Recent antibacterial carbohydrate-based prodrugs, drugs and delivery systems to overcome antimicrobial resistance.

Antimicrobial resistance is an increasing phenomenon that is threatening global health. Tuberculosis causative bacteria and several resistant and multidrug-resistant bacteria are widely spread and listed by the World Health Organization as global priorities for research and development. Hence, new antibacterial agents with new modes of action are urgently required. In this context, carbohydrate-based drugs have been extensively studied and used, presenting several benefits for therapeutical purposes. In this review, the latest efforts done in the carbohydrate-based antibacterial agents research field, reported from 2021 to 2023, are summarized. Carbohydrate-based prodrugs, drugs, and delivery systems are covered, highlighting derivatization of existing antibiotics, use of nanotechnology, and repurposing of available therapeutical agents as the most popular strategies used in antibacterial agents' development.

Alkyl deoxyglycoside-polymyxin combinations against critical priority carbapenem-resistant gram-negative bacteria.

The escalating antimicrobial resistance crisis urges the development of new antibacterial treatments with innovative mechanisms of action, particularly against the critical priority carbapenem-resistant Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA) and Enterobacteriaceae (CRE). Membrane-disrupting dodecyl deoxyglycosides have been reported for their interesting phosphatidylethanolamine-associated bactericidal activity against Gram-positive strains; however, their inability to penetrate the Gram-negative outer membrane (OM) renders them useless against the most challenging pathogens. Aiming to repurpose alkyl deoxyglycosides against Gram-negative bacteria, this study investigates the antimicrobial effects of five reference compounds with different deoxygenation patterns or anomeric configurations in combination with polymyxins as adjuvants for enhanced OM permeability. The generation of the lead 4,6-dideoxy scaffold was optimized through a simultaneous dideoxygenation step and applied to the synthesis of a novel alkyl 4,6-dideoxy C-glycoside 5, herein reported for the first time. When combined with subtherapeutic colistin concentrations, most glycosides demonstrated potent antimicrobial activity against several multidrug-resistant clinical isolates of CRAB, CRE and CRPA exhibiting distinct carbapenem resistance mechanisms, together with acceptable cytotoxicity against human HEK-293T and Caco-2 cells. The novel 4,6-dideoxy C-glycoside 5 emerged as the most promising prototype structure for further development (MIC 3.1 µg/mL when combined with colistin 0.5 µg/mL against CRPA or 0.25 µg/mL against several CRE and CRAB strains), highlighting the potential of C-glycosylation for an improved bioactive profile. This study is the first to show the potential of IM-targeting carbohydrate-based compounds for the treatment of infections caused by MDR Gram-negative pathogens of clinical importance.

Nucleoside analogues: N-glycosylation methodologies, synthesis of antiviral and antitumor drugs and potential against drug-resistant bacteria and Alzheimer's disease.

Nucleosides have gained significant attention since the discovery of the structure of DNA. Nucleoside analogues may be synthesized through multiple synthetic pathways, however the N-glycosylation of a nucleobase is the most common method. Amongst the different classical N-glycosylation methodologies, the Vorbrüggen glycosylation is the most popular method. This review focuses on the synthesis and therapeutic applications of several FDA approved nucleoside analogues as antiviral and anticancer agents. Moreover, this review also focuses on the potential of these compounds as new antibacterial and anti-Alzheimer's disease agents, offering an overview of the most recent research in these fields.

Synthesis, Biological Evaluation, and Docking Studies of Open-Chain Carbohydrate Amides as Acetylcholinesterase Inhibitors.

