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It is estimated that Trichomonas vaginalis affects an astonishing 3.9% of the world's population, and while many of those infected are asymptomatic, progression of the disease can lead to serious health problems. Currently, the nitroimidazoles constitute the only drug class approved to treat trichomoniasis in the United States, which makes the spread of drug resistance a realistic concern. We developed a new image-based, high-throughput, and high-content assay for testing natural products (purified compounds and extracts) for antitrichomonal activity. Applying this assay system to a library of fungal natural product extracts led to the identification of three general classes of natural product inhibitors that exhibited moderate to strong activities against T. vaginalis: anthraquinones, xanthone-anthraquinone heterodimers, and decalin-linked tetramic-acid-containing metabolites. The tetramate natural products emerged as the most promising candidate molecules with pyrrolocin A (51) exhibiting potent activity against the parasite (EC50 = 60 nM), yet this metabolite showed limited toxicity to mammalian cell lines (selectivity index values of 100 and 167 versus 3T3 fibroblast and Ect1 normal cervical cells, respectively). The imaging-based assay system is a powerful tool for the bioassay-guided purification of single-component antitrichomonal biomolecules from complex natural product mixtures.

Direct displacement of chlorine atoms by alkoxy groups in 2,3-disubstituted juglones (5-hydroxy-1,4-naphthoquinones), naphthazarines (5,8-dihydroxy-1,4-naphthoquinones), and quinizarines (1,4-dihydroxy-9,10-anthraquinones) is generally ineffective, howeve

Mono- and diamino-derivatives of naphthazarin, 2-methoxynaphthazarin, juglone and their methylethers were prepared by reaction with ammonia. The structure of the products was established by NMR studies. Some compounds were tested for cytotoxic activity. C

A synthetic protocol has been designed to synthesize grecoketidone (2k), 5-hydroxylapachol (2g), and the recently discovered natural products juglonbutin (2o) and its derivatives, leading to a small library of different 1,4-naphthoquinones with the intention of finding new active compounds. Within our collection, 2-O-alkylated naphthoquinones with an ester functionality in the side-chain and a free OH group at C-5 showed the best activities. Compounds 2f, 2m, and 2n showed GI50 values against 12 tumor cell lines in the lower micromolar range and juglonbutin (2o) showed remarkably efficient inhibition of the glycogen synthase kinase 3β with an IC50 value of 2.03 μM. Furthermore, studies on the mode of action of the most active cytotoxic compounds have been carried out. To the best of our knowledge, this is the first report on the synthesis of juglonbutin (2o) and its biological activity. Copyright

Trimethyl orthoacetate was found to be a convenient reagent for methylation of the β-OH groups of (poly)hydroxynaphthazarins. The substrates bearing one β-OH group react with MeC(OMe)3 to give the corresponding methoxy derivatives in 79–89% yields. Depending on the reaction conditions, methylation of substrates with two β-OH groups on the different and the same rings affords either the corresponding mono-O-methylated (43–70%) or di-Omethylated (71–78%) derivatives. Trimethyl orthoacetate offers a good alternative to CH2N2 in the preparative synthesis of O-methylated (poly)hydroxynaphthazarin derivatives.

Ruthenium-catalysis enabled the C-5 selective C-H oxygenation of naphthoquinones, and also sets the stage for the site-selective introduction of a hydroxyl group into anthraquinones. A-ring modified naphthoquinoidal compounds represent an important class of bioactive quinones for which the present study encompasses the first C-H oxygenation strategy by weak O-coordination.

An efficient protocol for Ru(II)-catalyzed direct C-H oxygenation of a broad range of flavone and chromone substrates was developed. This convenient and powerful synthetic tool allows for the rapid installation of the hydroxyl group into the flavone, chromone, and other related scaffolds and opens the way for analog synthesis of highly potent Aurora kinase inhibitors. The molecular docking simulations indicate that the formation of bidentate H-bonding patterns in the hinge regions between the 5-hydroxyflavonoids and Ala213 was the significant binding force, which is consistent with experimental and computational findings.

By the reaction of 2-chloro-3-alkyl-, 2,3-dichloro(dibromo)-, trichloro(tribromo)-and tetrachloro(tetrabromo)-naphthazarins and 2,3- dichloroquinizarin with Fe/HOAc followed by oxidation with an air in a mild basic conditions the corresponding naphthazarins and quinizarin were obtained in good to excellent yields.

The fungal tetrahydroanthraquinones austrocortirubin (1) and austrocortilutein (3) and their deoxy derivatives (2) and (4), respectively, are synthesized in racemic form from naphthopurpurin (6).

The condensation of 1,2,4 trimethoxybenzene with maleic anhydride in the presence of AlCl3-NaCl affords, in a single step, naphtopurpurine 1, an important intermediate in the synthesis of naphtoquinone derived natural products.A different synthesis of compound 1 consists in the substitution of the halogen atom in 2-chloro or 2-bromo-naphthazirin by a methoxy group which is subsequently cleaved in an acidic medium or by a Lewis acid.