Hani D. Tabba

Isolation, purification, and partial characterization of prunellin, an anti-HIV component from aqueous extracts of Prunella vulgaris

Prunellin, an anti-HIV active compound, was isolated from aqueous extracts of the Chinese medicinal herb, Prunella vulgaris, and purified to chromatographic homogeneity. Infrared and NMR spectroscopy identified prunellin as a polysaccharide. Elemental analyses, precipitation with calcium(II), barium(II), or 9-aminoacridine suggest a sulfated polysaccharide. Paper chromatography of the exhaustively hydrolyzed material indicates the presence of glucose, galactose, xylose, gluconic acid, galactonic acid and galactosamine as the constituent monosaccharides. The molecular size of prunellin, as determined by gel permeation chromatography and the Squire method on Sephadex G-75, is about 10 kDa.

Isolation, purification and partial characterization of an active anti-HIV compound from the Chinese medicinal herb viola yedoensis.

The dimethylsulfoxide extract of the Chinese medicinal herb Viola yedoensis demonstrates high inhibitory activity toward HIV-1 in vitro. The corresponding methanol extract also showed inhibitory activity but not as high as the dimethylsulfoxide extract. Anti-HIV activity in the extracts is accompanied by cytotoxicity, and we describe here the separation of the cytotoxic material from the active fraction. We also describe the procedure for isolation, purification, and separation of the active component from crude extracts of V. yedoensis as well as details of its activity against HIV-1. The UV-visible, infrared (IR) and proton nuclear magnetic resonance (NMR) data and certain other characteristics of the active compound are also presented. Initial chemical tests and the proton NMR and IR spectra indicate a high molecular weight sulphonated carbohydrate polymer, and chromatographic evidence suggests an MW between 10,000 and 15,000.

Dextran Sulfate as an Inhibitor against the Human Immunodeficiency Virus

Abstract Dextran sulfate (DS) is a potent inhibitor of the growth of human immunodeficiency virus type 1 (HIV-1) in the H9 cell. Its minimal inhibitory concentration is about 1 μg/ml. Its therapeutic index is ≥200 which is higher than that of 38 for zidovudine. At the ID100 range, DS blocks the synthesis of HIV-1 antigens completely for at least 21 days; zidovudine at the subtoxic concentration of 3 μg/ml is incapable of achieving such a complete blockage. DS is still active when added to H9 cell cultures 4 hr after the addition of HIV-1. DS does not inactivate extracellular HIV-1 and is incapable of inducing interferons. It interferes partially with the infection of the H9 cells by the HIV-1. It inhibits the activity of HIV-1 reverse transcriptase. These activities may account, at least in part, for the inhibitory activity of dextran sulfate against the HIV-1. DS has a narrow antiviral spectrum; it is noninhibitory to the herpes simplex, vesicular stomatitis, polio, or adeno viruses. Dextran is not inhibitory to HIV-1. After sulfonation, the sulfonated dextran is highly inhibitory. Therefore, the sulfate group in the DS molecule appears to be essential for its anti-HIV-1 activity. The molecular weights of DS within the range 4000 to 12,000 do not appear to influence its anti-HIV potency.

Condensation of cinnamonitriles with arylacetonitriles

Abstract The Michael addition of arylacetonitriles to Michael acceptors such as α,β-unsaturated nitriles occurred with a stoichiometric amount of sodium ethoxide to give only the 1,4-addition product in pure diastereomeric form. The structures of the reaction products were established by infrared, H-1 and C-13 nuclear magnetic resonance spectroscopy as well as by elemental analysis. The diastereomeric purity was determined by chromatographic and NMR measurements using achiral lanthanide shift reagents techniques. The observed resonances did not show any resolution of the diastereomeric proton signals. The stereochemistry and absolute configuration of the condensation product were established from X-ray crystallography.

Polyformylation of copper(II) porphyrins

Abstract Vilsmeier formylation of copper(II) octaethylporphyrin (1) is shown to yield the copper(II) complexes of meso-monoformyloctaethylporphyrin, meso-α,β- and meso-α,γ-diformyloctaethylporphyrins, meso-α,β,γ-triformyloctaethylporphyrin, and meso-α,β,γ,δ-tetraformyloctaethylporphyrin. There is therefore no difference in regioselectivity of meso-diformylation between the octaethylporphyrin and etioporphyrin-I series.

On the partial synthesis of optically pure bacteriopheophorbides -C and -D

Abstract Methyl bacteriopheophorbides-c or -d (obtained by partial synthesis, or by Markownikoff hydration of methyl pyropheophorbide-a, respectively) are obtained as a mixture of the (R,S) diastereomers at the 2(1-hydroxyethyl) group; these can be efficiently and completely separated using reverse phase high performance liquid chromatography (HPLC). Purity of the resolved mixture is demonstrated by 360 MHz NMR spectra.

The phototransformation of phytochrome probed by 360 MHz proton NMR spectra

The 360 MHz proton NMR spectra of the Pr and Pfr forms of phytochrome have been recorded to probe the nature of the phytochrome phototransformation (Pr → Pfr). The NMR spectra of aliphatic protons in Pr and Pfr proteins are similar, suggesting that the conformation of both proteins are not drastically different. However, the NMR spectrum of aromatic and the -NH- proton resonance region of Pfr differs significantly from that of Pr, including the absence of a resonance at 6.15 ppm in the former. Differences in the NMR spectra of small and large mol wt phytochromes have also been noted.

Neighboring group participation by the pyrrole nucleus

Abstract Using proton and carbon-13 NMR spectroscopy, the transformation of 2-hydroxyethylpyrroles (5,15) into 2-haloethylpyrroles by treatment with thionyl chloride or carbon tetrabromide/triphenylphosphine is shown to proceed by randomization of the two side-chain carbon atoms. A spirocyclopropylpyrrolium ion (19) is postulated as an intermediate in this unexpected process.

Polyformylation of copper(II) complexes of octa-alkylporphyrins

Vilsmeier formylation of copper(II) octaethylporphyrin (1) affords the copper(II) complexes of α-formyloctaethylporphyrin, α,γ- and α,β-diformyloctaethylporphyrins, α,β,γ-triformyloctaethylporphyrin, and α,β,γ,δ-tetraformyloctaethylporphyrin [(13), (2), (3), (14), and (15), respectively]. Similar results are obtained when copper(II) etioporphyrin-I (5) is formylated. It therefore appears that there exists no difference in regioselectivity in the diformylation reactions between the copper(II) octaethyl- and copper(II) etioporphyrin-I series. Earlier work which indicated that in the octaethylporphyrin series there is a preference for formation only of the copper(II)α,γ-diformylporphyrin (2) is suggested to be a result of preferential crystallization of the least-soluble α,γ-compound from an almost equal mixture of the two isomers.