Mario Piattelli

Pigments of centrospermae—II. : Distribution of betacyanins

Abstract The distribution of betacyanins in thirty-seven plants, including examples from seven families of the order Centrospermae, has been investigated by using an automatic method of analysis on polyamide column. A large number (forty-four) of betacyanins, most of them previously undescribed, have been observed and the spectrophotometric and electrophoretic properties of these pigments have been determined. When sufficient amounts were available, the betacyanins were subjected to acid hydrolysis; analysis of the hydrolysate has shown that they are all derived from betanidin and isobetanidin.Abstract The distribution of betacyanins in thirty-seven plants, including examples from seven families of the order Centrospermae, has been investigated by using an automatic method of analysis on polyamide column. A large number (forty-four) of betacyanins, most of them previously undescribed, have been observed and the spectrophotometric and electrophoretic properties of these pigments have been determined. When sufficient amounts were available, the betacyanins were subjected to acid hydrolysis; analysis of the hydrolysate has shown that they are all derived from betanidin and isobetanidin.

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.

Photocontrol of amaranthin synthesis in amaranthus tricolor

Abstract Amaranthin formation in seedlings of Amaranthus tricolor is controlled by two photoreactions, one, a high-energy reaction, and the other a low-energy reaction controlled by phytochrome. Elongation of the hypocotyl in A. tricolor seedlings is also phytochrome controlled.

Pigments of centrospermae—V. : Betaxanthins from Mirabilis jalapa L.

Abstract Eight betaxanthins have been isolated from Mirabilis jalapa flowers. Two of them were identified as indicaxanthin (I) and vulgaxanthin-I (II), respectively. Structures IV–VII were assigned to four other pigments (miraxanthin-I, -II, -III and -V). The remaming two compounds (miraxanthin-IV and -VI) were not completely characterized. The synthesis of betaxanthins from betanin is also described.

Pigments of centrospermae—VI.: Acylated betacyanins

Abstract Characterization of eight betacyanins from three species plant ( Phyllocactus hybridus, Celosia cristala, Iresine herbstii ) is described. All these pigments have been shown to be acyl derivatives of betanin (III), amarantin (IV), or their corresponding C-15 diastereoisomers (isobetanin and isoamarantin). Both aliphatic (malonic acid and 3-hydroxy-3-methylglutaric acid) and hydroxycinnamic (ferulic, p -coumaric sinapic and caffeic acids) acids are present in the pigments as acyl residues. In seven of the compounds the acyl groups are linked to the sugar residue of the molecule, in the other evidence was obtained that the acid is directly linked to the aglycone moiety. For most of them, the number and position of the acyl group(s) in the molecule has also been established.

Biosynthesis of indicaxanthin in opuntia ficus-indica fruits

Abstract The result of the incorporation of doubly labelled tyrosine into indicaxanthin in the fruits of Opuntia ficus-indica shows that the dihydropyridine moiety of the pigment originates from dopa by extradiol cleavage of the aromatic ring.

Pigments of centrospermae—I. : Betacyanins from Phyllocactus hybridus hort. And Opuntia ficus-indica mill

Abstract Pour betacyanins are present in the flowers of Phyllocactus hybridus Hort. Of these pigments, two were shown to be betanin and isobetanin), the remainuig two being other glucosides of betanidin and isobetanidin, respectively. Only the first two betacyanins are present in the fruits of Opuntia ficus-indica Mill.

Diterpenes based on the dolabellane skeleton from dictyota dichotoma

From a variety of Dictyota dichotoma we have isolated, in addition to previously reported dolabellane (6-8) and perhydroazulene diterpenes (9,10), four new diterpenoids (2-5). Their structure have been elucidated by spectral analysis and chemical degradation. All the new dolabellane derivatives possess antimicrobial activity against gram-positive and gram-negative organisms.

Further perhydroazulene diterpenes from marine organisms

3 novel diterpenes,4–6, having the perhydroazulene skeleton already found in pachydictiol A (1) and dictyol A (2) and B (3), have been isolated from both the digestive gland of Aplysia depilans and algae of the family Dictyotaceae.