INTRODUCTION: Alzheimer's disease is a multifactorial syndrome, which is not yet fully understood, causing memory loss, dementia, and, ultimately, death. Acetylcholinesterase inhibitors are the mainstay drugs that are used in disease-symptomatic treatment. In this work, we report a new synthetic route yielding sugar amides as low to moderate acetylcholinesterase inhibitors. METHODS: Commercially available diacetone glucose was converted into perbenzyl D-glucono-1,4- lactone, which reacted with aromatic or aliphatic amines to afford the corresponding new amides in a high isolated yield. Docking studies of the most promising hydroxybutylamide and benzylamide were performed to assign binding interactions with acetylcholinesterase and determine the key features for bioactivity. RESULTS: The inhibitors are accommodated in enzyme gorge, blocking the access to Ser203 mainly due to π-π stacking interactions of sugar benzyl groups with the aromatic gorge residues, Tyr337 and Tyr341 for both inhibitors and Trp439 only for the hydroxybutylamide. CONCLUSION: Bonding is also significant through sugar interaction with the residues Tyr124 and Ser125-OH in both inhibitors. Flexibility of these open-chain structures seems to be quite relevant for the observed binding to acetylcholinesterase.

Marine Sources of DHA-Rich Phospholipids with Anti-Alzheimer Effect.

Alzheimer's disease (AD) is a complex and progressive disease, which affects millions of people around the world. Despite the many efforts over the years to find efficient therapeutics, there is no cure yet. Nonetheless, many compounds have been proven to decrease Alzheimer's symptoms. After a short overview of the hypotheses considered in AD drug development and the drugs approved for AD treatment, which lead to symptom release, we focus on the valorization of natural marine sources that decrease AD symptoms, particularly on docosahexaenoic acid (DHA), an important component in membrane phospholipids and the most abundant n-3 polyunsaturated fatty acids (PUFA) found in gray matter of the brain and in retina and on the DHA-containing phospholipids (DHA-PLs) present in marine sources, namely fish, krill, mollusks and in fisheries and aquaculture by-products. DHA-PLs' bioactivities are presented, namely their properties in anti-neurodegeneration, neuroinflammation, as anticancer agents, as well as their benefits to obesity and visual problems. Fisheries and aquaculture by-products are also highlighted as they have a high content of DHA and DHA-rich phospholipids, can be extracted by green methodologies and should be considered in a circular economy for a healthy sustainable future.

Resolvins, Protectins, and Maresins: DHA-Derived Specialized Pro-Resolving Mediators, Biosynthetic Pathways, Synthetic Approaches, and Their Role in Inflammation.

Marine organisms are an important source of natural products with unique and diverse chemical structures that may hold the key for the development of novel drugs. Docosahexaenoic acid (DHA) is an omega-3 fatty acid marine natural product playing a crucial regulatory role in the resolution of inflammation and acting as a precursor for the biosynthesis of the anti-inflammatory specialized pro-resolving mediators (SPMs) resolvins, protectins, and maresins. These metabolites exert many beneficial actions including neuroprotection, anti-hypertension, or anti-tumorigenesis. As dysregulation of SPMs is associated with diseases of prolonged inflammation, the disclosure of their bioactivities may be correlated with anti-inflammatory and pro-resolving capabilities, offering new targets for drug design. The availability of these SPMs from natural resources is very low, but the evaluation of their pharmacological properties requires their access in larger amounts, as achieved by synthetic routes. In this report, the first review of the total organic syntheses carried out for resolvins, protectins, and maresins is presented. Recently, it was proposed that DHA-derived pro-resolving mediators play a key role in the treatment of COVID-19. In this work we also review the current evidence on the structures, biosynthesis, and functional and new-found roles of these novel lipid mediators of disease resolution.

Exploring Mannosylpurines as Copper Chelators and Cholinesterase Inhibitors with Potential for Alzheimer's Disease.

