Salim S. Sabri

Effects of 3,3′‐di‐O‐methylquercetin on guinea‐pig isolated smooth muscle

Abstract— The effects of the flavone 3,3′‐di‐O‐methylquercetin (DOMQ) have been examined and compared with those of quercetin, on guinea‐pig isolated ileum, trachea, and main pulmonary artery (MPA). Except for transient contractions induced by low concentrations (10−8‐3 × 10−6 M), DOMQ and quercetin (up to 3 × 10−4M) caused reduction of the tone and the phasic contractions of the ileum. A23187 reversed the inhibitory effects of quercetin but not those of DOMQ. DOMQ and quercetin caused concentration‐dependent relaxation of the trachea and the adrenaline‐contracted MPA. DOMQ shifted to the right the concentration‐effect curves induced by acetylcholine on the ileum and the trachea, and by adrenaline on MPA and those induced by CaCl2 on ileum, trachea and MPA. DOMQ also inhibited the contractions induced, in Ca2+‐free EGTA‐containing buffer, by histamine on ileum and by adrenaline on MPA. These observations suggest that DOMQ inhibits Ca2+ influx, Ca2+ release from intracellular stores and, more likely, Ca2+ binding to intracellular receptor proteins.

A New Eudesmane Type Sesquiterpene from Inula Viscosa

Investigation of Inula viscosa of Jordanian origin afforded the new sesquiterpene 1 g -hydroxyilicic acid in addition to the known 2 g -hydroxyilicic acid.

Effects of hispidulin, a flavone isolated from Inula viscosa, on isolated guinea-pig smooth muscle

1. In small concentrations (10(-7)-3 X 10(-6) M), hispidulin caused concentration-dependent contraction of isolated guinea-pig ileum and only mild relaxation of guinea-pig tracheal rings. 2. Larger concentrations (up to 3 X 10(-4) M) caused concentration-dependent relaxation of the ileum and the trachea. All the effects on the ileum and the trachea are reversible upon removal of the compound. 3. In concentrations from 10(-7) to 3 X 10(-4) M, hispidulin had no effect on the tone of the epinephrine-contracted rings of the guinea-pig main pulmonary artery. 4. Hispidulin caused a shift to the right of the acetylcholine concentration-effect curves on ileum and trachea and significantly inhibited the maximum contractions induced by acetylcholine. 5. In Ca2+-free, depolarizing solution, hispidulin caused both a shift to the right, and an inhibition of the maximum contractions, of the CaCl2 concentration-effect curves on ileum, trachea and pulmonary artery. 6. In Ca2+-free, EGTA-containing solution, hispidulin caused concentration-dependent inhibition of the contractions induced in the pulmonary artery by epinephrine and in the ileum by histamine. 7. These observations suggest that hispidulin may interfere with Ca2+ binding to the Ca2+-receptor protein(s) in the smooth muscle cell and/or with the agonist-induced Ca2+-release from intracellular stores. Less likely, hispidulin may interfere with Ca2+ influx through smooth muscle cell membrane.

Differential Use of Anhydropyranosides for Enantiopure Routes to Bis-γ-butyrolactones: A New Approach to the Frameworks of Antibiotic and Anticancer Agents Isoavenaciolide and Ethisolide

Regio- and chemoselective syntheses of enantiopure bis-furanoids are described. These compounds are chirons for several families of bioactive natural products, including isoavenaciolide and ethisolide. Reaction of a 3,4-epoxy pyran with beta-ketoester dianions delivers substituted pyranosides in high yield. Cyclization then yields fused furan-pyran intermediates. Oxidation, deprotection, and rearrangement lead to bis-furanoids that bear the essential framework and stereochemistry of ethisolide and isoavenaciolide.

