处于更线性延展的标志,其光谱行为和吸收光谱 A_vis/A_uv所表征的发色团分子构象的结果相一致.     

Two New Xylanases with Different Substrate Specificities from the Human Gut Bacterium Bacteroides intestinalis DSM 17393

Xylan is an abundant plant cell wall polysaccharide and is a dominant component of dietary fiber. Bacteria in the distal human gastrointestinal tract produce xylanase enzymes to initiate the degradation of this complex heteropolymer. These xylanases typically derive from glycoside hydrolase (GH) families 10 and 11; however, analysis of the genome sequence of the xylan-degrading human gut bacterium Bacteroides intestinalis DSM 17393 revealed the presence of two putative GH8 xylanases. In the current study, we demonstrate that the two genes encode enzymes that differ in activity. The xyn8A gene encodes an endoxylanase (Xyn8A), and rex8A encodes a reducing-end xylose-releasing exo-oligoxylanase (Rex8A). Xyn8A hydrolyzed both xylopentaose (X₅) and xylohexaose (X₆) to a mixture of xylobiose (X₂) and xylotriose (X₃), while Rex8A hydrolyzed X₃ through X₆ to a mixture of xylose (X₁) and X₂. Moreover, rex8A is located downstream of a GH3 gene (xyl3A) that was demonstrated to exhibit β-xylosidase activity and would be able to further hydrolyze X₂ to X₁. Mutational analyses of putative active site residues of both Xyn8A and Rex8A confirm their importance in catalysis by these enzymes. Recent genome sequences of gut bacteria reveal an increase in GH8 Rex enzymes, especially among the Bacteroidetes, indicating that these genes contribute to xylan utilization in the human gut.     

Anion effects on construction of Zn compounds with a chelating ligand bis(2-pyridylmethyl)amine and their catalytic activities

Three Zn^II complexes containing bispicam ligands (bispicam = bis(2-pyridylmethyl)amine), [Zn(bispicam)₂](NO₃)₂·2CH₃OH 4A, [Zn(bispicam)(NO₃)₂] 4B, and [Zn(bispicam)₂](OTf)₂6, were obtained, and their structures were determined by X-ray crystallography. Complexes of the general formulation [Zn(bispicam)₂]X₂ (X = Cl⁻ (1), Br⁻ (2), I⁻ (3), NO₃⁻ (4A), ClO₄⁻ (5), and OTf⁻ (6)) show fac geometric isomers (a) or enantiomers (c) and (d) according to anions. Moreover, complexes 4-6 could carry out the catalytic transesterification of a range of esters with methanol under the mild conditions. Importantly, the catalyst 4B with an unsaturated structure has shown better efficiency than the catalysts, 4A, 5, and 6, having saturated structures. To explain this reactivity difference, two different reaction mechanisms have been proposed (metal-based vs. amide N-H-based).     

Manganese(II) complexes of di-2-pyridinylmethylene-1,2-diimine di-Schiff base ligands: Structures and reactivity

Manganese(II) complexes [Mn(L)X₂] were prepared and characterized, where L is a neutral di-Schiff base ligand incorporating pyridylimine donor arms, including (1R,2R)-N,N′-bis(2-pyridylmethylidene)-1,2-diphenylethylenediimine (L¹), (1R,2R)-N,N′-bis(6-methyl-2-pyridylmethylidene)-1,2-cyclohexyldiimine (L²), or (1R,2R)-, (1S,2S)- or racemic N,N′-bis(2-pyridylmethylidene)-1,2-cyclohexyldiimine (L³), and X⁻ =  or Cl⁻. Product complexes were structurally characterized, specifically including [Mn(R,R-L¹)(NCCH₃)₃](ClO₄)₂, [Mn(R,R-L²)(OH₂)₂](ClO₄)₂ and racemic [Mn(L³)Cl₂]. The first of these complexes features a heptacoordinate ligand field in a distorted pentagonal bipyramid, and the latter two are hexacoordinate, but retain equatorially monovacant pentagonal bipyramidal structures. Complexes [Mn(L³)X₂] (X⁻ = Cl⁻, ) were reacted with the primary phosphine FcCH₂PH₂ (Fc = -C₅H₄FeC₅H₅), H₂O and ethyldiazoacetate (EDA). The first two substrates prompted reactivity at a single ligand imine bond, resulting in hydrophosphination and hydrolysis, respectively. Complexes of the derivative ligands were also structurally characterized. Evidence for EDA activation was obtained by electrospray ionization mass spectrometry, but catalytic carbene transfer was not obtained.     

