Selective cytotoxicity of marine algae extracts to several human leukemic cell lines

Microwave-Assisted Hydrothermal Processing of Rugulopteryx okamurae

One possible scheme of Rugulopteryx okamurae biomass valorization based on a green, rapid and efficient fractionation technique was proposed. Microwave-assisted pressurized hot water extraction was the technology selected as the initial stage for the solubilization of different seaweed components. Operation at 180 °C for 10 min with a 30 liquid-to-solid ratio solubilized more than 40% of the initial material. Both the alginate recovery yield (3.2%) and the phenolic content of the water-soluble extracts (2.3%) were slightly higher when distilled water was used as solvent. However, the carbohydrate content in the extract (60%) was similar for both solvents, but the sulfate content was higher for samples processed with salt water collected from the same coast as the seaweeds. The antiradical capacity of the extracts was related to the phenolic content in the extracts, but the cytotoxicity towards HeLa229 cancer cells was highest (EC50 = 48 µg/mL) for the extract obtained with distilled water at the lowest temperature evaluated. Operation time showed a relevant enhancement of the extraction performance and bioactive properties of the soluble extracts. The further fractionation and study of this extract would be recommended to extend its potential applications. However, due to the low extraction yield, emphasis was given to the solid residue, which showed a heating value in the range 16,102-18,413 kJ/kg and could be useful for the preparation of biomaterials according to its rheological properties.

Isolation, structural characterization and bioactivities of polysaccharides from Laminaria japonica: A review

Laminaria japonica is a familiar marine plant and is often used as food due to its abundant carbohydrates, vitamins and minerals. As one of the main types of active substances in L. japonica, polysaccharides are widely used in the food and chemical industries and in medicine and healthcare due to their health benefits, such as immunoregulatory, antioxidant, and antidiabetic effects. However, there has been no systematic summary of the isolation, structural characterization and bioactivities of L. japonica polysaccharides (LJPs). Therefore, the present review includes a survey of extraction and purification methods for these bioactive molecules, along with a dissertation on the structural characterization of the carbohydrate components. Moreover, an overview of the most recent results related to LJP biological activities is provided. This review provides a useful reference for further research, production, and application of LJPs in functional foods and therapeutic agents.

Preliminary screening of the aqueous extracts of twenty-three different seaweed species in Sri Lanka with in-vitro and in-vivo assays

Background

Seaweeds are an important source of bioactive compounds which are applied in various aspects of medicinal investigations. The present study was conducted to investigate cytoxicity (in-vitro and in-vivo) and wound healing activity of different seaweed species in Sri Lanka.

Methods

Twenty-three seaweed samples, belonging to Phaeophyta (Brown), Chlorophyta (Green) and Rhodophyta (Red) were used for the experiments. Samples were collected from the inter-tidal and the sub-tidal habitats around Sri Lankan coast (Southern, Northern and North-western). Aqueous seaweed extracts were tested for cytotoxic and wound healing activity; in-vitro and in-vivo. To determine toxicity of aqueous seaweed extracts, brine shrimp lethality assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay on mouse fibroblasts (L929) cell line were performed. Cell migration induction of seaweed extracts was assessed by scratch wound healing assay using L929 cell line. Based on the our previous experiments S.ilicifolium (SW23) was selected for the in vivo study to confirm our hypothesis. Albino mice (BALB/c) were divided into three groups (12 in each) and a circular area (44.07 ± 02.51 mm²) of full skin was excised to create a wound in mice group II and III. Group III received aqueous extract of Sargasum illicifolium (400 mg/kg BW/day for 12 days, orally), Group II received distilled water for 12 days whereas Group I was used as the control group and it was tested without forming wounds and without providing any treatment. Further, the expression level of Tumor Necrosis Factor (TNF-α) and Transforming Growth Factor-β (TGF-β) via RT-PCR were measured every three days until the end of the experiment.

Results

Phytochemical tests showed positive results to flavonoids in all the selected green seaweeds and alkaloids were observed in red seaweeds. In the toxicity assay, red seaweed, Acanthophora spicifera (SW17) was found to be highly effective on nauplii of brine shrimp (LC₅₀ = 0.072 μg/μl). LC₅₀ value of green seaweed species, Caulerpa racemosa (SW02 and SW08) and Caulerpa sertularioides (SW10) was not found within the tested concentration series. The highest cytotoxic effect on L929 cell line was exhibited by aqueous extracts of red seaweed; Jania adhaereus with 50.70 ± 7.304% cell viability compared with control group. The highest cell migration activity was observed in L929 cell line group treated with extracts of green seaweed namely; Halimeda opuntin (SW07) and extracts of brown seaweed namely; Stoechospermum polypodioides (SW11). Extracts of S. illicifolium (SW23) exhibited a significantly enhanced wound healing activity in mice group III within three days (P < 0.05) with an open wound area of 17.35 ± 1.94 mm² compared with control group (26.29 ± 2.42 mm²). TGF-β gene expression peaked on 6^th day of post-wound and subsequently decreased on 9^th day of post-wound in mice group III. TNF-α expression was suppressed in mice group III whereas it was elevated in group II. TGF-β expression is enhanced in the treatment group compared to the control group.

