Christian Francisco

Total structure and biological properties of laxaphycins A and B, cyclic lipopeptides from the marine cyanobacterium Lyngbya majuscula

The tropical marine cyanobacteriumLyngbya majuscula produces a series of cytotoxic and antimicrobial cyclic peptides. The total structure of the two major components, laxaphycins A and B, was determined by interpretation of physical data, principally high field NMR, FAB MS and MS/MS, in combination with chemical derivatization and degradation schemes. Absolute stereochemistries of the natural and ‘exotic’ amino acids were determined. The two cyclic peptides exhibited an unusual biological synergism when tested for antifungal or cytotoxic effects.

Mediterraneol a, a novel rearranged diterpenoid-hydroquinone from the marine alga cystoseira mediterranea

The isolation and structure determination by combined chemical and spectral methods of a novel biologically active metabolite mediterraneol A (Ia) from Cystoseira mediterranea are reported. Mediterraneol A was found to be an inhibitor of mitotic cell division.

Diterpenoid metabolites from the marine alga Cystoseira elegans

Abstract The isolation and structure determination of three new diterpenoids from the brown alga Cystoseira elegans is reported. The structures of these compounds were determined by combined chemical and spectral ( 13 C and 1 H NMR with decoupling experiments, high resolution mass spectral) methods.

An acyclic diterpene from the brown alga Bifurcaria bifurcata

Abstract Structure elucidation and total assignment of the 13 C NMR spectrum of 12-( S )-hydroxygeranylgeraniol, a new acyclic diterpene from the grown alga Bifurcaria bifurcata , was accomplished through the use of 1 HNMR, 13 C NMR and 2D NMR spectroscope including 2D long range 1 H- 13 C chemical shift correlations.

Cystodamine, a new cytotoxic fused polyaromatic alkaloid from the Mediterranean ascidian Cystodytes delle chiajei

Abstract a fused pentacyclic aromatic alkaloid - cystodamine - was isolated from a Mediterranean ascidian Cystodytes delle chiajei (Polycitoridae). The structure, determinated by extensive 2D-NMR means, is the first example of a marine product displaying a 1 H- 14 N coupling during 1 H NMR analysis.

Total synthesis of the marine pentacyclic alkaloid meridine

Abstract The synthesis of the marine pyridoacridine alkaloid meridine (1) has been accomplished in eight steps from 2,5-dimethoxy-3-nitroaniline in 9% overall yield.

Volatile constituents of Cupressus dupreziana and the sesquiterpenes of Cupressus sempervirens

Abstract Analysis of wood essential oil of Cupressus dupreziana revealed 26 components: 13 monoterpenes and 13 sesquiterpenes. The main components were carv

Nouveaux cyclotétrapeptides isolés de l'ascidie cystodytes delle chiajei.

Resume Three cyclotetrapeptides cyclo (L- Pro - L - Leu) 2 , cyclo (L - Pro - L - Val) 2 and cyclo (L - Pro - L - Phe) 2 were isolated from the marine ascidian Cystodytes delle chiajei (Didemnidae). Their structures were determined by spectroscopic means and confirmed by synthesis.

Cystoseirol A, a novel rearranged diterpene of mixed biosynthesis from the brown alga Cystoseira mediterranea

Abstract The skeleton of a novel class of rearranged meroditerpenoids was established by chemical and spectral methods, including heteronuclear shift correlations 1 H- 13 C 2D-NMR with long range coupling correlation.

The complete spectral assignment of didemnin H a new constituent of the tunicate Trididemnum cyanophorum

Abstract Complete 1H and 13C spectral assignments by 2D NMR means are presented for a new cyclodepsipeptide namely didemnin H, isolated from Trididemnum cyanophorum (Didemnidae).