Short- and long-term responses to seasonal drought in ponderosa pines growing at different plantation densities in Patagonia, South America

Trees drought responses could be developed in the short- or in the long-term, aiming at sustaining carbon fixation and water use efficiency (WUE). The objective of this study was to examine short- and long-term adjustments occurring in different size Pinus ponderosa Dougl. ex P. & C. Laws trees in response to seasonal drought when they are growing under different competition level. The following variables were studied: branch and stem hydraulic conductivity, canopy and stomatal conductance (gc, gs), transpiration (E), photosynthesis (A _max), wood δ¹³C (as a proxy of intrinsic WUE), leaf to sapwood area ratio (A _L:A _s) and growth in the biggest (B) and the smallest (S) trees of high (H) and low (L) density stands. A _L:A _s was positively correlated with tree size and negatively correlated with competition level, increasing leaf hydraulic conductance in H trees. Accordingly, higher gc and E per unit A _L were found in H than in L trees when soil water availability was high, but decreased abruptly during dry periods. BL trees maintained stable gc and E values even during the summer drought. The functional adjustments observed in H trees allow them to maintain their hydraulic integrity (no apparent k _s losses), but their stem and leaf growth were severely affected by drought events. _iWUE was similar between all tree groups in a wet season, whereas it significantly decreased in SH trees in a dry season suggesting that when radiation and water are co-limiting gas exchange, functional adjustments not only affect absolute growth, but also WUE.     

Energetics of Active Transport Processes

Discussions of active transport usually assume stoichiometry between the rate of transport J₊ and the metabolic rate J_r. However, the observation of a linear relationship between J₊ and J_r does not imply a stoichiometric relationship, i.e., complete coupling. Since coupling may possibly be incomplete, we examine systems of an arbitrary degree of coupling q, regarding stoichiometry as a limiting case. We consider a sodium pump, with J₊ and J_r linear functions of the electrochemical potential difference, -X₊, and the chemical affinity of the metabolic driving reaction, A. The affinity is well defined even for various complex reaction pathways. Incorporation of a series barrier and a parallel leak does not affect the linearity of the composite observable system. The affinity of some region of the metabolic chain may be maintained constant, either by large pools of reactants or by regulation. If so, this affinity can be evaluated by two independent methods. Sodium transport is conveniently characterized by the open-circuit potential (Δψ)_I=0 and the natural limits, level flow (J₊)_X+=0, and static head X⁰₊ = (X₊)_J+=0. With high degrees of coupling -X⁰₊/F approaches the electromotive force E_Na (Ussing); -X⁰₊/F cannot be identified with ((RT/F) ln f)_X+=0, where f is the flux ratio. The efficiency η = -J₊X₊/J_rA is of significance only when appreciable energy is being converted from one form to another. When either J₊ or -X₊ is small η is low; the significant parameters are then the efficacies ε_J+ = J₊/J_rA and ε_X+ = -X₊/J_rA, respectively maximal at level flow and static head. Leak increases both J₊ and ε_J+ for isotonic saline reabsorption, but diminishes -X⁰₊ and ε_X♀. Electrical resistance reflects both passive parameters and metabolism. Various fundamental relations are preserved despite coupling of passive ion and water flows.     

