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Synthesis, antifeedant activity against Coleoptera and 3D QSAR study of alphaasarone derivatives a
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B. Łozowicka , P. Kaczyński , T. Magdziarz & A.T. Dubis a
Institute of Plant Protection - National Research Institute, Bialystok, Poland b
University of Silesia, Department of Organic Chemistry, Katowice, Poland c
University of Bialystok, Institute of Chemistry, Bialystok, Poland Published online: 07 Mar 2014. To cite this article: B. Łozowicka, P. Kaczyński, T. Magdziarz & A.T. Dubis (2014) Synthesis, antifeedant activity against Coleoptera and 3D QSAR study of alpha-asarone derivatives, SAR and QSAR in Environmental Research, 25:3, 173-188, DOI: 10.1080/1062936X.2013.875061 To link to this article: http://dx.doi.org/10.1080/1062936X.2013.875061
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SAR and QSAR in Environmental Research, 2014 Vol. 25, No. 3, 173–188, http://dx.doi.org/10.1080/1062936X.2013.875061
Synthesis, antifeedant activity against Coleoptera and 3D QSAR study of alpha-asarone derivatives B. Łozowickaa*, P. Kaczyńskia, T. Magdziarzb and A.T. Dubisc
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Institute of Plant Protection - National Research Institute, Bialystok, Poland; bUniversity of Silesia, Department of Organic Chemistry, Katowice, Poland; cUniversity of Bialystok, Institute of Chemistry, Bialystok, Poland (Received 20 August 2013; in final form 19 November 2013) For the first time, a set of 56 compounds representing structural derivatives of naturally occurring alpha-asarone as an antifeedants against stored product pests Sitophilus granarius L., Trogoderma granarium Ev., and Tribolium confusum Duv., were subjected to the 3D QSAR studies. Three-dimensional quantitative structure–activity relationships (3D-QSAR) for 56 compounds, including 15 newly synthesized, were performed using comparative molecular field analysis s-CoMFA and SOM-CoMSA techniques. QSAR was conducted based on a combination of biological activity (against Coleoptera larvae and beetles) and various geometrical, topological, quantum-mechanical, electronic, and chromatographic descriptors. The CoMSA formalism coupled with IVE (CoMSA–IVE) allowed us to obtain highly predictive models for Trogoderma granarium Ev. larvae. We have found that this novel method indicates a clear molecular basis for activity and lipophilicity. This investigation will facilitate optimization of the design of new potential antifeedants. Keywords: 3D QSAR; CoMSA; antifeedant activity; stored product pests; alpha asarones derivatives; synthesis
1. Introduction The threat of destruction of stored grain products and their infection by pests of stored products necessitates the application of a chemical method of crop protection. In recent years, the number of registered pest control products has been reduced, which is the result of negative evaluation of their active substances during a review conducted by the European Commission directive 91/414/EEC. This creates a risk that individuals resistant to applied insecticides will appear [1]. Thus, intensive scientific studies are being conducted with the purpose of finding new, selective, environmentally friendly and non-toxic pesticides. A current trend is to limit insect populations, not to completely destroy them, through the application of compounds acting on the taste organs of insects, called deterrents [2–5]. To date, several hundred compounds of plant origin that naturally protect crops against pests have been tested; however, they are expensive to produce. An alternative option is to synthesize chemical analogues of active substances of plant origin, called semi-compounds [6]. QSAR, the quantitative study of the dependence of biological activity on chemical structure, is a powerful method that has been routinely employed in the design of new drugs and the understanding of toxicity [7]. This strategy is also applied more and more often in *Corresponding author. Email: [email protected] © 2014 Taylor & Francis
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pesticide chemistry [8–12]. This means that QSAR is beginning to play a significant role in the process of rational pesticide design [11–13], which also encompasses semi-compounds with deterrent action. The recognition and understanding of the effects of their action depending on structure and physicochemical properties makes it possible to effectively reduce the time necessary for developing new substances. One promising direction of studies on finding substances which limit the populations of stored products pests is the synthesis of chemical isomers, analogues or derivatives of alphaasarone. Asarone is a natural compound isolated from calamus roots (Acorus calamus L.) and asarabacca roots (Asarum europaeum L.), and it is a growth inhibitor and antifeedant for Peridroma saucia Hubner larvae [14]. Our previous studies concerned the synthesis of positional isomers of alpha-asarone [15] and of its analogues [16]. All synthesized alpha-asarone derivatives, as well as a group of commercially available compounds structurally similar to asarone, were used for studies of deterrent action against Sitophilus granarius L., Trogoderma granarium Ev. and Tribolium confusum Duv. larvae and beetles. Thus, the goal of this study was to conduct 3D-QSAR analysis for 57 compounds of specific deterrent activity against three species of stored product pests with the application of comparative molecular surface analysis (CoMSA) for determination of quantitative dependencies between the structure and the studied biological activity based on determined chromatographic parameters of lipophilicity and computational physicochemical descriptors.
