Application of circular dichroism to the study of interactions between small molecular compounds and DNA / 药学学报

Circular dichroism (CD) is an useful technique for monitoring DNA conformation changes resulting from changes in environmental conditions, such as temperature, ionic strength, and pH, and also for the study of the interaction between DNA and ligands (including small molecules and proteins). CD spectroscopy of DNA arises from the asymmetric backbone sugars and by the helical structures often adopted by nucleic acids. By the interpretation of induced circular dichroism (ICD) of ligand signals resulting from the coupling of electric transition moments of the ligand, DNA bases within the asymmetric DNA environment, ligand-DNA interactions, as well as the DNA-binding mode can be assessed. A number of important conclusions have been reported that related to the observed ICD signals resulting from the interactions between intercalators and groove binders with DNA. If short oligonucleotide sequences are used in the study, sequences-specific of binding also can be deduced. CD determination requires smaller amounts of sample, and not limited by the molecular weight or size and can be performed rapidly; though CD is of low resolution, but it's a complement to NMR and X-ray diffraction methods. This review will introduce the characters of the CD spectra of DNA, and its application to the studies of DNA with small molecules; some progress of the studies in our laboratory will also be discussed. CD is expected to be used as a screening method in seeking more DNA-targeted drugs, such as, antineoplastic, antimicrobial and antiviral drugs.

Studies on chemical constituents in herb from Artemisia rupestris / 中国中药杂志

<p><b>OBJECTIVE</b>To study the chemical constituents of Artemisia rupestris.</p><p><b>METHOD</b>The chemical constituents were isolated by column chromatography on silical gel and sephadex LH - 20. Their structures were elucidated on the basis of spectral analysis.</p><p><b>RESULT</b>8 compounds have isolated from this plant, and the structures of them have identified as rupestonic acid (1), chrysosplenetin B (2), artemetin (3), herniarin (4), isokaempferide (5), vanillic acid (6), kaempferol 3, 3', 4'-trimethyl ether (7) and ermanine (8).</p><p><b>CONCLUSION</b>Compounds 2-8 have been isolated from this plant for the first time.</p>

Xanthones from Tibetan medicine Halenia elliptica and their antioxidant activity / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the xanthones from Tibetan medicine Halenia elliptica and their antioxidant activity.</p><p><b>METHODS</b>Column chromatography over normal phase silica gel, reversed phase silica gel, Sephadex LH-20, and recrystallization techniques were used to isolate and purify constituents from Halenia elliptica. Infrared spectrometry, mass spectrometry, and nuclear magnetic resonance spectrometry were used to identify the structure of compounds. The antioxidant activity was evaluated by measuring the content of malondialdehyde product in mice liver cell microsomal induced by ferrous-cysteine.</p><p><b>RESULTS</b>Eight xanthones (compound I-VIII) were isolated and identified from the ethyl acetate extract of Halenia elliptica, among which 1,7-dihydroxy-2,3,5-trimethoxyxanthone was a novel compound. Compound I, III at 10 microg/ml and 100 microg/ml could inhibit the production of malondialdehyde in mouse liver microsomes in vitro.</p><p><b>CONCLUSION</b>Eight xanthones were isolated and they have certain antioxidant activity.</p>

Studies on chemical constituents of Halenia elliptica guided by in vivo absorption and distribution of the constituents / 药学学报

<p><b>AIM</b>To investigate the chemical constituents of the Tibetan herbal medicine Halenia elliptica by guidance of in vivo absorption and distribution of the constituents.</p><p><b>METHODS</b>HPLC with a diode array detector (DAD) and HPLC-MS were used for detecting the constituents of extracts of Halenia elliptica and animal samples. Several kinds of column chromatography were used for the isolation and purification of the main in vivo absorbed and distributed compounds from the extract of Halenia elliptica.</p><p><b>RESULTS</b>Six main components detected in the extracts of the animal samples were isolated from the ethanolic extract of Halenia elliptica.</p><p><b>CONCLUSION</b>After rats were treated with different extracts of Halenia elliplica, low polar components xanthone aglycon of Halenia elliptica were clearly observed in the extracts of liver, lipid, blood, hidney, heart and brain tissue of rats, while the polar components xanthone glycosides were detected in very small amounts in the animal samples. The xanthone glycosides can be decomposed into xanthone aglycons during the digestion, absorption and metabolism procedure. Therefore, the in vivo activity of the xanthone glycosides might be exhibited by their decomposed products. It is an accessibly valuable method to investigate chemical components of herbal medicines under the guidance by detecting in vivo absorption and distribution of chemical components of the herbal medicine extract.</p>