Free sterols of the red alga Gigartina skottsbergii

The free sterols of the red alga Gigartina skottsbergii have been identified by means of GC and GC/MS analyses. The mixture contained saturated and unsaturated C²⁷, C²⁸ and C²⁹ sterols. The major component was cholest-5-en-3β-ol. Cholesta-5,24-dien-3β-ol (desmosterol) was present in low proportion but no side chain hydroxylated components were detected.     

The occurrence of C28 sterols in red algae

Lenormandia prolifera and Amansia glomerata contain large amounts of 24-methylenecholesterol. These two algae belong to the Amansia group of Rhodomelaceae as do Rytiphloea tinctoria and Vidalia volubilis, which are already known to be able to alkylate sterols at C-24. Halopythis pinastroides is an exception in the Amansia group, no C-28 sterols being present in this alga.     

Sterols of some chilean algae

The distribution of sterols in 14 Chilean Rhodophyceae and in Lessonia sp. (Phaeophyceae) has been examined. Cholesterol is present in all the red algae examined. Golidium filicinum contains, in addition desmosterol and 24-methylene-cholesterol. Cholest-7-en-3-β-ol was found in Cryptonemia angustate and Neoagardhiella gaudichaudii. Fucosterol and 24-methylenecholesterol were found in Lessonia sp.     

Sterols of the red alga Rissoella verruculosa

The Mediterranean red alga Rissoella verruculosa contains desmosterol in the esterified form whereas this sterol is not present in the free state.     

Carotenoids in red algae

The carotenoid composition of the following 8 species of red algae has been studied quantitatively and qualitatively: Bangia fuscopurpurea, Nemalion helminthoides, Bonnemaisonia hamifera (tetrasporophyte), Gigartina stellata, Rhodymenia palmata, Ceramium rubrum, Polysiphonia brodiaei, and Polysiphonia urceolata. Naturally occurring material of G. stellata, R. palmata, and P. brodiaei was investigated, while monoalgally cultured material was obtained from the remaining 5 species. α- and β-carotene, lutein, zeaxanthin, and small amounts of α- or β-cryptoxanthin were commonly present, but the two species P. brodiaei and P. urceolata were devoid of carotenoids containing α-ionone rings. Fucoxanthin was detected in naturally occurring material of B. fuscopurpurea, N. helminthoides, C. rubrum, and P. brodiaei, but could not be found in cultured material of the 3 first-mentioned species. The possible origin of the fucoxanthin is discussed as well as the biochemical and phylogenetic implications of the results obtained. As judged from the electronic spectrum of the total extracts, chlorophyll d was not present in any of the algae investigated. The total amounts of carotenoids and the ratio carotenoids: chlorophyll a were similar to those reported in previous work.     

Sterol composition of some mediterranean green algae

The distribution of sterols in ten Mediterranean green algae has been examined. Clionasterol is typical for the Siphonocladales and all the species of the Siphonales not belonging to the genus Codium, which is characterized by clerosterol. 28-Isofucosterol has been confirmed to be characteristic of the Ulotrichales.     

Configurational studies on red algae carotenoids

The configurations of (6′R)-β,ε-carotene, (3′R,6′R)-β,ε-caroten-3′-ol (α-cryptoxanthin), (3R,3′R,6′R)-β,ε-carotene-3,3′-diol (lutein), (3R)-β,β-caroten-3-ol (β-cryptoxanthin), (3R,3′R)-β,β-carotene-3,3′-diol (zeaxanthin) and all-trans (3S,5R,6S,3′R)-5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol (antheraxanthin) were established by CD and ¹H NMR studies. The red algal carotenoids consequently possessed chiralities at each chiral center (C-3, C-5, C-6, C-3′, C-6′), corresponding to the chiralities established for the same carotenoids in higher plants. Two post mortem artifacts from Erythrotrichia carnea were assigned the chiral structures (3S,5R,8R,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8R)-mutatoxanthin] and (3S,5R,8S,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8S)-mutatoxanthin]. This is the first well documented report of a naturally occurring β,ε-caroten-3′-ol (¹H NMR, CD, chemical derivatization).     

