Antioxidant properties of β-carotene isomers and their role in photosystems: insights from Ab initio simulations

In this work we investigate the effect of cis isomerizations and conformational changes on the antioxidant activity of β-carotene, one of the most important pigments in nature. The electrodonating (ω(-)) and electroaccepting (ω(+)) powers of the most relevant isomers of β-carotene are first evaluated in polar and nonpolar solvents using density functional theory (DFT), and these quantities are then used to establish an antioxidant scale of the isomers. The electrodonating power, which is directly related to the antioxidant activity, is shown to provide a very good correlation with the experimental data. Next, we compute the intermediate twisted structures of the β-carotene isomers generated by partial rotation of every single bond in the polyenic chain. The electrodonating and electroaccepting powers are evaluated for each of these intermediate structures along with their maximum absorption wavelengths, which are computed using time-dependent DFT (TD-DFT). The trends observed for both the electrodonating power and the maximum absorption wavelength can be rationalized in terms of the effective conjugated chain length of the structure resulting from single bond rotations. The results obtained are used to analyze the conformational distribution of β-carotene in the well-resolved photosystem I (PS-I) of purple cyanobacteria. It is then shown that the isomers present in this photosystem are those having the lowest calculated relative energies and that those with enhanced antioxidant activity are preferentially located in the inner core of the protein complex.     

Effects of Ta content on the phase stability and elastic properties of β Ti–Ta alloys from first-principles calculations

The effects of Ta content on the phase stability, the elastic property and the electronic structure of β type Ti–Ta alloys were studied from first-principles calculations based on the density functional theory. It is found that the phase stability, tetragonal shear constant C′, bulk modulus, elastic modulus and shear modulus of β type Ti–Ta alloys increase with the Ta content increasing monotonously. The lowest elastic modulus of the alloys is realized when the valence electron number (e/a) is around 4.25. Moreover, the phase stability of the alloys was discussed based on the calculated density of state (DOS).     

The Influence of β-Diketones on the Hydrolysis and Growth of Particles from Zirconium(IV) n-Propoxide

The influence of low ligand/Zr mole ratios ( = 0–0.1) on the hydrolysis and growth of oligomers from Zr(O ⁿ Pr)₄ modified with a series of -diketones (trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, dibenzoylmethane and dipivaloylmethane), and their subsequent aggregation to form uniform, dense spheres, has been investigated by light scattering and turbidometry. The addition of -diketones results in a large increase in the induction time, t _i (reduction in hydrolysis/condensation rates). A remarkable feature of the data is the dramatic reductions in rate observed even when a maximum of one in forty Zr–OR bonds have been replaced by the -diketone and are no longer available for hydrolysis or further condensation. The largest effect is observed with dibenzoylmethane, which increases t _i by a factor of 26 relative to acetylacetone.A mechanism rationalising the origin of the effect is discussed, which involves segregation of the -diketone ligands on the surface of the growing particle, with subsequent particle growth restricted to those sites not occupied by the chelating ligands.     

Effect of ultrasonic waves on crocin and safranal content and expression of their controlling genes in suspension culture of saffron (Crocus sativus L.)

The expression of biosynthesis controlling genes of crocin and safranal in saffron (Crocus sativus) can be influenced by ultrasonic waves. Sterilized saffron corms were cultured in a ½-MS medium supplemented by 2-4-D and BAP. Saffron callus cells were treated with ultrasonic waves in a cellular suspension culture under optimal growth conditions. The samples were collected at 24 and 72 hours after treatment in three replications. The secondary metabolites were measured by high-performance liquid chromatography and the gene expression was analysed by the real-time polymerase chain reaction. Results indicate that this elicitor can influence the expressions of genes CsBCH, CsLYC and CsGT-2; the ultrasonic waves acted as an effective mechanical stimulus to the suspension cultures. The analysis of variance of the ultrasonically produced amounts of safranal and crocin indicates that there is a significant difference between once- and twice-treated samples in that the amount of safranal was the highest within the samples taken from the twice-treated suspension culture at 72 h after the ultrasound treatment, and the crocin was maximised after 24 h passed the twice-applied ultrasound treatment.     

