Kooi-Mow Sim

Alkaloids from Kopsia griffithii

Nineteen alkaloids were isolated from the leaf extract of Kopsia griffithii, of which two were new, viz., 12-methoxypleiocarpine and the tetrahydro-β-carboline derivative, harmicine.

Leishmanicidal alkaloids from Kopsia griffithii

Thirteen alkaloids were isolated from the stem-bark extract of Kopsia griffithii, of which three were new. These were the N(4)-oxides of akuammiline, 16-epi-deacetylakuammiline and 11,12-methylenedioxykopsinaline. Harmane, pleiocarpine and buchtienine showed antileishmanial activity.

Reversal of multidrug resistance (MDR) by aspidofractinine-type indole alkaloids.

A series of indole alkaloids of the aspidofractinine-type was assessed for their potential in reversing MDR in vincristine-resistant KB cells. Of the compounds tested, kopsiflorine, kopsamine, pleiocarpine, 11-methoxykopsilongine, lahadinine A and N-methoxycarbonyl-11,12-methylenedioxy-delta 16,17-kopsinine were found to show appreciable activity.

Conodiparines A-D, New bisindoles from Tabernaemontana. Reversal of vincristine-resistance with cultured cells

Four new bisindoles of the vobasine-iboga type, conodiparines A-D were obtained from Tabernaemontana corymbosa which showed appreciable activity in reversing resistance in vincristine-resistant KB cells.

Tronocarpine, a novel pentacyclic indole incorporating a seven-membered lactam moiety

Abstract A novel pentacyclic indole alkaloid, tronocarpine, incorporating a seven-membered lactam unit, was obtained from the stem-bark extract of Tabernaemontana corymbosa and its structure elucidated by spectral analysis.

Voastrictine, a novel pentacyclic quinolinic alkaloid from Tabernaemontana

Abstract A novel pentacyclic quinolinic alkaloid, voastrictine, was obtained from Tabernaemontana corymbosa and its structure elucidated by spectroscopic analysis.

TRONOHARINE, A NOVEL HEXACYCLIC INDOLE ALKALOID FROM A MALAYAN TABERNAEMONTANA

Abstract A novel hexacylic indole alkaloid, tronoharine, was obtained from the stem-bark extract of Tabernaemontana corymbosa and its structure elucidated by spectral analysis.

Dippinines A - D, new Iboga-derived indole alkaloids from Tabernaemontana

Four new indole alkaloids, viz., dippinines A - D, belonging to the chippiine group were isolated from the leaf and stem extract of Tabernaemontana corymbosa and the structures established by spectroscopic analysis.

Four tetracyclic oxindole alkaloids and a taberpsychine derivative from a Malayan Tabernaemontana.

Four tetracyclic oxindole alkaloids, 7(R)- and 7(S)-geissoschizol oxindole (1 and 2), 7(R),16(R)- and 7(S),16(R)-19(E)-isositsirikine oxindole (3 and 4), in addition to a taberpsychine derivative, N(4)-demethyltaberpsychine (5), were isolated from the Malayan Tabernaemontana corymbosa and the structures were established using NMR and MS analysis.

ANGUSTIMALINE, AN UNUSUAL NITROGENOUS COMPOUND FROM ALSTONIA ANGUSTIFOLIA

Abstract An unusual nitrogenous compound probably derived from a macroline-type precursor was obtained from the stem-extract of Alstonia angustifolia .