Ahmed A. Mahmoud

Two highly oxygenated eudesmanes and 10 lignans from Achillea holosericea

Two new highly oxygenated eudesmanes and 10 known lignans were isolated from the aerial parts of Achillea holosericea. Their structures were elucidated by extensive application of one- and two-dimensional 1H and 13C NMR spectroscopy.

7-epi-eudesmanes eudesmanoic acids, eudesmanolides and other sesquiterpenes from Pluchea dioscoridis

Abstract Re-examination of the chemical constituents of leaves of Pluchea dioscoridis afforded, in addition to known compounds, seven new sesquiterpene derivatives (two 7-epi-eudesmanes, two eudesmanoic acids, a eudesmanolide, a guaiane and a xanthane epoxide). The structures were elucidated by spectroscopic methods.

Eudesmane derivatives from Laggera crispata and Pluchea carolonesis

Investigation of the aerial parts of Laggera crispata and Pluchea carolonesis afforded in addition to several known compounds, three new eudesmane derivatives, 3β,4α-dihydroxy-7-epi-eudesm-11(13)-ene, 3α-(2′,3′-dihydroxy-2′-methylbutanoyl)-4,11-dihydroxy-6,7-dehydroeudesman-8-one and 3α-(3′-chloro-2′-hydroxy-2′-methylbutanoyl)cuauhtemone. The structures were elucidated by spectroscopic methods

Jasonol, a rare tricyclic eudesmane sesquiterpene and six other new sesquiterpenoids from Jasonia candicans

Abstract The extract of the leaves of Jasonia candicans yielded, seven new sesquiterpenes and sesquiterpene lactones including a eudesmane containing a rare type of 6/6/4 membered ring system, two 7-epi-eudesmanes (12-hydroxyisointermedeol and 7-epi-ilicic acid), two guaianolides (inuviscolide and its 8-epi- derivative), iphionane and cadinane-triol derivatives. The structures were elucidated by spectroscopic analysis particularly high-resolution 1D and 2D NMR spectroscopy and the extensive NOE analysis.

Further monoterpene 5-methylcoumarins and an acetophenone derivative from Ethulia conyzoides

Abstract Re-investigation of the aerial parts of Ethulia conyzoides from Egypt afforded two new monoterpene 5-methylcoumarins, namely 5′-epi-isoethuliacoumarin B and 5′-epi-isoethuliacoumarin A, and a new monoterpene acetophenone derivative, ethuliaconyzophenone, in addition to the five known compounds, ethulia-coumarin, cycloethuliacoumarin, isoethuliacoumarin A, isoethuliacoumarin B and 4- hydroxy-5-methyl-coumarin -4-O-β- d -glucopyranoside .

2,3-Secogermacranolides and germacranolides from Pyrethrum santolionoides

Abstract Re-investigation of the chemical constituents of the aerial parts of Pyrethrum santolionoides gave six new sesquiterpene lactones (two 2,3-secogermacranolides and four germacranolides) in addition to eight known compounds. The structures were elucidated by spectroscopic analysis.

A new heterocyclic glucoside from the fruits of Xanthium pungens.

A new thiazinedione glucoside, 7-(β-D-glucopyranosyloxymethyl)-8,8-dimethyl-4,8-dihydrobenzo[1,4]thiazine-3,5-dione (1) and named xanthiside, was isolated from the methanol extract of the fruits of Xanthium pungens. Its structure was determined by spectroscopic techniques including, IR, CIMS, high-resolution-EIMS, and extensive 400 MHz one- and two-dimensional NMR-analysis (1H, 13C-NMR, DEPT, 1H-1H COSY, HMQC, COLOC, and NOE experiments).

Carvotacetone derivatives from the Egyptian plant Sphaeranthus suaveolens

Extraction of the aerial parts of Sphaeranthus suaveolens afforded three new carvotacetone derivatives, together with four known compounds. The structures were elucidated by spectroscopic analysis.

Two methylated flavonols from jasonia candicans

Abstract Two new flavonols, 6,4′-dihydroxy-3,5,7-trimethoxyflavone (6-hydroxykaempferol 3,5,7-trimethyl ether) and 3′-hydroxy-3,5,7,4′-tetramethoxyflavone (quercetagetin 3,5,7,4′-tetramethyl ether) were isolated from the leaves of Jasonia candicans (Compositae) in addition to luteolin, isokaempferide, penduletin, jacedin, and methyl ethers of 6-hydroxykaempferol and quercetagetin. The structures of the new flavonols were characterized by spectroscopic analysis.

A new chlorosesquiterpene lactone from Ambrosia maritima

Abstract A new chloro-pseudoguaianolide-type sesquiterpene lactone, 11β-hydroxy-13-chloro-11,13-dihydrohymenin ( 1 ), was isolated from the Egyptian medicinal plant Ambrosia maritima . The structure was determined by spectroscopic methods, particularly high-resolution 1 H, 13 C-NMR and 2D 1 H– 1 H and 1 H– 13 C COSY NMR analysis.