Włodzimierz M. Daniewski

Bioefficacy and mode-of-action of some limonoids of salannin group from Azadirachta indica A. Juss and their role in a multicomponent system against lepidopteran larvae

Biological activities of the salannin type of limonoids isolated fromAzadirachta indica A. Juss were assessed using the gram pod borerHelicoverpa armigera (Hubner) and the tobacco armywormSpodoptera litura (Fabricius) (Lepidoptera: Noctuidae). Inhibition of larval growth was concomitant with reduced feeding by neonate and third instar larvae. All three compounds exhibited strong antifeedant activity in a choice leaf disc bioassay with 2.0, 2.3 and 2.8 (μ/cm2 of 3-O-acetyl salannol, salannol and salannin, respectively deterring feeding by 50% inS. litura larvae. In nutritional assays, all three comounds reduced growth and consumption when fed to larvae without any effect on efficiency of conversion of ingested food (ECI), suggesting antifeedant activity alone. No toxicity was observed nor was there any significant affect on nutritional indices following topical application, further suggesting specific action as feeding deterrents. When relative growth rates were plotted against relative consumption rates, growth efficiency of theH. armigera fed diet containing 3-O-acetyl salannol, salannol or salannin did not differ from that of starved control larvae (used as calibration curve), further confirming the specific antifeedant action of salannin type of limonoids. Where the three compounds were co-administered, no enhancement in activity was observed. Non-azadirachtin limonoids having structural similarities and explicitly similar modes of action, like feeding deterrence in the present case, have no potentiating effect in any combination.

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.

Isolation of 12-hydroxycaryophyllene-4,5-oxide, a sesquiterpene from Lactarius camphoratus

Abstract A new sesquiterpene, 12-hydroxycaryophyllene-4,5-oxide, has been isolated from the ethanolic extract of Lactarius camphoratus . The structure, stereochemistry and absolute configuration were determined by a combination of spectral data and single-crystal X-ray analysis of the p -bromobenzoate derivative.

Salograviolide A, a sesquiterpene from Centaurea salonitana

Abstract A methanol extract of Centaurea salonitana gave 3β-acetoxy-8α,9β-dihydroxy-1αH,5αH,6βH,7αH-guai-4(15),10(14),11(13)-triene-6,12-olide. The structure of the new polyunsaturated dihydroxyguaianolide was established by spectroscopy and confirmed by single crystal X-ray diffraction.

Structural studies on lactarius sesquiterpenes: structure elucidation of lactarorufins D and E and conformational analysis of lactaran-5-olides

Abstract The structures of lactarorufins D and E, two new sesquiterpenes from Lactarius necator, have been elucidated. Conformational analysis of lactarorufins and blennins is discussed.

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.

Normarasmane sesquiterpenes from Lactarius vellereus

Abstract Ethanolic extracts of Lactarius vellereus gave, in addition to known sesquiterpenes, one new highly oxygenated marasmane lactone and two new 13-normarasmane sesquiterpenes, which are the first representatives of such a class of compounds. Molecular configurations and conformations have been established by spectroscopic methods.