Specific Optical Rotation Values Research Articles

Distinctive properties of the pine, oak, chestnut and multifloral blossom and honeydew honeys

Although blossom and honeydew honeys are produced from different nectar sources, it is very difficult to distinguish them. In this study, physicochemical and biochemical properties were compared to distinguish honeydew and blossom honeys obtained from different botanical sources. The honeys of pine (Pinus spp.) and oak (Quercus, spp.) were used as honeydew honey, and chestnut (Castania sativa L.) and highland honey were used as blossom honey. Turbidity, specific optical rotation (SOR) [α]20, electrical conductivity (EC), CIEL* a*b color parameters, and moisture and pH were assessed as physical parameters. Proline, invertase activity, sugar composition, total phenolic and flavonoid contents, and antioxidant capacity were used as biochemical properties. It was determined that SOR values were the most important parameters in distinguishing honeydew and blossom honeys. Turbidity stands out as a crucial factor in differentiating between pine and oak honeys. Except for chestnut honey, electrical conductivity, CIE color Lab values, and sugar profiles were identified as additional distinguishing factors among the tested honeys.

Iridoids from the aerial parts of Adenosma caeruleum with their nitric oxide inhibitory effects

Three new iridoids, adenocaeroids A−C (1−3), and seven known analogs, umbellatolide B (4), pedicularis-lactone (5), iridolactone (6), artselaenin C (7), eucommiol (8), rehmaglutin D (9), and 3-deoxy-artselaenin C (10) were isolated from the aerial parts of Adenosma caeruleum. Their chemical structures were identified by the comprehensive spectroscopic methods, including 1D and 2D NMR and HRESI mass spectra. The relative configurations of 1−3 were established by analyzing their NOESY spectra as well as by DFT-GIAO NMR calculations followed by ML-J-DP4, DP4+, and DU8 methods. The absolute configurations of 1−3 were determined by comparing experimental and calculated ECD spectra and specific optical rotation values. All of the compounds, except 7 and 10, inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV2 microglial cells in a dose-dependent manner, with IC50 values ranging from 28.4−61.8 µM. However, none of the compounds showed inhibitory effect on protein-tyrosine phosphatase 1B (PTP1B) activity.

Nor-24-homoscalaranes, Neutrophilic Inflammatory Mediators from the Marine Sponge Lendenfeldia sp.

The marine sponge Lendenfeldia sp., collected from the Southern waters of Taiwan, was subjected to chemical composition screening, resulting in the isolation of four new 24-homoscalarane compounds, namely lendenfeldaranes R-U (1-4). The structures and relative stereochemistry of the new metabolites 1-4 were assigned based on NMR studies. The absolute configurations of compounds 1-4 were determined by comparing the calculated and experimental values of specific optical rotation. The antioxidant and anti-inflammatory activities of the isolated compounds were assayed using superoxide anion generation and elastase release assays. These assays are used to determine neutrophilic inflammatory responses of respiratory burst and degranulation. Compounds 2 and 4 inhibited superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (fMLP/CB) with IC50: 3.98-4.46 μM. Compounds 2 and 4 inhibited fMLP/CB-induced elastase release, with IC50 values ranging from 4.73 to 5.24 μM. These findings suggested that these new 24-homoscalarane compounds possess unique structures and potential anti-inflammatory activity.

Antimicrobial Furancarboxylic Acids from a Penicillium sp.

Ten novel (1, 2, 3a, 3b, 4a, 4b, 5a, 5b, 6a, and 6b) furancarboxylic acids including four pairs of epimers (3a, 3b; 4a, 4b; 5a, 5b; 6a, 6b), together with seven known analogues (7a, 7b, 8a, 8b, 9a, 9b, and 10), were isolated from the fermentation of the soil-derived fungus Penicillium sp. sb62. Their structures were established on the basis of spectroscopic data analysis, and the absolute configurations were determined by time-dependent density functional theory electronic circular dichroism calculations, comparison of the specific optical rotation values, and modified Mosher's method. Compounds 1-4 represent the first class of natural furancarboxylic acids featuring a thiophene moiety. Compounds 1-7 showed antimicrobial inhibitory activities against Escherichia coli, Staphylococcus aureus, and Candida albicans with MIC values ranging from 0.9 to 7.0 μg/mL, from 1.7 to 3.5 μg/mL, and from 3.3 to 7.0 μg/mL, respectively.