Studies on Structure and Porperties of Water Soluble Polysaccharide from Fruiting Body of Cordyceps Militarvs(L.) Link

A water soluble crude polysaccharide has been isolated from the fruiting body of cultivated Cordyceps militarvs(L.)Link.The GC analysis indicated that it contained the monosaccharides of Gal,Man,Glc and GlcA.Their molar ratio is 1.00:1.58:7.89:0.19.The crude polysaccharide was fractionated with ethanol to get three fractions,which were CM-Ⅰand CM-Ⅲ,CM-Ⅱ was further purified to get one homogeneous fraction named CMB.The molecular weight was estimated to be 6000by means of gel filtration.CMB is a greyish white powder.The GC analysis indicated that it was composed of Gal.Man,Glc and the molar ratio is 1.00:1.38:5.10.Partial hydrolysis with an acid.periodate oxidation.Smith degradation.IR,GC and methylation analyses,GC/MS analyses were used for the structure analyses of CMB.Man,(1→6)-linked-Glc,(1→4)-linked-Glc and (1→4)-linked-Gal.Some of (1→4) -linked-Glc and all(1→4)-linked-Gal residues are substituted at 3-O and 6-O respectively,(1→4)-linked-Glc and minor(1→6)-linked-Gle.The nonreduced end is composed of Gal and Glc.The main glycosidic link of CMB is α configuration.     

The influence of ms-substitution on the properties of 3,3′-bis(dipyrrolylmethenes) and their coordination compounds

We have compared the coordination properties of decamethyl-substituted 3,3′-bis-(dipyrrolylmethenes) (H₂L) with different ms-spacers separating the dipyrrolylmethene domains: methylene -CH₂-, methoxyphenylmethylene -CH(p-C₆H₄OMe)-, and trifluoromethylmethylene -CH(CF₃)-. The stable binuclear homoligand complexes [M₂L₂] are formed in reactions of the ligands with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) acetates. In the cases of all H₂L ligands the thermodynamic constants of the complex formation reactions increase in the following series: Cu(II) < Cd(II) < Hg(II) < Ni(II) < Co(II) < Zn(II). The change in -CH₂- ms-spacer to -CH(p-C₆H₄OMe)- or -CH(CF₃)- results in a decrease in the constant of H₂L complex formation by 1–4 orders of magnitude, the cation being the same. The influence of ms-substitution on the stability and luminescence properties of [M₂L₂] has been discussed.     

Influence of conjugated nitrogenous bases on the spectra and structure of mixed-ligand nickel(II) chelates containing β-diones

The infrared and electronic excitation spectra of a series of new nickel(II) chelates containing an-diimine (or nitrogenous base, enR) and the anion of a-dione (1,3-ketoenol or 1,3-ketoester,H) were obtained in the solid state and in solution. The composition and the overall structure of the new chelates in the solid state depends on ligand concentration, the substituents within the-dionato moiety and the counterion present. The IR and electronic excitation spectra of [Ni(enR)₂ ]NO₃ and [Ni(enR)(O₂NO)] indicate, in conjunction with other physicochemical measurements, bidentate coordination of the ligands, while the spectral shifts reveal replacement of the (O,O)nitrato group by basic solvents. The existence of the nickel(II) in an octahedral environment is confirmed by an X-ray structure analysis of [Ni(dpamH)₂acac]NO₃ · CH₃OH (monoclinic, space groupP2_l/n, a=17.296(1),b=7.462(1),c=21.604(3) å,=95.65(1),Z=4, R=0.0534,Rw=0.0600), where dpamH denotes the 2,2-dipyridylamine.     

Theoretical studies on electronic structures and spectroscopic properties of a series of novel β-diketonate Os(II) complexes

