Atef G. Hanna

Complete 1H and 13C signal assignments of 5α-cardenolides isolated from Calotropis procera R. BR.

Abstract Four cardenolides were isolated from Calotropis procera. Their structure and conformational behaviour were investigated by the extensive application of one- and two-dimensional 1 H and 13 C NMR spectroscopy. Complete 1 H and 13 C assignments for the compounds were achieved.

Two cardenolides from Calotropis procera

Two cardiotonic glycosides were isolated from Calotropois procera; one of them (1) is a new natural product. Their structures were elucidated by extensive application of one‐ and two‐dimensional 1H and 13C NMR spectroscopy. Copyright

Complete 1H and 13C signal assignments of 5β-cardenolides isolated from Acokanthera spectabilis Hook F.

Four cardiotonic glycosides were isolated from Acokanthera spectabilis. Their structures and conformational behaviour were investigated by extensive application of one‐ and two‐dimensional 1H and 13NMR spectroscopy.

Comparative studies of acidic and enzymatic hydrolysis for production of soyasapogenols from soybean saponin

Abstract Soyasapogenols, aglycones of soyasaponins, can be produced from crude soybean saponin extract by acid or enzymatic hydrolysis. Soyasapogenol B is known to have hepatoprotective, antimutagenic, antivirus, and anti-inflammatory activities. Hydrolysis of soyabean saponin extract for 72 h with 2 M HCl in methanol gave three soyasapogenols, namely: soyasapogenol D, soyasapogenol B1 and soyasapogenol A. However, the microbial hydrolysis of soybean saponin extract by Aspergillus terreus led to isolation of soyasapogenol B as a major product. A systematic evaluation of the effect of key operational parameters on the microbial transformation was performed. Maximum production of soyasapogenol B (about 152.3 mg/50ml) was observed using 1.5% (w/v) soybean saponin and 1.5% (w/v) glucose, 32°C after 72 h at pH 7 using phosphate buffer. Under these optimal conditions, the cells’ bioconversion efficiency increased from 20.5 to 85.3%. The isolation of soyasapogenols was performed using chromatographic methods and their structures identified on the basis of spectroscopic tools.

Synthesis and mass spectra of adamantylphosphoryl derivatives

Abstract The syntheses of 25 phosphorylated adamantane derivatives are described and their mass spectra are discussed.

Dendrophen, a Novel Glycyrrhetyl Amino Acid from Dendronephthya hemprichi

Chemical investigation of the extract of Dendronephthya hemprichi, collected from the Red Sea, Egypt, delivered dendrophen (1), the first 3β -acetoxy-glycyrrhetyl amino acid conjugate obtained from nature. Additionally, a new polyhydroxy sterol, dendrotriol (2), together with cholesterol and hexitol were isolated. Chromatographic separation of the low-polarity components of the D. hemprichi extract afforded 4-oxo-pentanoic acid, 2-methyl-acrylic acid 2-diethylaminoethyl ester (3), juniper camphor (4), and 2-octadecanone. The structures of 1 and 2 were confirmed by 1D and 2D NMR studies and mass spectrometry. Graphical Abstract Dendrophen, a Novel Glycyrrhetyl Amino Acid from Dendronephthya hemprichi

Design, Synthesis and Antitumor Activity of Novel D-Glucuronic Acid Derivatives

A series of D-glucuronic acid derivatives were chemically synthesized including acetylated and deacetylated glucuronamides, as well as N-glucuronides starting from the D-glucuronic acid itself by means of protection/deprotection, activation and condensation protocols. Structure elucidation of all products along with optimization of the synthetic steps is described. The synthesized compounds were evaluated for their in vitro antitumor activity against MCF-7, TK-10 and UACC-62 cell lines. The compounds 4, 5, 7, 8, 14, 16 and 18 were the most active against TK-10 cell line. On the other hand, the most active compounds against the MCF-7 cell line were 9, 18 and 20. However, compounds 7-10 13-15 and 17 were the most active against the UACC-62 cell line.

Studies on phosphonium ylides. XIII, The reactivity of N,N'-2,5-cyclohexadienes-1,4-diylidenebis [benzenesulfonamide] towards Wittig reagents

Abstract Cyanomethylenetriphenylphosphorane (IIa) reacts with N,N′-2,5-cyclohexadiene-1,4-diylidenebis (benzenesulfonamide] (Ia) affording the new azacyclopropane adduct IIIa. On the other hand, methylenetriphenylphosphoranes (IIb-d) react with quinoneimine (Ia) and its 2-chloro-derivative (Ib) yielding the corresponding ylid-phosphorane adducts IIIb-g. Structural reasoning for compounds III was based on compatible analytical and spectral data (IR, 1H, 31P, 13C, NMR and MS). A mechanism is proposed to explain the formation of compounds III.

Synthesis of Some Novel D-Glucuronic Acid Acetylated Derivatives as Potential Anti-Tumor Agents

A structurally diverse series of Δ4,5‐uronamide derivatives have been chemically synthesized starting from D‐glucuronic acid itself by means of acetylation, activation, amide bond formation and base‐catalyzed elimination protocols. Structure elucidation for all products along with optimization of the synthetic steps is described. The synthesized compounds were evaluated for their in‐vitro anti‐tumor activity against MCF‐7, TK‐10 and UACC‐62 cell lines. The compounds 5, 11, 13, 15 and 16 were the most active against TK‐10 cell line. On the other hand, the most active compounds against the MCF‐7 cell line were 11 and 15. However, compounds 5, 7, 11, 13, 15 and 16 were the most active against the UACC‐62 cell line.

A Further Contribution to the Triterpenoid Constituents of Glycyrrhiza glabra L

Abstract Pentacyclic Triterpenoids, G lycyrrhiza glabra, 1H and 13C Chemical Shifts Five pentacyclic triterpenoids have been isolated from the minor constituents of local liquorice roots, one of them (8) has not been isolated before from liquorice root. Their struc tural formulae and stereochemical configuration was determined by spectroscopic methods. 13C and 1H NMR data have been compiled.