Topology and self-assembly of defect-colloidal superstructure in confined chiral nematic liquid crystals.

We describe formation of defect-colloidal superstructures induced by microspheres with normal surface anchoring dispersed in chiral nematic liquid crystals in confinement-unwound homeotropic cells. Using three-dimensional nonlinear optical imaging of the director field, we demonstrate that some of the induced defects have nonsingular solitonic nature while others are singular point and line topological defects. The common director structures induced by individual microspheres have dipolar symmetry. These topological dipoles are formed by the particle and a hyperbolic point defect (or small disclination loop) of elementary hedgehog charge opposite to that of a sphere with perpendicular boundary conditions, which in cells with thickness over equilibrium cholesteric pitch ratio approaching unity are additionally interspaced by a looped double-twist cylinder of continuous director deformations. The long-range elastic interactions are probed by holographic optical tweezers and videomicroscopy, providing insights to the physical underpinnings behind self-assembled colloidal structures entangled by twisted solitons. Computer-simulated field and defect configurations induced by the colloidal particles and their assemblies, which are obtained by numerically minimizing the Landau-de Gennes free energy, are in agreement with the experimental findings.

Topological switching and orbiting dynamics of colloidal spheres dressed with chiral nematic solitons.

Metastable configurations formed by defects, inclusions, elastic deformations and topological solitons in liquid crystals are a promising choice for building photonic crystals and metamaterials with a potential for new optical applications. Local optical modification of the director or introduction of colloidal inclusions into a moderately chiral nematic liquid crystal confined to a homeotropic cell creates localized multistable chiral solitons. Here we induce solitons that "dress" the dispersed spherical particles treated for tangential degenerate boundary conditions, and perform controlled switching of their state using focused optical beams. Two optically switchable distinct metastable states, toron and hopfion, bound to colloidal spheres into structures with different topological charges are investigated. Their structures are examined using Q-tensor based numerical simulations and compared to the profiles reconstructed from the experiments. A topological explanation of observed multistability is constructed.

Self-assembly of skyrmion-dressed chiral nematic colloids with tangential anchoring.

We describe dipolar nematic colloids comprising mutually bound solid microspheres, three-dimensional skyrmions, and point defects in a molecular alignment field of chiral nematic liquid crystals. Nonlinear optical imaging and numerical modeling based on minimization of Landau-de Gennes free energy reveal that the particle-induced skyrmions resemble torons and hopfions, while matching surface boundary conditions at the interfaces of liquid crystal and colloidal spheres. Laser tweezers and videomicroscopy reveal that the skyrmion-colloidal hybrids exhibit purely repulsive elastic pair interactions in the case of parallel dipoles and an unexpected reversal of interaction forces from repulsive to attractive as the center-to-center distance decreases for antiparallel dipoles. The ensuing elastic self-assembly gives rise to colloidal chains of antiparallel dipoles with particles entangled by skyrmions.

A new indole alkaloid from Alstonia scholaris.

A new indole alkaloid, N-formylscholarine, together with picrinine, strictamine and nareline has been isolated from the fruit pods of Alstonia scholaris, and their structures were established by various spectral data. This is the first report of these alkaloids in A. scholaris fruit pods.

Antifungal activity of the alkaloids from Eschscholzia californica.

The isoquinoline alkaloids hunnemanine and norsanguinarine have been isolated from methanolic extract of the whole plant of Eschscholzia californica. These two alkaloids were checked for their antifungal activity against phytopathogenic fungi Alternaria melongenae, A. brassicola, A. brassicae, Curvularia lunata, C. maculans, Helminthosporium pennisetti, H. oryzae, H. turcicum, Fusarium undum and F. lini. Hunnemanine exhibited 100 % inhibition of spore germination of A. brassicae, H. pennisetti and F. lini at 1000 ppm whereas norsanguinarine exhibited 100 % inhibition of A. brassicicola and C. maculans at this concentration.

New alkaloids from Corydalis species.