The geometries, electronic structures, and spectroscopic properties of a series of [Os^(II)(CO)₃(tfa)(acac(X)₂)] (tfa = trifluoroacetate; acac = acetoylacetonate; X = H (1), CF₃ (2), C₆H₅ (3), and C₁₀H₇ (4)) complexes have been investigated theoretically. The ground and excited state geometries were optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ levels, respectively. The optimized geometry structural parameters agreed well with the corresponding experimental results. As indicated in this paper, the highest occupied molecular orbitals were dominantly localized on the Os atom, ctfa (abbv. of CO and tfa), and acac ligand for 1 and 2, acac ligand and X substituent for 3 and 4, while the lowest unoccupied molecular orbitals were mainly composed of acac ligand and X substituent. Under the time-dependent density functional theory (TDDFT) level with the polarized continuum model (PCM), the absorption and phosphorescence in CH₂Cl₂ media were calculated based on the optimized ground- and excited-state geometries, respectively. The calculated results show that the lowest energy absorptions at 317 (1), 342 (2), 377 (3), and 420 nm (4) are attributed to a change of ππ*/MLCT mixing transition to pure ππ* transition for 1–4, while their phosphorescence emission have similar transition properties. This indicates that the absorption and emission transition characters could be altered by adjusting the π electron-donating ability.     

Surface structures of adsorption layers of sodium hyaluronate and bovine serum albumin complexes on poly(γ-methyl-l-glutamate) film and their surface properties

Two-dimensional structures and characteristics of the complexes between sodium hyaluronate (NaHA) and bovine serum albumin (BSA) were studied by using a quartz crystal microbalance method and an atomic force microscope (AFM). NaHA did not adsorb on poly(-methyl-l-glutamate) (PMLG) film. On the other hand, the complexes adsorbed on it and the adsorption behaviors were found to be Langmuir types. With increasing weight ratio of BSA to NaHA, W _BSA, the adsorption constants K decreased and the saturated adsorption masses increased. The adsorbed complexes were spherical particles and at saturated adsorption states they covered compactly on the PMLG film. The mean diameters d _AFM estimated from the topographic images decreased from 70 to 54 nm with increasing W _BSA. The adhesion force F _ad and the frictional force F _f between the complex layers and the AFM tip were obtained by using the contact mode of the AFM. With increasing W _BSA, the values of F _ad decreased and the values of F _f increased. Compared with the frictional coefficient of the NaHA adsorption layer on the BSA monolayer, the values for the NaHA–BSA complex layer were found to be much higher.     

A systematic investigation on flavonoids,catechin, β-sitosterol and lignin glycosides from Saraca asoca (ashoka) having anti-cancer & antioxidant properties with no side effect

Saraca asoca is an IUCN red-listed tree species that extensively famous in the Ayurvedic medicine field. Saraca asoca (Roxb.) de Wilde belongs to the family Fabaceae, has been used to treat various gynecological disorders, bacterial infections, worm infestations, haemmorhagic dysentery, uterine pain, skin diseases, cancer, circulatory, cardiovascular disorders, and many others. All parts of the Saraca asoca have medicinal values. Numerous antioxidant compounds like flavonoids, catechin, beta-sitosterol, lignin glycosides are present in the bark, leaf, and flower of Saraca asoca plant, which help to stabilize free radicals molecules that are associated with the development of cancer conditions. Currently in the cancer research study field new and more effective modes of natural therapies are recently being analyzed. Traditional medicines have been used for their preventative role against various diseases in the human population. Plant based therapy for cancer prevention is becoming more demanding due to its various unique properties such as natural chemical composition, less expensiveness, naturally available., easily orally administrable, significant chemo-protective activities, nontoxic to normal cells in the body, less side effects compared to other synthetic chemotherapeutic drugs. The chemotherapeutic drugs will be harmful to both cancer and normal cells. Additionally, some common side effects or health consequences like vomiting, nausea, bleeding, hair fall, alopecia, hyperuricemia, thrombocytopenia, bone marrow depression, mucositis are very common after chemotherapeutic drug treatment in cancer. This review paper summarizes the evidences which agree with the fact that flavonoids and other phenolic compounds in Saraca asoca plant possess significant antioxidant activity and an efficient chemopreventive characteristic against different types of cancer. This paper reviews the anticancer activities of Saraca asoca bark and flower and discusses the potential preventive roles of phenolic and flavonoids compounds, present in bark and flower of Saraca asoca in the cancer treatment process.     

