Marco Clericuzio

Terpenoids from Russula lepida and R. amarissima (Basidiomycota, Russulaceae)

Four aristolane sesquiterpenes were isolated from the fruiting bodies of Russula lepida and R. amarissima, namely (1R,2S)-1,2-dihydroxyaristolone (6), (2S,11S)-2,12-dihydroxy-aristolone (7), (1R,2S,11S)-1,2,12-trihydroxyaristolone (8), (1S,2S,11S)-1,2,12-trihydroxy-aristolone (9). In addition, a seco-cucurbitane triterpene, i.e. 3,4-secocucurbita-4,24E-diene-3-hydroxy-26-carboxylic acid (14) was isolated from both species. The configuration at C-2 of the already known rulepidol (2-hydroxyaristolone, 5) was corrected as S instead of R. Several more aristolane and nardosinane sesquiterpenes, as well as cucurbitane triterpenes, already reported both from European and Chinese samples of R. lepida, were also isolated. Compound 14 showed moderate cell growth inhibitory activity.

Structure and absolute configuration of protoilludane sesquiterpenes from Russula delica

Abstract Three new protoilludane sesquiterpenes, plorantinone A, B and C (1, 2a and 3), were isolated from injured fruit bodies of the Basidiomycete Russula delica, presumably formed from stearoylplorantinone B (2b) which was isolated from intact fruit bodies. The isolation and structure elucidation including the determination of the absolute configuration of the four compounds is reported.

Conversion of velutinal esters in the fruit bodies of Russula cuprea

Abstract The only sesquiterpenoid present in intact fruit bodies of Russula cuprea was found to be velutinal, as a mixture of stearic, oleic, linoleic and palmitic acid esters. As a response to injury, the velutinal esters are converted to the marasmane sesquiterpenes isovelleral, isovellerol, isovellerdiol and the new aldehyde cupreal [(2 S , 3 R , 6 R , 7 S , 8 S , 9 R )-8,13-dihydroxy-5-oxo-marasmane]. The structure of cupreal was determined by a combination of spectroscopic and computational methods.

Stearoyldelicone, an unstable protoilludane sesquiterpenoid from intact fruit bodies of Russula delica

Stearoyldelicone (3), containing an unusual and reactive bicyclo[4.2.0]octa-1,4-dien-3-one moiety, was isolated from the methylene chloride extracts of intact fruit bodies of the Basidiomycete Russula delica. 3 is unstable and easily transformed to the illudalane sesquiterpenoid 4a during chromatography on silica gel.

Isolation of a New Caryophyllane Ester fromLactarius subumbonatus: Conformational Analysis and Absolute Configuration

(1R,6R,9S)-6-Hydroxycaryophyllene (S)-6-hydroxystearate, a sesquiterpene alcohol esterified by the unusual fatty acid (S)-(+)-6-hydroxystearic acid, has been isolated from the fruiting bodies of the Basidiomycete Lactarius subumbonatus. Both NMR data and AM1 calculations indicate that the caryophyllene macrocyclic ring adopts a ββ conformation. The absolute configuration of the sesquiterpene moiety has been established by theoretical Circular Dichroism calculations (De Voe coupled oscillators theory) and that of the fatty acid by NMR studies of the (R)-2-methoxy-2-naphthylacetic acid (2-NMA) ester.

Structures and biological significance of lactarane sesquiterpenes from the European mushroom Russula nobilis

The results of the first investigation on secondary metabolites occurring in intact and damaged fruiting bodies of Russula nobilis growing in Europe, are reported. Intact mushrooms contain fatty acid esters of velutinal, while three new sesquiterpenoids, russulanobilines A–C, along with eight known ones were isolated from extracts of injured fruiting bodies. The structures of the new compounds were elucidated on the basis of spectral data, molecular modeling, and 13C NMR spectra calculation. This pattern of sesquiterpenes constitutes a new variant of a chemical defense machinery which protects mushrooms against predators, parasites, and microorganisms.

Cadinane sesquiterpenes from the mushroom Lyophyllum transforme

Two rare cadinane-type sesquiterpenes, lyophyllone A (1) and lyophyllanetriol A (2), were isolated from the mushroom Lyophyllum transforme. The structures were elucidated on the basis of exhaustive NMR techniques, together with MS, UV-Vis and molecular modelling. The absolute configuration of lyophyllone A was determined by ab initio theoretical CD calculation performed by Density Functional Theory (DFT) using the B3PW91/6-31G(d,p) basis set. The experimental CD were found to be in good agreement with the corresponding population-weighted theoretical CD spectra, allowing for the determination of the absolute stereochemistry of the compound.

Two New Ergosterol Derivatives from the Basidiomycete Cortinarius glaucopus

Two new sterols 1 and 2 and five known ones 3 – 7 were isolated for the first time from the fruiting bodies of Cortinarius glaucopus. Their structures were established by 1‐ and 2D‐NMR spectra and HR‐FABS‐MS. The relative configuration of 1 was firmly determined by comparison of the observed 1H–1H couplings and NOESY correlations, with those predicted for the computed geometries of the conformers. Calculations were performed by means of DFT with the B3LYP functional at 6‐31 + G(d,p) level of theory, in CHCl3 as the solvent. The structures of the new ergosterol derivatives, called glaucoposterol A (1) and B (2), were thus established as (3S,5R,7R,10R,13R,17R,20S,22R,23R,24R)‐5,6‐epoxy‐3,7,23‐trihydroxystrophast‐8‐en‐14‐one and (22E,3S,5S,9S,10R,13R,17R,20R,24R)‐3,5‐dihydroxyergosta‐6,8(14),22‐trien‐15‐one, respectively. Moreover, the configuration of known strophasterol C (3) was determined as (3S,5R,6S,7R,10R,13R,17R,20S,22S,24R). Glaucoposterol A (1) and strophasterol C (3) represent the second finding in nature of steroids with the rare strophastane skeleton.

A New Iridoid Dimer and Other Constituents from the Traditional Kurdish Plant Pterocephalus nestorianus Nab

Accompanied by other rare compounds, a new iridoid dimer, named kurdnestorianoside (1), showing an unprecedented secologanol configuration, has been isolated for the first time from the Kurdish medicinal plant Pterocephalus nestorianus, which is used in Kurdistan for treating oral diseases and inflammation. The structure of 1 was established from 1D‐ and 2D‐NMR spectroscopic data. Kaempferol 3‐O‐[3,6‐di‐O‐(E)‐p‐coumaroyl]‐β‐d‐glucopyranoside (7) showed a remarkable antiproliferative activity against several human tumor cell lines.