Maria Gumułka

Why the yew tree (Taxus baccata) is not attacked by insects

Abstract In recent years, the yew tree has attracted considerable attention due to the isolation from it of the important antitumour drug Taxol ® . The fact that the wood is not attacked by woodworm and its needles are attacked by very few insects has so far neither been examined nor exploited. Extracts of Taxus baccata have strong antifeedant activity against storage pests Tribolium confusum , Trogoderma granarium and Sitophilus granarius . Nine pure compounds were isolated from the extract and very strong antifeedant activity was exhibited by 10-deacetylbaccatin III and 10-deacetylbaccatin V, which most probably are responsible for the activity and the resistance to insects.

Sesquiterpenes of Lactarius origin, antifeedant structure-activity relationships

Antifeedant activity of 53 sesquiterpenes of Lactarius origin was measured against the storage pests Tribolium confusum, Trogoderma granarium and Sitophilus granarius. The activities of the compounds are discussed in relation to their structures and oxidation state. Conclusions concerning structure-activity relationships have been drawn. It was found that compounds with lactarane and marasmane skeletons were more active than isolactaranes. Also an increasing number of hydroxyl groups present in a molecule decreased its activity. Generally compounds of natural origin, with the exception of keto derivatives, possessed stronger activity than their chemically modified analogues.

Synthesis and antifeedant properties of N-benzoylphenylisoserinates of Lactarius sesquiterpenoid alcohols

The esterification of various sesquiterpenoid alcohols of Lactarius origin with N-benzoyl-[2R,3S]-phenylisoserine (side chain of Taxol) produced compounds whose antifeedant properties against storage pests Tribolium confusum, Trogoderma granarium and Sitophylus granarius were measured. The introduction of the taxol side chain in these molecules, in comparison to original compounds, moderately enhanced their antifeedant activities, as well as changed their selectivity of activity towards the test insects.

Marasmane lactones from Lactarius vellereus

Abstract An ethanol extract of Lactarius vellereus gave 7α,8α,13-trihydroxy-marasm-5-oic acid γ-lactone and 13-hydroxy-marasm-7(8)-en-5-oic acid γ-lactone in addition to known compounds. The structure of the dihydroxylactone was established by spectroscopy and confirmed by single crystal X-ray diffraction. The structure of the unsaturated lactone was substantiated by spectroscopy and transformation to the former dihydroxylactone.

Furantriol, a lactarane sesquiterpene from Lactarius mitissimus

Abstract An ethanolic extract of Lactarius mitissimus gave the furantriol (2S*,3S*,8S*,9R*,11S*)-3,8,14-trihydroxy-5,13-oxa-lactaran-5,6-7,13-diene in addition to known sesquiterpenes. The structure of this new trihydroxylactarane was established by1H and13C NMR spectroscopy and confirmed by chemical correlation with lactarorufin B.

3-Deoxy-3-epi-lactaroscrobiculide b, a sesquiterpene from Lactarius vellereus

Abstract An ethanol extract of Lactarius vellereus contained a new 5-hydroxy-lactara-6,8-dien-13-oic acid γ-lactone in addition to known sesquiterpenes. The structure of the new compound was established by 1 H and 13 CNMR spectroscopy. An unambiguous assignment of stereochemistry at C-3 of this compound was accomplished by independent synthesis of both C-3 epimers.

Sesquiterpenoid constituents of Entandrophragma cylindricum

A petrol extract of Entandrophragma cylindricum afforded six sesquiterpenes. Two of them, 3-hydroxy-copa-2-en and 2α-hydroxy-copa-3-en, are new. 10-Hydroxy-trans-calamenene, T-cadinol, ledol and mustacon have already been reported. The structures of all these compounds were substantiated by extensive NMR experiments.

Utilin B, a tetranortriterpenoid of the mexicanolide group from bark of Entandrophragma utile

Abstract New tetranortriterpenoid utilin B has been isolated from the bark of Entandrophragma utile , its structure assigned on the basis of extensive NMR experiments and confirmed by single crystal structure X-ray measurement.

A tetranortriterpenoid from the bark of Entandrophragma utile.

Abstract A new tetranortriterpenoid, utilin C, has been isolated from the bark of Entandrophragma utile. Its structure was assigned on the basis of extensive NMR experiments, and confirmed by single crystal structure X-ray measurement.

Monohydroxylactones of Lactarius vellereus

Reinvestigation of the monohydroxylactone fraction of an ethanolic extract of Lactarius vellereus resulted in the isolation of four new monohydroxylactones with the marasmane skeleton. The structures were elucidated by extensive NMR investigations and in one case confirmed by X-ray measurements.