Structure-related antifeedant activity of halolactones with a p-menthane system against the lesser mealworm, Alphitobius diaperinus Panzer

BACKGROUND

Feeding deterrent activity of synthetic halogen lactones against larvae and adults of the lesser mealworm, Alphitobius diaperinus Panzer, in laboratory choice and no-choice tests was studied. The compounds were synthesised from racemic and enantiomerically enriched (ee = 91-98%) cis- and trans-piperitols, which were obtained from (±)-piperitone.

RESULTS

Structure-activity relationship studies identified several synthetic halolactones with a very strong feeding deterrent activity. The most active were the enantiomeric chlorolactones with chiral centre configurations (1S,4S,5R,6R) and (1R,4R,5S,6S) and their racemic mixture. The racemic bromo- and iodolactones obtained from cis-piperitol and saturated lactones with a chiral centre configuration (1R,4S,6R) were also very good antifeedants in comparison with piperitone. Most of the studied compounds were better antifeedants against adults than against larvae-among the 21 compounds, only one bromolactone with a chiral centre configuration (1S,4R,5R,6R) was a weaker deterrent for adults.

CONCLUSION

Chemical transformation of the piperitone molecule by the introduction of a lactone function and a halogen atom strongly changed its antifeedant properties against the lesser mealworm. Optimum activity is dependent on the presence of a chlorine atom at C-5 of the cyclohexane ring. The activity of bromo- and iodolactones depended strongly on the chiral centre configuration and the halogen substituent.

Lactones 43. New biologically active lactones: β-cyclocitral derivatives

BACKGROUND

In our previous studies bicyclic γ-lactones with cyclohexane ring exhibited high antifeedant activity against storage pests. The activity was correlated with the type and number of substituents in the cyclohexane ring. One of the most potent group of antifeedant agents was δ-iodo-γ-lactones.

RESULTS

We present the synthesis of new bicyclic γ-lactones with the cyclohexane ring containing different halogen atoms. To determine the impact of halogen type on biological activity the lactone without halogen atom was also synthesized. The lactones were tested for their antifeedant activity toward the granary weevil beetle (Sitophilus granarius L.), the khapra beetle (Trogoderma granarium Everts) and the confused flour beetle (Tribolium confusum Du Val.). The results of the tests proved that the highest activity was observed for chlorolactone (7) towards larvae and adults of Tribolium confusum. Antibacterial activity of new lactones was also evaluated. Lactone without halogen atom (8) was active against Staphylococcus aureus and Listeria monocytogenes.

CONCLUSIONS

Studies on the biological activity of synthesised lactones revealed high selectivity towards insect pests as well as bacterial strains. Only the halolactones exhibited significant antifeedant activity. In contrast, antibacterial activity was shown only by the lactone (8) without halogen.

Piperitone-derived saturated lactones: synthesis and aphid behavior-modifying activity

Two racemic and two enantiomeric pairs of new saturated lactones with the p-menthane system were obtained. The lactones were synthesized from racemic and enantiomerically enriched cis- and trans-piperitols, which were obtained from piperitone. The structures of the compounds were confirmed by spectroscopic data. The antifeedant activity of piperitone to Myzus persicae was studied, and the biological consequences of structural modifications of piperitone, that is, lactonization and chiral center configuration, were examined as well. The behavioral responses of M. persicae to piperitone and piperitone-derived saturated lactones were investigated to reveal the biological background of their deterrent activity. Piperitone appeared rather neutral or weakly deterrent to aphids. The introduction of a lactone moiety into a piperitone molecule dramatically changed its biological activity. All piperitone-derived lactones evoked negative aphid responses. However, the deterrent activity of individual compounds varied in potency, the time of expression, and the duration of the effect, depending on the spatial structure of the lactone. Lactones (1R,3S,6R)-3-isopropyl-6-methyl-9-oxabicyclo[4.3.0]nonan-8-one and trans-3-isopropyl-6-methyl-9-oxabicyclo[4.3.0]nonan-8-one showed the broadest ranges and the highest potencies and durabilities of deterrent activity to M. persicae: they acted immediately after application, caused a cessation of probing before aphids reached phloem elements, and decreased the quality of phloem sap.

Synthesis and cytotoxic activity of new betulin and betulinic acid esters with conjugated linoleic acid (CLA)

The synthesis of new ester derivatives of betulin (3a-c) and betulinic acid (4) with conjugated linoleic acid isomers (CLA; in a mixture of 43.4% 9c, 11t; 49.5% 10t, 12c; 7.1% other isomers) is presented. Esterification was carried out with N,N'-dicyclohexylcarbodiimide (DCC) as the coupling agent in the presence of 4-dimethylamino-pyridine (DMAP) in dichloromethane (or pyridine). The in vitro cytotoxic effect of betulin (1), betulinic acid (2), a mixture of CLA isomers and their derivatives (3a-c, 4) was examined using the MTT assay against four cancer cell lines (P388, CEM/C2, CCRF/CEM and HL-60) and the SRB assay on the HT-29 cell line. Ester 4 was the most active among the esters synthesized against the CEM/C2 cell line with an ID50 value 16.9 +/- 6.5 microg/mL. Betulin (1), betulinic acid (2) and CLA were the most active agents against the cancer cell lines studied.

