Carrageenans from the Red Seaweed Sarconema filiforme Attenuate Symptoms of Diet-Induced Metabolic Syndrome in Rats

Carrageenans are thickening and gelling agents that may provide health benefits. Iota (ι)-carrageenan, a linear sulfated polysaccharide, is produced by the red seaweed, Sarconema filiforme. This study investigated the potential of this seaweed as a functional food for the reversal of metabolic syndrome and possible mechanisms. Male Wistar rats were divided into four groups in a 16-week protocol: corn starch diet-fed rats (C); C rats supplemented with 5% S. filiforme for the last 8 weeks (CSF); high-carbohydrate, high-fat diet-fed rats (H); and H rats supplemented with 5% S. filiforme for the last 8 weeks (HSF). S. filiforme was produced in tank-based aquaculture yielding 27 g dry weight/day/m2 of culture area. H rats developed obesity, hypertension, dyslipidaemia, glucose intolerance, fatty liver and increased left ventricular collagen deposition. S. filiforme supplementation decreased body weight, abdominal and liver fat, systolic blood pressure, plasma total cholesterol concentrations, and plasma activities of alanine transaminase and aspartate transaminase. S. filiforme supplementation modulated gut microbiota without changing the Firmicutes to Bacteroidetes ratio. S. filiforme improved symptoms of high-carbohydrate, high-fat diet-induced metabolic syndrome in rats. Possible mechanisms include a reduced infiltration of inflammatory cells into organs as well as prebiotic actions in the gastrointestinal tract.

Chemical Investigation of Carrageenan from the Red alga Sarconema filiforme (Gigartinales, Rhodophyta) of Indian Waters

Sulphated galactan (SFA) containing alpha (α), iota (í) and pyruvated α-carrageenans (17.6:18.8:25.3 mol %) was extracted and characterized from Sarconema filiforme of Indian waters. The SFA and its alkali modified derivative (SFAM) were composed of D-galactose, 3, 6-anhydro-D-galactose, 6- O-methylated-D-galactose (64.5:23.0:9.8 and 59.6:29.8:7.6 mol %) respectively. The linkage analysis, physicochemical analysis, infra red and 13C nuclear magnetic resonance spectra of SFA along with linkage analysis of the desulphated derivative (SFD) of SFA, reveals that it was a hybrid/combination of α/í carrageenan as well as 3-linked 4′,6 ‘-O-(1-carboxyethylidene)-galactose (pyruvated α carrageenan) and 6 -O-methylated α-carrageenan. The flow behavior of SFA obtained from rheological measurements suggested strong network formation in presence of 1% aqueous KCl and CaCl2 solutions.

Taxonomic studies of the genus Gracilaria (Gracilariales, Rhodophyta) from Australia

The taxonomic history of the genus Gracilaria in Australia is reviewed, and nine species are described and illustrated in detail. Two (G. comosa and G. stipitata) are newly described, and the new name G. cliftonii is proposed for the species previously known as G. furcellata Harvey [non G. furcellata (Montagne) Zanardini = Sarconema filiforme (Sonder) Kylin]. New records and observations are given for four species [G. harveyana J.Agardh, G. preissiana (Sonder) Womersley, G. salicornia (C.Agardh) Dawson, and G. urvillei (Montagne) Abbott in Abbott, Zhang & Xia], and two species [G. blodgettii Harvey and G. cf. vieillardii Silva in Silva, Menez & Moe] are added to the Australian flora. An additional seven or eight species that are incompletely known also occur on the continent and are briefly discussed but not illustrated. For nomenclatural and anatomical reasons we propose that G. spinulosa (Okamura) Chang & Xia forma srilankia Chang & Xia, based on G. purpurascens Harvey ex J. Agardh [non G. purpurascens (Hudson) Greville = Cystoclonium purpurascens (Hudson) Kutzing] and not yet recorded from Australia, be elevated to species status as G. srilankia (Chang & Xia) comb. nov. We propose that Gracilaria harveyana J. Agardh 1885 be conserved against Polyides flagelliformis Sonder 1845, which Professor H.B.S. Womersley has determined is an obscure but earlier name for this well-known Western Australian species.