B.R. Chhabra

Guaianolides from Saussurea lappa

Two new sesquiterpene lactones with an α,β-unsaturated aldehyde group have been isolated from the roots of Saussurea lappa. Their stereostructures have been established by the combined use of spectroscopic as well as chemical methods via their synthesis from dehydrocostus lactone.

Sesquiterpene lactones from Saussurea lappa

Abstract Three new guaianolides, namely 11,13 epoxydehydrocostuslactone, 11,13 epoxyisozaluzanin C and 11,13 epoxy-3-keto dehydrocostus-lactone were isolated from the petrol extract of powdered costus roots (Saussurea lappa). The structures of the new compounds have been deduced from spectral data and chemical transformations.

Biomimetic synthesis of 2,3-dioxabicyclo [4,4,0] decanes as plant growth regulators

Abstract Naturally occurring derivatives of 2,3-dioxabicyclo [4,4,0] decane from Ecucalyptus grandis have been reported to possess a wide range of biological control in various plants including the parent one. The biogenetic type synthesis of these compounds have been discussed in this Paper.

Three oxygenated alantolides from Inula racemosa

Abstract Three oxygenated alantolides have been isolated from Inula racemosa . Two of these are epoxyalantolides while the third is perhydroxy derivative. Stereostructures have been assigned to these compounds on the basis of spectral data and chemical correlation.

Stereostructures of two biologically active sesquiterpene lactones from Inula racemosa

Abstract Two new sesquiterpene lactones, alantodiene and isoalantodiene, have been isolated from Inula racemosa . Both lactones display biological activity as plant growth regulators. Their structures have been elucidated using spectral data and chemical correlation. The most active plant growth regulator yet isolated from this source is isoalantodiene which is a potent root initiator with hypocotyl cuttings of Vigna radiata and it also increases the nitrate reductase activity in this plant.

A biologically active guaianolide from Saussurea lappa

Abstract 4β-Methoxydehydrocostus lactone has been isolated from costus roots ( Saussurea lappa ). Its structure and stereochemistry have been established by spectral methods and chemical correlation with dehydrocostus lactone. The compound displayed significant biological activity as a plant growth regulator.

Carota-1,4-β-oxide, a sesquiterpene from Daucus carota

Abstract A new sesquiterpene ether, carota-1,4-β-oxide, has been isolated from the essential oil of the seeds of carrot 1 ( Daucus carota ). The structure and stereochemistry of this compound have been established by spectroscopic and chemical methods by its synthesis from carotol.

Epoxy alantolides: Isoinunal—a new potent plant growth regulator from Inula racemosa

Abstract An investigation of Inula racemosa roots afforded, in addition to known sesquiterpene lactones, four new lactones with close biogenetic relationships. Their structures have been elucidated using spectral data and chemical correlation. The most interesting of these is isoinunal which is a potent root initiator with hypocotyl cuttings of Phaseolus aureus .

Conjugated terpenoid ketones: a new group of plant growth regulators

α,β-unsaturated terpenoid ketones have a root-inducing property on the hypocotyl cuttings ofPhaseoulus aureus. Significantly isopathcoulenone, (I) is distinctly more active in causeing rooting over IAA.

A biogenetically important hydrocarbon from Cyperus scariosus

Abstract A new hydrocarbon isopatchoul-3-ene has been isolated from the essential oil of Cyperus scariosus . The structure and stereochemistry was assigned on the basis of spectroscopic and chemical data. Its biomimetic conversion to isopatchoulenol has been achieved.