Yolanda Freile-Pelegrín

Antibacterial activity in marine algae from the coast of Yucatan, Mexico

Abstract Ethanolic and lipid-soluble extracts from 21 marine algal species (10 Chlorophyta, 2 Phaeophyta and 9 Rhodophyta) from the coast of Yucatan, Mexico, were evaluated for antibacterial activity against pathogenic microbes (4 Gram-positive, 5 Gram-negative and one fungus). All species with antibacterial activity (18) were active against the Gram-positive bacteria (Bacillus subtilis, Streptococcus faecalis and Micrococcus luteus), and most of the algal species exhibited activity against B. subtilis (89% in ethanolic soluble extracts and 94% in lipid-soluble extracts). The lipid-soluble extract of Ceramium nitens exhibited the highest activity among the species tested. The results are significant because no antibacterial activity has been found in previous research on this, or any other, species from this genus. The antimicrobial activities associated with extracts from different thallus regions (apical, basal and stolon) of selected Caulerpa species (C. ashmeadii, C. paspaloides and C. prolifera) were also evaluated. Results generally indicate that the stolon of Caulerpa has the highest antibacterial activity.

Influence of alkali treatment on agar from Gracilaria cornea from Yucatán, México

The effect of alkali treatments on the yield, rheological and chemical properties of agar from Gracilaria cornea growing along the Yucatáncoast were studied in order to evaluate its potential for industrial use inan attractive economic standpoint. Alkali treatment was carried out with NaOH concentrations of 0.5%, 1%, 3% and 5% in a water bath at 80, 85 and 90 °C. Agar yield, gel strength, gelling and melting temperatures, sulphate, 3,6-anhydro-galactose and ash content weredetermined. The different combinations of NaOH concentration and treatment temperature strongly influenced agar characteristics. There was a variation in the agar content for all NaOH treatments and temperature combinations, ranging between 14.5% to 22.1%. Although the yields obtained for 0.5% NaOH at all temperatures and 1% NaOH at 80 and 85°C were higher than those required by the industry, the physical and chemical characteristics of the agar were similar to those obtained fornative agar from the same species. The gel strengths, sulphate content and gelation hysteresis obtained with agar from the 1% NaOH treatment at 90 °C are in the range required by the food industry. Treatments with 3% and 5% NaOH at all temperatures improved significantly the agar quality giving higher gel strengths (974–1758 g cm -2) than those reported for other Gracilaria species.

Antileishmanial properties of tropical marine algae extracts

Aqueous and organic extracts of twenty-seven species of marine algae (14 species of Rhodophyta, 5 species of Phaeophyta and 8 species of Chlorophyta) collected from the Gulf of Mexico and Caribbean coast of the Yucatan Peninsula (Mexico) were evaluated for their antileishmanial in vitro activity against Leishmania mexicana promastigote forms. The cytotoxicity of these extracts was also assessed using brine shrimp. Organic extracts from Laurencia microcladia (Rhodophyta), Dictyota caribaea, Turbinaria turbinata and Lobophora variegata (Phaeophyta) possessed promising in vitro activity against L. mexicana promastigotes (LC(50) values ranging from 10.9 to 49.9 microg/ml). No toxicity of algal extracts against Artemia salina was observed with LC50 ranging from 119 to >or=1000 microg/ml. Further studies on bio-guided fractionation, isolation and characterization of pure compounds from these species as well as in vivo experiments are needed and are already in progress.

