Yun-Cheung Kong

A chemotaxonomic division of Murraya based on the distribution of the alkaloids yuehchukene and girinimbine

Abstract An examination of the roots of eight species and one variety of Murraya for the presence of the dimeric indole yuehchukene has revealed a dichotomy in the genus between species producing this alkaloid and those producing the carbazole alkaloid girinimbine, with no apparent overlap between the two groups of species.

The Biochemical of Tetradium, Euodia and Melicope and their significance in the Rutaceae

Abstract From the stem and root barks of Tetradium glabrifolium (Rutaceae) benzophenanthridine alkaloids have been isolated together with furoquinoline alkaloids, coumarins and limonoids. The occurrence of the l-benzyltetrahydroisoquinolinederived benzophenanthridines adds Tetradium to the small group of rutaceous genera ( Fagaropsis, Phellodendron, Toddalia, Zanthoxylum ) known to produce alkaloids of this type. These findings support Hartleys decision to reassign taxa from Euodia (sensu Engler) into the three genera Tetradium, Euodia s. s. and Melicope and his contention that Tetradium is closely allied to Zanthoxylum and Phellodendron , with which it shares several unusual chemical characters. Hartleys re-alignment of Tetradium , which cuts across Englers sub-families Rutoideae and Toddalioideae, is therefore sustained by the known distribution of secondary metabolites, whilst available information suggests a wide disparity between the chemical profiles of Tetradium and Melicope . The chemosystematic significance of the addition of Tetradium to the 1-benzyltetrahydroisoquinoline producing genera and the potential of these taxa to have acted as a starting point for biochemical evolution within the Rutaceae is discussed.

Monoterpene and sesquiterpene rich oils from the leaves of Murraya species: chemotaxonomic significance

Abstract The volatile oils from the leaves of six species of the genus Murraya have been studied by GC-MS and about 60 monoterpene and sesquiterpenes components identified. From these results and published data on other species it appears that oils are either predominantly sesquiterpenoid or monoterpenoid in nature. The distinction between the two oil types coincides with other chemical data that supports the division of the genus into two sections, Murraya and Bergera .

Micromelum: a key genus in the chemosystematics of the Clauseneae

An investigation of the roots of Micromelum falcatum revealed the occurrence of the indole alkaloid yuehchukene, the novel carbazole alkaloid 5,6-pyranoglycozoline, the 6-prenylated coumarin micromelin and the 8-prenylated coumarins phebalosin and mupanidin. Micromelin, phebalosin and yuehchukene were also obtained from the roots of M. integerrinum. The significance of these observations in respect to the phylogeny of the tribe Clauseneae is discussed.

Yuehchukene: a novel indole alkaloid with anti-implantation activity

Yuehchukene, a novel dimeric indole alkaloid with potent anti-implantation activity has been isolated from the roots of Murraya paniculata and identified as a racemic mixture of 6β-(3′-indolyl)-7α,7β,9-trimethyl-6aβ7,8,10aβ-tetrahydroindeno[2,1-b]indole (1) and its enantiomer.

Structure function relationship study of yuehchukene. I: Anti-implantation and estrogenic activities of substituted yuehchukene derivatives

Abstract (±)-Yuehchukene (YCK) is a novel bis-indole alkaloid with potent anti-implantation activity in rats. The present paper reports the activity of YCK derivatives by substitution on the parent compound. Substitutions on the indole nitrogens or on 2- and 5′-positions of the indole moiety abolished activity. N -1′-methylation of the free indole only permitted a 30% residual activity. Saturation of the C 9 C 10 cyclohexenyl double bond did not affect activity at all. Hydroxylation, whether on the C 9 C 10 double bond, or at C 2 or C 5 , rendered the hydroxylated derivatives inactive. This suggests that the active metabolite in anti-implantation was probably not a hydroxylated derivative carrying estrogenic activity.

The biochemical systematics of Merrillia; in relation to Murraya, the clauseneae and the aurantioideae

Abstract From the stem and root barks of Merrillia caloxylon (Rutaceae) the dimeric indole alkaloid yuehchukene has been isolated together with a simple prenylated indole, the 8-prenylated coumarins sibiricin and phebalosin, and the polyoxygenated flavonoid, eupatorin. The finding of these three classes of metabolites in Merrillia strongly supports Swingle in his proposal that this taxon is closely allied to Murraya paniculata , a member of Murraya section Murraya. The possible significance of these findings for the phylogeny of the tribe Clauseneae is explored and their implications for predicting the potential distribution of yuehchukene in the Aurantioideae is discussed.

Structure-function relationship of Yuehchukene II. The effect of C-6 indole rotation on anti-implantation activity

Abstract In a first attempts to define the structural requirements for the expression of anti-implantation activity in Yuehchukene (YCK), it was found that the relative position or planarity of the aromatic centres may be crucial. New synthetic routes leading to analogues with modification of C-7 substituents were established. Results indicated that a bulky group at C-7 that served to restrict the rotation of the C-6 indole was indispensable. Further steric hindrance by 2′-methyl would increase potency in all weak analogues. It was concluded that YCK required an optimal conformation that was defined by a narrowly-fixed angle between the planes of the C-6 indole and the tetracyclic unit.

Antifertility agents: a synthetic entry to yuehchukene analogues; stereoselective synthesis of 7,7-bis-nor-yuehchukene via 9-methyl-6-oxo-6aβ-7,8,10aβ-tetrahydroindeno[2,1-b]indole

Intermolecular Diels–Alder reaction and polyphosphate ester-catalysed intramolecular acylation are used in a synthetic approach to 9-methyl-6-oxo-6aβ-7,8,10aβ-tetrahydroindeno[2,1-b] indole (15), the basic structure of the antifertility agent yuehchukene (1). Stereoselective conversion of (15) into 7,7-bis-nor-yuehchukene (19) is also described.

New tirucallane-type triterpenoid saponins from Sapindus mukorossi Gaetn

Two new tirucallane-type triterpenoid saponins, sapimukoside C (1) and sapimukoside D (2), have been isolated from the roots of Sapindus mukorossi Gaetn. Their structures have been determined, on the basis of spectral and chemical analysis, as 3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-arabinopyranosyl-(1→3)]-β-D-glucopyranosyl (21,23R)-epoxyl tirucalla-7,24-diene-(21S)-ethoxyl-3β-ol (1) and 3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-arabinopyranosyl-(1→3)]-β-D-glucopyranosyl (21,23R)-epoxyl tirucall-7, 24-diene-(21S)-methoxyl-3β-ol (2).