Sugar-substituted fluorous 1,2,3-triazoles: Helical twists in fluoroalkyl chains and their molecular association in the solid state and correlations with physicochemical properties

This paper describes a novel study of thirty closely related polyfluoroalkyl-substituted glycosidyl-1,2,3-triazoles with systematic variations in the type of sugar, d-glucos-1′-yl or d-galactos-6′-yl derivatives, the protected or unprotected form of the sugar, the length and nature of linker groups to the triazole, the point of attachment and the atom of attachment between the substituent and the triazole, and the length of the perfluoroalkyl chain. It reports for the first time the molecular structure and crystal structures of three of the candidates, as defined by single crystal X-ray diffraction analysis, and compares melting point and specific optical rotation values, in combination with the diffraction, NMR spectroscopic and computational data to establish structural features, such as the helical twist of the fluoroalkyl chains, that influence physicochemical properties in the solid and solution states. The results provide a valuable reference source for practitioners in the field and will aid in the design of future materials.

Towards Acacia seyal protocol in Sudan: Preliminary study pertinent to colour identification and physiochemical properties

Despite the significant contribution of A. seyal to the exports portfolio of Sudan, farmers have slightly poor knowledge regarding post-harvest cultural practices in terms of proper methods of gum drying, storage conditions and gum stacking which might significantly be resulted in colour deterioration and inferior quality. Nevertheless, the current preliminary investigation is intended to study colour identification and physiochemical properties of A. seyal gums from samples obtained viafour exporting companies in Sudan and produced in three different geographical areas namely Buram, Hejleij and Deain.Each sample was graded visually into three colours: light, pale and dark and based on further chemical analysis to the colour within the samples and across the production areas significant variation was obtained as the colour is ranging from 16.73 to 44.53 within the different graded samples and across the production areas. The results show that each sample is graded into three different colour scale refereed to light, pale and dark.The physiochemical properties within the tested samples and across the production areas showed no significant differences between all parameters including moisture content, ash content and pH. The specific optical rotation varies from + 40 to + 60 within the samples and across the different production areas. However, both minimum and maximum values of specific optical rotation were obtained from Hejleij production area and representing light and dark colour, respectively.

Chiroptical properties of 2,2'-bioxirane.

The two enantiomers of 2,2'-bioxirane were synthesized, and their chiroptical properties were thoroughly investigated in various solvents by polarimetry, vibrational circular dichroism (VCD), and Raman optical activity (ROA). Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVTZ level revealed the presence of three conformers (G+ , G- , and cis) with Gibbs populations of 51, 44, and 5% for the isolated molecule, respectively. The population ratios of the two main conformers were modified for solvents exhibiting higher dielectric constants (G- form decreases whereas G+ form increases). The behavior of the specific optical rotation values with the different solvents was correctly reproduced by time-dependent DFT calculations using the polarizable continuum model (PCM), except for the benzene for which explicit solvent model should be necessary. Finally, VCD and ROA spectra were perfectly reproduced by the DFT/PCM calculations for the Boltzmann-averaged G+ and G- conformers.

Specific optical rotation is a versatile tool for the identification of critical micelle concentration and micellar growth of tartaric acid-based diastereomeric amphiphiles.

Four novel tartaric acid-based diastereomeric chiral amphiphiles, two being enantiomers of the other two, have been synthesized and investigated using chiroptical spectroscopic methods, along with tensiometry and dynamic light scattering experiments. We found that an inflection point in specific optical rotation (SOR) values at ~0.32mM corresponds to the critical micelle concentration (CMC). The increase in magnitude of SOR values beyond CMC corresponds to the growth of aggregates. For enantiomers, oppositely signed SOR values were observed, ruling out the possibility for the presence of aggregation size mediated artefacts. SOR values did not exhibit concentration dependence for a chiral tartaric acid based non-aggregating analogue further establishing the absence of artefacts or anomalous interaction of tartaric acid based head group with solvent. Electronic circular dichroism spectra showed no significant changes in band positions or intensities with concentration. Due to the requirement for higher concentrations (~200mM) needed to obtain vibrational circular dichroism spectra, these measurements are not found to be useful for studying concentration dependent properties of chiral amphiphiles.