A new alkaloid, chaerophylline (1), together with known alkaloids (-)-corypalmine, berberine chloride, (-)-isocorypalmine, (-)-corydalmine and (+)-bicuculline have been isolated from the crude base fraction of Corydalis chaerophylla. The crude base fractions of Corydalis longipes gave a new alkaloid, longicine (4), together with known alkaloids (+/-)-alpha-hydrastine, (+/-)-beta-hydrastine, N-methylhydrasteine hydroxylactam, 1-methoxyberberine chloride and berberinium hydroxide. These alkaloids are reported for the first time from the above species and their structures were established by chemical and spectroscopic evidence.

A new chalcone glycoside from Rhamnus nipalensis.

A new chalcone glycoside, chalcone-2',4-dihydroxy-4'-O-beta-D-glucoside has been isolated from Rhamnus nipalensis together with sitosterol, lupeol, di-O-methyldaidzein, kaempferol-4'-methylether, quercetin, physcion, sitosterol glucoside, emodin and their structures established by spectroscopic data. Isolation of these compounds are the first report from this plant.

Fuyuziphine, a new alkaloid from Fumaria indica.

A new alkaloid, fuyuziphine together with (+/-)-alpha-hydrastine has been isolated from the whole plant of Fumaria indica. The structures of these alkaloids have been established by spectral and chemical evidences.

Characteristics of the collective dielectric relaxation mode of the incommensurate SmC(α)(*) phase.

Employing the dielectric relaxation spectroscopy technique, we have observed two different characteristics of the collective relaxation mode of an incommensurate SmC(α)(*) phase. Recent theoretical advances predict two different natures for the dielectric relaxation mode in the SmC(α)(*) phase. Our experimental results confirm two different behaviours of the relaxation mode in different temperature ranges for this phase for one unique compound having an exceptionally wide temperature range (∼9 °C) for the SmC(α)(*) phase.

Antifungal Activity of Securinine against Some Plant Pathogenic Fungi.

The alkaloid securinine was assessed against spore germination of some plant pathogenic and saprophytic fungi (Alternaria alternata, Alternaria brassicae, Alternaria brassicicola, Curvularia lunata, Curvularia maculans, Curvularia pallenscens, Colletotrichum musae, Colletotrichum sp., Erysiphe pisi, Helminthosporium echinoclova, Helminthosporium spiciferum, Heterosporium sp.). Spore germinations of all the tested fungi were inhibited. Alternaria brassicicola, C. lunata, C. pallenscens and H. spiciferum were highly sensitive as complete inhibition of spore germination was observed at very low concentrations (200 ppm).

Antifungal Activity of an Alkaloid Allosecurinine against Some Fungi.

An allosecurinine alkaloid was assayed against spore germination of some saprophytic and pathogenic fungi e.g., Alternaria alternata, A. solani, A. brassicicola, A. brassicae, Curvularia lunata, C. pallescens, C. maculans, Curvularia species, Colletotrichum species, C. musae, C. gloeosporioides, Erysiphe pisi, Fusarium udum, Helminthosporium echinoclova, H. pennisetti, H. spiciferum, and Heterosporium sp. It inhibited mild spore germination of all the fungi tested. Curvularia lunata, Curvularia sp., Collectotrichum sp., C. musae and Heterosporium sp. were most sensitive as complete inhibition of spore germination was observed at very low concentrations.

Inhibitive Effect of Fuyuziphine isolated from Plant (Pittapapra) (Fumaria indica) on Spore Germination of Some Fungi.

The alkaloid fuyuziphine was isolated from the whole plant of Fumaria indica. It had inhibitive effect against spore germination of some plant pathogenic fungi (Collectotrichum sp., C. gloeosporioides, C. falcatum, Curvularia maculans, C. lunata, Erysiphe cichoracearum, Helminthosporium pennisetti, Oidium erysiphoides, Ustilago cynodontis, Alternaria chieranthi, A. melongenae, A. brassicicola and A. solani). Curvularia lunata, Oidium erysiphoides, Alternaria brassicicola and A. solani did not germinate at 750 and 1000 ppm and Colletotrichum gloeosporioides, C. falcatum, Curvularia maculans were inhibited at 1000 ppm for 24 hr incubation. Germination of most fungi was significantly inhibited at 100~750 ppm.

Peptide alkaloids from Zizyphus sativa bark.

Two new cyclopeptide alkaloids, sativanine-N and sativanine-O were isolated from the stem bark of Zizyphussativa and their structures were established by spectral analysis.

Flavonoids from Echinops echinatus.