Evaluation of selected tropical seaweeds for in vitro anti-trichomonal activity

ETHNOPHARMACOLOGICAL RELEVANCE Human parasitic infections are a serious problem in tropical and sub-tropical developing countries. Trichomoniasis, responsible for the annual infection of 180 million people, is a common sexually transmitted disease caused by the protozoan Trichomonas vaginalis. Traditionally seaweeds have been used in folk medicine by coastal people in Asia and the Caribbean to treat parasitic infections and are a valuable source of novel anti-trichomonals. AIM OF THE STUDY In our search for therapeutical alternatives to anti-protozoal chemotherapy, we collected a selection of 25 tropical seaweeds (12 Rhodophyta, 5 Phaeophyta and 8 Chlorophyta) from the coast of Yucatan (Mexico) in order to undertake ethnopharmacological and chemotaxonomic investigations. MATERIALS AND METHODS Organic algal extracts were tested for their anti-trichomonal properties on the growth inhibition of Trichomonas vaginalis. The cytotoxicity of seaweed extracts on mammal cell lines was also assessed. RESULTS The results indicated that 44% of the seaweeds studied had high to moderate anti-trichomonal activity. Lobophora variegata and Udotea conglutinata showed the maximal anti-trichomonal activity with IC(50) values of 1.39 and 1.66microg/ml, respectively, with good selectivity. CONCLUSIONS Lobophora variegata and Udotea conglutinata demonstrated promising anti-trichomonal potential and have been selected for further bio-guided fractionation and isolation of active anti-trichomonal compounds.

The Tropical Brown Alga Lobophora variegata: A Source of Antiprotozoal Compounds

Lobophora variegata, a brown alga collected from the coast of the Yucatan peninsula, Mexico, was studied for antiprotozoal activity against Giardia intestinalis, Entamoeba histolytica and Trichomonas vaginalis. The whole extract showed the highest activity against T. vaginalis, with an IC50 value of 3.2 μg/mL. For the fractions, the best antiprotozoal activity was found in non-polar fractions. The chloroform fraction of the extract contained a major sulfoquinovosyldiacylglycerol (SQDG), identified as 1-O-palmitoyl-2-O-myristoyl-3-O-(6‴-sulfo-α-d-quinovopyranosyl)-glycerol (1), together with small amounts of 1,2-di-O-palmitoyl-3-O-(6‴-sulfo-α-d-quinovopyranosyl)-glycerol (2) and a new compound identified as 1-O-palmitoyl-2-O-oleoyl-3-O-(6‴-sulfo-α-d-quinovopyranosyl)-glycerol (3). Their structures were elucidated on the basis of chemical and enzymatic hydrolysis and careful analysis of FAB-MS and NMR spectroscopic data. This is the first report on the isolation of SQDGs from L. variegata. The mixture of 1–3 showed good activity against E. histolytica and moderate activity against T. vaginalis with IC50s of 3.9 and 8.0 μg/mL, respectively, however, the activity of 1–3 is not as effective as metronidazole. These results afford ground information for the potential use of the whole extract and fractions of this species in protozoal infections.

Polysaccharides composition from tropical brown seaweeds

Polysaccharides composition of the tropical brown seaweeds Turbinaria turbinata, Sargassum filipendula, Dictyota caribaea and Padina perindusiata collected at Yucatan Peninsula (Mexico) was determined in this study. Crude fucoidan extracted with HCl and alginate extracted with a hot alkali solution were characterized in terms of their molecular weight, sulfate content, uronic acid, total carbohydrate and neutral sugar components. Low molecular weight sulfated‐fucoidan was the major component in all species studied. Fucoidan from T. turbinata and from D. caribaea were characterized as a homofucan, with fucose as the neutral sugar. Fucoidan from S. filipendula was composed of a galactofucan, and fucoidan from P. perindusiata was characterized as a heterofucan consisting of fucose, glucose and galactose. The Fourier transform infrared (FT‐IR) spectra of fucoidan extracted from species studied indicated that the majority of sulfate groups are located at C‐4 and to a lesser extent at C‐2 and/or C‐3 of the fucopyranose residues. This could be advantageous since several therapeutic effects have been reported for fucoidans with similar characteristics. FT‐IR spectra from D. caribaea and P. perindusiata revealed the presence of O‐acetyl groups in crude fucoidan, which could be potentially utilized as an immune stimulant. Molecular weight of alginate varied between 595 and 1301 kDa with similar uronic acid content in all species. Alginate M : G ratio inferred from FT‐IR spectra suggests a high content of G‐block in all species. Potential applications of these polysaccharides are discussed.