Synthesis and Cytotoxic Activity of New Betulin and Betulinic Acid Esters with Conjugated Linoleic Acid (CLA)

The synthesis of new ester derivatives of betulin (3a-c) and betulinic acid (4) with conjugated linoleic acid isomers (CLA; in a mixture of 43.4% 9c, 11t; 49.5% 10 t, 12 c; 7.1% other isomers) is presented. Esterification was carried out with N,N’-dicyclohexylcarbodiimide (DCC) as the coupling agent in the presence of 4-dimethylamino-pyridine (DMAP) in dichloromethane (or pyridine). The in vitro cytotoxic effect of betulin (1), betulinic acid (2), a mixture of CLA isomers and their derivatives (3a-c, 4) was examined using the MTT assay against four cancer cell lines (P388, CEM/C2, CCRF/CEM and HL-60) and the SRB assay on the HT-29 cell line. Ester 4 was the most active among the esters synthesized against the CEM/C2 cell line with an ID50 value 16.9 ± 6.5 μg/mL. Betulin (1), betulinic acid (2) and CLA were the most active agents against the cancer cell lines studied.

Lactones 41. Synthesis and microbial hydroxylation of unsaturated terpenoid lactones with p-menthane ring systems

Racemic [(±)-4-isopropyl-1-methyl-7-oxa-cis-bicyclo[4.3.0]non-4-en-8-one] and optically active δ,ε-unsaturated lactones [(-)-(1R,6R)-4-isopropyl-1-methyl-7-oxabicyclo[4.3.0]non-4-en-8-one and (+)-(1S,6S)-4-isopropyl-1-methyl-7-oxabicyclo[4.3.0] non-4-en-8-one)] with the p-menthane system were obtained and their odoriferous properties were evaluated. Biotransformations of the racemic lactone with three fungal strains: Absidia cylindrospora AM336, Absidia glauca AM177 and Syncephalastrum racemosum AM105, were carried out. Microbial transformations afforded hydroxylactones with the hydroxy group in the allylic position.

Synthesis of Phosphatidylcholine with Conjugated Linoleic Acid and Studies on Its Cytotoxic Activity

Phospholipids with conjugated linoleic acid (CLA), which are potential lipid prodrugs, were synthesised. CLA was obtained by the alkali-isomerisation of linoleic acid and was subsequently used in the synthesis of 1,2-di(conjugated)linoleoyl-sn-glycero-3-phosphocholine in good (82 %) yield. 1-Palmitoyl-2-(conjugated)linoleoyl-sn-glycero-3-phosphocholine was obtained by a two-step synthesis in 87 % yield. All the compounds were tested in an in vitro cytotoxicity assay against two human cancer cell lines, HL-60 and MCF-7, and a mouse fibroblast cell line, Balb/3T3. The free form of CLA exhibited the highest activity against all cancer cell lines. Results obtained for the Balb/3T3 line proved that phosphatidylcholine derivatives decreased the cytotoxic effect of CLA against healthy cell lines.

An LC method for the analysis of phosphatidylcholine hydrolysis products and its application to the monitoring of the acyl migration process

An assay for quantitative analysis of phosphatidylcholine (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and its hydrolysis products: 1-hydroxy-2-palmitoyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine, sn-glycero-3-phosphocholine and palmitic acid using high-performance liquid chromatography with charge aerosol detector (CAD) was developed. The separation of the compounds of interest was achieved on a reversed-phase/hydrophilic interaction stationary phase with a mobile phase consisting of acetonitrile:methanol:10mM ammonium acetate solution. The method was applied to control the acyl migration process of LPC regioisomers in the most common solvents used in the synthesis or modification of PC.

Synthesis of a natural gamma-butyrolactone from nerylacetone by Acremonium roseum and Fusarium oxysporum cultures

Natural gamma-butyrolactone - (4R, 5R)-5-(4'-methyl-3'pentenyl)-4-hydroxy-5-methyl-dihydrofuran-2-one (2) was isolated as the product of microbial transformation of nerylacetone (1) by fungal strains. This product was obtained as the enantiomer (+) in high yields 24% and 61% with ee=94% and 82% by the biotransformation in the cultures of Acremonium roseum AM336 and Fusarium oxysporum AM13 respectively.

Synthesis of dehydroepiandrosterone analogues modified with phosphatidic acid moiety

Dehydroepiandrosterone (DHEA) and its metabolite 7α-OH DHEA have many diverse physiological, biological and biochemical effects encompassing various cell types, tissues and organs. In in vitro studies, DHEA analogues have myriad biological actions, but in vivo, especially in oral administration, DHEA produces far more limited clinical effects. One of the possible solutions of this problem is conversion of DHEA to active analogues and/or its transformation into prodrug form. In this article, the studies on the conversion of DHEA and 7α-OH DHEA into their phosphatides by the phosphodiester approach are described. In this esterification, N,N-dicyclohexylcarbodiimide (DCC) was the most efficient coupling agent as well as p-toluenesulphonyl chloride (TsCl).