Synthesis, characterisation and cytotoxicity of chloro derivatives of prenylnaphthohydroquinone

New Antineoplastic Naphthohydroquinones Attached to Labdane and Rearranged Diterpene Skeletons

Terpenylquinones are mixed biogenesis primary or secondary metabolites widespread in Nature with many biological activities, including the antineoplastic cytotoxicity, that have inspired this work. Here, we present a cytotoxic structure-activity relationship of several diterpenylhydroquinone (DTHQ) derivatives, obtained from the natural labdane diterpenoid myrceocommunic acid used as starting material. Different structural modifications, that changed the functionality and stereochemistry of the decalin, have been implemented on the bicyclic core through epoxidation, ozonolysis or decarboxylation, and through induction of biomimetic breaks and rearrangements of the diterpene skeleton. All the isomers generated were completely characterized by spectroscopic procedures. The resulting compounds have been tested in vitro on cultured cancer cells, showing their relevant antineoplastic cytotoxicity, with GI₅₀ values in the μM and sub-μM range. The rearranged compound 8 showed the best cytotoxic results, with GI₅₀ at the submicromolar range, retaining the cytotoxicity level of the parent compounds. In this report, the versatility of the labdane skeleton for chemical transformation and the interest to continue using structural modifications to obtain new bioactive compounds are demonstrated.

Bioactive Prenyl- and Terpenyl-Quinones/Hydroquinones of Marine Origin †

The sea is a rich source of biological active compounds, among which terpenyl-quinones/hydroquinones constitute a family of secondary metabolites with diverse pharmacological properties. The chemical diversity and bioactivity of those isolated from marine organisms in the last 10 years are summarized in this review. Aspects related to synthetic approaches towards the preparation of improved bioactive analogues from inactive terpenoids are also outlined.

Synthesis and evaluation as antitumor agents of 1,4-naphthohydroquinone derivatives conjugated with amino acids and purines

We report on the synthesis of two series of 1,4-naphthohydroquinone derivatives conjugated with amino acids (Gly, Ala, Phe, and Glu) and with substituted purines linked by an aliphatic chain. The compounds were obtained through Diels-Alder cycloaddition between myrcene and 1,4-benzoquinone and evaluated in vitro for their cytotoxicity (GI50 ) against cultured human cancer cells of A-549 lung carcinoma, HT-29 colon adenocarcinoma, and MCF-7 breast carcinoma. The GI50 values found for some hydroquinone-amino acid and hydroquinone-purine hybrids against MCF-7 are in an activity range comparable to that of the reference drug doxorubicin.

Synthesis and pharmacological activity of diterpenylnaphthoquinone derivatives

New diterpenylquinones, combining a diterpene diacid and a naphthoquinone, were prepared from junicedric acid and lapachol. The new derivatives were assessed as gastroprotective agents by the HCl-EtOH-induced gastric lesions model in mice as well as for basal cytotoxicity on the following human cell lines: Normal lung fibroblasts (MRC-5), gastric epithelial adenocarcinoma (AGS), and hepatocellular carcinoma (Hep G2). Several of the new compounds were significantly active as antiulcer agents and showed selective cytotoxicity against AGS cells.

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.

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.