Synthesis and bioactivity of new antineoplastic terpenylquinones

Novel drug design for Chagas disease via targeting Trypanosoma cruzi tubulin: Homology modeling and binding pocket prediction on Trypanosoma cruzi tubulin polymerization inhibition by naphthoquinone derivatives

Chagas disease, also called American trypanosomiasis, is a parasitic disease caused by Trypanosoma cruzi (T. cruzi). Recent findings have underscored the abundance of the causative organism, (T. cruzi), especially in the southern tier states of the US and the risk burden for the rural farming communities there. Due to a lack of safe and effective drugs, there is an urgent need for novel therapeutic options for treating Chagas disease. We report here our first scientific effort to pursue a novel drug design for treating Chagas disease via the targeting of T. cruzi tubulin. First, the anti T. cruzi tubulin activities of five naphthoquinone derivatives were determined and correlated to their anti-trypanosomal activities. The correlation between the ligand activities against the T. cruzi organism and their tubulin inhibitory activities was very strong with a Pearson's r value of 0.88 (P value <0.05), indicating that this class of compounds could inhibit the activity of the trypanosome organism via T. cruzi tubulin polymerization inhibition. Subsequent molecular modeling studies were carried out to understand the mechanisms of the anti-tubulin activities, wherein, the homology model of T. cruzi tubulin dimer was generated and the putative binding site of naphthoquinone derivatives was predicted. The correlation coefficient for ligand anti-tubulin activities and their binding energies at the putative pocket was found to be r=0.79, a high correlation efficiency that was not replicated in contiguous candidate pockets. The homology model of T. cruzi tubulin and the identification of its putative binding site lay a solid ground for further structure based drug design, including molecular docking and pharmacophore analysis. This study presents a new opportunity for designing potent and selective drugs for Chagas disease.

Synthetic strategies to terpene quinones/hydroquinones

The cytotoxic and antiproliferative properties of many natural sesquiterpene-quinones and -hydroquinones from sponges offer promising opportunities for the development of new drugs. A review dealing with different strategies for obtaining bioactive terpenyl quinones/hydroquinones is presented. The different synthetic approches for the preparation of the most relevant quinones/hydroquinones are described.

Myrcene as a natural base chemical in sustainable chemistry: a critical review

Currently, a shift towards chemical products derived from renewable, biological feedstocks is observed more and more. However, substantial differences with traditional feedstocks, such as their "hyperfunctionalization," ethical problems caused by competition with foods, and problems with a constant qualitative/quantitative availability of the natural products, occasionally complicate the large-scale market entry of renewable resources. In this context the vast family of terpenes is often not taken into consideration, although the terpenes have been known for hundreds of years as components of essential oils obtained from leaves, flowers, and fruits of many plants. The simple acyclic monoterpenes, particularly the industrially available myrcene, provide a classical chemistry similar to unsaturated hydrocarbons already known from oil and gas. Hence, this Review is aimed at reviving myrcene as a renewable compound suitable for sustainable chemistry in the area of fine chemicals. The versatility of the unsaturated C(10)-hydrocarbon myrcene, leading to products with several different areas of application, is pointed out.

Effects of 9,10-dihydroxy-4,4-dimethyl-5,8-dihydro-1(4H)-anthracenone derivatives on tumor cell respiration

A series of tricyclic hydroquinones, incorporating a carbonyl group in the ortho position relative to the phenol function, were tested as inhibitors of oxygen uptake against the TA3 mouse carcinoma cell line and its multidrug-resistant variant TA3-MTX-R. The title compound, which proved to be the most active one, also exhibited low micromolar dose-dependent growth inhibition of the human tumor U937 cell line (human monocytic leukemia). A tentative structure-activity relationship is proposed for these substances. A comparison between the cytotoxicities of the title compound and 4,4-dimethyl-5,8-dihydroxynaphthalene-1-one, with their activities as inhibitors of oxygen uptake by the TA3-MTX-R cell line, is presented. Also, the inhibition of oxygen uptake by 6-(4-methylpent-3-enyl)-1,4-naphthoquinone was determined and compared with its reported cytotoxicity toward P-388 (murine lymphocytic leukemia), A-549 (human lung carcinoma), HT-29 (human colon carcinoma), and MEL-28 (human melanoma) cells. The inhibition of oxygen uptake by TA3-MTX-R cells is useful as a quick test for preliminary screening of possible anticancer activity.