2. Methods 2.1 Compounds Structures of tested synthesized (1–45) and commercially available (46–57) compounds are presented in Figure 1. The synthesis of compounds 1–30 was described in our previous publications [15,16]. Compounds 46–57 are commercially available. The synthesis and characteristics of compounds 31-45 are described below. 2.1.1 Synthesis In 50 mL THF, 0.2 mol of alkyl bromide (1-bromoethane, 1-bromopropane, 1-bromobutane, 1-bromopentane, 1-bromohexane, 1-bromoheptane or 1-bromooctane) was added dropwise to the mixture (5 g, 0.21 mol) of magnesium turnings in 50 mL THF. The solution of 2,4,6-trimethoxybenzaldehyde or 3,4-trimethoxybenzaldehyde or 2,6-trimethoxybenzaldehyde (0.05 mol) in 50 mL of THF was added dropwise after the formation of Grignard reagent. The solution was stirred for 2 h at room temperature and monitored by thin-layer chromatography (TLC). After the completion of the reaction, 50 mL of methanol was added to the reaction mixture and extracted with ethyl ether (3 × 50 mL). The combined extract was washed with water and dried over anhydrous magnesium sulphate (VI) and filtered. The filtrate was evaporated, and the crude product was purified via silica gel column chromatography using mixture of hexane and ethyl ether (4:6 v/v) as the eluting solution. A solution of 1-(2,4,6-trimethoxyphenyl)alkan-1-ol or 1-(3,4-dimethoxyphenyl)propan-1-ol or 1-(2,6-dimethoxyphenyl)propan-1-ol 0.04 mol in 50 mL of dry toluene was treated with 0.05 mol of anhydrous CuSO4. The reaction mixture was heated for 2 h at reflux and monitored by TLC. After completion of the reaction, the mixture was filtered and evaporated. The
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Figure 1.
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Structures of tested compounds.
crude product was purified via silica gel column chromatography using mixture of hexane and ethyl ether (3:7 v/v) as the eluting solution. 2.1.2 Instruments Melting points were determined on a Köffler apparatus of the Böetius type and uncorrected. 1 HNMR and 13CNMR spectra were recorded on a Bruker Avance II spectrometer using CDCl3 solution with TMS as internal standard (chemical shifts in δ ppm). IR spectra were recorded on a Nicolet IS10 FTIR spectrometer in chloroform solutions. The reaction products were isolated by column chromatography or flash chromatography performed on silica gel
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70–230 mesh ASTM (Merck, Darmstad, Germany). Thin-layer chromatograms were developed on aluminium TLC sheets pre-coated with silica gel F254 (Merck, Darmstadt, Germany). The spots were visualized with 50% sulphuric acid after heating. All the solvents were dried and freshly distilled prior to use. Starting materials and reagents were purchased from SigmaAldrich (Steiheim, Germany) or Merck (Darmstadt, Germany).
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2.1.3 Characteristics of the compounds 31: 1H NMR (CDCl3, 500 MHz) δ: 6.61 (s, 2H, Ar-H), 6.36 (d, J=15.9 Hz, 1H, Ar-CH=CH-), 6.22 (dt, J1=15.9 Hz, J2=5.8 Hz, 1H, Ar-CH=CH-), 3.87 (s, 6H, -OCH3), 3.84 (s, 3H, -OCH3), 2.25 (m, 2H, -CH2-CH3), 1.11 (t, J=7.2 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.3 (C), 159.9 (C), 141.5 (CH), 123.5 (CH), 105.2 (C), 91.1 (CH), 55.6 (CH3), 55.2 (CH3), 24.8 (CH2), 13.8 (CH3); IR (CHCl3, cm−1) ν: 3065, 1625, 961; anal. calcd (%) for C13H18O3: C 70.24, H 8.16; found: C 70.22, H 8.11; yield, 74.6%. 