Isolation and properties of somatic and testicular cytochromes c from rat tissues

Somatic (c_s) and a testis-specific (c_{t I}) cytochromes c were purified to homogeneity from rat tissues (heart, liver, kidney, and testis). The purification procedure involved (1) homogenization of tissues at pH 4.5, (2) treatment with methanol-chloroform solvents, (3) hydroxylapatite column chromatography, (4) carboxymethyl-cellulose column chromatography, and (5) Sephacryl S-200 gel filtration. The isolated cytochromes c were free from polymeric and other “modified” forms, and did not bind CO, azide, or cyanide. The absorption maxima and the molecular weights of both cytochromes c_s and c_{t I} were identical. The ratio of $\text{A}{}_{\mathrm{<mtext>549.5\; </mtext><mtext>nm</mtext>}}\text{(}\text{reduced}\text{)}\text{A}{}_{\mathrm{<mtext>280\; </mtext><mtext>nm</mtext>}}\text{(}\text{oxidized}\text{)}$ for cytochromes c_s averaged 1.28. The unique properties of cytochrome c_{t I}, compared to somatic cytochrome c, were as follows: (1) different elution profiles from hydroxylapatite and carboxymethyl-cellulose column chromatography experiments, (2) less basic intrinsic molecular charge shown by the slow mobility in native polyacrylamide gel electrophoresis, (3) probable asymmetric molecular shape as evidenced from gel filtration experiments, (4) significantly higher millimolar extinction coefficient values (33.6 at 549.5 nm), (5) a low ratio (1.04) of $\text{A}{}_{\mathrm{<mtext>549.5\; </mtext><mtext>nm</mtext>}}\text{(}\text{reduced}\text{)}\text{A}{}_{\mathrm{<mtext>280\; </mtext><mtext>nm</mtext>}}\text{(}\text{oxidized}\text{)}$, and (6) difference of about 20 amino acid residues per mole.     

Synthesis and characterization of new imidorhenium(V) and imidorhenium(VI) complexes of pyridyltriazines and pyrazinyltriazine with halide coligands including rare iodide

The blue colored imido complexes [Re(NC₆H₄Cl)X₃(L)] have been synthesized by three methods: (i) reaction of [Re^VOX₃(L)] with p-ClC₆H₄NH₂, (ii) reaction of [Re^III(OPPh₃)X₃(L)] with p-ClC₆H₄NH₂ and (iii) reaction of [Re^VOX₃(PPh₃)₂] with L followed by the addition of p-ClC₆H₄NH₂ in boiling toluene. Here, X = Cl, Br, I and L are 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine (L²) and its dimethyl (L¹) and pyrazinyl (L³) analogues. The [Re(NC₆H₄Cl)Cl₃(L¹)] (1a), [Re(NC₆H₄Cl)Cl₃(L²)] (1b), [Re(NC₆H₄Cl)Br₃(L²)] (1c), [Re(NC₆H₄Cl)I₃(L²)] (1d), [Re(NC₆H₄Cl)Cl₃(L³)] (1e), [Re(NC₆H₄Cl)Br₃(L³)] (1f), [Re(NC₆H₄Cl)I₃(L³)] (1g), complexes have been characterized electrochemically and spectroscopically. The X-ray structures of [Re(NC₆H₄Cl)Cl₃(L²)] and [Re(NC₆H₄Cl)I₃(L³)] reveal that the ReCl₃ fragment is meridionally disposed and that the L ligand is N,N-coordinated such that the pyridine/pyrazine nitrogen lies trans to the imide nitrogen. The feasibility of generating the rhenium(VI) congener of the imidorhenium(V) complex is also examined with the help of six-line EPR spectra at room temperature.     