Semi-preparative HPLC purification of δ-tocotrienol (δ-T3) from Elaeis guineensis Jacq. and Bixa orellana L. and evaluation of its in vitro anticancer activity in human A375 melanoma cells

In this work, we report a rapid and convenient HPLC-UV-DAD method for the isolation of δ-T3 on semi-preparative scale from two different vitamin E rich processed, commercially available products obtained from the fruits of Elaeis guineensis Jacq. (oil palm) and from the seeds of Bixa orellana L. (achiote tree). Chromatography was run using reverse phase (RP) C-18 columns and HPLC-grade acetonitrile as mobile phase. The purity of the isolated δ-T3, assessed by GC–MS and ¹H NMR was above 98%. The δ-T3 cytotoxic activity found in vitro against the proliferation of human A375 melanoma cells compared to that of the other δ-T3 free tocols mixture suggest its primary role in the experimental anticancer activity observed for palm oil derived products. Taken altogether, the results of this study highlight the importance of the application of suitable purification systems for the preparations of tocotrienols prior to their experimental or clinical testing.     

Volatile components from flower-heads of Centaurea nicaeensis All., C. parlatoris Helder and C. solstitialis L. ssp. schouwii (DC.) Dostál growing wild in southern Italy and their biological activity

The volatile constituents of the flowerheads of Centaurea nicaeensis All., C. parlatoris Helder and C. solstitialis L. ssp. schouwii (DC.) Dostál were extracted by hydrodistillation and analysed by GC and GC-MS. Altogether 113 components were identified. Fatty acids and hydrocarbons were the most abundant components in the oils. Caryophyllene and caryophyllene oxide were the main compounds of the sesquiterpene fraction. The study on the biological activity of the oils shows no significant activity.     

Preparation of weak cation exchange packings based on monodisperse poly(glycidyl methacrylate-<Emphasis Type="Italic">co</Emphasis>-ethylene dimethacrylate) beads and their chromatographic properties

The monodisperse, macroporous poly(glycidyl methacrylate- co-ethylene dimethacrylate) beads were synthesized by a single-step swelling and polymerization method. Based on this media, a weak cation exchange (WCX) stationary phase for HPLC was synthesized by a new chemically modified method. The prepared resin has advantages for biopolymer separation, high column efficiency, low column backpressure, high protein mass recovery, and good resolution for proteins. The measured bioactivity recovery for lysozyme was 98+/-5%. The dynamic protein loading capacity of the WCX packings was 17.3 mg g(-1). The experimental results show that the synthesized WCX resin has very weak hydrophobicity.     

Influence of the composition and morphology of nanosized transition metal sulfides prepared using the Anderson-type heteropoly compounds [X(OH)6Mo6O18]n? (X = Co, Ni, Mn, Zn) and [Co2Mo10O38H4]6? on their catalytic properties

Using the Anderson-type heteropoly compounds (HPCs) [X(OH)₆Mo₆O₁₈] _n− (X = Co, Ni, Mn, Zn) and [Co₂Mo₁₀O₃₈H₄]₆₋ and cobalt (or nickel) nitrate, XMo/Al₂O₃ and Co(Ni)-XMo/Al₂O₃ catalysts were prepared. The catalysts were studied by low-temperature nitrogen adsorption, X-ray diffraction, and high-resolution transmission electron microscopy. The average length of the active-phase particles of the catalysts was 3.5 to 3.9 nm, and the average number of MoS₂ layers in a packet was 1.4 to 2.1. The catalytic properties of the samples, which were estimated in dibenzothiophene (DBT) hydrodesulfurization and in the hydrotreating of the diesel fraction, are considerably dependent upon both the type and composition of the HPC, and the nature of the applied promoter (Ni or Co). As compared to the Ni-promoted catalysts, the Co-promoted samples exhibit a higher desulfurization activity, whereas the hydrogenation ability of the Ni-XMo/Al₂O₃ catalysts surpasses that of the Co-XMo/Al₂O₃ ones. The catalytic properties depend on the morphology of the nanostructured active phase. With a growing number of MoS₂ layers in the packet of the catalysts’ active phase, the DBT hydrodesulfurization rate constants for both the direct desulfurization route and the preliminary hydrogenation rote rise linearly and the selectivity falls linearly for the hydrogenation route. The selectivity of Ni-XMo/Al₂O₃ decreases to a greater extent than that of Co-XMo/Al₂O₃. The dependences of the catalytic properties on the morphology of the catalysts’ active phase are consistent with the “dynamic” model of the functioning of the active sites of transition metal sulfides.