The present study was conducted to evaluate the antioxidant and antimicrobial activity of methanol, dichloromethane and hexane extracts, as well as the essential oils of brown algae (Phaeophyta) Colpomenia sinuosa, Dictyota dichotoma, Dictyota dichotoma var. implexa, Petalonia fascia and Scytosiphon lomentaria. The essential oil of the macroalgae was obtained by steam distillation and analyzed by GC and GC/MS. The antioxidant activity of the algal extracts was determined using the procedures of inhibition of ?-carotene bleaching and ABTS+ methods. The antioxidant effects of the extracts were compared with those of commercial antioxidants, such as butylated hydroxytoluene (BHT), butylated hydroxyanisol (BHA) and ?-tocopherol. The hexane extracts of D. dichofoma var. implexa had a higher phenolic content than the other extracts. The dichloromethane extract of S. lomentaria was found to be more active in the decolorization of ABTS+ than the other extracts and generally the dichloromethane extracts were more active than the methanol and hexane extracts. Antimicrobial activities of the extracts were assessed against Gram (+) and Gram (-) bacteria and one yeast strain by the disk diffusion method. According to the results, the dichloromethane extracts generally showed more potent antimicrobial activity than the methanol and hexane extracts at concentrations 1.5 and 1.0 mg/disk.

The methanol, dichloromethane, hexane, chloroform and volatile oil extracts of the red alga Jania rubens were tested in vitro for their antimicrobial activity (five Gram-positive, four Gram-negative bacteria and Candida albicans ATCC 10239). GC-MS analysis of the volatile components of J. rubens identified 40 compounds which constituted 77.53% of the total. The volatile components of J. rubens consisted of n-docosane (6.35%), n-eicosane (5.77%) and n-tetratriacontane (5.58%) as major components. The methanol and chloroform extracts (4 mg/disc) showed more potent antimicrobial activity than the hexane and dichloromethane extracts and the volatile oil of J. rubens.

The aim of the study was to evaluate the biological activities with toxic properties of the methanol, hexane, and chloroform extracts of Cystoseira compressa (Esper) Gerloff & Nizamuddin from the Coast of Urla in the Aegean Sea. The extracts of C. compressa were tested for their antimicrobial and antioxidant activities in this study. Cytotoxic and mutagenic potentials of the extracts were also evaluated using cell culture and mutagenicity assays. Hexane extract was found to have higher total flavonoid and phenolic contents than the other extracts and exerted higher antioxidant activity than other extracts. All extracts exhibited moderate antimicrobial activity against tested microorganisms (minimum inhibitory concentration ranges are 32-256 lg/mL). The results indicated that the extracts had no significant cytotoxic activity against human hepatocellular carcinoma Hep 3B cell line in all treated concentrations (5-50 lg/mL) and did not show mutagenicity in the Ames test. Lethality was not observed among mice treated with oral doses of the extracts. In conclusion, results of investigations indicate that brown alga C. compressa is a natural source of antioxidant. It has moderate antimicrobial activities with no toxicity.

The methanol, dichloromethane, hexane, chloroform, and volatile components of Dictyopteris membranaceae (Stackhouse) Batters (Dictyotaceae) and Cystoseira barbata (Good et Woodw.) J. Agardh (Cystoseiraceae) were tested for their antimicrobial activities (four Grampositive bacteria, four Gram-negative bacteria, and Candida albicans ATCC 10239). Five compounds were identified in the volatile oil of D. membranaceae accounting for > 85% of the composition of the volatile oil. Twenty-eight compounds were identified in the volatile oil of C. barbata accounting for > 67% of the composition of the volatile oil. Major components were 6-butyl-1,4cycloheptadiene (43.21%) for D. membranaceae and docosane (7.61%) and tetratriacontane (7.47%) for C. barbata. Many compounds in the volatile oil of C. barbata were identified as hydrocarbon compounds. The volatile oils of these algae did not remarkably inhibit the growth of tested microorganisms. However, the hexane extracts showed more potent antimicrobial activity than methanol, dichloromethane, and chloroform extracts.

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The aim of this study was to reveal the biological activities and in vivo toxicity profiles of nhexane, chloroform and methanol extracts of brown algae Halopteris scoparia L. Sauvageau. In this study, extracts were tested for their phytochemical contents and antioxidant activities. The cytotoxic activities of the extracts against cervical adenocarcinoma (HeLa), colon colorectal adenocarcinoma (CaCo-2) and breast adenocarcinoma (MCF7) cells were assessed by MTT assay and total RNAs derived from cell lines to analyze gene expression were analyzed by Real Time Ready Human Apoptosis Panel 96. Also, in vivo toxicity and irritation effects of extracts were evaluated by LD 50 acute toxicity test and Hen's egg test chorioallantoic membrane (HET-CAM) assay, respectively. Our results showed that the phenolic and flavonoid contents were determined only in methanol extract (33.20 ± 1.41 mg GAE/g and 1.26 ± 0.95 mg QE/g). Also, n-hexane has a broader spectrum of content than methanol and chloroform extracts. Furthermore, n-hexane extract in DPPH and methanol extract in ABTS ? exhibited the best antioxidant activity. In addition, MTT results revealed that each three extracts cause a significant reduction in cell viability, especially in HeLa cells. When the apoptotic gene expressions were examined after treatment of extracts, the expression of many pro-apoptotic genes in both caspase-independent and caspase-dependent intrinsic and extrinsic pathways increased. These findings suggest that, considering that it had not led to irritation and toxicity in vivo, edible H. scoparia is a natural antioxidant and its apoptotic/cytotoxic activities can potentially be used against human cancers.

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In this study, 24 marine macroalgae collected from the coastline of Izmir Gulf were examined for their antioxidant activities and their effects on cell proliferation. Crude extracts were obtained from samples with cold methanol extraction. Antioxidant activity was evaluated as 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging activity and total phenolic content (TPC); growth inhibitory effects of the extracts were determined by using WST-8. Amongst the species, Polysiphonia denuata (Rhodophyta) and Cystoseira species (Phaeophyceae) have been noticed by their high DPPH radical scavenging activities and TPCs. As expected, there was a strong correlation between these tests. Dictyota dichotoma (Phaeophyceae) showed the highest anti-cancer activity on MCF-7 cells with an IC 50 of 17.2 ng mL -1 . Flow cytometry analyses demonstrated that D. dichotoma methanolic extract strongly induced apoptosis.This extract exhibited moderate viability inhibition on MCF10A cells (IC 50 : 49.3 ng mL -1 ), suggesting a potential use of the extracts or its compounds for cancer therapy. There was no correlation between anticancer potential and antioxidant content of the extracts.