Alzheimer's Disease (AD) is characterized by a progressive cholinergic neurotransmission imbalance, with a decrease of acetylcholinesterase (AChE) activity followed by a significant increase of butyrylcholinesterase (BChE) in the later AD stages. BChE activity is also crucial for the development of Aß plaques, the main hallmarks of this pathology. Moreover, systemic copper dyshomeostasis alters neurotransmission leading to AD. In the search for structures targeting both events, a set of novel 6-benzamide purine nucleosides was synthesized, differing in glycone configuration and N7/N9 linkage to the purine. Their AChE/BChE inhibitory activity and metal ion chelating properties were evaluated. Selectivity for human BChE inhibition required N9-linked 6-deoxy-α-d-mannosylpurine structure, while all three tested ß-d-derivatives appeared as non-selective inhibitors. The N9-linked l-nucleosides were cholinesterase inhibitors except the one embodying either the acetylated sugar or the N-benzyl-protected nucleobase. These findings highlight that sugar-enriched molecular entities can tune bioactivity and selectivity against cholinesterases. In addition, selective copper chelating properties over zinc, aluminum, and iron were found for the benzyl and acetyl-protected 6-deoxy-α-l-mannosyl N9-linked purine nucleosides. Computational studies highlight molecular conformations and the chelating molecular site. The first dual target compounds were disclosed with the perspective of generating drug candidates by improving water solubility.

Amyloid binding and beyond: a new approach for Alzheimer's disease drug discovery targeting Aßo-PrPC binding and downstream pathways.

Amyloid ß oligomers (Aßo) are the main toxic species in Alzheimer's disease, which have been targeted for single drug treatment with very little success. In this work we report a new approach for identifying functional Aßo binding compounds. A tailored library of 971 fluorine containing compounds was selected by a computational method, developed to generate molecular diversity. These compounds were screened for Aßo binding by a combined 19F and STD NMR technique. Six hits were evaluated in three parallel biochemical and functional assays. Two compounds disrupted Aßo binding to its receptor PrPC in HEK293 cells. They reduced the pFyn levels triggered by Aßo treatment in neuroprogenitor cells derived from human induced pluripotent stem cells (hiPSC). Inhibitory effects on pTau production in cortical neurons derived from hiPSC were also observed. These drug-like compounds connect three of the pillars in Alzheimer's disease pathology, i.e. prion, Aß and Tau, affecting three different pathways through specific binding to Aßo and are, indeed, promising candidates for further development.

C-Glucosylation as a tool for the prevention of PAINS-induced membrane dipole potential alterations.

The concept of Pan-Assay Interference Compounds (PAINS) is regarded as a threat to the recognition of the broad bioactivity of natural products. Based on the established relationship between altered membrane dipole potential and transmembrane protein conformation and function, we investigate here polyphenols' ability to induce changes in cell membrane dipole potential. Ultimately, we are interested in finding a tool to prevent polyphenol PAINS-type behavior and produce compounds less prone to untargeted and promiscuous interactions with the cell membrane. Di-8-ANEPPS fluorescence ratiometric measurements suggest that planar lipophilic polyphenols-phloretin, genistein and resveratrol-act by decreasing membrane dipole potential, especially in cholesterol-rich domains such as lipid rafts, which play a role in important cellular processes. These results provide a mechanism for their labelling as PAINS through their ability to disrupt cell membrane homeostasis. Aiming to explore the role of C-glucosylation in PAINS membrane-interfering behavior, we disclose herein the first synthesis of 4-glucosylresveratrol, starting from 5-hydroxymethylbenzene-1,3-diol, via C-glucosylation, oxidation and Horner-Wadsworth-Emmons olefination, and resynthesize phloretin and genistein C-glucosides. We show that C-glucosylation generates compounds which are no longer able to modify membrane dipole potential. Therefore, it can be devised as a strategy to generate bioactive natural product derivatives that no longer act as membrane dipole potential modifiers. Our results offer a new technology towards rescuing bioactive polyphenols from their PAINS danger label through C-C ligation of sugars.

Glucosylpolyphenols as Inhibitors of Aß-Induced Fyn Kinase Activation and Tau Phosphorylation: Synthesis, Membrane Permeability, and Exploratory Target Assessment within the Scope of Type 2 Diabetes and Alzheimer's Disease.

