Anti-Hepatocellular Carcinoma (HepG2) Activities of Monoterpene Hydroxy Lactones Isolated from the Marine Microalga Tisochrysis Lutea.

Tisochrysis lutea is a marine haptophyte rich in omega-3 polyunsaturated fatty acids (e.g., docosahexaenoic acid (DHA)) and carotenoids (e.g., fucoxanthin). Because of the nutraceutical applications of these compounds, this microalga is being used in aquaculture to feed oyster and shrimp larvae. In our earlier report, T. lutea organic crude extracts exhibited in vitro cytotoxic activity against human hepatocarcinoma (HepG2) cells. However, so far, the compound(s) accountable for the observed bioactivity have not been identified. Therefore, the aim of this study was to isolate and identify the chemical component(s) responsible for the bioactivity observed. Bioassay-guided fractionation through a combination of silica-gel column chromatography, followed by preparative thin layer chromatography (PTLC), led to the isolation of two diastereomers of a monoterpenoid lactone, namely, loliolide (1) and epi-loliolide (2), isolated for the first time in this species. The structural elucidation of both compounds was carried out by GC-MS and 1D (1H and 13C APT) and 2D (COSY, HMBC, HSQC-ed, and NOESY) NMR analysis. Both compounds significantly reduced the viability of HepG2 cells and were considerably less toxic towards a non-tumoral murine stromal (S17) cell line, although epi-loliolide was found to be more active than loliolide.

Improvement of carotenoid extraction from a recently isolated, robust microalga, Tetraselmis sp. CTP4 (chlorophyta).

In recent years, there has been increasing consumer interest in carotenoids, particularly of marine sustainable origin with applications in the food, cosmeceutical, nutritional supplement and pharmaceutical industries. For instance, microalgae belonging to the genus Tetraselmis are known for their biotechnologically relevant carotenoid profile. The recently isolated marine microalgal strain Tetraselmis sp. CTP4 is a fast-growing, robust industrial strain, which has successfully been produced in 100-m3 photobioreactors. However, there are no reports on total carotenoid contents from this strain belonging to T. striata/convolutae clade. Although there are several reports on extraction methods targeting chlorophytes, extraction depends on the strength of cell coverings, solvent polarity and the nature of the targeted carotenoids. Therefore, this article evaluates different extraction methods targeting Tetraselmis sp. CTP4, a strain known to contain a mechanically resistant theca. Here, we propose a factorial experimental design to compare extraction of total carotenoids from wet and freeze-dried microalgal biomass using four different solvents (acetone, ethanol, methanol or tetrahydrofuran) in combination with two types of mechanical cell disruption (glass beads or dispersion). The extraction efficiency of the methods was assessed by pigment contents and profiles present in the extracts. Extraction of wet biomass by means of glass bead-assisted cell disruption using tetrahydrofuran yielded the highest amounts of lutein and ß-carotene (622 ± 40 and 618 ± 32 µg g-1 DW, respectively). Although acetone was slightly less efficient than tetrahydrofuran, it is preferable due to its lower costs and toxicity.

Nutritional Potential and Toxicological Evaluation of Tetraselmis sp. CTP4 Microalgal Biomass Produced in Industrial Photobioreactors.

Commercial production of microalgal biomass for food and feed is a recent worldwide trend. Although it is common to publish nutritional data for microalgae grown at the lab-scale, data about industrial strains cultivated in an industrial setting are scarce in the literature. Thus, here we present the nutritional composition and a microbiological and toxicological evaluation of Tetraselmis sp. CTP4 biomass, cultivated in 100-m3 photobioreactors at an industrial production facility (AlgaFarm). This microalga contained high amounts of protein (31.2 g/100 g), dietary fibres (24.6 g/100 g), digestible carbohydrates (18.1 g/100 g) and ashes (15.2 g/100 g), but low lipid content (7.04 g/100 g). The biomass displayed a balanced amount of essential amino acids, n-3 polyunsaturated fatty acids, and starch-like polysaccharides. Significant levels of chlorophyll (3.5 g/100 g), carotenoids (0.61 g/100 g), and vitamins (e.g., 79.2 mg ascorbic acid /100 g) were also found in the biomass. Conversely, pathogenic bacteria, heavy metals, cyanotoxins, mycotoxins, polycyclic aromatic hydrocarbons, and pesticides were absent. The biomass showed moderate antioxidant activity in several in vitro assays. Taken together, as the biomass produced has a balanced biochemical composition of macronutrients and (pro-)vitamins, lacking any toxic contaminants, these results suggest that this strain can be used for nutritional applications.

