Optimization of Maceration Conditions for Improving the Extraction of Phenolic Compounds and Antioxidant Effects of Momordica Charantia L. Leaves Through Response Surface Methodology (RSM) and Artificial Neural Networks (ANNs)

The main goals of this research were the chemical and biological characterization of the bitter melon (Momordica charantia) isolate obtained by traditional (maceration) extraction, as well as optimization of this process using response surface methodology (RSM) and artificial neural networks (ANNs). Experiments were performed using Box–Behnken experimental design on three levels and three variables: extraction temperature (20?°C, 40?°C, and 60?°C), solvent concentration (30%, 50%, and 70%) and extraction time (30, 60, and 90?min). The measurements consisted of 15 randomized runs with 3 replicates in a central point. The antioxidant activity of obtained extracts was determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH), cupric ion reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) assays while chemical characterization was done in terms of the total phenolic content (TPC). The methodology shows positive influence of solvent concentration on all four observed outputs, while temperature showed a negative impact. RSM showed that the optimal extraction conditions were 20?°C, 70% methanol, and an extraction time of 52.2?min. Under these conditions, the TPCs were 20.66 milligrams of gallic acid equivalents (mg GAE/g extract), DPPH 30.22 milligrams of trolox equivalents (mg TE/g extract), CUPRAC 67.78 milligrams of trolox equivalents (mg TE/g extract), and FRAP 45.48 milligrams of trolox equivalents (mg TE/g extract). The neural network coupled with genetic algorithms (ANN-GA) was also used to optimize the conditions for each of the outputs separately. It is anticipated that results reported herein will establish baseline data and also demonstrate that that the present model can be applied in the food and pharmaceutical industries.     

An effective theory of a compositeZ

It is shown that the experimental value of sin² θ_w can be obtained if theZ is a bound state of two haplons provided that the haplons carry a new hypercolour quantum number in addition to colour. This approach also leads to the prediction that the electromagnetic couplings of theZ are substantially larger than they are in standard electroweak theory. It may be possible to observe these anomalous couplings in the processe ⁺ e ^? →Zγ at LEP 200 where theZ is longitudinally polarised.     

2-Pyridinamin-Addukte von Übergangsmetall-bis(acetyl-acetonaten) und ihre Reaktionen. Hydrogencarbonat als Chelatligand in cis-(Ampy)2Co(acac)(HCO3)

2-Pyridinamine Adducts of Transition Metal Bis(acetylacetonates) and their Reactions. Hydrogencarbonate as a Chelating Ligand in cis-(Ampy)₂Co(acac)(HCO₃) The reaction of cobalt(II) salts, acetylacetone (acacH), 2-pyridinamine (Ampy), and the carbon dioxide of the air in methanol affords a mixture of (Ampy)₂Co(acac)₂( II ) and (Ampy)₂Co(CO₃)(H₂O)₂. On heating in toluene, appropriately in the presence of carbon dioxide, these complexes are converted into cis-(Ampy)₂Co(acac)(HCO₃) ( III ). Characteristic of compound III is a four-membered ring with the hydrogencarbonate as a bidentate ligand. The two Co? O distances are distinctly different (215.9 and 224.4 pm). In the complexes II and III 2-pyridinamine is a bidentate ligand coordinating by the endo-nitrogen. The Co-n-N bond lengths vary between 210.9 and 225.3 pm. Reasons are both the different trans-influence of the hydrogencarbonate or the acetylacetonato donor atoms and the π-interaction between cobalt(II) and the pyridine ring. This interaction is more significant in the cis-complex III . II and III are stabilized by a system of N? H …? O- and O? H …?O-bridges. With nickel(II) complexes analogous to II and III were obtained, while only the type II was characterized for manganese( II ).     

Novel heterocycles. Synthesis of 2,3-dihydro-6-methyl-2-phenyl-4H,6H-pyrano[3,2-c][2,1]benzothiazin-4-one 5,5-dioxide and related compounds

The reaction of 2-chloro-4-(methylsulfonyl)benzoyl chloride ( 5 ) with 1-methyl-1H-2,1-benzothiazin-4-(3H)-one 2,2-dioxide ( 4 ) gave the O-benzoyl compound, 1-methyl-2,2-dioxido-1H-2,1-benzothiazin-4-yl 2-chloro-4-(methylsulfonyl)benzoate ( 6 ), which rearranged to give the C-benzoyl isomer, [2-chloro-4-(methylsulfonyl)phenyl] (4-hydroxy-1-mefhyl-2,2-dioxido-1H-2,1-benzothiazin-3-yl)methanone ( 7 ). The O-cinnamoyl compound 13 that resulted from the addition of 2,4-dichlorocinnamoyl chloride ( 11 ) to compound 4 rearranged to give the C-cinnamoyl compound, 3-(2,4-dichlorophenyl)-1-(4-hydroxy-1-methyl-2,2-dioxido-1H-2,1-benzothiazin-3yl)-2-propen-1-one ( 15 ). On the other hand, 1-methyl-2,2-dioxido-1H-2,1-benzothiazin-4-yl 3-phenyl-2-propenoate ( 19 ) (from cinnamoyl chloride ( 17 ) and compound 4 ) rearranged to give 2,3-dihydro-6-methyl-2-phenyl-4H,6H-pyrano[3,2-c][2,1]benzothiazin-4-one 5,5-dioxide ( 21 ), an example of a hitherto unknown ring system. Additional examples of this novel heterocycle were prepared from 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 23 ) and 1-methyl-1H-thieno[3,2-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 8 ).     

Structure and dynamics of the Abeta(21-30) peptide from the interplay of NMR experiments and molecular simulations

We combine molecular dynamics simulations and new high-field NMR experiments to describe the solution structure of the Abeta(21-30) peptide fragment that may be relevant for understanding structural mechanisms related to Alzheimer's disease. By using two different empirical force-field combinations, we provide predictions of the three-bond scalar coupling constants ((3)J(H(N)H(alpha))), chemical-shift values, (13)C relaxation parameters, and rotating-frame nuclear Overhauser effect spectroscopy (ROESY) crosspeaks that can then be compared directly to the same observables measured in the corresponding NMR experiment of Abeta(21-30). We find robust prediction of the (13)C relaxation parameters and medium-range ROESY crosspeaks by using new generation TIP4P-Ew water and Amber ff99SB protein force fields, in which the NMR validates that the simulation yields both a structurally and dynamically correct ensemble over the entire Abeta(21-30) peptide. Analysis of the simulated ensemble shows that all medium-range ROE restraints are not satisfied simultaneously and demonstrates the structural diversity of the Abeta(21-30) conformations more completely than when determined from the experimental medium-range ROE restraints alone. We find that the structural ensemble of the Abeta(21-30) peptide involves a majority population (approximately 60%) of unstructured conformers, lacking any secondary structure or persistent hydrogen-bonding networks. However, the remaining minority population contains a substantial percentage of conformers with a beta-turn centered at Val24 and Gly25, as well as evidence of the Asp23 to Lys28 salt bridge important to the fibril structure. This study sets the stage for robust theoretical work on Abeta(1-40) and Abeta(1-42), for which collection of detailed NMR data on the monomer will be more challenging because of aggregation and fibril formation on experimental timescales at physiological conditions. In addition, we believe that the interplay of modern molecular simulation and high-quality NMR experiments has reached a fruitful stage for characterizing structural ensembles of disordered peptides and proteins in general.