Toxicity and structure-activity relationship (SAR) of α,β-dehydroamino acids against human cancer cell lines

An Experimental Approach to Address the Functional Relationship between Antioxidant Enzymes and Mitochondrial Respiratory Complexes

Mitochondrial dysfunction and cytosolic oxidative stress are pathological biomarkers interlinked in several chronic diseases and cellular toxicity promoted by high-energy radiation or xenobiotics. Thus, assessing the activities of the mitochondrial redox chain complexes and the cytosolic antioxidant enzymes in the same cell culture system is a valuable approach to addressing the challenge of chronic diseases or unveiling the molecular mechanisms underlying the toxicity of physical and chemical stress agents. The present article gathers the experimental procedures to obtain, from isolated cells, a mitochondria-free cytosolic fraction and a mitochondria-rich fraction. Furthermore, we describe the methodologies to evaluate the activity of the main antioxidant enzymes in the mitochondria-free cytosolic fraction (superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase), and the activity of the individual mitochondrial complexes I, II and IV, as well as the conjugated activity of complexes I-III and complexes II-III in the mitochondria-rich fraction. The protocol to test the citrate synthase activity was also considered and used to normalize complexes. The procedures were optimized within an experimental setup to allow that each condition to be tested only requires sampling of one T-25 flask of cells 2D cultured, as the typical results presented and discussed here.

Eugenol β-Amino/β-Alkoxy Alcohols with Selective Anticancer Activity

Eugenol, 4-allyl-2-methoxyphenol, is the main constituent of clove essential oil and has demonstrated relevant biological activity, namely anticancer activity. Aiming to increase this activity, we synthesized a series of eugenol β-amino alcohol and β-alkoxy alcohol derivatives, which were then tested against two human cancer cell lines, namely gastric adenocarcinoma cells (AGS) and lung adenocarcinoma cells (A549). An initial screening was performed to identify the most cytotoxic compounds. The results demonstrated that three β-amino alcohol derivatives had anticancer activity that justified subsequent studies, having been shown to trigger apoptosis. Importantly, the most potent molecules displayed no appreciable toxicity towards human noncancer cells. Structure-activity relationships show that changes in eugenol structure led to enhanced cytotoxic activity and can contribute to the future design of more potent and selective drugs.

Total synthesis and stereochemistry establishment of tumescenamide A

Tumescenamide A (1), isolated from Streptomyces tumescens YM23-20, consists of a cyclic depsipeptide and a side-chain 2,4-dimethylheptanoate (Dmh).

A nanophytosomes formulation based on elderberry anthocyanins and Codium lipids to mitigate mitochondrial dysfunctions

The development of nanomedicines to modulate the mitochondrial function is a great scientific challenge since mitochondrial dysfunction is a pathological hallmark of many chronic diseases, including degenerative brain pathologies like Parkinson's and Alzheimer's diseases. To address this challenge, the mitochondriotropic features of the elderberry anthocyanin-enriched extract (Sambucus nigra) were combined with the self-assembling properties of the membrane polar lipids from Codium tomentosum in an innovative SC-Nanophytosomes formulation. Membrane polar lipids, obtained by a new procedure as chlorophyll-free extract, are characterized by 26% of non-phosphorus polar lipids and 74% of phospholipids (dominated by anionic lipids) containing a high degree of polyunsaturated fatty acids. The anthocyanin-enriched extract is dominated by a mixture of four cyanidin-glycosides, representing about 86% of their phenolic content. SC-Nanophytosomes engineered with 600 µM algae membrane polar lipids and 0.5 mg/L of the anthocyanin-enriched extract are nanosized vesicles (diameter =108.74 ± 24.74 nm) with a negative surface charge (Zeta potential = -46.93 ± 6.63 mV) that exhibit stability during storage at 4 ºC. In vitro assays with SH-SY5Y cells showed that SC-Nanophytosomes have the competence to target mitochondria, improving the mitochondrial respiratory chain complexes I and II and preserving the mitochondrial membrane potential in the presence of rotenone. Additionally, SC-Nanophytosomes protect SH-SY5Y cells against the toxicity induced by rotenone or glutamate. Green-fluorescent labeled SC-Nanophytosomes were used to reveal that they are mainly internalized by cells via caveola-mediated endocytosis, escape from endosome and reach the cytoplasm organelles, including mitochondria. Overall, data indicate that SC-Nanophytosomes have the potential to support a mitochondria-targeted therapy for neurodegenerative diseases.

Dipeptides of S-Substituted Dehydrocysteine as Artzyme Building Blocks: Synthesis, Complexing Abilities and Antiproliferative Properties

BACKGROUND

Dehydropeptides are analogs of peptides containing at least one conjugate double bond between α,β-carbon atoms. Its presence provides unique structural properties and reaction centre for chemical modification. In this study, the series of new class of dipeptides containing S-substituted dehydrocysteine with variety of heterocyclic moieties was prepared. The compounds were designed as the building blocks for the construction of artificial metalloenzymes (artzymes). Therefore, the complexing properties of representative compounds were also evaluated. Furthermore, the acknowledged biological activity of natural dehydropeptides was the reason to extend the study for antiproliferative action of against several cancer cell lines.

METHODS

The synthetic strategy involves glycyl and phenylalanyl-(Z)-β-bromodehydroalanine as a substrate in one pot addition/elimination reaction of thiols. After deprotection of N-terminal amino group the compounds with triazole ring were tested as complexones for copper(II) ions using potentiometric titration and spectroscopic techniques (UV-Vis, CD, EPR). Finally, the antiproliferative activity was evaluated by sulforhodamine B assay.

RESULTS AND CONCLUSIONS

A simple and efficient procedure for preparation of dipeptides containing S-substituded dehydrocysteine was provided. The peptides containing triazole appeared to be strong complexones of copper(II) ions. Some of the peptides exhibited promising antiproliferative activities against number of cancer cell lines, including cell lines resistant to widely used anticancer agent.

Novel styrylpyrazole-glucosides and their dioxolo-bridged doppelgangers: synthesis and cytotoxicity

Novel styrylpyrazole-glucoside conjugates4and5are reported, with5c, aN-glucosyldioxolo derivative being very active against stomach cancer (AGS) cells.