Tran Van Sung

Bisquinolinone alkaloids from Melicope ptelefolia

The investigation of the leaves of Melicope ptelefolia (Rutaceae) afforded, besides N-methylflindersine, two new bisquinolinone alkaloids named melicobisquinolinone A and B. Their structures were established by MS and NMR spectroscopy, especially NOE and HMBC experiments.

3α,11α-Dihydroxylup-20(29)-ene-23,28-dioic acid from Schefflera octophylla

Abstract The main triterpene from leaves of Schefflera octophylla was isolated in a high yield (7%) and its structure determined as 3α-hydroxy-lup-20(29)-

Constituents from Miliusa balansae (Annonaceae)

The styryl derivatives 3,4-dimethoxy-6-styryl-pyran-2-one and (2E,5E)-2-methoxy-4-oxo-6-phenyl-hexa-2,5-dienoic acid methyl ester were isolated from leaves and branches of Miliusa balansae (Annonaceae). In addition, the geranylated homogentisic acid derivative miliusate, four flavanones and two dihydrochalcones were identified. Their structures were elucidated by spectroscopic means.

Benzopyrans from Melicope ptelefolia leaves

Abstract Investigation of leaves of Melicope ptelefolia afforded 18 2,2-dimethyl-2H-1-benzopyrans, consisting of 14 new members, including one benzodipyran and four known compounds. Their structures were established by mass and NMR spectroscopy, especially NOE and HMBC experiments.

Counlarins, limonoids and an alkaloid from Clausena excavata

In addition to a known alkaloid, some limonoids and coumarins, the new coumarins excavatins A–M have been isolated from Clausena excavata. Their structures have been assigned by NMR and CD investigations.

Two 24-nor-triterpenoid carboxylic acids from acanthopanax trifoliatus

Abstract From Acanthopanax trifoliatus the new nor-triterpenes 24-nor-3α, 11α-dihydroxy-lup-20(29)-en-28-oic acid and 24-nor-11α-hydroxy-3-oxo-lup-20(29)-en-28-oic acid were isolated. Their structures were determined on the basis of spectroscopic data, X-ray analysis and chemical transformations.

Triterpenoids and their glycosides from the bark ofSchefflera octophylla

A new triterpene and its glycosides were isolated from the bark of Schefflera octophylla together with asiatic acid and asiaticoside. Based on spectroscopic data, especially 2DNMR, and chemical transformations the structures of the new compounds were determined as 3 alpha-hydroxy-urs-12-ene-23,28-dioic acid and 3 alpha-hydroxy-urs-12-ene-23,28-dioic acid 28-O-[alpha-L-rhamnopyranosyl (1----4)-O-beta-D-glucopyranosyl (1----6)]-beta-D-glucopyranoside. For the first time asiaticoside was isolated from a plant other than Centella asiatica.

Chalcones and ecdysteroids from Vitex leptobotrys

Abstract In addition to some known chalcones and ecdysteroids three new chalcones have been isolated from aerial parts of Vitex leptobotrys , the structures of which have been identified as 2′,4′-dihydroxy-4,6′-dimethoxychalcone, 4′-hydroxy-4,2′,6′-trimethoxychalcone and 4,2′,4′, β -tetrahydroxy-6′-methoxy- α , β -dihydrochalcone, respectively.

Coumarins and dihydrocinnamic acid derivatives from Micromelum falcatum

Abstract Besides the known coumarins microminutinin and 6-methoxymicrominutinin, the new dihydrocinnamic acid derivatives 3,4-dihydro-1,2-secomicrominutinin, 3,4-dihydro-1,2-secomicrominutinin methylester and 3,4-dihydro-1,2-secomicrominutinin-9-O-glucoside as well as the new 8-prenylated coumarin microfalcatin isovalerate were isolated from the leaves of Micromelum falcatum (Rutaceae). The structures were elucidated by mass and NMR spectroscopy. The relative configuration of microfalcatin isovalerate was established as 1′,2′-threo by analysis of the NOE effects of its acetonide.

β-Carboline alkaloids from Hedyotis capitellata

Three new β-carboline alkaloids were isolated from Hedyotis capitellata (Rubiaceae). Their structures were elucidated by spectroscopic data and X-ray analysis.