A lupine alkaloid from Leontice leontopetalum

Abstract Leontice leontopetalum from Jordan has yielded the new lupine alkaloid, 3α-hydroxylupanine. Its structure was confirmed by the use of mono- and bi-dimensional NMR techniques (GASPE, DEPT, homonuclear spindecoupling experiments, 1 H/ 1 H-COSY, 1 H/ 13 C-COSY), linked scan measurements and by chemical transformation. The isolation of 13α-hydroxylupanine and isolupanine are also described and their 1 H and 13 C NMR spectral data have been reinvestigated employing GASPE, DEPT, HMQC and HOHAHA experiments.

Phenolics from Colchicum decaisnei

Abstract Colchicum decaisnei has yielded three new compounds, namely, dibenzo[ b , f ][1,5]dioxocin, 4,6-dimethoxy-3,7-dimethyl coumarin and 3- O -demethyl- N -desacetyl- N -formyl-β-lumicolchicine, as well as the first report of 2-hydroxy-3-methoxy benzoic acid from a natural source.

Fumadensine a phthalideisoquinoline from Fumaria densiflora

Abstract The new phthalideisoqunoline, fumadensine, has been isolated from extracts of Fumaria densiflora .

A arylnaphthalene lignan from Haplophyllum buxbaumii.

Haplophyllum buxbaumii has yielded a new diphyllin glycoside, which was characterized as 4-O-{bis-alpha-L-xylopyranosyl (1-->2, 1-->5) beta-D-apiofuranosyloxy}-6,7-dimethoxy-1-(3,4-methylenedioxyphenyl)-3-hydroxymethyl naphthalene-2-carboxylic acid lactone. Taiwanin-H is also reported for the first time from a member of the Rutaceae.

Effects of Cirsiliol, a Flavone Isolated from Achillea fragrantissima, on rat isolated smooth muscle

AbstractThe effects of the flavone cirsiliol on rat isolated phenylephrine-precontracted proximal aorta, acetylcholine-pre-contracted trachea, urinary bladder, and uterus were studied. Cirsiliol (10−8-3×10−4M) caused concentration-dependent relaxation of the rat isolated phenylephrine-precontracted proximal aorta, acetylcholine-precontracted trachea, urinary bladder and inhibited the phasic contractions and the tone of the uterus. Cirsiliol (3×10−5, 1×10−4 and 3×10−4M) shifted to the right epinephrine concentration-effect curves on the proximal aorta and significantly inhibited the maximum contractions induced by epinephrine in this preparation. In Ca2+-free, depolarizing salt solution, cirsiliol (3×10−5, 1×10−4 and 3×10−4M) also shifted to the right CaCl2 concentration-effect curves on the proximal aorta and inhibited the maximum contractions induced by 3×10−2M CaCl2 whereas it had no effect on epinephrine-induced contractions in Ca2+-free salt solution on the same preparation. These observations suggest...

Selective monodeoxygenation of quinoxaline-amino acid and ester dioxides

Trimethyl phosphite selectively removes the N-1-oxygen in N-(3-methyl-2-quinoxaloyl) L-α-amino ester-1,4-dioxides, whereas it removes the N-4-oxygen in the corresponding series of dioxides lacking the C3-Me. This selectivity reversal reflects the relative strength of the intrahydrogen-bridging to the N-1-oxygen. The monoxides having the favourable N-oxygen are not reduced to the quinoxalines, implying that the reagent requires doubling of the N-oxide function for deoxygenation. However, alkaline sodium dithionite removes the N-1-oxygen in both series of the amino acid-dioxides, as well as in the parent quinoxaline-2-carboxylic acid-dioxides, a result that contradicts the report stating removal of the N-4-oxygen. The N-oxygenated quinoxalinium ion (me 145 or 159) prevails in the MS of the 4-oxides, but it is not observed (<1%) for the isomeric 1-oxides. 1H NMR, 13C NMR and UV spectral data also offer diagnostic criteria for differentiation between the isomeric 1- and 4-oxides. Aryl-heteryl “interaction” (as revealed by 1H NMR, though not by 13C NMR in the aromatic amino ester dioxides) is not manifested in the corresponding monoxides.