Silvana Magno

Amino acids and low-molecular-weight carbohydrates of some marine red algae

Abstract Amino acids and low-MW carbohydrates of 18 red algae have been analyzed. Several non-protein amino acids have been identified, including pyrrolidine-2,5-dicarboxylic acid ( 3 c) and N -methylmethionine sulfoxide ( 5 ), new natural products, and 13 known compounds, citrulline, β-alanine, γ-aminobutyric acid, baikiain ( 1 ), pipecolic acid ( 2 ), domoic acid ( 3 a), kainic acid ( 3 b), azetidine-2-carboxylic acid ( 4 ), methionine sulfoxide taurine, N -methyltaurine, N,N -dimethyltaurine and N,N,N -trimethyltaurine. Sugars present were mainly floridoside, isofloridoside and mannoglyceric acid. Details of the structural elucidation of new compounds are also given.

The structure of melanins and melanogenesis—V : Ustilagomelanin☆☆☆★

Abstract The black pigment from Ustilago mydis spores has been studied. Analytical data and degradation experiments show it to be related to catecholmelanin.

Complex yessotoxins profile in Protoceratium reticulatum from north-western Adriatic sea revealed by LC-MS analysis.

While the occurrence of yessotoxin (YTX) has been reported worldwide from Protoceratium reticulatum, the biogenetic origin of some YTX analogues is still unknown, thus raising an issue whether they are metabolites of YTX formed in mussels or true products of different dinoflagellate species. Findings reported herein suggest that P. reticulatum from the north-western Adriatic sea is responsible for production, together with YTX (1), of homoYTX (2), 45-OHYTX (3), carboxyYTX (5), and noroxoYTX (7). YTX and its analogues have been determined by high performance liquid chromatography coupled with electrospray ion trap mass spectrometry (HPLC-MS and HPLC-MSn experiments). The result is the first to confirm production of these YTX analogues from this species and indicate it as a producing organism of homoYTX, 45-OHYTX, carboxyYTX, and noroxoYTX found in shellfish.

Isolation of adriatoxin, a new analogue of yessotoxin from mussels of the Adriatic Sea

Abstract Diarrhetic shellfish toxin composition in the hepatopancreas of mussels from northern Adriatic sea was investigated. Along with yessotoxin (YTX), homoyessotoxin (homoYTX) and 45-hydroxyyessotoxin (45-OHYTX), identified by comparison of their chromatographic and spectral properties with those reported in the literature, we isolated a new analogue of YTX, adriatoxin (ATX), whose structure was determined on the basis of spectral evidence.

Yessotoxin in mussels of the northern Adriatic Sea

This study investigated the composition of diarrhoetic shellfish toxins in the hepatopancreas of mussels from the northern Adriatic Sea. The major toxins were shown to be yessotoxin, identified by its chromatographic properties and spectral data, and okadaic acid, detected both by fluorometric high-performance liquid chromatography and by comparison of its spectral properties with those of an authentic sample.

Scalarin, a new pentacyclic C-25 terpenoid from the sponge Cacospongia scalaris☆

Abstract On the basis of chemical and physico-chemical evidence, structure I has been assigned to scalarin, a new C-25 terpenoid isolated from the marine sponge Cacospongia scalaris.

Isolation and structure of axisonitrile-1 and axisothiocyanate-1 two unusual sesquiterpenoids from the marine spongeAxinella cannabina

Abstract Two sesquiterpenoids, axisonitrile-1 and axisothiocyanate-1, have been isolated from the spongeAxinella cannabina. On the basis of chemical and physico-chemical evidence structure1 is suggested for axisonitrile-1 and structure2 for axisothiocyanate-1.

The structure of melanins and melanogenesis—II : Sepiomelanin and synthethic pigments

Abstract A comparative study on sepiomelanin and three synthetic pigments, namely dopa melanin, 5,6-dihydroxyindole melanin and pyrrole black, has been carried out. Sepiomelanin is structurally related to 5,6-dihydroxyindole and dopa melanins. The only observed differences are the absence of carboxyl groups in position 2 of the indole nuclei in the synthetic pigments (this result, obvious for 5,6-dihydroxyindole melanin, is rather surprising for dopa melanin) and the presence of α-amino acid chains in dopa melanin. Some carboxyl groups found in dopa and 5,6-dihydroxyindole melanins are located on pyrrole units. Considerable differences arise when comparing pyrrole black with sepiomelanin.

The flavonoids of Allium ursinum

From wild garlic Allium ursinum three new flavonoid glycosides were identified as kaempferol 3-O-beta-neohesperidoside-7-O-[2-O-(trans-p-coumaroyl)]-beta -D- glucopyranoside, kaempferol 3-O-beta-neohesperidoside-7-O-[2-O-(trans-feruloyl)]-beta-D- glucopyranoside, kaempferol 3-O-beta-neohesperidoside-7-O-[2-O-(trans-p-coumaroyl)-3-O-b eta-D- glucopyranosyl]-beta-D-glucopyranoside and characterized as the peracetates. Additionally, two known flavonoid glycosides kaempferol 3-O-beta-glucopyranoside and kaempferol 3-O-beta-neohesperidoside were isolated. The isolated compounds showed an inhibition of human platelet aggregation.

New sesquiterpenoids from the sponge axinella cannabina

On the basis of chemical and spectral evidence, the structureIV has been assigned to Axisonitrile-4, an axane-sesquiterpenoid isonitrile, isolated from the spongeAxinella cannabina; in the same organism have been also found Axisothiocyanate-4 (V) and Axammide-4 (VI).