Synthesis and in vitro affinities of various MDL 100907 derivatives as potential 18F-radioligands for 5-HT2A receptor imaging with PET

Radiolabelled piperidine derivatives such as [¹¹C]MDL 100907 and [¹⁸F]altanserin have played an important role in diagnosing malfunction in the serotonergic neurotransmission. A variety of novel piperidine MDL 100907 derivatives, possible to label with ¹⁸F-fluorine, were synthesized to improve molecular imaging properties of [¹¹C]MDL 100907. Their in vitro affinities to a broad spectrum of neuroreceptors and their lipophilicities were determined and compared to the clinically used reference compounds MDL 100907 and altanserin. The novel compounds MA-1 (53) and (R)-MH.MZ (56) show K_i-values in the nanomolar range towards the 5-HT_2A receptor and insignificant binding to other 5-HT receptor subtypes or receptors. Interestingly, compounds MA-1 (53), MH.MZ (55) and (R)-MH.MZ (56) provide a receptor selectivity profile similar to MDL 100907. These compounds could possibly be preferable antagonistic ¹⁸F-tracers for visualization of the 5-HT_2A receptor status. Medium affine compounds (VK-1 (32), (51), (52), (54)) were synthesized and have K_i values between 30 and 120 nM. All promising compounds show log P values between 2 and 3, that is, within the range of those for the established radiotracers altanserin and MDL 100907. The novel compounds MA-1 (53) and (R)-MH.MZ (56) thus appear to be promising high affine and selective tracers of ¹⁸F-labelled analogues for 5-HT_2A imaging with PET.     

Effect of outer sphere anions on the structure and color of nitrosylpentaamminechromium complex

Three kinds of crystalline compounds containing the nitrosylpentaamminechromium complexes [Cr(NO)(NH₃)₅]²⁺(A) were obtained: chloride ACl₂ (red-orange), chloride perchlorate ACl(ClO₄) (brown), and perchlorate A(ClO₄)₂ (green). The cause of the color change of the complex A with the change of outer sphere anions was sought using X-ray structural data of ACl₂, ACl(ClO₄), and A(ClO₄)₂. Crystal data: ACl₂, orthorhombic, space group Cmcm, a=10.0236 (9) Å, b=9.098 (3) Å, c=10.357(1) Å, V=944.5 (5) ų, Z=4; ACl(ClO₄), tetragonal, space group P4/nmm, a=7.6986 (8) Å, c=9.9566(8) Å, V=590.1 (1) Å^3,Z=2; A(ClO₄)₂, orthorhombic, space group Pnma, a=15.760 (2) Å, b=11.480(2) Å, c=7.920 (2) Å, V=1432.9 (4) ų, Z=4. The complex cation in ACl₂ has a distorted octahedral structure with a linear CrNO moiety. The short CrN (nitrosyl) distance of 1.692 (7) Å indicates the presence of multiple bonding between the chromium atom and the nitrogen atom in the nitrosyl group. The interatomic distances and angles within the complex cations hardly change with the change of the counter anions, while the distances between the complex cations in each crystal increase in the order ACl₂<ACl(ClO₄)<A(ClO₄)₂. The bulky perchlorate anions seems to separate the complex cations, while smaller chloride anions are not large enough to separate them. The distance (3.213(5) Å) between O(NO) and N(NH₃ in the adjacent complex cation) is rather short in the crystal of ACl₂, and there are six hydrogen bonds, where the NO group is surrounded by four NH₃ ligands. The distance (4.002(5) Å) between O(NO) and N(NH₃) is much longer in the crystal of A(ClO₄)₂, indicating the presence of no hydrogen bonding. In the crystal of ACl(ClO₄) the distance (3.452(4) Å) between O(NO) and N(NH₃) is in between those of ACl₂ and A(ClO₄)₂. The presence of hydrogen bonding between O(NO) and N(NH₃ in the adjacent complex cation) seems to cause the color change with the change of outer sphere anions.     