Despite the rapidly increasing number of patients suffering from type 2 diabetes, Alzheimer's disease, and diabetes-induced dementia, there are no disease-modifying therapies that are able to prevent or block disease progress. In this work, we investigate the potential of nature-inspired glucosylpolyphenols against relevant targets, including islet amyloid polypeptide, glucosidases, and cholinesterases. Moreover, with the premise of Fyn kinase as a paradigm-shifting target in Alzheimer's drug discovery, we explore glucosylpolyphenols as blockers of Aß-induced Fyn kinase activation while looking into downstream effects leading to Tau hyperphosphorylation. Several compounds inhibit Aß-induced Fyn kinase activation and decrease pTau levels at 10 µM concentration, particularly the per-O-methylated glucosylacetophloroglucinol and the 4-glucosylcatechol dibenzoate, the latter inhibiting also butyrylcholinesterase and ß-glucosidase. Both compounds are nontoxic with ideal pharmacokinetic properties for further development. This work ultimately highlights the multitarget nature, fine structural tuning capacity, and valuable therapeutic significance of glucosylpolyphenols in the context of these metabolic and neurodegenerative disorders.

Design and Synthesis of CNS-targeted Flavones and Analogues with Neuroprotective Potential Against H2O2- and Aß1-42-Induced Toxicity in SH-SY5Y Human Neuroblastoma Cells.

With the lack of available drugs able to prevent the progression of Alzheimer's disease (AD), the discovery of new neuroprotective treatments able to rescue neurons from cell injury is presently a matter of extreme importance and urgency. Here, we were inspired by the widely reported potential of natural flavonoids to build a library of novel flavones, chromen-4-ones and their C-glucosyl derivatives, and to explore their ability as neuroprotective agents with suitable pharmacokinetic profiles. All compounds were firstly evaluated in a parallel artificial membrane permeability assay (PAMPA) to assess their effective permeability across biological membranes, namely the blood-brain barrier (BBB). With this test, we aimed not only at assessing if our candidates would be well-distributed, but also at rationalizing the influence of the sugar moiety on the physicochemical properties. To complement our analysis, logD7.4 was determined. From all screened compounds, the p-morpholinyl flavones stood out for their ability to fully rescue SH-SY5Y human neuroblastoma cells against both H2O2- and Aß1-42-induced cell death. Cholinesterase inhibition was also evaluated, and modest inhibitory activities were found. This work highlights the potential of C-glucosylflavones as neuroprotective agents, and presents the p-morpholinyl C-glucosylflavone 37, which did not show any cytotoxicity towards HepG2 and Caco-2 cells at 100 µM, as a new lead structure for further development against AD.

Membrane-targeting antibiotics: recent developments outside the peptide space.

The rise of antibiotic resistant bacteria requires unconventional strategies toward efficient chemotherapeutic agents, preferably with alternative mechanisms of action. The bacterial cell membrane has become an appealing target since its essential and highly conservative structure are key challenges to resistance mechanisms. Inspired by natural antimicrobial peptides, research on membrane-targeting antimicrobials has been growing out of the peptide space. The pursuit of more druggable molecules led to the discovery that the pharmacophore of antimicrobial peptides is smaller than anticipated. Several promising classes of membrane-targeting antimicrobials have been discovered, such as ceragenins, reutericyclines, carbohydrate amphiphiles - among others. This review will discuss the most recent findings on membrane-targeting antibiotics, focusing on small molecules outside the antimicrobial peptide molecular space.

Sugar-based bactericides targeting phosphatidylethanolamine-enriched membranes.

