Biomedical subjects

Jing-Zhen Deng

Publications and source records attributed to Jing-Zhen Deng.

5 recordsLinked to original sources

PubMed2005

(+)-Myristinin A, a naturally occurring DNA polymerase beta inhibitor and potent DNA-damaging agent.

The first stereoselective total synthesis of the naturally occurring flavan myristinin A has been accomplished, as well as its biochemical evaluation. This synthesis verified the structural assignment and allowed for the determination of the absolute stereochemistry. Myristinin A exhibits biochemical activity both as a potent DNA-damaging agent and DNA polymerase beta inhibitor. Relaxation of supercoiled plasmid DNA was observed at picomolar concentrations, in addition to inhibition of polymerase beta at low micromolar concentrations.

DNA Damage↗

PubMed2005

Umbelactonyl cinnamate derivatives from Crypteronia paniculata that mediate DNA strand scission.

As part of an initiative to discover functional natural product analogues of bleomycin guided by the use of the COMPARE algorithm, a CH(2)Cl(2)-MeOH extract prepared from Crypteronia paniculata was found to exhibit relaxation of supercoiled pSP64 DNA in the presence of Cu(2+). Bioassay-guided fractionation employing a DNA strand scission assay resulted in the isolation of three novel DNA cleavage agents. Their structures were elucidated as umbelactonyl cinnamate derivatives 1-3 through their NMR and MS spectral data analyses. This is the first example of the isolation and structural characterization of naturally occurring umbelactonyl cinnamate derivatives. Compound 1 exhibited strong Cu(2+)-dependent relaxation of supercoiled pSP64 DNA, while compounds 2 and 3 had only weak DNA cleavage activity.

Algorithms↗

PubMed2005

(+)-Myristinins A and D from Knema elegans, which inhibit DNA polymerase beta and cleave DNA.

A survey of crude plant extracts for DNA polymerase beta inhibitors resulted in the identification of a methyl ethyl ketone extract prepared from Knema elegans that strongly inhibited the enzyme. Subsequent bioassay-guided fractionation of the extract, using an assay to monitor the activity of DNA polymerase beta, led to the isolation of two potent inhibitors, (+)-myristinins A (1) and D (2), which are known flavans having unusual structures. (+)-Myristinins A and D exhibited IC50 values of 12 and 4.3 microM, respectively, as inhibitors of DNA polymerase beta in the presence of bovine serum albumin (BSA), and 2.7 and 1.2 microM in the absence of BSA. As such, they are the most potent DNA polymerase beta inhibitors reported to date. Compounds 1 and 2 potentiated the cytotoxicity of bleomycin toward cultured P388D1 cells, reducing the number of viable cells by at least 30% when employed at 9 microM concentration for 6 h in the presence of an otherwise nontoxic concentration of bleomycin (75 nM). Principles 1 and 2 also induced strong Cu2+-dependent DNA strand scission in a DNA cleavage assay. Accordingly, 1 and 2 exhibit two activities, namely, DNA polymerase beta inhibition and DNA damage.

Animals↗

PubMed2003

DNA damaging activity of ellagic acid derivatives.

A strain of yeast rendered repair deficient by the conditional expression of the RAD52 locus was used to search for natural products capable of damaging DNA. Four ellagic acid derivatives, namely 3,3'-dimethyl-4'-O-beta-D-glucopyranosyl ellagic acid (1), 3,3',4-trimethyl-4'-O-beta-D-glucopyranosyl ellagic acid (2), 3'-methyl-3,4-O,O-methylidene ellagic acid (3) and 3'-methyl-3,4-O,O-methylidene-4'-O-beta-D-glucopyranosyl ellagic acid (4), were identified by this assay as DNA damaging natural principles from several plants, including Alangium javanicum, Anisophyllea apetala, Crypteronia paniculata, Mouririi sp. and Scholtzia parviflora. Although none of the isolated principles mediated frank strand scission of DNA in vitro, all of them potently inhibited the growth of yeast in the absence of expression of RAD52.

Biological Assay↗

PubMed2002

DNA-damaging agents from Crypteronia paniculata.

A survey of crude plant extracts using a new yeast strain designed to identify DNA-damaging agents resulted in the identification of an extract prepared from Crypteronia paniculata. Bioassay-guided fractionation resulted in the isolation of three active compounds. Two of these were ellagic acid derivatives, namely, 3,3'-di-O-methylellagic acid 4'-O-beta-d-xylopyranoside (1) and 3'-O-methyl-3,4-methylenedioxyellagic acid 4'-O-beta-d-glucopyranoside (2). The third was identified as kaempferol-3-O-alpha-l-rhamnoside (3). The three principles exhibited strong, selective cytotoxity toward the RAD52 repair-deficient yeast strain.

Antifungal Agents↗