Conclusions

Aqueous extracts of selected seaweeds are a significant source of potential compounds with wound healing properties, which might be helpful in the healing of various wounds. This also infers that many species of brown and red seaweeds have the potential of wound healing, specifically, Sargasum illicifolium and Jania adhaereus could be a potential candidate for in-vivo studies related to wound healing and cancer therapy in the near future.

Cytotoxic activity of ten algae from the Persian Gulf and Oman Sea on human breast cancer cell lines; MDA-MB-231, MCF-7, and T-47D

BACKGROUND

Seaweeds have proven to be a promising natural source of bioactive metabolites for drug development.

OBJECTIVE

This study aimed to monitor the ethanol extract of ten algae from the Persian Gulf and Oman Sea, for their in vitro cytotoxic activity on three human breast cancer cell lines.

MATERIALS AND METHODS

Three human breast cancer cell lines including MDA-MB-231(ER(-)), MCF-7(ER(+)), and T-47D (ER(+)) were treated by different concentrations of total ethanol (90%) algae extracts and the cytotoxic effects were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Doxorubicin (Ebewe, Austria) was used as a positive control. After 72 h of incubation, the cytotoxic effect of the algae was calculated and presented as 50%-inhibitory concentration (IC50).

RESULTS

The results indicated Gracilaria foliifera and Cladophoropsis sp. to be the most active algae in terms of cytotoxic effects on the investigated cancer cell lines. The IC50 values against MDA-MB-231, MCF-7, and T-47D cells were, respectively, 74.89 ± 21.71, 207.81 ± 12.07, and 203.25 ± 30.98 µg/ml for G. foliifera and 66.48 ± 4.96, 150.86 ± 51.56 and >400 µg/ml for Cladophoropsis sp. The rest of the algal extracts were observed not to have significant cytotoxic effects in the concentration range from 6.25 µg/ml to 400 µg/ml.

CONCLUSION

Our data conclusively suggest that G. foliifera and Cladophoropsis sp. may be good candidates for further fractionation to obtain novel anticancer substances. Moreover, stronger cytotoxic effects on estrogen negative breast cancer cell line (MDA-MB-231(ER(-))) in comparison to estrogen positive cells (MCF-7 and T-47D) suggest that the extract of G. foliifera and Cladophoropsis sp. may have an estrogen receptor/progesterone receptor-independent mechanism for their cellular growth inhibition.

Potential pharmacological applications of polyphenolic derivatives from marine brown algae

Recently, the isolation and characterization of the biologically active components from seaweeds have gained much attention from various research groups across the world. The marine algae have been studied for biologically active components and phlorotannins are one among them. Among marine algae, brown algal species such as Ecklonia cava, Eisenia arborea, Ecklonia stolinifera and Eisenia bicyclis have been studied for their potential biological activities. Majority of the investigations on phlorotannins derived from brown algae have exhibited their potentiality as antioxidant, anti-inflammatory, antidiabetic, antitumor, antihypertensive, anti-allergic, hyaluronidase enzyme inhibition and in matrix metalloproteinases (MMPs) inhibition activity. In this review, we have made an attempt to discuss the potential biological activities of phlorotannins from marine brown algae and their possible candidature in the pharmaceutical applications.

Novel anti-infective compounds from marine bacteria

As a result of the continuous evolution of microbial pathogens towards antibiotic-resistance, there have been demands for the development of new and effective antimicrobial compounds. Since the 1960s, the scientific literature has accumulated many publications about novel pharmaceutical compounds produced by a diverse range of marine bacteria. Indeed, marine micro-organisms continue to be a productive and successful focus for natural products research, with many newly isolated compounds possessing potentially valuable pharmacological activities. In this regard, the marine environment will undoubtedly prove to be an increasingly important source of novel antimicrobial metabolites, and selective or targeted approaches are already enabling the recovery of a significant number of antibiotic-producing micro-organisms. The aim of this review is to consider advances made in the discovery of new secondary metabolites derived from marine bacteria, and in particular those effective against the so called "superbugs", including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), which are largely responsible for the increase in numbers of hospital acquired, i.e., nosocomial, infections.