Anthrax is an infectious disease caused by Bacillus anthracis, a bioterrorism agent that develops resistance to clinically used antibiotics. Therefore, alternative mechanisms of action remain a challenge. Herein, we disclose deoxy glycosides responsible for specific carbohydrate-phospholipid interactions, causing phosphatidylethanolamine lamellar-to-inverted hexagonal phase transition and acting over B. anthracis and Bacillus cereus as potent and selective bactericides. Biological studies of the synthesized compound series differing in the anomeric atom, glycone configuration and deoxygenation pattern show that the latter is indeed a key modulator of efficacy and selectivity. Biomolecular simulations show no tendency to pore formation, whereas differential metabolomics and genomics rule out proteins as targets. Complete bacteria cell death in 10 min and cellular envelope disruption corroborate an effect over lipid polymorphism. Biophysical approaches show monolayer and bilayer reorganization with fast and high permeabilizing activity toward phosphatidylethanolamine membranes. Absence of bacterial resistance further supports this mechanism, triggering innovation on membrane-targeting antimicrobials.

Broad bean (Vicia faba L.) pods: a rich source of bioactive ingredients with antimicrobial, antioxidant, enzyme inhibitory, anti-diabetic and health-promoting properties.

This study was aimed at investigating the chemical composition (proximate, minerals, fatty acids and phenolic compounds) and the in vitro (antimicrobial, radical scavenging, anti-acetylcholinesterase and protein denaturing activities) and in vivo (anti-diabetic and histo-protective effects in alloxan-induced diabetic mice) biological activities of broad bean pods (BBPs), a food waste by-product material. The results showed that BBPs have high dietary fiber (57.46%), carbohydrate (18.93%) and protein (13.81%) content versus low fat content (<1%) contributing to a low energy value of 139.24 kcal per 100 g. Profiling of fatty acids showed an abundance of the essential polyunsaturated α-linolenic and linoleic acids, exhibiting an excellent nutritional quality as revealed by their low atherogenic and thrombogenic indices and their hypocholesterolemic properties. The methanol extract which exhibited the highest total phenolic, flavonoid and tannin contents was found to be the most active extract in terms of antimicrobial and anti-radical activities. In alloxan-induced diabetic mice, the oral administration of a methanol extract (500 mg per kg bw) attenuated the elevated levels of serum alanine aminotransferase (ALA), aspartate aminotransferase (AST), and alkaline phosphatase activities, and urea, uric acid, and creatinine. It effectively normalized the status of lipid profiles, mitigated oxidative stress through the activation of antioxidant enzymes (CAT, GPx and SOD), and alleviated oxidative stress-mediated histopathological changes in the pancreas, liver, kidney and testis. Compositional analysis by HPLC-PDA-ESI-MS/MS revealed the presence of flavan-3-ols (catechin, epicatechin and their derivatives), flavones (apigenin derivatives) and flavonols (glycosides of quercetin and kaempferol), among others. These findings suggest that BBPs may be an effective functional food for the management of diabetes and its complications.

Exploring Anti-Prion Glyco-Based and Aromatic Scaffolds: A Chemical Strategy for the Quality of Life.

Prion diseases are fatal neurodegenerative disorders caused by protein misfolding and aggregation, affecting the brain progressively and consequently the quality of life. Alzheimer's is also a protein misfolding disease, causing dementia in over 40 million people worldwide. There are no therapeutics able to cure these diseases. Cellular prion protein is a high-affinity binding partner of amyloid ß (Aß) oligomers, the most toxic species in Alzheimer's pathology. These findings motivate the development of new chemicals for a better understanding of the events involved. Disease control is far from being reached by the presently known therapeutics. In this review we describe the synthesis and mode of action of molecular entities with intervention in prion diseases' biological processes and, if known, their role in Alzheimer's. A diversity of structures is covered, based on glycans, steroids and terpenes, heterocycles, polyphenols, most of them embodying aromatics and a structural complexity. These molecules may be regarded as chemical tools to foster the understanding of the complex mechanisms involved, and to encourage the scientific community towards further developments for the cure of these devastating diseases.

Unlocking the in vitro anti-inflammatory and antidiabetic potential of Polygonum maritimum.