Acylated dolabellane-type diterpenes from Nigella sativa seeds with triglyceride metabolism-promoting activity in high glucose-pretreated HepG2 cells

Two new acylated dolabellane-type diterpenes, nigellamines B₃ (9) and D (10), were isolated from Nigella sativa (Ranunculaceae) seeds using column chromatography and preparative HPLC. Their structures were determined based on chemical and physicochemical evidence, and confirmed using previously isolated related compounds as reference. Of the seed constituents, nigellamines A₂ (2), A₃ (3), A₅ (5), B₁ (6), and B₂ (7) had in vitro triglyceride metabolism-promoting activities in the high glucose-pretreated human liver carcinoma cell line, HepG2.     

Assignment of a kinetic component to electron transfer between iron-sulfur clusters FX and FA/B of Photosystem I

We studied the kinetics of reoxidation of the phylloquinones in Chlamydomonas reinhardtii Photosystem I using site-directed mutations in the PhQ_A-binding site and of the residues serving as the axial ligand to ec3_A and ec3_B chlorophylls. In wild type PS I, these kinetics are biphasic, and mutations in the binding region of PhQ_A induced a specific slowing down of the slow component. This slowing allowed detection of a previously unobserved 180-ns phase having spectral characteristics that differ from electron transfer between phylloquinones and F_X. The new kinetic phase thus reflects a different reaction that we ascribe to oxidation of F_X⁻ by the F_A/B FeS clusters. These absorption changes partly account for the differences between the spectra associated with the two kinetic components assigned to phylloquinone reoxidation. In the mutant in which the axial ligand to ec3_A (PsaA-Met688) was targeted, about 25% of charge separations ended in P₇₀₀⁺A₀⁻ charge recombination; no such recombination was detected in the B-side symmetric mutant. Despite significant changes in the amplitude of the components ascribed to phylloquinone reoxidation in the two mutants, the overall nanosecond absorption changes were similar to the wild type. This suggests that these absorption changes are similar for the two different phylloquinones and that part of the differences between the decay-associated spectra of the two components reflect a contribution from different electron acceptors, i.e. from an inter-FeS cluster electron transfer.     

Cytogenetic characterization of ten araneomorph spiders (Araneae): Karyotypes and meiotic features

Karyotypes, sex chromosome systems and meiotic characteristics are reported for ten spider species belonging to the families Gnaphosidae, Philodromidae, Salticidae, Oxyopidae and Sicariidae by using standard Giemsa staining. The male diploid numbers (2n) and sex chromosome systems are as follows: Berinda hakani 2n = 22 (X₁X₂), Berinda ensigera 2n = 22 (X₁X₂), Trachyzelotes lyonneti 2n = 22 (X₁X₂), Trachyzelotes malkini 2n = 22 (X₁X₂), Zelotes caucasius 2n = 22 (X₁X₂) (Gnaphosidae); Thanatus pictus 2n = 28 (X₁ X₂), Tibellus macellus 2n = 24 (X₁ X₂) (Philodromidae); Neon reticulatus 2n = 21 (X₀) (Salticidae); Peucetia virescens 2n = 28 (X₁X₂) (Oxyopidae) and Loxosceles rufescens 2n = 21 (X₁ X₂Y) (Sicariidae). All species have monoarmed chromosomes with the exception of L. rufescens that has biarmed (metacentric and submetacentric) chromosomes. The obtained data are the first results for the genera Berinda, Trachyzelotes and Neon. Additionally, with the exception of L. rufescens, all species are being chromosomally analyzed for the first time.     

The Spacer Cations Interplay for Efficient and Stable Layered 2D Perovskite Solar Cells

