Browsing by Author "Vidya B. Pandey"

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A new class of organometallic compound
(Kluwer Academic Publishers, 1990) Virendra P. Singh; Vidya B. Pandey; Sanjay K. Pandey
Organometallic compounds of general formula (SCN)2M(NCSeHgR)2 (M=CoII, NiII, R=n-C5H11, i-C5H11) have been prepared. They behave as Lewis acids, forming complexes with pyridine and 2,2′-bipyridyl, characterized by elemental analysis, molecular weight, molar conductance, i.r. spectral (4000-200 cm-1), electronic spectral and magnetic susceptibility measurements. The Lewis acids are monomeric with bridging thiocyanate, or selenocyanate between M2+ and Hg2+. Cobalt and nickel acquire tetrahedral and octahedral configurations respectively through axial bridging, whereas mercury retains its linearity. Pyridine links to the metal in the Lewis acid and forms L2(SCN)2M(NCSeHgR)2 complexes. Bipyridyl ruptures the NCX bridge and forms cationic-anionic [M(bipy)3][(NCS)(NCSe)HgR]2 complexes. © 1990 Chapman and Hall Ltd.
Alkaloids of Argemone mexicana
(Indian Chemical Society, 2009) Sarita Singh; Tryambak Deo Singh; Virendra P. Singh; Vidya B. Pandey
Four isoquinoline alkaloids dl-tetrahydrocoptisine, dihydrocoptisine, 8-methoxydihydrosanguinarine and 13-oxoprotopine have been isolated from the whole plant of Argemone mexicana and their structures have been established by spectral evidences. This is the first report of these alkaloids from Argemone mexicana.
Antifungal activity of two alkaloids of Zephyranthes citrina and their field efficacy against powdery mildew (Erysiphe cichoracearum) of balsam
(2010) Udai P. Singh; Leena Gohain; Sudarshan Maurya; Amitabh Singh; Vidya B. Pandey; Ashok K. Singh
The anti-fungal activity of two alkaloids isolated from bulbs of Zephyranthes citrina was observed against 10 fungi, viz, Aternaria solani, A. triticina, Curvularia lunata, C. maculuns, Cercospora malvacearum, Erysiphe sp., Fusarium udum, Helminthosporium pisi, H. speciferum and Ustilago cynodontis. Different concentrations (200, 400, 600, 800, 1000 μg/ml of alkaloids (A and B) were used. Spore germination was inhibited at 600, 800, 1000 μg/ml. B alkaloid was used against Erysiphe cichoracearum causing powdery mildew in balsam (Impatiens balsamina) in the field as pre-and post-inoculation treatments at 1000, 1500, 2000 μg/ml doses. The extract was effective in both pre-and post-inoculation treatments. Foliar application of this alkaloid resulted in inducing synthesis of phenolic acid in the leaves of balsam. Maximum phenolics were detected in the leaves treated with 1500 μg/ml in both pre-and post-inoculation treatments. The increase in the production of phenolics in treated leaves of balsam can be correlated with the induction of resistance in treated plants against powdery mildew. The significant efficacy of the alkaloid under field conditions opens the possibility of its use by farmers for also controlling other diseases. © 2010 Taylor & Francis.
Pindrolactone, a lanostane derivative from the leaves of Abies pindrow
(Elsevier Ltd, 1996) Manju Tripathi; Luna Jain; Vidya B. Pandey; Anil B. Ray; Gerhard Rücker
Pindrolactone, a new tetracyclic triterpenoid, has been isolated from the leaves of Abies pindrow and its structure advanced as 3α-hydroxylanosta- 7,9(11),22E,24-tetraen-26,23-olide.
Three new cyclopeptide alkaloids from Zizyphus species
(2008) Manoj B. Pandey; Ashok K. Singh; Jagdish P. Singh; Virendra P. Singh; Vidya B. Pandey
Two new cyclopeptide alkaloids, xylopyrine-D and xylopyrine-E, from Zizyphus xylopyra and a new alkaloid, jubanine-E, from Zizyphus jujuba have been isolated and their structures were established by chemical and spectral evidences. © 2008 Taylor & Francis.
Triterpenoid saponins from the stem bark of Symplocos spicata
(1982) Ryuichi Higuchi; Toshio Kawasaki; Momota Biswas; Vidya B. Pandey; Biswanath Dasgupta
From the stem bark of Symplocos spicata a mixture of triterpenoid saponins was obtained. It behaved as a pure compound in TLC and HPLC, but heterogeneity was suspected on the basis of chemical and NMR spectral data. It was separated to give two analogous glycosides, which were identified as 3,28-O-bis-β-d-glucopyranosides of 19α-hydroxyarjunolic and 19α-hydroxyasiatic acids. © 1982.
Two new 14-membered cyclopeptide alkaloids from Zizyphus xylopyra
(2012) Manoj B. Pandey; Sarita Singh; Meenakshi Malhotra; Vidya B. Pandey; Tryambak D. Singh
The phytochemical investigation of the bark of Zizyphus xylopyra resulted in the isolation of two new 14-membered ring cyclopeptide alkaloids, xylopyrine-G and xylopyrine H. Their structures have been established by chemical and spectral evidences. © 2011 Taylor & Francis.
Xylopyrine-C, a new cyclopeptide alkaloid from Zizyphus xylopyra
(Taylor and Francis Ltd., 2008) Ashok K. Singh; Manoj B. Pandey; Virendra P. Singh; Vidya B. Pandey
Xylopyrine-C, a new 14-membered ring cyclopeptide alkaloid, has been isolated from the root bark of Zizyphus xylopyra together with a known alkaloid scutianine-C, and their structures were established by chemical and spectral evidences. © 2008 Taylor & Francis.