CONTEXT: Several Polygonum species (Polygonaceae) are used in traditional medicine in Asia, Europe and Africa to treat inflammation and diabetes. OBJECTIVE: Evaluate the in vitro antioxidant, anti-inflammatory and antidiabetic potential of methanol and dichloromethane extracts of leaves and roots of the halophyte Polygonum maritimum L. MATERIAL AND METHODS: Antioxidant activity was determined (up to 1 mg/mL) as radical-scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), copper (CCA) and iron (ICA) chelating activities and iron reducing power (FRAP). NO production was measured in lipopolysaccharide (LPS)-stimulated macrophages for 24 h at concentrations up to 100 µg/mL and antidiabetic potential was assessed by α-amylase and α-glucosidase inhibition (up to 10 mg/mL) assays. The phytochemical composition of the extracts was determined by gas chromatography-mass spectrometry (GC-MS). RESULTS: The methanol leaf extract had the highest activity against DPPH• (IC50 = 26 µg/mL) and ABTS+• (IC50 = 140 µg/mL), FRAP (IC50 = 48 µg/mL) and CCA (IC50 = 770 µg/mL). Only the dichloromethane leaf extract (LDCM) showed anti-inflammatory activity (IC50 = 48 µg/mL). The methanol root (IC50 = 19 µg/mL) and leaf (IC50 = 29 µg/mL) extracts strongly inhibited baker's yeast α-glucosidase, but LDCM had higher rat's α-glucosidase inhibition (IC50 = 2527 µg/mL) than acarbose (IC50 = 4638 µg/mL). GC-MS analysis identified ß-sitosterol, stigmasterol, 1-octacosanol and linolenic acid as possible molecules responsible for the observed bioactivities. CONCLUSIONS: Our findings suggest P. maritimum as a source of high-value health promoting commodities for alleviating symptoms associated with oxidative and inflammatory diseases, including diabetes.

Targeting Type 2 Diabetes with C-Glucosyl Dihydrochalcones as Selective Sodium Glucose Co-Transporter 2 (SGLT2) Inhibitors: Synthesis and Biological Evaluation.

Inhibiting glucose reabsorption by sodium glucose co-transporter proteins (SGLTs) in the kidneys is a relatively new strategy for treating type 2 diabetes. Selective inhibition of SGLT2 over SGLT1 is critical for minimizing adverse side effects associated with SGLT1 inhibition. A library of C-glucosyl dihydrochalcones and their dihydrochalcone and chalcone precursors was synthesized and tested as SGLT1/SGLT2 inhibitors using a cell-based fluorescence assay of glucose uptake. The most potent inhibitors of SGLT2 (IC50 = 9-23 nM) were considerably weaker inhibitors of SGLT1 (IC50 = 10-19 µM). They showed no effect on the sodium independent GLUT family of glucose transporters, and the most potent ones were not acutely toxic to cultured cells. The interaction of a C-glucosyl dihydrochalcone with a POPC membrane was modeled computationally, providing evidence that it is not a pan-assay interference compound. These results point toward the discovery of structures that are potent and highly selective inhibitors of SGLT2.

Isololiolide, a carotenoid metabolite isolated from the brown alga Cystoseira tamariscifolia, is cytotoxic and able to induce apoptosis in hepatocarcinoma cells through caspase-3 activation, decreased Bcl-2 levels, increased p53 expression and PARP cleavage.