Antileishmanial activity of meroditerpenoids from the macroalgae Cystoseira baccata.

The development of novel drugs for the treatment of leishmaniases continues to be crucial to overcome the severe impacts of these diseases on human and animal health. Several bioactivities have been described in extracts from macroalgae belonging to the Cystoseira genus. However, none of the studies has reported the chemical compounds responsible for the antileishmanial activity observed upon incubation of the parasite with the aforementioned extracts. Thus, this work aimed to isolate and characterize the molecules present in a hexane extract of Cystoseira baccata that was found to be bioactive against Leishmania infantum in a previous screening effort. A bioactivity-guided fractionation of the C. baccata extract was carried out and the inhibitory potential of the isolated compounds was evaluated via the MTT assay against promastigotes and murine macrophages as well as direct counting against intracellular amastigotes. Moreover, the promastigote ultrastructure, DNA fragmentation and changes in the mitochondrial potential were assessed to unravel their mechanism of action. In this process, two antileishmanial meroditerpenoids, (3R)- and (3S)-tetraprenyltoluquinol (1a/1b) and (3R)- and (3S)-tetraprenyltoluquinone (2a/2b), were isolated. Compounds 1 and 2 inhibited the growth of the L. infantum promastigotes (IC50 = 44.9 ± 4.3 and 94.4 ± 10.1 µM, respectively), inducing cytoplasmic vacuolization and the presence of coiled multilamellar structures in mitochondria as well as an intense disruption of the mitochondrial membrane potential. Compound 1 decreased the intracellular infection index (IC50 = 25.0 ± 4.1 µM), while compound 2 eliminated 50% of the intracellular amastigotes at a concentration > 88.0 µM. This work identified compound 2 as a novel metabolite and compound 1 as a biochemical isolated from Cystoseira algae displaying antileishmanial activity. Compound 1 can thus be an interesting scaffold for the development of novel chemotherapeutic molecules for canine and human visceral leishmaniases studies. This work reinforces the evidence of the marine environment as source of novel molecules.

Maritime halophyte species from southern Portugal as sources of bioactive molecules.

Extracts of five halophytes from southern Portugal (Arthrocnemum macrostachyum, Mesembryanthemum edule, Juncus acutus, Plantago coronopus and Halimione portulacoides), were studied for antioxidant, anti-inflammatory and in vitro antitumor properties. The most active extracts towards the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical were the methanol extracts of M. edule (IC50 = 0.1 mg/mL) and J. acutus (IC50 = 0.4 mg/mL), and the ether extracts of J. acutus (IC50 = 0.2 mg/mL) and A. macrostachyum (IC50 = 0.3 mg/mL). The highest radical scavenging activity (RSA) against the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical was obtained in the ether extract of J. acutus (IC50 = 0.4 mg/mL) and H. portulacoides (IC50 = 0.9 mg/mL). The maximum total phenolic content (TPC) was found in the methanol extract of M. edule (147 mg gallic acid equivalents (GAE)/g) and in the ether extract of J. acutus (94 mg GAE/g). Significant decreases in nitric oxide (NO) production were observed after incubation of macrophages with lipopolysaccharide (LPS) and the chloroform extract of H. portulacoides (IC50 = 109 µg/mL) and the hexane extract of P. coronopus (IC50 = 98.0 µg/mL). High in vitro cytotoxic activity and selectivity was obtained with the ether extract of J. acutus. Juncunol was identified as the active compound and for the first time was shown to display selective in vitro cytotoxicity towards various human cancer cells.

In vitro and in silico approaches to unveil the mechanisms underlying the cytotoxic effect of juncunol on human hepatocarcinoma cells.

