Susete Pinteus

Cytoprotective effect of seaweeds with high antioxidant activity from the Peniche coast (Portugal)

Screening of antioxidant potential of dichloromethane and methanolic extracts of twenty-seven seaweeds from the Peniche coast was performed by: total phenolic contents (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Seaweeds revealing the highest antioxidant activity were screened for cytoprotective potential in MCF-7 cells, including the mitochondrial membrane potential analysis and the caspase-9 activity. High correlation was found between TPC of seaweed extracts and their scavenging capacity on DPPH and peroxyl radicals. The highest antioxidant activity was displayed by the methanolic fraction of brown seaweeds belonging to Fucales, however Ulva compressa presented the highest cytoprotective effect by blunting the apoptosis process. These results suggest that high antioxidant activity may not be directly related with high cytoprotective potential. Thus, seaweeds reveal to be a promising source of compounds with potential against oxidative stress.

Antitumor and Antimicrobial Potential of Bromoditerpenes Isolated from the Red Alga, Sphaerococcus coronopifolius

Cancer and infectious diseases continue to be a major public health problem, and new drugs are necessary. As marine organisms are well known to provide a wide range of original compounds, the aim of this study was to investigate the bioactivity of the main constituents of the cosmopolitan red alga, Sphaerococcus coronopifolius. The structure of several bromoditerpenes was determined by extensive spectroscopic analysis and comparison with literature data. Five molecules were isolated and characterized which include a new brominated diterpene belonging to the rare dactylomelane family and named sphaerodactylomelol (1), along with four already known sphaerane bromoditerpenes (2–5). Antitumor activity was assessed by cytotoxicity and anti-proliferative assays on an in vitro model of human hepatocellular carcinoma (HepG-2 cells). Antimicrobial activity was evaluated against four pathogenic microorganisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. Compound 4 exhibited the highest antimicrobial activity against S. aureus (IC50 6.35 µM) and compound 5 the highest anti-proliferative activity on HepG-2 cells (IC50 42.9 µM). The new diterpene, sphaerodactylomelol (1), induced inhibition of cell proliferation (IC50 280 µM) and cytotoxicity (IC50 720 µM) on HepG-2 cells and showed antimicrobial activity against S. aureus (IC50 96.3 µM).

Antioxidant and Antimicrobial Potential of the Bifurcaria bifurcata Epiphytic Bacteria

Surface-associated marine bacteria are an interesting source of new secondary metabolites. The aim of this study was the isolation and identification of epiphytic bacteria from the marine brown alga, Bifurcaria bifurcata, and the evaluation of the antioxidant and antimicrobial activity of bacteria extracts. The identification of epiphytic bacteria was determined by 16S rRNA gene sequencing. Bacteria extracts were obtained with methanol and dichloromethane (1:1) extraction. The antioxidant activity of extracts was performed by quantification of total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae and Candida albicans. A total of 39 Bifurcaria bifurcata-associated bacteria were isolated and 33 were identified as Vibrio sp. (48.72%), Alteromonas sp. (12.82%), Shewanella sp. (12.26%), Serratia sp. (2.56%), Citricoccus sp. (2.56%), Cellulophaga sp. (2.56%), Ruegeria sp. (2.56%) and Staphylococcus sp. (2.56%). Six (15.38%) of the 39 bacteria Bifurcaria bifurcata-associated bacteria presented less than a 90% Basic Local Alignment Search Tool (BLAST) match, and some of those could be new. The highest antioxidant activity and antimicrobial activity (against B. subtilis) was exhibited by strain 16 (Shewanella sp.). Several strains also presented high antimicrobial activity against S. aureus, mainly belonging to Alteromonas sp. and Vibrio sp. There were no positive results against fungi and Gram-negative bacteria. Bifurcaria bifurcata epiphytic bacteria were revealed to be excellent sources of natural antioxidant and antimicrobial compounds.

Antioxidant and Cytoprotective Activities of Fucus spiralis Seaweed on a Human Cell in Vitro Model

Antioxidants play an important role as Reactive Oxygen Species (ROS) chelating agents and, therefore, the screening for potent antioxidants from natural sources as potential protective agents is of great relevance. The main aim of this study was to obtain antioxidant-enriched fractions from the common seaweed Fucus spiralis and evaluate their activity and efficiency in protecting human cells (MCF-7 cells) on an oxidative stress condition induced by H2O2. Five fractions, F1–F5, were obtained by reversed-phase vacuum liquid chromatography. F3, F4 and F5 revealed the highest phlorotannin content, also showing the strongest antioxidant effects. The cell death induced by H2O2 was reduced by all fractions following the potency order F4 > F2 > F3 > F5 > F1. Only fraction F4 completely inhibited the H2O2 effect. To understand the possible mechanisms of action of these fractions, the cellular production of H2O2, the mitochondrial membrane potential and the caspase 9 activity were studied. Fractions F3 and F4 presented the highest reduction on H2O2 cell production. All fractions decreased both caspase-9 activity and cell membrane depolarization (except F1). Taken all together, the edible F. spiralis reveal that they provide protection against oxidative stress induced by H2O2 on the human MCF-7 cellular model, probably acting as upstream blockers of apoptosis.

Neuromodulatory effects of Calyptranthes grandifolia extracts against 6-hydroxydopamine-induced neurotoxicity in SH-SY5Y cells.

