The glaucophyte Cyanophora paradoxa (Cp) was chemically investigated to identify pigments efficiently inhibiting malignant melanoma, mammary carcinoma and lung adenocarcinoma cells growth. Cp water and ethanol extracts significantly inhibited the growth of the three cancer cell lines in vitro, at 100 µg·mL−1. Flash chromatography of the Cp ethanol extract, devoid of c-phycocyanin and allophycocyanin, enabled the collection of eight fractions, four of which strongly inhibited cancer cells growth at 100 µg·mL−1. Particularly, two fractions inhibited more than 90% of the melanoma cells growth, one inducing apoptosis in the three cancer cells lines. The detailed analysis of Cp pigment composition resulted in the discrimination of 17 molecules, ten of which were unequivocally identified by high resolution mass spectrometry. Pheophorbide a, β-cryptoxanthin and zeaxanthin were the three main pigments or derivatives responsible for the strong cytotoxicity of Cp fractions in cancer cells. These data point to Cyanophora paradoxa as a new microalgal source to purify potent anticancer pigments, and demonstrate for the first time the strong antiproliferative activity of zeaxanthin and β-cryptoxanthin in melanoma cells.
The in vitro antimicrobial activity of the marine green algae Chaetomorpha aerea was investigated against gram-positive bacteria, gram-negative bacteria, and a fungus. The water-soluble extract of algae was composed of a sulfated (6.3%) galactan with a molecular weight of 1.160 × 10 6 Da and a global composition close to commercial polysaccharides, such as dextran sulfate or fucoidan. The polysaccharide was composed of 18% arabinose, 24% glucose, and 58% galactose. The re-suspended extracts (methanol, water) exhibited selective antibacterial activities against 3 gram-positive bacteria including Staphylococcus aureus (ATCC 25923). Minimum inhibitory concentration and minimum bactericidal concentration tests showed that the sulfated galactan could be a bactericidal agent for this strain (40 mg/mL). The results of this study confirmed the potential use of the green algae Chaetomorpha aerea as a source of antibacterial compounds.
In the present study, microwave-assisted extraction was first employed to extract the phycobiliproteins of Porphyridium purpureum (Pp). Freeze-dried Pp cells were subjected to microwave-assisted extraction (MAE) to extract phycoerythin (PE), phycocyanin (PC), and allophycocyanin (APC). MAE combined reproducibility and high extraction yields and allowed a 180- to 1,080-fold reduction of the extraction time compared to a conventional soaking process. The maximal PE extraction yield was obtained after 10-s MAE at 40 °C, and PE was thermally damaged at temperatures higher than 40 °C. In contrast, a flash irradiation for 10 s at 100 °C was the best process to efficiently extract PC and APC, as it combined a high temperature necessary to extract them from the thylakoid membrane to a short exposure to thermal denaturation. The extraction order of the three phycobiliproteins was coherent with the structure of Pp phycobilisomes. Moreover, the absorption and fluorescence properties of MAE extracted phycobiliproteins were stable for several months after the microwave treatment. Scanning electron microscopy indicated that MAE at 100 °C induced major changes in the Pp cell morphology, including fusion of the exopolysaccharidic cell walls and cytoplasmic membranes of adjacent cells. As a conclusion, MAE is a fast and high yield process efficient to extract and pre-purify phycobiliproteins, even from microalgae containing a thick exopolysaccharidic cell wall.
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