BACKGROUND: Juncunol is a phenanthrene isolated from the halophyte species Juncus acutus, with selective cytotoxic activity towards human hepatocarcinoma (HepG2) cells. However, its mechanism of action is unknown. METHODS: The in vitro cytotoxic mechanism of juncunol was evaluated on HepG2 cells through several methods to elucidate its potential to induce apoptotic features, decrease mitochondrial membrane potential, promote internal ROS production and influence cell cycle. We also report its haemolytic activity on human erythrocytes and in silico DNA-binding studies. RESULTS: Juncunol induced an increase in the number of apoptotic cells in a concentration-dependent manner, accompanied by a decrease in the mitochondrial membrane potential. No significant differences were observed in production of reactive oxygen species (ROS). Moreover, juncunol application at the IC50 value significantly induced cell cycle arrest in the G0/G1 phase comparatively to the control group. No significant haemolysis was detected. In silico studies indicate that juncunol seems to bind between GC base pairs. CONCLUSION: Juncunol reduced HepG2 cells proliferation through the induction of apoptotic cellular death, in a concentration-dependent manner. Apoptosis induction seems to be related with a decrease of the mitochondrial membrane potential but not with ROS production. Juncunol had no haemolytic activity and may act as a DNA intercalator. Our data suggests juncunol as a suitable candidate for more detailed studies, including in vivo experiments, in order to completely characterize its mode of action.

Juncaceae species as sources of innovative bioactive compounds for the food industry: In vitro antioxidant activity, neuroprotective properties and in silico studies.

Several Juncus species are traditionally used as sedative and to treat health problems like insomnia. This work was based on the hypothesis that Juncus acutus, J. maritimus and J. inflexus may have molecules with bioactivities relevant for the improvement of cognitive functions and thus with potential use as food additives and/or nutraceuticals. Therefore leaves and roots extracts of those species were evaluated for radical scavenging (RSA) and metal chelating activities, and for in vitro inhibition of acetyl-(AChE) and butyrylcholinesterase (BuChE). The bioactive compound was isolated and identified by HPLC-DAD, and its anticholinesterase capacity was determined by different assays. Docking studies were performed to elucidate its inhibitory mechanism. The dichloromethane root extract of J. acutus had the highest RSA against DPPH and ABTS radicals, and the dichloromethane extract of J. maritimus leaves had the uppermost FRAP. The dichloromethane extract from J. acutus leaves had the strongest BuChE inhibition. Juncunol was the bioactive compound, exhibiting dual anticholinesterase capacity on enzyme-based assays and AChE inhibition in neuronal and glial cells in vitro. Molecular docking studies indicate juncunol as a competitive reversible inhibitor. Our results suggest that Juncus spp. can be sources of bioactive compounds with application in the food industry as cognitive-enhancer nutraceuticals.

Urban wastewater treatment by Tetraselmis sp. CTP4 (Chlorophyta).

The ability of a recent isolate, Tetraselmis sp. CTP4, for nutrient removal from sewage effluents before and after the nitrification process under batch and continuous cultivation was studied. Biomass productivities in both wastewaters were similar under continuous conditions (0.343±0.053gL-1d-1) and nutrient uptake rates were maximal 31.4±0.4mgNL-1d-1 and 6.66±1.57mgP-PO43-L-1d-1 in WW before nitrification when cultivated in batch. Among batch treatments, cellular protein, carbohydrate and lipid levels shifted with aging cultures from 71.7±6.3 to 29.2±1.2%, 17.4±7.2 to 57.2±3.9% and 10.9±1.7 to 13.7±4.7%, respectively. In contrast, CTP4 cultivated continuously in Algal medium (control) showed lower biomass productivities (0.282gVSSL-1d-1) although improved lipid content (up to 20% lipids) in batch cultivation. Overall, Tetraselmis sp. CTP4 is promising for WW treatment as a replacement of the costly nitrification process, fixating more nutrients and providing a protein and carbohydrate-rich biomass as by-product.

Isolation of a euryhaline microalgal strain, Tetraselmis sp. CTP4, as a robust feedstock for biodiesel production.

