Marine Cyanobacteria as Sources of Lead Anticancer Compounds: A Review of Families of Metabolites with Cytotoxic,Antiproliferative, and Antineoplastic Effects

The marine environment is highly diverse, each living creature fighting to establish and proliferate. Among marine organisms, cyanobacteria are astounding secondary metabolite producers representing a wonderful source of biologically active molecules aimed to communicate, defend from predators, or compete. Studies on these molecules’ origins and activities have been systematic, although much is still to be discovered. Their broad chemical diversity results from integrating peptide and polyketide synthetases and synthases, along with cascades of biosynthetic transformations resulting in new chemical structures. Cyanobacteria are glycolipid, macrolide, peptide, and polyketide producers, and to date, hundreds of these molecules have been isolated and tested. Many of these compounds have demonstrated important bioactivities such as cytotoxicity, antineoplastic, and antiproliferative activity with potential pharmacological uses. Some are currently under clinical investigation. Additionally, conventional chemotherapeutic treatments include drugs with a well-known range of side effects, making anticancer drug research from new sources, such as marine cyanobacteria, necessary. This review is focused on the anticancer bioactivities of metabolites produced by marine cyanobacteria, emphasizing the identification of each variant of the metabolite family, their chemical structures, and the mechanisms of action underlying their biological and pharmacological activities.     

A Novel Domino Reaction: Cyclization of Alkynyl Sulfides by Reaction with IPy2BF4

Formation of polycyclic structures within a few minutes: The intramolecular cyclization of diynes, activated by a benzenesulfenyl substituent, upon reaction with IPy₂BF₄ proceeds as an efficient exo–endo coupling. A subsequent novel Friedel–Crafts-like ring closure provides the product [Eq. (1)]. Thus, intra- and intermolecular cyclizations can be carried out.     

A comparative study of hydroxyl‐ and carboxylate‐functionalized imidazolium and benzimidazolium salts as precursors for N‐heterocyclic carbene ligands

The preparation of imidazolium and benzimidazolium salts with hydroxyl or carboxylate functions has been achieved using straightforward synthetic pathways. These salts in combination with palladium(II) acetate give active catalytic systems for Suzuki reaction. A comparative study has been performed, which has revealed that both the heterocycle and the functional group are important for the catalytic activity and stability of the catalyst. Copyright © 2015 John Wiley & Sons, Ltd.     

Noticeable Quantities of Functional Compounds and Antioxidant Activities Remain after Cooking of Colored Fleshed Potatoes Native from Southern Chile

The effect of cooking on the concentrations of phenolic compounds and antioxidant activities in 33 colored-fleshed potatoes genotypes was evaluated. The phenolic profiles, concentrations, and antioxidant activity were evaluated with a liquid chromatography diode array detector coupled to a mass spectrometer with an electrospray ionization interface (HPLC-DAD-ESI-MS/MS). Eleven anthocyanins were detected; in the case of red-fleshed genotypes, these were mainly acyl-glycosides derivatives of pelargonidin, whereas, in purple-fleshed genotypes, acyl-glycosides derivatives of petunidin were the most important. In the case of the purple-fleshed genotypes, the most important compound was petunidin-3-coumaroylrutinoside-5-glucoside. Concentrations of total anthocyanins varied between 1.21 g kg⁻¹ in fresh and 1.05 g kg⁻¹ in cooked potato and the decreases due to cooking ranged between 3% and 59%. The genotypes that showed the highest levels of total phenols also presented the highest levels of antioxidant activity. These results are of relevance because they suggest anthocyanins are important contributors to the antioxidant activity of these potato genotypes, which is significant even after the drastic process of cooking.     

Highly functionalised cyclohexa-1,3-dienes by sulfonyl Nazarov reagents

The Hayashi–Jørgensen organocatalyst has made possible a sulfonyl Nazarov analogue reagent to give a Diels–Alder reaction at the double bond, without involving the activated methylene affording chiral highly functionalised cyclohexa-1,3-dienes.     

Ring-closing metathesis as key step in the synthesis of Luffarin I, 16-<Emphasis Type="Italic">epi</Emphasis>-Luffarin I and Luffarin A

Natural sesterterpenolides, luffarin I and luffarin A, from Luffariella geometrica have been synthesized, and this is the first reported synthesis of luffarin A. The Yamaguchi esterification of the nor-diterpenic fragment, obtained from 2.8–15 \(\upmu \)M, with the appropriate furane alcohols yielded the necessary diene intermediates for the synthesis of the target molecules. The key strategic step in this synthesis was the ring-closing metathesis (RCM) reaction of the diene intermediates. This strategy allowed for the synthesis of 16-epi-luffarin I and analogues for structure–activity relationship (SAR) studies. The most active compound exhibited antiproliferative activity against a panel of six human solid tumour cell lines with \(\hbox {GI}_{50}\) values in the range 2.8–15 M.     

Easy selective generation of (lithiomethyl)cyclopropane or homoallyllithium by a chlorine-lithium exchange

The reaction of (chloromethyl)cyclopropane 5 with lithium and a catalytic amount of DTBB (5 mol %) in the presence of different carbonyl compounds [Et₂CO, n-Pr₂CO, (c-C₃H₅)₂CO, (CH₂)₅CO, PhCOMe, t-BuCHO, i-PrCHO, PhCHO] as electrophiles in THF at −78 °C leads, after hydrolysis with water, to the corresponding cyclopropyl alcohols 6. However, when the same starting material is lithiated using naphthalene as the arene catalyst in ether at 0 °C and then reacts with the same series of electrophiles, the final hydrolysis with water yields the corresponding unsaturated alcohols 7.     

Thermodynamic study on phase equilibrium of epoxy resin/thermoplastic blends

The experimental phase diagrams (cloud point curves) of three series of epoxy/thermoplastic blends, namely, epoxy/polystyrene (PS), epoxy/poly(ether sulfone) (PES), and epoxy/poly(ether imide) (PEI) as a function of molar mass and composition have been analysed from a thermodynamic point of view. A model based on the Flory–Huggins lattice theory considering the concentration dependence of the interaction parameter as predicted by Koningsveld was employed to determine the equilibrium compositions, and concentration and temperature dependent interaction parameters. Binodal, spinodal, and critical point data have been computed and show good agreement with experimental data.