New comonomers in malic acid polyesters

Here, we report the synthesis of polyesters of l-malic acid, β-cyclodextrin, and two other comonomers, resorcinol and salicylic acid that, involved in the polyester chain by direct polycondensation, could improve the antibacterial activity. The copolymers were characterized by thermal analysis, infrared spectroscopy as well as by specific optical rotation values. The thermogravimetric and differential scanning calorimetry (TG–DSC) measurement results showed the influence of the comonomers on the thermal stability of the copolymers, which was higher when ZnO was present in the reaction mixture. The FTIR spectra confirmed the presence of the comonomers in the polyesters and the influence of the ZnO on the products. The specific optical rotation values showed similar tendency, and the results were in accordance with those got by TG–DSC and FTIR techniques. In short, the zinc oxide helped not only in ester formation but improved the polyester stability. Results allowed elaboration of reproducible polyester synthesis with tailor-made characteristic.

Reversed-Phase UHPLC Enantiomeric Separation of Rasagiline Salts Using a Chiralpak® AGP Column.

We report the first rapid ultra-high performance liquid chromatographic (UHPLC) enantiomeric reversed-phase separation of rasagiline mesylate and its tartrate salts using a Chiralpak® AGP column (50 mm × 2.1 mm, 5 μm) as a stationary phase. This method was developed as an alternative to the usage of previously reported normal-phase chiral LC columns for isomer separation. Our method is based on an isocratic approach using a mixture of ammonium acetate and isopropyl alcohol (90:10, v/v) as the mobile phase (0.6 mL/min flow rate). The detection limit (at a detection wavelength of 210 nm) and quantification limit for the rasagiline enantiomers were 0.06 and 0.2 μg/mL, respectively. This method is compatible with the UHPLC-MS technique. The successful separation of rasagiline and its enantiomer was confirmed by determining the corresponding specific optical rotation values. Our method will be applicable for detecting rasagiline enantiomers during the control of manufacturing processes, and for use in rapid analysis for quality control in pharmaceutical industry to obtain optically pure pharmaceutical substances. This method was validated in terms of its precision, limit of detection, limit of quantification, linearity, accuracy, robustness, ruggedness, specificity, forced degradation, and solution stability, according to International Council on Harmonization Validation Guidelines Q2 (R1).

Chiroptical characterization of homopolymeric block fractions in alginates

Homopolymannuronic and homopolyguluronic fractions were obtained by partial hydrolysis of the alkaline extracts from the brown seaweeds Ascoseira mirabilis, Desmarestia menziessi, Desmarestia ligulata and Durvillaea sp. collected in southern Chile. Full characterization of the fractions was achieved by FT-IR and NMR spectroscopy. Total hydrolysis with 90% formic acid of the homopolymeric fractions allowed the preparation of mannuronic and guluronic acids. Both monomers and homopolymeric fractions as neutral salts were studied by CD and ORD. Chiroptical spectra were similar in shape and sign to those previously published in the literature, and permitted to assign D configuration to mannuronic acid and L configuration to guluronic acid in alginic acids. Specific optical rotation values at the sodium D light for the homopolymannuronic (∼−100°) and homopolyguluronic (∼−110°) acid fractions were obtained. These high negative values are proposed for the assignment of the absolute configuration of monomers in homopolymeric fractions.

Antiproliferative Butyrolactones from Mezilaurus crassiramea

Bioassay-guided fractionation of the ethanol extract from the leaves of Mezilaurus crassiramea, which was toxic to Artemia salina larvae, afforded 3′-acetylrubrenolide (1), 2′,3′-diacetylrubrenolide (2), and rubrenolide (3) from the active dichloromethane soluble fraction. Compound 1 is new, while 2 and 3 are first reported from a natural source and in the Mezilaurus genus, respectively. Compound 3 showed significant cytotoxicity against UACC-62, MCF-7, HT-29, and PC-3 human cancer cell lines, with GI50 values ranging from 3.3 to 9.9 µg/mL, while 1 and 2 exhibited marginal activities against at least five of the six investigated cell lines. The structures of 1–3 were established on the basis of 1D- and 2D-nuclear magnetic resonance analyses, high-resolution electrospray ionization mass spectrometry data and specific optical rotation values.