Alzheimers and Parkinsons diseases are neurodegenerative disorders characterized by progressive neuronal dysfunction. Previous studies revealed that some natural products have neuroprotective properties, including species of the Myrtaceae family. However, the neuromodulatory potential of Calyptranthes grandifolia is not clear. In the present study, we examined the ability of the ethanol and hexane leaf extracts of C. grandifolia to prevent 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in vitro. Initially, we investigated the potential of the extracts to inhibit the neurodegenerative-related enzymes c-Jun N-terminal kinase 3 (JNK3) and acetylcholinesterase (AChE). In addition, SH-SY5Y cell viability was assessed by MTT assay after 100μM 6-OHDA-induced cell damage. In order to verify the possible effects of both extracts on 6-OHDA-induced cell death, hydrogen peroxide generation, mitochondrial potential and caspases-3 activity were assessed. Our findings revealed that ethanol extract exhibited inhibitory activity against JNK3 and AChE. In addition, when co-treating SH-SY5Y cells with 6-OHDA and the extracts, oxidative stress was inhibited by both extracts through a decrease of mitochondrial depolarization and caspases-3 activity. In summary, ethanol and hexane extracts of C. grandifolia have some suppressive property against neurotoxicity induced by 6-OHDA.

From Marine Origin to Therapeutics: The Antitumor Potential of Marine Algae-Derived Compounds

Marine environment has demonstrated to be an interesting source of compounds with uncommon and unique chemical features on which the molecular modeling and chemical synthesis of new drugs can be based with greater efficacy and specificity for the therapeutics. Cancer is a growing public health threat, and despite the advances in biomedical research and technology, there is an urgent need for the development of new anticancer drugs. In this field, it is estimated that more than 60% of commercially available anticancer drugs are natural biomimetic inspired. Among the marine organisms, algae have revealed to be one of the major sources of new compounds of marine origin, including those exhibiting antitumor and cytotoxic potential. These compounds demonstrated ability to mediate specific inhibitory activities on a number of key cellular processes, including apoptosis pathways, angiogenesis, migration and invasion, in both in vitro and in vivo models, revealing their potential to be used as anticancer drugs. This review will focus on the bioactive molecules from algae with antitumor potential, from their origin to their potential uses, with special emphasis to the alga Sphaerococcus coronopifolius as a producer of cytotoxic compounds.

An Insight into Sargassum muticum Cytoprotective Mechanisms against Oxidative Stress on a Human Cell In Vitro Model

Sargassum muticum is a brown seaweed with strong potential to be used as a functional food ingredient, mainly due to its antioxidant properties. It is widely used in traditional oriental medicine for the treatment of numerous diseases. Nevertheless, few studies have been conducted to add scientific evidence on its effects as well as on the mechanisms of action involved. In this work, the human cell line MCF-7 was used as an in vitro cellular model to evaluate the capability of Sargassum muticum enriched fractions to protect cells on an oxidative stress condition. The concentration of the bioactive compounds was obtained by vacuum liquid chromatography applied on methanol (M) and 1:1 methanol:dichloromethane (MD) crude extracts, resulting in seven enriched fractions from the M extraction (MF2–MF8), and eight fractions from the MD extraction (MDF1–MDF8). All fractions were tested for cytotoxic properties on MCF-7 cells and the nontoxic ones were tested for their capacity to blunt the damaging effects of hydrogen peroxide-induced oxidative stress. The nontoxic effects were also confirmed in 3T3 fibroblast cells as a nontumor cell line. The antioxidant potential of each fraction, as well as changes in the cell’s real-time hydrogen peroxide production, in the mitochondrial membrane potential, and in Caspase-9 activity were evaluated. The results suggest that the protective effects evidenced by S. muticum can be related with the inhibition of hydrogen peroxide production and the inhibition of Caspase-9 activity.

In vitro activities of Ceiba speciosa (A.St.-Hil) Ravenna aqueous stem bark extract

Abstract Several species of the genus Ceiba (Malvaceae) are ethnopharmacologically used. Thus, this study aimed to investigate the in vitro beneficial properties of the aqueous stem bark extract of Ceiba speciosa. The extract presented a great amount of phenolic compounds (117.4 ± 6.2 mg GAE/g). The antioxidant activity was assessed by DPPH (IC50 = 42.87 μg/mL), ORAC (2351.17 μmol TE/g) and FRAP (235.94 μM FeSO4/g) methods. In addition, the extract reduced MCF-7 cell viability as assessed by MTT. However, it prevented mitochondrial membrane depolarization and reduced caspase-9 activity induced by hydrogen peroxide. In conclusion, these findings indicate the extract is an excellent source of natural antioxidants and is able to protect ROS-induced cell death. Therefore, C. speciosa extract may possess beneficial properties for application in pharmaceutical industry as an antioxidant. However, further studies to better elucidate its mechanisms and to isolate its active compounds are required.

In vitro activities of kappa -carrageenan isolated from red marine alga Hypnea musciformis : Antimicrobial, anticancer and neuroprotective potential

This study assessed the antioxidant, antimicrobial, anticancer and neuroprotective activities of the kappa(k)-carrageenan isolated from the red alga Hypnea musciformis (Hm-SP). The chemical spectrum of the k-carrageenan from Hm-SP was confirmed by Fourier transform infrared (FT-IR) spectroscopy. Hm-SP revealed an antibacterial and antifungal action against Staphylococcus aureus and Candida albicans, respectively. Hm-SP did not promoted cytotoxic effects against Human breast cancer (MCF-7) and Human neuroblastoma (SH-SY5Y) cell-lines. However, it was observed a significant reduction of the cellular proliferation capacity in these cancer cells in presence of the Hm-SP. Furthermore, Hm-SP showed neuroprotective activity in 6-hydroxydopamine-induced neurotoxicity on SH-SY5Y cells by modulation of the mitochondria transmembrane potential and reducing Caspase 3 activity. In addition, Hm-SP demonstrates low antioxidant potential and did not induce significant cytotoxic effects or changes in the cell proliferation on Balb/c 3T3 mouse fibroblast cell-line. In summary, our data suggest that Hm-SP shows antimicrobial, anticancer and neuprotective activities.