Ermias Dagne

Knipholone: a unique anthraquinone derivative from Kniphofia foliosa

Abstract The roots of Kniphofia foliosa afforded, in addition to chrysophanol, a novel anthraquinone named knipholone, whose structure was determined by spectroscopic methods as well as by degradation to known compounds

Furanosesquiterpenes from Commiphora sphaerocarpa and related adulterants of true myrrh

A new furanosesquiterpene, (1E)-8,12-epoxygermacra-1,7,10,11-tetraen-6-one (3), was isolated from the resin of Commiphora sphaerocarpa together with the known compounds curzerenone (1), furanodienone (2), (1E)-3-methoxy-8,12-epoxygermacra-1,7,10,11-tetraen-6-one (4), (1(10)E,2R*,4R*)-2-methoxy-8,12-epoxygermacra- 1(10),7,11-trien-6-one (5), and dihydropyrocurzerenone (6). Hydrodistillates of the resins of C. sphaerocarpa, C. holtziana, C. kataf and C. myrrha were analysed. The identifications were aided by NMR, GC and GC-MS.

The flavonoids of Millettia ferruginea subsp. ferruginea and subsp. darassana in ethiopia

Abstract Analysis of the bark and seed pods of plant material assigned to Millettia ferruginea subsp. darassana and M. ferruginea subsp. ferruginea has led to the isolation of eight isoflavones, a chalcone, a flavanone and a pterocarpene. Three of the isolated compounds appear to be novel and have been identified as 5-methoxydurmillone (5,6-dimethoxy-3′,4′-methylenedioxy-2″,2″-dimethylpyrano-[5″,6″:7,8]isoflavone), isojamaicin (3′-methoxy-4′,5′-methylenedioxy-2″,2″-dimethylpyrano[5″,6″:7,8]isoflavone) and 4′-hydroxyisolonchocarpin (4′-hydroxy-2″,2″-dimethylpyrano[5″,6″: 7,8]flavanone). Patterns of flavonoid production do not appear to distinguish the two subspecies.

Variability in the Chemical Compositions of the Essential Oils of Five Ocimum Species from Tropical African Area

Abstract As part of our research on aromatic plants from Africa, we have analyzed, via GC and CG/MS, the essential oils from fresh leaves of five Ocimum species from tropical Africa: Ocimum basilicum L., O. gratissimum L., O. americanum L. (syn: O. canum Sims), O. lamiifolium Hochst. ex Benth. and O. minimum L. The chemical compositions of O. basilicum, O. gratissimum and O. minimum essential oils could be related to some chemotypes already defined for these three species: linalool- or methyl chavicol-types for the first species, thymol- or eugenol- or ocimenes/far- nesenes-types for the second one; finally, a high content of methyl chavicol (34.3%) and linalool (17.8%) was found in O. minimum oil, similar to that already described for a Brazilian species. On the other hand, an essential oil dominated by 1,8-cineole was described for the first time for a sample of O. americanum. Finally, the oil of O. lamiifolium, which was rich in sabinene, is chemically described for the first time.

Chemotaxonomic significance of anthraquinones in the roots of asphodeloideae (asphodelaceae)

Abstract The distribution of seven anthraquinones in the roots of some 46 species belonging to the genera Asphodelus, Asphodeline, Bulbine, Bulbinella and Kniphofia was studied by TLC and HPLC, 1,8-Dihydroxyanthraquinones based on a chrysophanol unit are the main constituents of the subterranean metabolism in the subfamily Asphodeloideae. The genera Bulbine, Bulbinella and Kniphofia elaborate knipholone-type compounds. These compounds appear to be characteristic constituents for the three genera Bulbine, Bulbinella and Kniphofia and support the idea that Kniphofia is not related to the Alooideae.

Essential Oils of Twelve Eucalyptus Species from Ethiopia

Abstract The chemical composition of the essential oils obtained from the leaves of Eucalyptus camaldulensis Dehnh., E. citriodora Hook., E. dalrympleana Maiden, E. deanei Maiden, E. delegatensis R. Baker, E. globulus Labill, E. grandis W. Hill ex Maiden, E. nitens (Deane et Maiden) Maiden, E. saligna Smith, E. tereticornisSmith, E. urophylla S.T. Wake and E. vtminalis Labill, growing in Ethiopia were examined by capillary GC and GC/MS. The oil of E. camaldulensis was found to contain β-phellandrene (18.9%) and p-cymene (17.8%) while the oil of E. citriodora was rich in citronellal (73.3%) and citronellol (11.9%). E. dalrympleana oil contained α-pinene (26.2%), 1,8-cineole (19.3%) and α-terpineol (12.1%) and E. deanei oil contained 1,8-cineole (41.6%) and cryptone (17.6%); E. delegatensis oil contained α-pinene (28.3%), 1,8-cineole (26.4%) and γ-terpinene (18.0%), E. grandis oil contained α-pinene (44.7%) and β-pinene (30.5%) and E. saligna oil contained α-pinene (38.5%), β-phellandrene (12.2%) and 1,8-cineole (10.6%). Oils of the other Eucalyptus species contained α-pinene (13.2–44.7%) and 1,8-cineole (34.5–57.5%) as major constituents.

An O-geranylated isoflavone from Millettia griffoniana☆

Abstract A new O -geranylated isoflavone, 3′,4′-methylenedioxy-7- O -[( E )-3,7-dimethyl-2,6-octadienyl] isoflavone, 7- O -geranylpseudobaptigenin, was isolated in addition to seven other known compounds from the root bark of Millettia griffoniana . The structure of the new compound was elucidated on the basis of spectroscopic data.

Flavonoids and isoflavonoids from Tephrosia fulvinervis and Tephrosia pentaphylla

Abstract From the roots, leaves and pods of Tephrosia pentaphylla three new 6-oxygenated rotenoids (dihydrostemonal, 9-demethyldihydrostemonal and 6-acetoxydihydrostemonal) were isolated and characterized. In addition six known rotenoids (villosin, sumatrol, rotenone, cis -12a-hydroxyrotenone, 6-hydroxyrotenone and α-toxicarol) and the flavanone obovatin were obtained. A similar analysis of the roots of T. fulvinervis yielded only known rotenoids (α-toxicarol, deguelin, munduserone, cis -12a-hydroxymunduserone) and the common pterocarpan (-)-maackiain.

Sesquiterpene lactone and friedelane derivative from Drypetes molunduana

A new sesquiterpene lactone, drypemolundein A and a new friedelane derivative, drypemolundein B, along with seven known compounds have been isolated from the whole stems of Drypetes molunduana Pax and Hoffm. Their structures were established on the basis of one- and two-dimensional NMR, homo- and hetero-nuclear spectroscopic evidence.

O-Geranylated and O-prenylated flavonoids from Millettia ferruginea

Abstract Analysis of the root bark and seeds of Millettia ferruginea subsp. darassana led to the isolation of a chalcone and seven isoflavones. Three of the isolated compounds namely 4′- O -geranylisoliquiritigenin (4,2′-dihydroxy-4′- O -[( E )-3,7-dimethyl-2,6-octadienyl]chalcone), 7- O -geranylformononetin (4′-methoxy-7- O -[( E )-3,7-dimethyl-2,6-octadienyl] isoflavone and nordurlettone (7-hydroxy-4′- O -[3,3-dimethylallyl]isoflavone) appear to be novel.