Optical activity of solutions and films of chitosan acetate

The optical activity of solutions, oligomers, and films of chitosan acetate in a molecular weight (М) range of 660—640 000 g mol–1 was studied by the optical rotation dispersion method. Monotonic dispersion curves lying in the range of negative values of specific optical rotation [α] are observed for all samples in a wavelength range of 300—700 nm. The absolute value of [α] decreases as the degree of polymerization decreases for solutions of chitosan acetate. Three regions are observed on the dependence [α] = f(logМ): constant [α] values for solutions of highmolecular-weight chitosan samples, their relatively weak change for low-molecular-weight samples, and a sharp change for oligomers. The transition to the low-molecular-weight analog of the monomeric chitosan unit, d-glucosamine, is characterized by the inversion of the rotation sign as high positive values of [α] are attained. The nontrivial for high-molecular-weight compounds dependence [α] = f(logМ) was established for chitosan acetate films: the module of [α] of the films increases with a decrease in the degree of polymerization. It is shown that the module of optical activity of the studied samples is determined by the mobility of structural units of oligomer, polymer, or film. It is found by X-ray diffractometry that differences in optical activity of the solutions and films are due to restriction of the mobility of macromolecular segments during the formation of high-molecular-weight chitosan films and incomplete relaxation processes of film systems to the state of energetically favorable conformations.

Preparative Fractionation Analysis of Acacia polyacantha Gum Using Acetone as a Solvent

Five authentic Acacia polyacantha whole gum samples were collected as natural exudates and five acetone fractions were obtained. Analysis of the whole gum samples and the fractions were carried out t for nitrogen (protein), specific rotation, intrinsic viscosity, pH, equivalent weight, uronic acid content, refractive index and average molecular weight. Results of refractive index for the whole samples and the fractions were found to share the same value (1.3337). Significant differences were obtained between the values of these parameters for the whole gum samples as well as the fractions and it is also among the fractions themselves. In particular fractions 1,2,3,4and 5 showed nitrogen content of 0.32%, 0.35%, 0.40%, 0.39%and0.37% and protein content of (2.11%,2.31%,2.64%, 2.57% and2.44%) respectively. The mean values of specific optical rotation of the fractions was found-13.5 0, -14.50, -15.0 0,-16.00 and -14.50 respectively. The average molecular weight of the fractions gave 2.669x105, Original Research Article Omer et al.; ACSj, 6(3): 164-171, 2015; Article no.ACSj.2015.048 165 2.669X105, 2.714X105, 2.339X105 and 2.754X105 respectively. The statistical analysis showed significant differences (P ≤ 0.05) for some parameters such as, intrinsic viscosity, pH and the average molecular weight. These data confirms the heterogeneity of Acacia polyacantha gum, and their fractions.

Structural revision and absolute configuration of lateritin

‘Lateritin’ (1), a morpholine-2,5-dione (depsipeptide), was reinvestigated for its structure and absolute configuration. On the basis of thorough 1D and 2D NMR and mass spectrometrical analyses, the structure of 1 was revised to be identical with beauvericin (8) and confirmed that beauvericin (8) is the trimeric lactone of ‘lateritin’ (1). The absolute configuration was determined by acidic hydrolysis, followed by application of Marfey’s method, menthyl ester derivatization, and GC–MS analysis. In addition, the specific optical rotation values of the hydrolysis products were compared with those of available standards.