Organic spacer cations in layered 2D (A₁)₂(A₂)_n?1B_nX_3n+1 (where A₁ is an organic cation acting as a spacer between the perovskite layers, A₂ is a monovalent cation, e.g., Cs⁺,CH₃NH₃⁺, CH(NH₂)₂⁺) perovskite materials improve the long‐term stability of the resulting solar cells, but hamper their power conversion efficiency due to poor carrier generation/transportation. Rational guidelines are thus required to enable the design of organic spacer cations. Herein, mixed A₁ cations are employed in layered 2D perovskites to investigate the interplay between alkylamine cations and unsaturated alkylamine cations. It is revealed that alkylamine spacer cations are able to facilitate precursor assembly, which results in the orientated growth of perovskite crystals. Unsaturated alkylamine cations further lead to reduced exciton binding energy, which improves carrier pathway in the 2D perovskites. By mixing both cations, substantially improved open circuit voltage is observed in the resultant photovoltaic cells with the efficiency of 15.46%, one of the highest one based on (A₁)₂(A₂)₃Pb₄I₁₃ layered 2D perovskites. The generality of the design principle is further extended to other cation combinations.     

Cd(II) and Cu(II) complexes of polydentate Schiff base ligands: synthesis, characterization, properties and biological activity

We report the synthesis of the Schiff base ligands, 4-[(4-bromo-phenylimino)-methyl]-benzene-1,2,3-triol (A₁), 4-[(3,5-di-tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,2,3-triol (A₂), 3-(p-tolylimino-methyl)-benzene-1,2-diol (A₃), 3-[(4-bromo-phenylimino)-methyl]-benzene-1,2-diol (A₄), and 4-[(3,5-di-tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,3-diol (A₅), and their Cd(II) and Cu(II) metal complexes, stability constants and potentiometric studies. The structure of the ligands and their complexes was investigated using elemental analysis, FT-IR, UV-Vis, ¹H and ¹³C NMR, mass spectra, magnetic susceptibility and conductance measurements. In the complexes, all the ligands behave as bidentate ligands, the oxygen in the ortho position and azomethine nitrogen atoms of the ligands coordinate to the metal ions. The keto-enol tautomeric forms of the Schiff base ligands A₁-A₅ have been investigated in polar and non-polar organic solvents. Antimicrobial activity of the ligands and metal complexes were tested using the disc diffusion method and the strains Bacillus megaterium and Candida tropicalis.Protonation constants of the triol and diol Schiff bases and stability constants of their Cu²⁺ and Cd²⁺ complexes were determined by potentiometric titration method in 50% DMSO-water media at 25.00 ± 0.02 °C under nitrogen atmosphere and ionic strength of 0.1 M sodium perchlorate. It has been observed that all the Schiff base ligands titrated here have two protonation constants. The variation of protonation constant of these compounds was interpreted on the basis of structural effects associated with the substituents. The divalent metal ions of Cu²⁺ and Cd²⁺ form stable 1:2 complexes with Schiff bases.The Schiff base complexes of cadmium inhibit the intense chemiluminescence reaction in dimethylsulfoxide (DMSO) solution between luminol and dioxygen in the presence of a strong base. This effect is significantly correlated with the stability constants K_CdL of the complexes and the protonation constants K_OH of the ligands; it also has a nonsignificant association with antibacterial activity.     

Color measurements as a reliable method for estimating chlorophyll degradation to phaeopigments

The application of biocides is a traditional method of controlling biodecay of outdoor cultural heritage. Chlorophyll degradation to phaeopigments is used to test the biocidal efficacy of the antimicrobial agents. In the present study, the usefulness of color measurements in estimating chlorophyll degradation was investigated. An aeroterrestrial stone biofilm-forming cyanobacterium of the genus Nostoc was chosen as test organism, comparing its different behaviour in both planktonic and biofilm mode of growth against the isothiazoline biocide Biotin T^®. Changes in A_435 nm/A_415 nm and A_665 nm/A_665a nm and in the chlorophyll a and adenosine triphosphate (ATP) cell content were compared with the variations in the CIELAB color parameters (L*, a*, b*, C*_ab and h_ab). Our findings showed that both the phaeophytination indexes are useful in describing degradation of chlorophyl a to phaeopigments. Moreover, the CIELAB color parameters represented an effective tool in describing chlorophyll degradation. L* CIELAB parameter appeared to be the most informative parameter in describing the biocidal activity of Biotin T^® against Nostoc sp. in both planktonic and biofilm mode of growth.     

