Guido Sodano

Heterocyst glycolipids of the cyanobacterium Cyanospira rippkae

Abstract The heterocyst glycolipids of the cyanobacterium Cyanospira rippkae have been isolated and their structures established to be 1-(O-α- d -glucopyranosyl)-3R,27R-octacosanediol and 1-(O-α- d -glucopyranosyl)-27-keto-3R-octacosanol by spectroscopic and chemical means. The absolute configuration at the two stereogenic centres in the aglycone moiety of the former compound has been established in a single step by Moshers method on the triol derivative. The akinetes of C. rippkae contain the same glycolipids.

SYNTHESIS AND CYTOTOXIC ACTIVITY OF STEROID-ANTHRAQUINONE HYBRIDS

Abstract Synthesis of cytotoxic steroidal derivatives containing a quinone moiety is described. The synthetic strategy is based on an unsual A + CD → ABCD Diels-Alder approach which generates 9β-H cholestane analogs. The adducts formed are efficiently aromatized in basic media to give steroid-anthaquinones hybrids showing interesting cytotoxic activity on four tumor cell lines.

First enantioselective synthesis of manoalide: application of aldehyde–dioxinone enantioselective condensation

Abstract Manoalide, an analgesic and anti-inflammatory sesterterpene, has been stereoselectively synthesized for the first time. The C-4 stereogenic centre has been introduced in an early step by enantioselective aldol condensation using a Ti(OiPr)4/(R)-(+)-binol complex.

Structure of the “heterocyst glycolipids” of the marine cyanobacterium Nodularia harveyana

Abstract The “heterocyst glycolipids” have been reported to take part in the protection of the specialized cyanobacterial cells capable of N2 fixation against the penetration of O2. For the first time such glycolipids have been isolated in a pure form from a cyanobacterium, Nodularia harveyana , and their structures have been established by spectroscopic and chemical means to be 1-(O-α-D-glucopyranosyl)-3R,25R-hexacosanediol, 1-(O-α-D-glucopyranosyl)-3S,25R-hexacosanediol and 1-(O-α-D-glucopyranosyl)-3-keto-25R-hexacosanol.

SYNTHESIS OF (17R)-17-METHYLINCISTEROL, A HIGHLY DEGRADED MARINE STEROID

Abstract The synthesis of (17 R )-17-methylincisterol, a highly degraded marine steroid, has been achieved starting from vitamin D 2 in 8 steps and in 13% overall yield. Its O-demethyl analog, which is an intermediate in the synthetic sequence, is possibly the true naturally occurring molecule.

Biosynthesis of the heterocyst glycolipids in the cyanobacterium Anabaena cylindrica

Abstract Incorporation of [1- 13 C] acetate into the heterocyst glycolipids of the cyanobacterium Anabaena cylindrica indicated that (i) the long chain of the aglycones originates from a de novo biosynthesis and not by elongation of a preformed shorter molecule and that (ii) there is no apparent interconversion between the hydroxyketone and alcohol glucosides.

An easy approach to chiral non-racemic 6-(furan-3-yl)-5,6-dihydro-pyran-2-ones

Abstract Chiral non-racemic 6-(furan-3-yl)-pyran-2-one derivatives, key-intermediates in the preparation of compactin, manoalide and cacospongionolide subunits, are easily accessible through a rapid and convenient six-step sequence.

Chemoenzymatic synthesis and stereochemistry of aleppotrioloside, a naturally occurring glucoside

Abstract The stereochemistry of aleppotrioloside, a naturally occurring glucoside, has been determined as (3S)-3-[(1S)-1-hydroxyethyl]-4-methyl-1,4-pentanediol-1- O -β-D-glucopyranoside by its synthesis based on two key enzymatic reactions: Pseudomonas fluorescens lipase (PFL) catalyzed enantioselective resolution of an aglycone precursor and transglucosylation of the aglycone by thermophilic β-glycosidase from Sulfolobus solfataricus .

Reinvestigation of heterocyst glycolipids from the cyanobacterium, Anabaena cylindrica

Abstract The previously proposed structures for the heterocyst glycolipids of the nitrogen-fixing cyanobacterium Anabaena cylindrica have been revised. 13 C-enriched acetonides have been utilized for the determination of the relative stereochemistry of the 1,3-diol moiety in the aglycone of two glycolipids. The same glycolipids, which are thought to protect the nitrogenase from O 2 , have also been detected in A. torulosa .

Biosynthesis of calditol, the cyclopentanoid containing moiety of the membrane lipids of the archaeon Sulfolobus solfataricus

Abstract Calditol, the cyclopentane containing moiety of the membrane lipids of the archaeon Sulfolobus solfataricus , could be biosynthesized from d -glucose, via an ‘inositol like’ pathway.