Bioprospecting for novel microalgal strains is key to improving the feasibility of microalgae-derived biodiesel production. Tetraselmis sp. CTP4 (Chlorophyta, Chlorodendrophyceae) was isolated using fluorescence activated cell sorting (FACS) in order to screen novel lipid-rich microalgae. CTP4 is a robust, euryhaline strain able to grow in seawater growth medium as well as in non-sterile urban wastewater. Because of its large cell size (9-22 µm), CTP4 settles down after a six-hour sedimentation step. This leads to a medium removal efficiency of 80%, allowing a significant decrease of biomass dewatering costs. Using a two-stage system, a 3-fold increase in lipid content (up to 33% of DW) and a 2-fold enhancement in lipid productivity (up to 52.1 mg L-1 d-1) were observed upon exposure to nutrient depletion for 7 days. The biodiesel synthesized from the lipids of CTP4 contained high levels of oleic acid (25.67% of total fatty acids content) and minor amounts of polyunsaturated fatty acids with ≥4 double bonds (<1%). As a result, this biofuel complies with most of the European (EN14214) and American (ASTM D6751) specifications, which commonly used microalgal feedstocks are usually unable to meet. In conclusion, Tetraselmis sp. CTP4 displays promising features as feedstock with lower downstream processing costs for biomass dewatering and biodiesel refining.

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.

Synthesis and evaluation of sodium deoxycholate sulfate as a lipid drug carrier to enhance the solubility, stability and safety of an amphotericin B inhalation formulation.

Amphotericin B (AmB) is still used as the gold standard for therapy against invasive fungal diseases. However, the use of AmB through oral administration is restricted due to its low solubility and stability in aqueous solution, which is the cause for its poor bioavailability and highly varying absorption. Therefore, an attempt has been made to enhance the solubility and stability of AmB to evaluate its bioactivity and safety for use as an inhaler by using a new excipient sodium deoxycholate sulfate (SDS) with aim of using it as a drug carrier for AmB. Therefore, SDS was formulated together with AmB as a dry powder by lyophilization. The dry powder was reconstituted in distilled water and evaluated its physicochemical properties such as zeta potential, particle size and pH to compare its solubility and stability of the formulations with a SDC-AmB (i.e., known as Fungizone(®)). In vitro toxicity studies were carried out with red blood cells (RBC) and respiratory cell lines. Bioactivity was determined by a micro-dilution method against Candidaalbicans and Cryptococcusneoformans. We found that SDS-AmB had a zeta potential (-45.53 mV), which was higher than of Fungizone(®); and produced a stable particle size in solution (73.8 nm). The particle size distributions of both formulations were expressed as their mass median aerodynamic diameters (MMAD; 1.70 and 1.74 µm), their fine particle fractions (FPF; 70 and 80%) and geometric standard deviations (GSD; 2.3 and 2.0), respectively. These values indicated that the sizes were appropriate for use in an inhaler. Pure AmB was found to hemolyse RBC and was very toxic to alveolar macrophage cells, as their viability rapidly declined from 93 to 56% when the AmB concentration increased from 1 to 8 µg/mL. The SDS-AmB formulation had a significantly reduced toxicity compared to AmB. The results clearly indicated that the SDS-lipid based nanoparticles had the potential to be used as an alternative option to Fungizone(®) for an AmB formulation for inhalation.

Phase behavior of rifampicin in cholesterol-based liquid crystals and polyethylene glycol.

The phase behavior of rifampicin in cholesteryl-based carbonate esters (CCEs), cholesterol and polyethylene glycol4000 (PEG4000) was determined to evaluate their potential in the formulation of dry powder inhalation dosage forms. To guide the identification of the most suitable liquid crystalline system for the solubilization of rifampicin, the dielectric constants were evaluated. Thereafter, the phase behavior of various mixtures were characterized by polarized light microscope (PLM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Among the mixed-carrier systems, the cholesteryl cetyl carbonate (CCC) and PEG4000 system at 1:1 mole ratios yielded a homogeneous mixture with relatively high rifampicin content. This result was consistent with the prediction based on the dielectric constants. The phase diagram contained a eutectic point at CCC:PEG4000 (1:1) and 50 °C. Finally, the rifampicin drug was successfully incorporated into CCC and PEG system at a 1:6:6 mole ratio. Such a system would be amenable for oral inhalation.