Dimeric (Poly)Hydroxynaphthazarins, Metabolites of Echinoderms and Lichens: The History of the Synthesis and Structure Elucidation.

This review provides information on the synthesis and revision of the structures of natural dimeric (poly)hydroxynaphthazarins, metabolites of echinoderms and lichens, and on the refinement of the direction and mechanism of reactions in the synthesis of some of these compounds.

Activity of New Synthetic (2-Chloroethylthio)-1,4-naphthoquinones in Prostate Cancer Cells.

Development of resistance to currently available standard therapies in advanced prostate cancer (PCa) emphasizes the need for novel therapeutic options. Here, we report the synthesis of new hybrid molecules consisting of 2-chloroethylthio and 1,4-naphthoquinone pharmacophores and describe their activity in PCa. In screening analyses, the introduction of one 2-chloroethylthio group improved the anticancer properties of 1,4-naphthoquinones, whereas the introduction of a second 2-chloroethylthio moiety rather decreased activity.

Successful Targeting of the Warburg Effect in Prostate Cancer by Glucose-Conjugated 1,4-Naphthoquinones.

Treatment of castration-resistant prostate cancer (CRPC) remains challenging due to the development of drug resistance. The Warburg effect describes the ability of cancer cells to consume larger amounts of glucose compared to normal tissues. We identified derivatives of natural 1,4-naphthoquinones to be active in CRPC and further synthetically modified them via glucose conjugation to increase selectivity by Warburg effect targeting.

Concerning the structure of islandoquinone isolated from the lichen Cetraria islandica.

An investigation of the oxidative coupling products of some substituted hydroxynaphthazarins led to a revision of the proposed structure of islandoquinone, previously isolated from the lichen Cetraria islandica, and yielding (7aS*, 13aS*)-6,7a-diethyl-2,5,9,11,12,13a-hexahydroxy-7, 4-dioxabenzo[a]tetracene-1,4,8,13(7aH, 13aH)-tetraone through X-ray diffraction analysis of its 2,11-dimethyl ether.

Quinone-carbohydrate nonglucoside conjugates as a new type of cytotoxic agents: synthesis and determination of in vitro activity.

We have found that 2-methoxy-1,4-naphthoquinones easily react with primary alcohols to produce the corresponding 2-alkoxyderivatives. Using this reaction, we synthesized methyl-6-O-(naphthalene-1,4-dione-2-yl)-α-D-glucopyranosides, a new type of water soluble quinone-carbohydrate nonglucoside conjugates. The resulting conjugates induced apoptosis in human cancer HeLa and normal mouse JB6 P(+) Cl41 cells with simultaneous inhibition of p53-dependant transcriptional activity, suggesting that the observed cell death was p53-independent.

Metal-dependent repression of siderophore and biofilm formation in Actinomyces naeslundii.

Actinomyces naeslundii is a pioneer of the oral cavity and forms a biofilm on the tooth's surface. Most bacteria require iron for survival and in pathogenic bacteria iron availability regulates virulence gene expression. Metal-dependent repressors control gene expression involved in metal transport and uptake including siderophores.