New cytotoxic-antineoplastic prenyl-1,2-naphthohydroquinone derivatives

Several new prenylnaphthohydroquinone derivatives have been prepared through the Diels-Alder condensation between alpha-myrcene and 1,2-benzoquinone and evaluated for their cytotoxic activity against A-549, HT-29 and MB-231 cultured cell lines. All of them have shown GI50 values in the microM level.

Synthesis, characterisation and cytotoxicity of chloro derivatives of prenylnaphthohydroquinone

From the Diels-Alder adduct between alpha-myrcene and 2-chloro-1,4-benzoquinone, a family of chloro derivatives of prenylnaphthohydroquinone have been synthesised and evaluated for their cytotoxicity against 14 neoplastic cell lines.

Cytotoxic–antineoplastic activity of acetyl derivatives of prenylnaphthohydroquinone

Several acetyl derivatives of prenylnaphthohydroquinone have been synthetized and evaluated for their cytotoxicity against A-549 human lung carcinoma and H-116 human colon carcinoma neoplastic cells. The IC50 values against A-549 are compared with those observed for previously reported unsubstituted derivatives.

Reductive activation of terpenylnaphthoquinones

Four terpenylnaphthoquinones were found to enhance the rate of superoxide production in the presence of ascorbate as detected from the superoxide dismutase (SOD)-inhibitable initial oxygen consumption rates. Initial rates of oxygen consumption in the presence of ascorbate plus quinone increase with an increase in the half-wave reduction potentials of the quinones. These quinones also enhance the rate of Cyt(III)c reduction by xanthine/xanthine oxidase (X/XO) in both air- and nitrogen-saturated aqueous solutions at pH 7.4. Maximum rates of Cyt(III)c reduction in nitrogen and oxygen-saturated solutions (V(max)), in the presence of X/XO, increase with an increase in the half-wave reduction potentials of the quinones. SOD inhibits Cyt(III)c reduction rates in the presence of these quinones and X/XO in a manner which is also dependent on the quinone half-wave redox potential. The relative antineoplastic activity of two of these quinones follows the order in rates of oxygen consumption or Cyt(III)c reduction. This is consistent with an antineoplastic action of these quinones through the mechanism of redox cycling or possible interference or inhibition of mitochondrial respiration.

New selective cytotoxic diterpenylquinones and diterpenylhydroquinones

A new series of diterpenylquinone/hydroquinones has been prepared by Diels-Alder cycloaddition between three labdanic diterpenoids (myrceocommunic acid, methyl myrceocommunate, and myrceocommunyl acetate) and p-benzoquinone or 1,4-naphthoquinone. Influences of the quinone/hydroquinone fragment and other structural features, such as the different functionalities in the terpenic core, are considered in relation to the cytotoxicity toward neoplastic cells and the selectivity of these diterpenylnaphthoquinones/hydroquinones and anthraquinones. Several compounds showed IC50 values under the micromolar level, and four of these derivatives were evaluated at the NCI screening panel. The results showed an important selectivity toward renal cancer lines, identifying these compounds as a very promising group of antineoplastics.

New antineoplastic prenylhydroquinones. Synthesis and evaluation

Several prenylhydroquinones have been prepared through Diels-Alder condensation, further functionalized or degraded chemically and then evaluated for their cytotoxic activity against some neoplastic cultured cell lines. A number of them have shown IC50 values under the microM level.

Further antineoplastic terpenylquinones and terpenylhydroquinones

Influences of the quinone/hydroquinone fragment and other structural features are considered in relation with the antineoplastic activity and selectivity of terpenylquinones/hydroquinones. Several compounds have shown IC50 values under the microM level.