A new isoflavone glycoside, echinoside (7), together with 7-hydroxyisoflavone, kaempferol-4'-methylether, kaempferol-7-methylether, myrecetin-3-O-alpha-L-rhamnoside, kaempferol and kaempferol-3-O-alpha-L-rhamnoside, has been isolated from the whole plant of Echinops echinatus. The structure of echinoside has been established by chemical and spectral data. This is the first report of the occurrence of these flavonoids in E. echinatus.

A case of Hodgkin's disease presenting with recurrent laryngeal nerve palsy and tracheoesophageal fistula.

Malignancy is the most common cause of tracheoesophageal fistulas. The malignancies commonly implicated in the development of tracheoesophageal fistulas are primary bronchial or esophageal carcinomas. Hodgkins disease rarely leads to such a fistula. We report a case of Hodgkin's disease with a tracheoesophageal fistula as well as a left recurrent nerve palsy at presentation. This presentation has no precedent in literature. The patient was treated with systemic chemotherapy and involved field radiotherapy. On follow up 1 year after the completion of treatment, he was clinically and radiologically disease free.

Antifungal Activity of Narceine Methyl Ester and Narceine Isolated from Corydalis longipes Against Some Phytopathogenic Fungi.

Narceine methyl ester and narceine are potent alkaloids which were isolated from Corydalis longipes were found effective in vitro at very low concentration, i.e., 100~500 ppm against spore germination of some test plant pathogenic fungi (Alternaria solani, A. tagetica, Cercospora abelmoschi, Curvularia maculans, Erysiphe cichoracearum, E. pisi, Fusarium udum, Helminthosporium oryzae, H. penniseti, Ustilago cynodontis). Among the test, phytopathogens the spores of F. udum, C. maculans and H. penniseti were highly sensitive at 200 ppm. However, spores of E. pisi, A. solani and A. tagetica were less sensitive at low concentration followed by other test fungi. Most of the fungi showed zero or nearly zero percent spore germination at 400 and 500 ppm.

Individual and combined effect of (+/-)-alpha-hydrastine and (+/-)-beta-hydrastine on spore germination of some fungi.

(+/-)-alpha-Hydrastine and (+/-)-beta-hydrastine were isolated from Corydalis longipes; both exhibited considerable efficacy against spore germination of some saprophytic and phytopathogenic fungi. While (+/-)-alpha-hydrastine was effective against most of the fungi, Helminthosporium echinoclova was least affected even at the highest dose (150 ppm). (+/-)-beta-Hydrastine was equally effective against several fungi. Mixture of both compounds was more effective than each one individually. Helminthosporium species were again the most resistant toward the mixture. The effect of both alkaloids independently on germination and development of E. pisi conidia on excised pea leaves was also shown. After pre-inoculation with (+/-)-alpha-hydrastine, the effect was more pronounced than the addition post-inoculation; maximum inhibition occurred at 200 ppm. (+/-)-beta-Hydrastine also reduced germination of conidia but was less effective than (+/-)-alpha-hydrastine. The number of primary and secondary branches of conidia and number of appressoria were not affected significantly by either compound.

Triterpene glycoside from Terminalia arjuna.

A new triterpene glycoside, arjunetoside, together with oleanolic and arjunic acids has been isolated from the root bark of Terminalia arjuna. The structure of arjunetoside has been established as 3-O-beta-D-glucopyranosyl-2alpha,3beta, 19alpha-trihydroxyolean-12-en-28-oic acid, 28-O-beta-D-glucopyranoside by chemical and spectral data.

Eclalbatin, a triterpene saponin from Eclipta alba.

From the whole plant of Eclipta alba, a new triterpene saponin, named eclalbatin, together with alpha-amyrin, ursolic acid and oleanolic acid were isolated. The structure of eclalbatin has been established as 3-O-beta-D-glucopyranosyl-3-beta-hydroxy-olean-12-en-28-oic acid, 28-O-beta-D-arabinopyranoside (1) on the basis of chemical and spectral data.

Cyclopeptide alkaloids from Zizyphus jujuba.

A new cyclopeptide alkaloid, jubanine-C (1), together with known alkaloids scutianine-C (4) and zizyphine-A (5), have been isolated from the stem bark of Zizyphus jujuba and identified by spectral analysis.