The novel anti-Propionibacterium acnes compound, Sargafuran, found in the marine brown alga Sargassum macrocarpum

We screened extracts of 342 species of marine algae collected from Japanese coastlines for antibacterial activity against Propionibacterium acnes, and found a novel antibacterial compound, which we named Sargafuran, from the MeOH extract of the marine brown alga, Sargassum macrocarpum. Sargafuran has low cytotoxicity, and the MIC against P. acnes was 15 microg ml(-1), showing a broad antibacterial activity against Gram-positive bacteria. A time-kill study showed that Sargafuran was bactericidal and completely killed P. acnes at 4 x MIC by lysing bacterial cells. These results suggest that Sargafuran might be useful as a lead compound to develop new types of anti-P. acnes substances and new skin care cosmetics to prevent or improve acne.

Anti-methicillin-resistant Staphylococcus aureus (MRSA) activity of MC21-B, an antibacterial compound produced by the marine bacterium Pseudoalteromonas phenolica O-BC30T

The aim of this study was to purify, characterise and evaluate the in vitro activity of MC21-B, an antibiotic produced by the marine bacterium Pseudoalteromonas phenolica O-BC30(T). MC21-B was purified by sequential silica and Cosmosil chromatography followed by high-performance liquid chromatography (HPLC). The chemical structure of MC21-B was determined by ultraviolet, infrared, electron impact mass and nuclear magnetic resonance spectrometric analyses. To evaluate its antibacterial activity, minimum inhibitory concentrations (MICs) against 10 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) as well as kill times were determined. Antifungal activity was determined by the paper disk diffusion method. Cytotoxicity against human cells was determined with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]. Based on spectrophotometric analyses, MC21-B was predicted to be a novel substance, 2,2',3-tribromobiphenyl-4,4'-dicarboxylic acid. MC21-B exhibited anti-MRSA activity against all 10 clinical isolates of MRSA, with MICs between 1 microg/mL and 4 microg/mL. MC21-B was highly active against Bacillus subtilis and Enterococcus serolicida but was inactive against Gram-negative bacteria and fungi. Furthermore, MC21-B exhibited cytotoxic activity against human normal dermal fibroblasts and human leukaemic (MOLT) cells at 3-12-fold higher concentrations than required for its antibacterial activity. These results demonstrated that MC21-B has high in vitro activity against MRSA and might be useful as a lead compound in developing new anti-MRSA substances.

MC21-A, a bactericidal antibiotic produced by a new marine bacterium, Pseudoalteromonas phenolica sp. nov. O-BC30(T), against methicillin-resistant Staphylococcus aureus

We previously reported a new marine bacterium, Pseudoalteromonas phenolica sp. nov. O-BC30(T), which produced a bactericidal antibiotic against methicillin-resistant Staphylococcus aureus (MRSA). In the present study, we purified an anti-MRSA substance (MC21-A) from the methanol extract of the cells of P. phenolica O-BC30(T) and analyzed its chemical structure. MC21-A was determined to be 3,3',5,5'-tetrabromo-2,2'-biphenyldiol by spectrometric analyses. Its anti-MRSA activity against 10 clinical isolates of MRSA was comparable to that of vancomycin (MC21-A MICs, 1 to 2 micro g/ml; vancomycin MICs, <0.25 to 2 micro g/ml). This substance was also high active against Enterococcus serolicida, Enterococcus faecium, and Enterococcus faecalis but was less active against Streptococcus spp. A time-kill study also demonstrated that MC21-A was bactericidal and that its killing rate was much higher than that of vancomycin. The postantibiotic effect (PAE) of MC21-A against a clinical MRSA isolate, strain E 31243, was also comparable to that of vancomycin (MC21-A PAEs, 1.46 to 1.65 h; vancomycin PAEs, 0.84 to 1.43 h). However, a lysis experiment demonstrated that this substance failed to lyse MRSA cells. This substance also did not lyse human erythrocytes. A SYTOX Green staining experiment implied that this substance permeabilized the cell membrane of MRSA as its mode of action. When its activities against a hypersensitive Escherichia coli mutant (KO 1489) and wild-type strains were tested, MC21-A exhibited higher levels of activity against the former. Furthermore, MC21-A was not cytotoxic to human normal fibroblast, rat pheochromocytoma, and Vero cells at concentrations up to 50 micro g/ml. These results suggest that MC21-A might be useful as a lead compound in the development of new types of anti-MRSA substances with modes of action different from those of vancomycin and teicoplanin.

Telomerase inhibiting activity in vitro from natural resources, marine algae extracts

We attempted to screen for telomerase inhibitingactivity in vitro from a total of 304 marine algae samples which were collected from various Japancoasts by nonradioisotope telomeric repeatamplification protocol (Non-RI TRAP) assay using humanleukemia MOLT-4 cells. Ten of the MeOH extracts andtwo of the PBS extracts from those algal samplesshowed telomerase inhibiting activity. In particular,the MeOH extract from a green alga, Caulerpasertularioides strongly inhibited telomerase activitywhen added to MOLT-4 cell culture at a level of 1.25%(v/v), suggesting that it may be possible to developa novel anti-cancer agent in view of its specificanti-telomeric property.