Seasonal variation in photosynthesis and biochemical composition of Caulerpa spp. (Bryopsidales, Chlorophyta) from the Gulf of Mexico

D. Robledo and Y. Freile-Pelegrín. 2005. Seasonal variation in photosynthesis and biochemical composition of Caulerpa spp. (Bryopsidales, Chlorophyta) from the Gulf of Mexico. Phycologia 44: 312–319. Photosynthesis, pigment content, soluble carbohydrate, and protein levels of six Caulerpa species were examined on a seasonal basis from samples taken along the northern coast of the Yucatan Peninsula, Mexico, between June 1998 and August 1999. For Caulerpa ashmeadii, C. mexicana, C. paspaloides, and C. racemosa photosynthetic capacity changed depending on seasonal trends in photon flux density and water temperature in the study area. This pattern was not evident in Caulerpa prolifera and C. cupressoides. Maximum photosynthetic rates of 18.3 ± 0.8 mg O2 g dry weight−1 h−1 were obtained in C. mexicana during the cold season. Photosynthetic efficiency (α) showed a similar pattern to that of Pmax coinciding with low irradiances (photon flux density [PFD]: 151 ± 67 μmol photons m−2 s−1) and water temperature (23.8 ± 1.9°C), and the highest levels of dissolved inorganic nitrogen and dissolved reactive phosphorous in the water (9.1 μmol l−1 and 0.5 μmol l−1, respectively). Compensation (Ec) and saturation (Ek) irradiances were low and ranged from 3 to 35 and 44 to 280 μmol photons m−2 s−1, respectively. Maximum chlorophyll a and b (Chl a and b) levels occurred in C. racemosa and C. cupressoides during the cold to rainy seasons. The highest Chl b : a ratios were observed during the coldest months for all studied species. Protein and carbohydrate contents in Caulerpa spp. followed an inverse seasonal pattern. In general, high protein levels were observed in the dry season coinciding with increasing light and seawater temperatures. Photosynthesis in Caulerpa spp. from the Yucatan Peninsula coast is affected by high temperatures during the dry and rainy seasons. There is also a seasonal shift in the species proximate constituents indicative of a rapid growth period from January to May and a carbohydrate accumulation period during the rest of the year.

Does storage time influence yield and agar properties in the tropical agarophyte Gracilaria cornea

The agar yield and quality characteristics of Gracilaria cornea from Yucatán, Mexico, werestudied during 18 months of storage. Biomass wasstored at a temperature of 22.1 ± 0.9 °Cand humidity of 59.8±3.6%. The agar contentvaried erratically, but the average value waspractically constant over the storage period with an average of 20.1 ± 1.5±. Gel strength, gelling and meltingtemperatures were negatively affected by the totalstorage time. No significant changes were found duringthe first five months for these characteristics withmean values of 1134 ± 57 g cm-2, 40.8 ±0.4 °C and 91.2 ± 0.9 °Crespectively. Agar degradation was evident after thefifth month and accounted for a 17± loss in gelstrength and ∼ 7± in gelling and meltingtemperatures. Nevertheless, gel strength valuesremained around 930 ± 23 g cm-2 with nosignificant changes until the end of the storageperiod. The decrease in gel strength showed asignificant relationship with decrease in3,6-anhydrogalactose but not variation in sulphatecontent. This was probably due to agar hydrolysiscaused by enzymatic processes of endogenous and/ormicrobial origin. These results suggest that thetropical G. cornea had a similar resistance todegradation during storage to that observed for G. chilensis, a cold water species. Agar qualityand yield in G. cornea after one and a half yearof storage are within the range of food grade agar.

Conventional and alternative technologies for the extraction of algal polysaccharides

Abstract: Alginates, agar and carrageenan are the main commercial water-extracted polysaccharides sourced from brown and red marine algae. These phycocolloids exhibit high viscosity, and stabilizing, emulsifying and unique gelling properties. Agar and carrageenan form thermoreversible gels while alginates form ionic non-thermoreversible gels; therefore they play an irreplaceable role in foods, pharmaceuticals and biotechnology. The phycocolloid industry uses seaweeds from different parts of the world, and phycocolloid production amounts to 86 100 tons annually; equivalent to US

Antitrypanosomal in vitro activity of tropical marine algae extracts

1018 million. In this chapter we describe the conventional processes adopted in most factories for extracting and processing alginates, agar and carrageenan, and discuss the use of new eco-friendly extraction processes.