In Situ Forming Formulation: Development, Evaluation, and Optimization Using 33 Factorial Design

The present investigation concerns with the development and optimization of an in situ forming formulation using 3³ full factorial design experimentation. Metformin, an antidiabetic drug with upper part of gastrointestinal tract as absorption window was used as a model drug. The formulations were designed with an objective to retain in stomach for an extended time period. The effect of three independent factors—concentrations of sodium alginate (X ₁), gellan gum (X ₂), and metformin (X ₃) on in vitro drug release were used to characterize and optimize the formulation. Five dependent variables—release exponent (Y ₁), dissolution efficiency (Y ₂), drug release at 30 min (Y ₃), 210 min (Y ₄), and 480 min (Y ₅) were considered as optimization factors. The data were statistically analyzed using ANOVA, and a p < 0.05 was considered statistically significant. Three dimensional surface response plots were drawn to evaluate the interaction of independent variables on the chosen dependent variables. Of the prepared 27 formulations, the responses exhibited by batch F17 containing medium level sodium alginate (X ₁), low level gellan (X ₂), and medium level metformin (X ₃) were similar to the predicted responses.     

Dodonaea viscosa var. angustifolia leaf: New source of polysaccharide and its anti-oxidant activity

Ultrasonic technology was applied for polysaccharide extraction from the leaves of Dodonaea viscosa and response surface methodology (RSM) was used to optimize the effects of processing parameters on polysaccharide extraction yield. Three independent variables were extraction time (X₁), extraction temperature (X₂) and ultrasonic power (X₃), respectively. The statistical analysis indicated the independent variables (X₁, X₂, X₃), the quadratic terms (X₁₁ and X₃₃) and the interaction terms (X₁X₂, X₁X₃, X₂X₃) had significant effects on the yield of polysaccharides (P < 0.05). The optimal extraction conditions of D. viscosa leaf were determined as follows: extraction time 50.54 min, extraction temperature 85 °C and ultrasonic power 400 W. Under these conditions, the experimental yield of polysaccharides was 9.455 ± 0.24%, which was agreed closely with the predicted value (9.398%). The evaluation of anti-oxidant activity suggested that the polysaccharide exhibited significant protection against DPPH and hydroxyl radicals and could be explored as a nutraceutical agent.     

Effects of Elevated [CO2] and Low Soil Moisture on the Physiological Responses of Mountain Maple (Acer spicatum L.) Seedlings to Light

Global climate change is expected to affect how plants respond to their physical and biological environments. In this study, we examined the effects of elevated CO₂ ([CO₂]) and low soil moisture on the physiological responses of mountain maple (Acer spicatum L.) seedlings to light availability. The seedlings were grown at ambient (392 µmol mol⁻¹) and elevated (784 µmol mol⁻¹) [CO₂], low and high soil moisture (M) regimes, at high light (100%) and low light (30%) in the greenhouse for one growing season. We measured net photosynthesis (A), stomatal conductance (g _s), instantaneous water use efficiency (IWUE), maximum rate of carboxylation (V _cmax), rate of photosynthetic electron transport (J), triose phosphate utilization (TPU)), leaf respiration (R _d), light compensation point (LCP) and mid-day shoot water potential (Ψ_x). A and g _s did not show significant responses to light treatment in seedlings grown at low soil moisture treatment, but the high light significantly decreased the C _i/C _a in those seedlings. IWUE was significantly higher in the elevated compared with the ambient [CO₂], and the effect was greater at high than the low light treatment. LCP did not respond to the soil moisture treatments when seedlings were grown in high light under both [CO₂]. The low soil moisture significantly reduced Ψ_x but had no significant effect on the responses of other physiological traits to light or [CO₂]. These results suggest that as the atmospheric [CO₂] rises, the physiological performance of mountain maple seedlings in high light environments may be enhanced, particularly when soil moisture conditions are favourable.