Giorgio Mellerio

Characterization of phenolic and secoiridoid aglycons present in virgin olive oil by gas chromatography-chemical ionization mass spectrometry

Abstract Olive oil phenolic and secoiridoid compound derivatives were detected by mass spectrometry. Chemical ionization (CI) allowed us to obtain parent ions, that were not detectable in the electron impact mode. CI experiments were performed using either CH 4 or NH 3 as the reactant gas. Unlike CH 4 -CI, which fails to give molecular mass information, NH 3 -CI provided, in all the cases explored, an adduct ion [M+18] + that was sufficiently stable to be detected and recorded. Information about molecular masses was very useful for the complete characterization of aglycons from glycosides occurring in virgin olive oils. Aglycons of ligstroside, of decarbomethoxyoleuropein and of oleuropein were detected. Each aglycon, because of several tautomeric equilibria involving the ring opening of secoiridoid, showed up as compounds with four main structures after derivatization with bis(trimethylsilyl)trifluoracetamide.

Coatline A and B, two C-glucosyl-α-hydroxydihydrochalcones from Eysenhardtia polystachya

Abstract The first two examples of naturally occurring C -glucosyl-α-hydroxydihydrochalcones have been isolated from Eysenhardtia polystachya , a Mexica

New sesquiterpene hydroxylactones from Lactarius species

Abstract Four γ-hydroxybutenolide sesquiterpenes have been isolated from Lactarius scrobiculatus , L. blennius and L. pallidus . Their structures and absolute stereochemistry were determined by spectral data and by conversion to known compounds.

Morphological and chemical studies on the pygidial defence glands of some Carabidae (Coleoptera)

Etude effectuee sur 4 especes Pterostichus externepunctatus roccai, Nebria psammodes, Chlaenius velutinus et Chlaenius vestitus

Furanoeremophilanes and other constituents from Senecio Canescens

Abstract Investigation of the aerial parts and roots of Ecuadorian Senecio canescens afforded in addition to known furanoeremophilanes the first natural furanoeremophilane hydroperoxide and two new cacalohastine derivatives, one of which is a dimer. The volatile fraction was analysed by GC and GC-mass spectrometry.

High yield preparation of boronic esters of 1,2-diols with lithium trialkylborohydrides

Abstract Cyclic Boronic esters of 1,2-diols are easily prepared by reaction of 1,2-glycols with lithium trialkylborohydrides.

Fungal metabolites. Part 5. Uvidins, new drimane sesquiterpenes from Lactarius uvidus Fries

Uvidin A (IIa) and uvidin B (IIc) along with (–)-drimenol have been isolated from Lactarius uvidus Fries (Basidiomycetes). The structure and the stereochemistry of the two uvidins have been determined both by spectroscopic data and chemical reactions. Compound (IIa) has been correlated with (+)-drimanol (VIII) by transformations into (VI) and then (VII). Reactions and spectroscopic data are discussed.

Fungal metabolites. Part 15. Structure and chemical correlations of uvidin C, D, and E, new drimane sesquiterpenes from Lactarius uvidus Fries

Uvidin C (3), uvidin D (6), and uvidin E (10) have been isolated from Lactarius uvidus Fries (Basidiomycetes). The structures, including the absolute stereochemistry, of these three uvidins have been determined by spectroscopic data and chemical correlations with the known (+)-uvidin A (1).