Optically Active Helical Polymer From Anionic Polymerization of (S)-6-Acrylyl-2,2’-dimethoxy-1,1’-binaphthyl

(S)-6-Acrylyl-2,2’-dimethoxy-1,1’-binaphthyl (ADBN) was synthesized and anionically polymerized using n-BuLi as an initiator. The absolute value of specific optical rotation [α]25589 of poly-ADBN is −118.0 and that is about 8 times that of the starting monomer ADBN. Poly-ADBN was confirmed to exist in the form of one-handed helical structure in solution by means of comparing the specific optical rotation, the CD and UV-Vis spectra with that of ADBN and the model compounds such as (S)-6-propionyl-2,2’-dimethoxy-1,1’-binaphthyl (PDBN) and (S)-6-heptanoyl-2,2’-dimethoxy-1,1’-binaphthyl (HDBN). This conclusion was also confirmed by the fact that the g-value of poly-ADBN is about 13 times as high as that of its monomer and model compounds

Anomalous properties of flavonoids in reversed phase high performance liquid chromatography

It is shown through reversed phase high performance liquid chromatography that a characteristic feature of such abundant natural flavonoids as flavon-3-ols is an anomalously strong antibate dependence of their retention indices (RI) on the organic solvent concentration (C) in the eluent, dRI/dC < 0. In order to interpret this anomaly, the specific optical rotation values [α]D20 of natural (+)-(2R,3R)-dihydroquercetin in different solvents are compared, confirming the reverse formation of hydrated flavonoids in aqueous solutions.

Synthesis and phase behaviour of new cholesteric monomers and side chain smectic polymers based on cholesterol

The synthesis of five new cholesteryl-based monomers (M-1−M-5) and the corresponding smectic comb-like polymers containing cholesteryl groups (P-1−P-5) is presented. The chemical structures were characterised by FT-IR, 1H NMR and elemental analyses. The specific optical rotations were evaluated with a polarimeter. The phase behaviour was investigated by polarising optical microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction. The specific optical rotation values of these monomers and polymers with the same number of phenyl rings and terminal groups were nearly equal; however, they decreased with increasing the aryl numbers in the mesogenic core. The monomers M-1−M-5 showed oily streak and focal conic optical textures, or finger print textures characteristic of the chiral nematic phase. The polymers P-1−P-5 showed the smectic A phase. The melting, clearing, and glass transition temperatures increased, and the mesophase temperature ranges widened with increasing the aryl number in the mesogenic core. However, although the molecular structures of M-4 and M-5 were similar to those of M-3, namely their mesogenic cores contained three phenyl rings, their phase behaviour differed considerably, and T m and T i of M-4 and M-5 were less than those of M-3. In addition, M-4 and M-5 showed a clear glass transition similar to the polymer. Furthermore, the ester linkage bond and aryl arrangement in the mesogenic core also affected the phase behaviour.

Synthesis, structure and mesomorphism of new cholesteric monomers and smectic comblike polymers

Seven new cholesteric monomers ( M-1− M-7) and the corresponding smectic comblike polymers containing cholesteryl groups ( P-1− P-7) were synthesized. The chemical structures and purity were characterized by FT-IR, 1H NMR, and elemental analyses. The specific optical rotations were evaluated with a polarimeter. The mesomorphism was investigated by polarizing optical microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction. The specific optical rotation values of these monomers and polymers with the same numbers of phenyl ring and terminal groups were nearly equal, however, they decreased with increasing the aryl numbers in the mesogenic core. M-1− M-7 showed oily streak texture and focal conic texture, or fingerprint texture, or spiral texture of cholesteric phase. P-1− P-7 showed the smectic A phase. The melting, clearing, and glass transition temperatures increased, and the mesophase temperature ranges widened with increasing the aryl number in the mesogenic core. Surprisingly, although the molecular structures of M-6 and M-7 were similar to those of M-4, namely the mesogenic cores contained three phenyl rings, their phase behavior had a considerable difference, and T m and T i of M-6 and M-7 were less than those of M-4. In addition, M-6 and M-7 also showed an obvious glass transition. TGA showed that all the polymers had good thermal stabilities.

Optical activity of the anisotropic phases of cellulose acetates

AbstractIn this study, the optical activity of cellulose di and triacetate films with a highly oriented vitrified structure was studied. The systems possess high values of specific optical rotation [α], which is in favor of the formation of a cholesteric mesophase. [α] depends on the sample orientation angle relative to the light polarization vector in the plane perpendicular to the light ray (optical activity anisotropy). This dependence (indicatrix) is irregular and is described by a distorted sinusoid in the Cartesian coordinates. The results of indicatrix decomposition into harmonic components are discussed, with the contributions of the isotropic and anisotropic components (each with the corresponding structural element of a certain symmetry type) being separated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1605–1615, 2009