Yogendra N. Shukla

Phytotoxic and antimicrobial constituents of Argyreia speciosa and Oenothera biennis

The antifungal activity of hexadecanyl p-hydroxycinnamate (1), scopoletin (2) isolated from Argyreia speciosa roots and gallic acid (3) from Oenothera biennis roots was evaluated against three fungi. Compound 1 and 2 were found to be highly potent against Alternaria alternata compared to 3. The phytotoxicity in terms of root growth inhibition of germinating wheat seeds was observed in all the three test materials. At 250 ppm concentration the inhibition caused by 3, was 85.63%; 1, 79.42%; and 2, 91.57%. At higher concentrations (1000 ppm) the root growth of the wheat was completely inhibited. The structures of these compounds were established using spectral and chemical methods.

Effect of triacontanol and chlormequat on growth, plant hormones and artemisinin yield in Artemisia annua L

Artemisinin and herbage yield of Artemisia annua plants were determined after application of triacontanol (tria.) and chlormequat (2-chloroethyltrimethylammonium chloride). Tria. at 1.0 and 1.5 mgl−1 produced a statistically significant positive effect on artemisinin level as well as on plant height, leaf and herbage yield. Chlormequat at 1000 and 1500 mgl−1 also increased artemisinin level, decreased the plant height at higher concentrations and increased the leaf and herbage yield at lower concentrations. Tria. application enhanced GA-like activity, but ABA levels decreased, while chlormequat increased ABA but reduced GA-like substances. The effect of Tria. on artemisinin yield seems to be mediated through its effect on plant growth.

Euphane triterpenoid and lipid constituents from Butea monosperma

Besides stigmasterol, stigmasterol-betaD-glucopyranoside and nonacosanoic acid, two new compounds isolated from the stems of Butea monosperma have been characterised as 3alpha-hydroxyeuph-25-ene and 2,14-dihydroxy-11,12-dimethyl-8-oxo-octadec-11-enylcyclohexane+ ++ by spectral data and chemical studies.

Saponin production in callus and cell suspension cultures of Panax quinquefolium

Abstract Callus and cell suspension cultures of American ginseng (Panax quinquefolium) were compared for growth and in vitro ginsenoside production over a 35-day culture cycle on modified Murashige and Skoogs medium. A time course study at five day intervals revealed that biomass yield in suspension and callus cultures was maximal on the 25th and 30th day of growth, respectively. Both types of cultures were able to produce ginsenosides in amounts and quality comparable to the cultivated plants. TLC-densitometry and HPLC analyses of the crude ginsenosides revealed that yield and relative distribution of different fractions belonging to the Rb and Rg groups of ginsenosides were greatly influenced by culture age. For the Rb group components, 25-day-old callus or suspension cultures were the best source of these compounds, while for the Rg group fractions 30–35-day-old cell cultures gave the maximum yield. Appreciable amounts of ginsenosides, particularly Rg1, were found to leach out in the culture medium of 30–35-day-old suspension cultures.

5α-Stigmast-9(11)-en-3β-ol, a sterol from Costus speciosus roots☆

Abstract A new sterol isolated from Costus species roots has been characterized as 5α-stigmast-9(11)-en-3β-ol by spectroscopic data and chemical studies.

Steroid glycosides from Asparagus adscendens

Abstract The structures of two new glycosides isolated from the roots of Asparagus adscendens have been elucidated as 3-β- O -[β- d -2-tetracosylxylopyranosyl]-stigmasterol and 3-β- O -[β- d -glucopyranosyl(l → 2)-α- l -arabinopyranosyl]-stigmasterol by physicochemical data.

Cytokinins from marine organisms

Abstract Zeatin, zeatin riboside, dihydrozeatin and isopentenyladenine have been isolated from green algae and blue coral along with two new cytokinins, characterized as 2-hydroxy-6-methylaminopurine and 2-hydroxy-1′methylzeatin.

Relationship between gibberellin and cytokinin activity and flowering in Rosa damascena Mill.

Kinetin at 10 mg l−1 increased the number of flowers produced on Rosa damascena plants while GA3 inhibited flowering. In the leaves of non-flowering plants GA-like activity was high while specific cytokinin activity (fraction-II) was significantly higher in flowering plants. A novel compound 10- methyldihydrozeatin riboside and isopentenyl-adenine were identified from TLC fraction-II while TLC fraction-I yielded zeatin and 2-hydroxy-6-methylaminopurine.

A bibenzyl xyloside from Chlorophytum arundinaceum

Abstract The structure of a new bibenzyl isolated from the roots of Chlorophytum arundinaceum has been established as 2′,4,4′-trihydroxy-2-xylopyranosyl

Heptatriacontan-4-one, tetratriacontanyl octacosanoate and other constituents from Pedalium murex

Abstract Two new compounds isolated from the fruits of Pedalium murex are characterized as heptatriacontan-4-one and tetratriacontanyl octacosanoate by spectral studies. Pentatriacontane, sitosterol, hexatriacontanoic acid, hentriacontanoic acid, ursolic acid and vanillin have also been isolated and identified.