Reiner Waibel

Isolation of dammarane saponins from Panax notoginseng by high-speed counter-current chromatography

The Chinese phytomedicinal formulation Sanqi Zongdai Pian, traditionally prepared from crude extracts from roots of Panax notoginseng (Araliaceae), contains highly polar dammarane saponins which were separated at a preparative scale using high-speed counter-current chromatography (HSCCC). In each operation, 283 mg methanolic extract of five tablets was separated and yielded pure 157, 17, 13 and 56 mg of ginsenoside-Rb1, notoginsenoside-R1, ginsenoside-Re and ginsenoside-Rg1, respectively, n-hexane-n-butanol-water (3:4:7, v/v/v) was used for the two-phase solvent system of the HSCCC separation. The chemical structures of three ginsenosides and one notoginsenoside were elaborated by means of electrospray ionization MS-MS and NMR analysis.

Lignans and other constituents from Carissa edulis

Abstract The methanolic extract from the root of Carissa edulis contains ca 5% lignans, the main compounds among them being (−)-nortrachelogenin, carinol and the hitherto unknown carissanol.

Antimalarial compounds from Hoslundia opposita

Abstract Four new abietane-type esters, 3-O-benzoylhosloppone, 3-O-cinnamoylhosloppone, 3-O-benzoylhinokiol and 3-O-benzoylhosloquinone were isolated from the root bark of the antimalarial plant Hoslundia opposita Vahl. and their structures were determined by a combination of spectroscopic methods and chemical correlations. 3-O-Benzoylhosloppone inhibits the growth of the multidrug resistant strain K1 of Plasmodium falciparum in vitro with an IC50-value of 0.4 μg ml−1.

ALKALOIDS AND OTHER COMPOUNDS FROM PSYCHOTRIA CORREAE

Abstract From extracts of the leaves and/or the roots of Psychotria correae , isodolichantoside and the new alkaloids correantoside, 10-hydroxycorreantoside, correantines A to C, and 20-epi-correantine B were isolated, in addition to two cerebrosides and some isoprenoids. Structures were established by spectroscopic studies in combination with chemical interconversions and partial synthesis.

Three flavonoids from the stem bark of the antimalarial Uvaria dependens

Abstract From the chloroform extract of the root bark of Uvaria dependens the three new flavonoids dependensin, 5,7,8-trimethoxyflav-3-ene and 2-hydroxy-3,4

Sesquiterpenes from carissa edulis

Abstract The methanolic extract from the root of Carissa edulis contains about 5% sesquiterpenes. Besides carissone, cryptomeridiol and β-eudesmol, three hitherto unknown sesquiterpenes of the eudesmane-type and a novel germacrane derivate have been isolated.

Diterpenes from Gnaphalium pellitum and Gnaphalium graveolens

Abstract 13- epi -Cyclosclareol, a novel labdane-type diterpene with a cyclopropane ring has been isolated from Gnaphalium pellitum as well as from Gnaphalium graveolens . Structure elucidation was achieved by spectroscopic methods. The known diterpenes (−)-16-kauren-19-oic acid, (−)-11β-acetoxy-16-kauren-19-oic acid, 13- epi -sclareol and a mixture of sitosterol and stigmasterol were also isolated.

Schefflerin and isoschefflerin: prenylated chalcones and other constituents of Uvaria scheffleri.

Abstract Two new prenylated chalcones, schefflerin and isoschefflerin, were isolated from the petrol fraction of the ethanol extract of the stem bark of Uvaria scheffieri , in addition to D: B-friedoolean-5-en-3β-ol (= glutin-5-en-3β-ol), 3-farnesylindole, 2′-hydroxy-3′,4′,6′-trimethoxychalcone, 2′,6′-dihydroxy-3′,4′-dimethoxychalcone, β-sitosterol and benzyl benzoate.

Rosane diterpenes and bis-dinorditerpenes from Hugonia casteneifolia

Abstract From the root bark of Hugonia casteneifolia three new rosane-type diterpenes, hugorosenone (3β-hydroxy-l(10), 15-rosadien-2-one), hydroxyhugorosenone (3β, 18 dihydroxy-l(10), 15-rosadien-2-one), hugorosediol (3β, 18 dihydroxy-l (10), 15-rosadiene), and the two bis-dinorditerpenes, hugonone A and hugonone B,have been isolated. Structural determination was achieved by spectroscopic methods. Extracts of the root bark exhibited cytotoxic activity in the brine shrimp bioassay\ and hugorosenone was demonstrated to be the corresponding active principle.

Aporphinoid alkaloids and other constituents from Lettowianthus stellatus.

Two new aporphinoid alkaloids, f1ttowianthine and 11-methoxylettowianthine were isolated from the root bark of Lettowianthus stellatus, together with the new sesquiterpene 11-hydroxyguaia-4,6-diene and the known compounds liriodenine, (Z)-7-octadecen-9-ynoic acid, methyl (2E,6E,10R)-10,11-epoxy-3,7,11-trimethyl-2,6-dodecadienoate, methyl (2E,6E,10R)-10,11-dihydroxy-3,7,11-trimethyl-2,6-dodecadienoate , and 3,4,5-trimethoxyphenol. The structure elucidation was achieved by spectroscopic methods.