BACKGROUND: Brown macroalgae have attracted attention because they display a wide range of biological activities, including antitumoral properties. Inthis study we isolated isololiolide from Cystoseira tamariscifolia for the first time. PURPOSE: To examine the therapeutical potential of isololiolide against tumor cell lines. METHODS/STUDY DESIGN: The structure of the compound was established and confirmed by 1D and 2D NMR as well as HRMS spectral analysis. The in vitro cytotoxicity was analyzed by colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay in tumoral as well as in non-tumoral cell lines. Cell cycle arrest and induction of apoptosis were assessed by flow cytometry. Alteration of expression levels in proteins important in the apoptotic cascade was analyzed by western blotting. RESULTS: Isololiolidewas isolated for the first time from the brown macroalga C.tamariscifolia. Isololiolide exhibited significant cytotoxic activity against three human tumoral cell lines, namely hepatocarcinoma HepG2 cells, whereas no cytotoxicity was found in non-malignant MRC-5 and HFF-1 human fibroblasts. Isololiolide completely disrupted the HepG2 normal cell cycle and induced significant apoptosis. Moreover, western blot analysis showed that isololiolide altered the expression of proteins that are important in the apoptotic cascade, increasing PARP cleavage and p53 expression while decreasing procaspase-3 and Bcl-2 levels. CONCLUSION: Isololiolide isolated from C. tamariscifolia is able to exert a selective cytotoxic activity on hepatocarcinoma HepG2 cells as well as induce apoptosis through the modulation of apoptosis-related proteins.

Can macroalgae provide promising anti-tumoral compounds? A closer look at Cystoseira tamariscifolia as a source for antioxidant and anti-hepatocarcinoma compounds.

Marine organisms are a prolific source of drug leads in a variety of therapeutic areas. In the last few years, biomedical, pharmaceutical and nutraceutical industries have shown growing interest in novel compounds from marine organisms, including macroalgae. Cystoseira is a genus of Phaeophyceae (Fucales) macroalgae known to contain bioactive compounds. Organic extracts (hexane, diethyl ether, ethyl acetate and methanol extracts) from three Cystoseira species (C. humilis, C. tamariscifolia and C. usneoides) were evaluated for their total phenolic content, radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals, and antiproliferative activity against a human hepatocarcinoma cell line (HepG2 cells). C. tamariscifolia had the highest TPC and RSA. The hexane extract of C. tamariscifolia (CTH) had the highest cytotoxic activity (IC50 = 2.31 µg/mL), and was further tested in four human tumor (cervical adenocarcinoma HeLa; gastric adenocarcinoma AGS; colorectal adenocarcinoma HCT-15; neuroblastoma SH-SY5Y), and two non-tumor (murine bone marrow stroma S17 and human umbilical vein endothelial HUVEC) cell lines in order to determine its selectivity. CTH strongly reduced viability of all tumor cell lines, especially of HepG2 cells. Cytotoxicity was particularly selective for the latter cells with a selectivity index = 12.6 as compared to non-tumor cells. Incubation with CTH led to a 2-fold decrease of HepG2 cell proliferation as shown by the bromodeoxyuridine (BrdU) incorporation assay. CTH-treated HepG2 cells presented also pro-apoptotic features, such as increased Annexin V/propidium iodide (PI) binding and dose-dependent morphological alterations in DAPI-stained cells. Moreover, it had a noticeable disaggregating effect on 3D multicellular tumor spheroids. Demethoxy cystoketal chromane, a derivative of the meroditerpenoid cystoketal, was identified as the active compound in CTH and was shown to display selective in vitro cytotoxicity towards HepG2 cells.

In vitro antioxidant and anti-inflammatory properties of Limonium algarvense flowers' infusions and decoctions: A comparison with green tea (Camellia sinensis).

This work reports the in vitro antioxidant and anti-inflammatory activities and toxicity of infusions and decoctions of Limonium algarvense flowers, and green tea. The total contents in different phenolic groups and the quantification of individual phenolics by HPLC are also reported. L. algarvense and green tea had similar antioxidant properties, except for hydroxyl radical-scavenging activity, higher on green tea, and iron chelating potential, higher on L. algarvense. The later species also had the uppermost anti-inflammatory potential. Green tea decoction had the highest content of phenolic groups, but the infusion of L. algarvense had higher amounts of salicylic, gallic and coumaric acids. L. algarvense was not toxic, whereas green tea was toxic for S17 cells. Under our experimental conditions, infusions and decoctions of L. algarvense flowers had similar or higher antioxidant and anti-inflammatory properties than green tea, and thus, may be useful for alleviating symptoms associated with oxidative and inflammatory-related diseases.