Accessory polypeptides in phycobilisomes of red algae and cyanobacteria

Phycobilisomes of red algae and cyanobacteria contain small amounts of nonpigmented polypeptides in addition to the major constituent biliprotein pigments. The localization of these polypeptides is analyzed by gel electrophoresis of phycobilisome fragments obtained by selective dissociation and subsequent separation. Five groups of biliprotein aggregates are determined, belonging to the 6, 11, 16, 18 and 23 S categories. Accessory nonpigmented high molecular weight proteins (80,000 MW) are exclusively bound to phycobilisome core fractions and thylakoids, thus apparently serving as links between the phycobilisomes and the photosynthetic units of the thylakoids. In contrast, smaller nonpigmented accessory polypeptides of 20,000 to 60,000 MW are preferably found in the peripheral biliprotein stacks. They may either form a compatible link between the phycobilisome core and periphery or bind and co-polymerize with hexameric biliproteins in the peripheral stacks to enhance or effect binding of the aggregates. Furthermore, they may determine the arrangement and composition of the phycobilisomes during development and chromatic adaptation.Abbreviations PE phycoerythrin - PEC phycoerythrocyanin - PC phycocyanin - APC allophycocyanin     

Isethionate in certain red algae

Isethionic acid (2-hydroxyethanesulfonic acid) was isolated as salts from a methanolic extract ofHypnea musciformis collected in the Indian Ocean and identified by comparison (nuclear magnetic resonance, infrared and mass spectrometry) with an authentic sample. The compound has not previously been reported from plants. Investigations of 13 other species of red algae showed that only some samples of species of the families Gigartinaceae, Hypnaceae and Solieriaceae (all of order Gigartinales) contained isethionates.Author for correspondence     

Sterols of some red algae

The sterol composition of 17 red algae has been determined. Only C-27 sterols have been found in substantial amounts; details of the structural elucidation of liagosterol (cholesta-5,23-diene-3β,25-diol) are given. The possible taxonomic significance of the sterol distribution is briefly discussed.     

Amino-acid profiles in red algae

Free protein amino acids have been quantitatively determined in 30 red algae. In most of the species, aspartic acid (asparagine), glutamic acid (glutamine), alanine, glycine and serine dominate, while massive accumulation of proline (up to 80·5%) was observed in six species, all belonging to the family Rhodomelaceae.     

Characteristics and utility of nuclear-encoded large-subunit ribosomal gene sequences in phylogenetic studies of red algae

Primer sequences are described for amplifying and sequencing a large fragment (approximately 2500 b.p.) of the nuclear-encoded large-subunit ribosomal RNA gene (LSU) from red algae. In comparison to RuBisCo large-subunit gene (rbcL) and nuclear-encoded small-subunit ribosomal RNA gene (SSU) sequence data, LSU sequence data was intermediate in the number of phylogenetically informative positions and sequence divergence. Parsimony analysis of LSU sequences for 16 Gelidiales species resolved some nodes unresolved in rbcL and SSU parsimony trees. An analysis of LSU sequences from 13 species of red algae classified in 11 orders suggests that this gene may be useful in studies of higher-level relationships of red algae.     

Polysaccharide of the red alga rissoella verruculosa

The Mediterranean red alga, Rissoella verruculosa, contains a K-like carrageenan. ¹³CNMR studies indicate that the polysaccharide contains neocarrabiose sulphate units alternating with non-sulphated neocarrabiose residues.     

Sterol esters of Phycomyces blakesleeanus

The sterol esters of Phycomyces blakesleeanus are based on ergosterol, episterol, ergosta-7-en-3β-ol, ergosta-7,22-dien-3β-ol, cholesterol, lan     

Bio-active monoterpenes from red seaweeds

A new ochtodane from Chondrococcus hornemanii and the biotoxocity of other seaweed monoterpenes is reported.     

Halogenated monoterpenes of the red alga Microcladia

The red marine algae Microcladia borealis, M. californica and M. coulteri produce several unusual halogenated monoterpenes including violacene, plocamene-B, plocamene-C, and plocamane-D. The isolation of these terpenes along with a study of their variation in each Microcladia at different locations are described.     

Sesquiterpenes from the marine red alga Laurencia distichophylla

A new cuparene-type sesquiterpene, isolaurenisol, has been isolated and identified from the New Zealand red alga Laurencia distichophylla. Major differences in the chemical composition of two morphologically indistinguishable samples of L. distichophylla are noted.     

Sterol composition and the classification of the demospongiae

The Demospongiae (Porifera) have yielded a wide range of novel and conventional sterols; a sample of 55 species screened and reported on have yielded 45 distinct sterol structures. The taxonomic relevance of the occurrence of particular sterols or overall sterol complement is evaluated and has proved to be informative in the case of the Verongida, Nepheliospongida, Axinellida and Hadromerida. A possible relationship between the occurrence of 26-methyl sterols and oviparous reproductive patterns within the Ceractinomorpha is noted. Sterol complement is observed to be qualitatively stable despite season and location of collection. High molecular weight sterols, present as major components, are probable membrane constituents. They afford an interesting parallel to the occurrence of diverse, high carbon fatty acids in sponge membranes.