Ahmed A. Gohar

Antibacterial polyphenol from Erodium glaucophyllum

Abstract Geraniin and gallic acid were isolated from the alcohol extract of the aerial parts of Erodium glaucophyllum (Geraniaceae). The identity of the compounds was verified through different physical and spectrometric methods. The antibacterial and antifungal activity of geraniin is presented.

Two flavonoid glycosides from Chenopodium murale

Two new triglycosides, kaempferol-3-O-[(4-beta-D-apiofuranosyl)-alpha-L- rhamnopyranoside]-7-O-alpha-L-rhamnopyranoside and kaempferol-3-O-[(4-beta-D-xylopyranosyl)-alpha-L-rhamnopyranoside]-7-O- alpha-L-rhamnopyranoside were isolated from the methanol extract of Chenopodium murale, together with a known diglycoside, kaempferol-3-O-beta-D-glucopyranoside-7-O-alpha-L-rhamnopyranoside. The characterization of the three compounds was achieved by various spectroscopic methods.

A new antioxidant stilbene and other constituents from the stem bark of Morus nigra L.

A new stilbene, 2′,3,4′,5,5′-pentahydroxy-cis-stilbene (1), along with 13 known compounds, resveratrol (2), oxyresveratrol (3), norartocarpetin (4), kuwanon C (5), morusin (6), cudraflavone A (7), kuwanon G (8), albafurane C (9), mulberrofuran G (10), 3-O-acetyl-α-amyrin (11), 3-O-acetyl-β-amyrin (12) ursolic acid-3-O-acetate (13) and uvaol (14), were isolated from the barks of Morus nigra. Compounds 2, 8, 10, 12 and 14 are reported for the first time from this plant. The isolated compounds were elucidated by means of 1D and 2D NMR, UV, IR and MS, as well as by comparison with the literature data. The isolated compounds and the different extracts were evaluated for their potential antioxidant activity using 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)+ radical-scavenging capacity assay and compared with ascorbic acid. The new stilbene (1) exhibited remarkable antioxidant capacity with IC50 of 4.69 μM.

Flavonol glycosides from Cadaba glandulosa.

A new flavonol triglycoside, rhamnocitrin-3-O-neohesperoside-4′-O-glucoside was isolated from the ethanol extract of Cadaba glandulosa together with two known diglycosides rhamnocitrin- 3-O-neohesperoside and rhamnetin-3-neohesperoside. Characterization of the three compounds was achieved by various spectroscopic methods

A New Triterpene Saponin from Chenopodium ficifolium

The new triterpene saponin 3-O-β-ᴅ-glucopyranoside, 28-β-ᴅ-glucopyranosyl-(1→2)-β-d-glucopyranosiduronic acid oleanolate was isolated from the roots of Chenopodium ficifolium. The known compounds stigmasterol-3-O-glucoside and 3-O-β-ᴅ-glucopyranosiduronic acid, 28-β-ᴅ-glucopyranosyl oleanolate were also isolated. The latter compound, oleanolic acid, β-sitosterol and its glucoside were isolated from the aerial parts. The identity of these compounds was verified through different chemical and physico-chemical evidences including different 1D and 2D NMR experiments.

Phenylpropanoids from the stem bark of Jacaranda mimosaefolia

Two new compounds: 2-(3′,4′-dihydroxyphenyl) ethyl-3-O-α-L-rhamnopyranosyl-4-O-p-hydroxyphenylacetyl-6-O-caffeoyl-β-D-glucopyranoside and 2-(3′,4′-dihydroxyphenyl) ethyl-3-O-α-L-rhamnopyranosyl-4-O-piperidine-3-carboxylic acid-6-O-caffeoyl-β-D-glucopyranoside were isolated from the stem bark of Jacaranda mimosaefolia. In addition, the known compounds lupeol, betulinaldehyde, terminic acid, betulinic acid, maslinic acid, β-sitosterol glucoside and isoacteoside were isolated and identified.

Taxodione, a DNA-Binding Compound from Taxodium distichum L. (Rich.)

8-β-Hydroxypimar-15-en-19-oic acid (1), taxodione (2), 6,7-dehydro-8-hydrotaxodone (3), quercetin-3-O-β-d-glucopyranoside (4), and shikimic acid (5) were isolated from the leaves of Taxodium distichum L. (Rich.) for the first time. Previously reported compounds [β-sitosterol (6), isorhamnetin (7), quercetin (8), isorhamnetin-3-O-α-arabinofuranoside (9), quercetin- 3-O-α-arabinofuranoside (10)] have also been isolated. The activity of taxodione as an inhibitor for hepatic stellate cells was determined. The antitumour activity of 2, 3, and 5 using a DNA affinity probe was examined.

One new pyrroline compound from Callistemon viminalis (Sol. Ex Gaertner) G.Don Ex Loudon

One new compound: 3,4-dihydro-2-(hydroxymethyl)-4-methyl-2H-pyrrol-2-ol (5) was isolated from the fruits and bark of Callistemon viminalis along with the known compounds lupeol (1), octacosanol (2), β-sitosterol (3), betulin (4), betulinic acid (6), ursolic acid (7), corosolic acid (8), β-sitosterol-3-O-β-D-glucoside (9), methyl gallate (10), gallic acid (11), catechin (12), ellagic acid (13) and 3-O-acetylursolic acid (14) (compound 14 was isolated from the bark and not detected in the fruits). Structures of these compounds were elucidated on the basis of their spectroscopic data (NMR, MS, IR spectra and COSY and HR-MS for 5a). The antioxidant activity of the total extracts, petroleum ether, CH2Cl2 and EtOAc fractions together with the compounds 6, 7, 9, 10, 11, 12 and 13 was comparable with that of the standard antioxidant, ascorbic acid.

A new pregnane glycoside from Gomphocarpus fruticosus growing in Egypt

Abstract Phytochemical investigation of Gomphocarpus fruticosus (L.) Ait. of Egyptian origin afforded the new pregnane glycoside lineolon-3-O-[β-D-oleandropyranosyl-(1–4)-β-D-cymaropyranosyl-(1–4)-β-D-cymaropyranoside], along with six known compounds. The structures of the isolated compounds were elucidated on the basis of extensive spectroscopic evidences derived from 1D, 2D NMR experiments, mass spectrometry and by comparing their physical and spectroscopic data to literature. These included the triterpenoids 3β-taraxerol, 3β-taraxerol acetate and betulinic acid, which are identified for the first time in G. fruticosus and the cardenolides uzarigenin, gomphoside and calotropin.

Two oleananes from Ammannia auriculata Willd.

Two new compounds: 3-β,15-α,23,28-tetrahydroxyolean-12-en-3-O-arabinopyaranoside and 3-β,23,28-trihydroxy-olean-12-en-3-O-β-D-glucopyranoside were isolated from the aerial parts of Ammania auriculata along with the known compounds kaempferol, β-sitosterol-3-O-β- D-glucoside, 2-α,3-β,23-trihydroxyolean-12-en-28-oic acid-28-O-β-D-glucopyranoside, quercetin, kaempferol-3-O-α-L-arabinofuranoside, kaempferol-3-O-β-D-xylopyranoside and ellagic acid. Structures of these compounds were elucidated on the basis of their spectroscopic data (NMR, UV, MS and IR spectra). The antioxidant activities of the total extract, the fractions CH2Cl2, EtOAc and the remaining aqueous together with the compounds 1, 6 and 9 were comparable with that of the standard antioxidant, ascorbic acid.