Dawit Abebe

Antipyretic properties of the aqueous and ethanol extracts of the leaves of Ocimum suave and Ocimum lamiifolium in mice

Numerous plant species are used to treat ailments associated with pyrexia in the indigenous health care delivery system of Ethiopia. Notable among these are Ocimum suave and Ocimum lamiifolium. The objective of the present study was thus to evaluate the antipyretic effects of the aqueous and ethanol extracts of the leaves of Ocimum suave and Ocimum lamiifolium in mice. Rectal temperatures were recorded before and after inducing pyrexia as well as after administration of the respective extracts every half an hour for 3h. Parallel experiments were run with a standard antipyretic (acetylsalicylic acid) and the vehicle (distilled water). All the plant extracts showed antipyretic property with reasonable onset and duration of action. Both ethanol and aqueous extracts of Ocimum suave were observed to be more potent than those of Ocimum lamiifolium. Aqueous extract of Ocimum suave and ethanol extract of Ocimum lamiifolium were more potent than their other counterpart extracts. Time dependent antipyretic effect was also observed with some extracts; reduced with time with aqueous extract of Ocimum suave and increased with time with both extracts of Ocimum lamiifolium.

Steroidal saponins from Asparagus africanus

The structures of two new monodesmosidic spirostanosides and a new bisdesmosidic furostanol glycoside isolated from the roots of Asparagus africanus Lam. (Liliaceae) have been elucidated as (25R)-3 beta-hydroxy-5 beta-spirostan-12-one 3-O-{beta-D-glucopyranosyl-(1-->2)-[alpha-1-arabinopyranosyl-(1--> 6)]-beta- D-glucopyranoside} (1), (25R)-5 beta-spirostan-3 beta-ol 3-O-{beta-D-glucopyranosyl-(1-->2)-[alpha-L-arabinopyranosyl-(1--> 6)]-beta- D-glucopyranoside} (2) and 26-O-beta-D-glucopyranosyl]-22 alpha-methoxy-(25R)-furostan-3 beta,26-diol 3-O-{beta-D-glucopyranosyl-(1-->2)-[beta-D-glucopyranoside} (3), respectively, by the combined use of one and two dimensional NMR experiments. The complete 13C and 1H assignments of the peracetyl spirostanosides and the furostanol oligoside were derived. The interconversions between the methoxyl and hydroxyl group at C-22 of the furostanol glycoside was investigated and the genuine furostanol oligoside of A. africanus appears to be the hydroxyl type based on the comparative study of the methanol, pyridine and dioxane extracts.

Triterpenoid saponins and sapogenin lactones from Albizia gummifera.

The structures of two new monodesmosidic and bisdesmosidic triterpenoid saponins (1 and 2) and the known compound delta 5-stigmasterol-3-O-beta-D-glucopyranoside (3) as well as two new oleanane type triterpene lactone glycosides 4, 5 and a new sapogenin lactone 6 isolated from the stem bark of Albizia gummifera C.A. Smith (Mimosaceae) have been elucidated as 3-O-¿beta-D-glucopyranosyl(1-->2)-[alpha-L-arabinopyranosyl(1-->6) ]-beta-D- glucopyranosyl¿-oleanolic acid (1), beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl 3-O-¿beta-D-glucopyra-nosyl(1-->2)-[alpha-L-arabinopyrano syl(1-->6)]-beta-D- glucopyranosyl¿-oleanolate (2), 3 beta-¿O-D-glucopyranosyl-(1-->2)-[O-alpha-L-arabinopyranosyl(1-->6 )] beta-D-glucopyranosyloxy¿-machaerinic acid gamma-lactone (4), 3 beta-O-beta-D-glucopyranosiduronic acid (1-->2)-beta-D-glucopyranosyloxy]-machaerinic acid gamma-lactone (5), and A-homo-3a-oxa-5 beta-olean-12-en-3-one-28-oic acid (6), respectively. The complete assignment of the 1H and 13C resonances of 1, 2, 4 and 6 and of the peracetate of 5 were achieved by means of 2D-NMR studies.

A Diterpene, a Flavonol Glycoside, and a Phytosterol Glycoside from Securidaca longipedunculata and Entada abyssinica

Summary. The MeOH extract of the stem bark of Entada abyssinica and of the leaves and stem bark of Securidaca longipedunculata yielded a diterpene, a flavonol glycoside, and a phytosterol glycoside. Their structures were established on basis of NMR spectroscopic analysis; the complete 13C and 1H assignment of the compounds was achieved by means of 2D NMR studies.

New Triterpenoid Saponins from Achyrantes asperaLinn.

Two new bisdesmosidic triterpenoid saponins, i.e.1 and 2, were isolated, besides the three known saponins 3 – 5, from the MeOH extract of the aerial parts of Achyranthes asperaLinn. (Amaranthaceae). Their structures were elucidated as β-D-glucopyranosyl 3β-[O-α-L-rhamnopyranosyl-(13)-O-β-D-glucopyranuronosyloxy]machaerinate (1) and β-D-glucopyranosyl 3β-[O-β-D-galactopyranosyl-(12)-O-α-D-glucopyranuronosyloxy]machaerinate (2) by NMR spectroscopy, including 2D-NMR experiments (machaerinic acid=3β,21β-dihydroxyolean-12-en-28-oic acid). The other saponins were identified as β-D-glucopyranosyl 3β[O-α-L-rhamnopyranosyl-(13)-O-β-D-glucopyranuronosyloxy]oleanolate (3), β-D-glucopyranosyl 3-β-[O-β-D-galactopyranosyl-(12)-O-β-D-glucopyranuronosyloxy]oleanolate (4), and β-D-glucopyranosyl 3β-[O-β-D-glucopyranuronosyloxy]oleanolate (5) (oleanolic acid=3β-hydroxyolean-12-en-28-oic acid).

Three Saponins, a Steroid, and a Flavanol Glycoside from Achyrantes aspera

Summary. Three bisdesmosidic saponins, 20-hydroxyecdysone, and quercetin-3-O-β-D-galactoside were isolated from the methanol extract of the aerial parts of Achyranthes aspera L. (Amaranthaceae). Their structures were established on the basis of NMR spectroscopic analysis; the complete 1H and 13C assignments of the compounds were achieved by means of 2D NMR studies.