http://www.mdpi.com/journal/molecules/special_issues/quinones-hydroxyquinones/ Submission All papers should be submitted to molecules@mdpi.org with copy to the guest editor. To be published continuously until the deadline and papers will be listed together at the special websites. Submitted papers should not have been previously published nor be currently under consideration for publication elsewhere. All papers are refereed through a peer review process. A guide for authors, sample copies and other relevant information for submitting papers are available on the Instructions for Authors page. Molecules is an international peer-reviewed monthly journal published by Molecular Diversity Preservation International. Please visit the Instructions for Authors page before submitting a paper. Open Access publication fees are 800 CHF per paper. English correction fees (250 CHF) will be added in certain cases (1050 CHF per paper for those papers that require extensive additional formatting and/or English corrections.). http://www.mdpi.com/1420-3049/14/8/2857/ Two bioactive xanthones from Hypericum perforatum have been synthesized by direct routes. Benzo[c]xanthone 5 can be prepared from intermediate 4. http://www.mdpi.com/1420-3049/14/8/2857/ Mon, 03 Aug 2009 00:00:00 CEST Molecules 2009-08-03 14 8 Article 2857 2861 1420-3049 Quinones as Key Intermediates in Natural Products Synthesis. Syntheses of Bioactive Xanthones from Hypericum perforatum 2009-08-03 doi: 10.3390/molecules14082857 George A. Kraus John Mengwasser http://www.mdpi.com/1420-3049/14/7/2306/ Aziridine-containing compounds have been of interest as anticancer agents since late 1970s. The design, synthesis and study of triaziquone (TZQ) analogues with the aim of obtaining compounds with enhanced efficacy and reduced toxicity are an ongoing research effort in our group. A series of bis-type TZQ derivatives has been prepared and their cytotoxic activities were investigated. The cytotoxicity of these bis-type TZQ derivatives were tested on three cancer lines, including breast cancer (BC-M1), oral cancer (OEC-M1), larynx epidermal cancer (Hep2) and one normal skin fibroblast (SF). Most of these synthetic derivatives displayed significant cytotoxic activities against human carcinoma cell lines, but weak activities against SF. Among tested analogues the bis-type TZQ derivative 1a showed lethal effects on larynx epidermal carcinoma cells (Hep2), with an LC50 value of 2.02 mM, and also weak cytotoxic activity against SF cells with an LC50 value over 10 mM for 24 hr treatment. Comparing the viability of normal fibroblast cells treated with compound 1a and TZQ, the LC50 value of the latter was 2.52 mM, indicating more toxicity than compound 1a. This significantly decreased cytotoxicity of compound 1a towards normal SF cells, while still maintaining the anticancer activity towards Hep2 cells is an interesting feature. Among the seven compounds synthesized, compound 1c has similar toxicity effects on the three cancer cell lines and SF normal cells as the TZQ monomer. http://www.mdpi.com/1420-3049/14/7/2306/ Mon, 29 Jun 2009 00:00:00 CEST Molecules 2009-06-29 14 7 Article 2306 2316 1420-3049 Synthesis and Antitumor Evaluation of Novel Bis-Triaziquone Derivatives 2009-06-29 doi: 10.3390/molecules14072306 Cheng Hua Huang Hsien-Shou Kuo Jia-Wen Liu Yuh-Ling Lin http://www.mdpi.com/1420-3049/14/3/1013/ Brominated anthraquinones can be synthesized directly from bromothiophenes when these are reacted with 1,4-naphthoquinones in the presence of meta-chloroperoxybenzoic acid. The bromoanthraquinones are versatile building blocks in the preparation of arylated anthraquinones and of extended π-systems with interspersed anthraquinone units. http://www.mdpi.com/1420-3049/14/3/1013/ Wed, 04 Mar 2009 00:00:00 CET Molecules 2009-03-04 14 3 Article 1013 1031 1420-3049 Brominated Thiophenes as Precursors in the Preparation of Brominated and Arylated Anthraquinones 2009-03-04 doi: 10.3390/molecules14031013 Thies Thiemann Yasuko Tanaka Jesus Iniesta