32: 1H NMR (CDCl3, 500 MHz) δ: 6.63 (s, 2H, Ar-H), 6.32 (d, J=15.4 Hz, 1H, Ar-CH=CH), 6.28 (dt, J1=15.4 Hz, J2=6.3 Hz, 1H, Ar-CH=CH-), 3.86 (s, 6H, -OCH3), 3.80 (s, 3H, -OCH3), 2.11 (m, 2H, -CH=CH-CH2-), 1.52 (m, 2H, -CH2-CH3), 0.96 (t, J=7.1 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.5 (C), 106.4 (C), 142.5 (CH), 118.3 (CH), 105.4 (C), 91.6 (CH), 55.6 (CH3), 55.2 (CH3), 33.6 (CH2), 24.5 (CH2), 13.0 (CH3); IR (CHCl3, cm−1) ν: 3025, 1115, 963; anal. calcd (%) for C14H20O3: C 71.16, H 8.53; found: C 71.20, H 8.48; yield, 72.1%. 33: 1H NMR (CDCl3, 500 Mz) δ: 6.52 (s, 2H, Ar-H), 6.43 (d, J=16.0 Hz, 1H, Ar-CH=CH-), 6.29 (dt, J1=16.0 Hz, J2=6.2 Hz, 1H, Ar-CH=CH-), 3.88 (s, 6H, -OCH3), 3.87 (s, 3H, -OCH3), 2.12 (m, 2H, -CH=CH-CH2-), 1.43 (m, 4H, -(CH2)2-), 0.91 (t, J=6.0 Hz, 3H, -CH3); 13 C NMR (CDCl3, 50 MHz) δ: 161.8 (C), 160.2 (C), 139.8 (CH), 118.3 (CH), 105.6 (C), 91.5 (CH), 55.6 (CH3), 55.2 (CH3), 34.2 (CH2), 31.2 (CH2), 22.0 (CH2), 13.8 (CH3); IR (CHCl3, cm−1) ν: 3025, 1135, 973; anal. calcd (%) for C15H22O3: C 71.97, H 8.86; found: C 71.76, H 8.79; yield, 77.5%. 34: 1H NMR (CDCl3, 500 Mz) δ: 6.63 (s, 2H, Ar-H), 6.28 (d, J=16.1 Hz, 1H, Ar-CH=CH-), 6.11 (dt, J2=16.1 Hz, J1=6.4 Hz, 1H, Ar-CH=CH-), 3.88 (s, 6H, -OCH3), 3.84 (s, 3H, -OCH3), 2.11 (m, 2H, -CH=CH-CH2-), 1.38 (m, 6H, -(CH2)3-), 0.90 (t, J=6.4 Hz, 3H, -CH3); 13 C NMR (CDCl3, 50 MHz) δ: 160.8 (C), 160.2 (C), 141.5 (CH), 123.2 (CH), 105.5 (C), 90.8 (CH), 55.6 (CH3), 55.2 (CH3), 34.2 (CH2), 32.2 (CH2), 29.0 (CH2), 23.1 (CH2), 14.4 (CH3); IR (CHCl3, cm−1) ν: 3018, 1139, 962; anal. calcd (%) for C16H24O3: C 72.69, H 9.15; found: C 72.58, H 9.11; yield, 73.2%; mp, 38–39°C. 35: 1H NMR (CDCl3, 500 Mz) δ: 6.67 (s, 2H, Ar-H), 6.44 (d, J=15.9 Hz, 1H, Ar-CH=CH-), 6.28 (dt, J1=15.9 Hz, J2=6.3 Hz, 1H, Ar-CH=CH-), 3.89 (s, 6H, -OCH3), 3.85 (s, 3H, -OCH3), 2.12 (m, 2H, -CH=CH-CH2-), 1.40 (m, 8H, -(CH2)4-), 0.95 (t, J=6.1 Hz, 3H, -CH3); 13 C NMR (CDCl3, 50 MHz) δ: 160.8 (C), 159.5 (C), 141.5 (CH), 122.4 (CH), 105.4 (C), 90.8 (CH), 55.6 (CH3), 55.2 (CH3), 33.0 (CH2), 31.6 (CH2), 29.6 (CH2), 28.2 (CH2), 22.2 (CH2), 13.5 (CH3); IR (CHCl3, cm−1) ν: 3028, 1117, 969; anal. calcd (%) for C17H26O3: C 73.34, H 9.41; found: C 73.18, H 9.32; yield, 70.6%; mp, 41–42°C. 36: 1H NMR (CDCl3, 500 MHz) δ: 6.62 (s, 2H, Ar-H), 6.36 (d, J=15.7 Hz, 1H, Ar-CH=CH), 6.29 (dt, J1=15.7 Hz, J2=6.3 Hz, 1H, Ar-CH=CH-), 3.91 (s, 6H, -OCH3), 3.84 (s, 3H, -OCH3), 2.25 (m, 2H, -CH=CH-CH2-), 1.38 (m, 10H, -(CH2)5-), 0.91 (t, J=5.9 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.8 (C), 159.5 (C), 141.5 (CH), 117.2 (CH), 104.2 (C), 90.8 (CH), 55.6 (CH3), 55.2 (CH3), 33.1 (CH2), 31.9 (CH2), 29.7 (CH2), 29.1 (CH2),
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28.8 (CH2), 22.7 (CH2), 14.1(CH3); IR (CHCl3, cm−1) ν: 3033, 1123, 975; anal. calcd (%) for C13H28O3: C 73.93, H 9.65; found: C 73.77, H 9.61; yield, 67.2%; mp, 45–46°C. 37: 1H NMR (CDCl3, 500 MHz) δ: 6.06 (s, 2H, Ar-H), 5.48 (t, J=6.2 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 2.93 (s, 1H, -OH), 1.95 (m, 2H, -CH2-), 0.92 (t, J=7.1 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.7 (C), 160.5 (C), 99.1 (C), 92.1 (CH), 57.9 (CH), 55.9 (CH3), 55.5 (CH3), 32.3 (CH2), 10.0 (CH3); IR (CHCl3, cm−1) ν: 3392, 2897, 1085; anal. calcd (%) for C12H18O4: C 63.70, H 8.02; found: C 63.90, H 8.12; yield, 83.4%. 38: 1H NMR (CDCl3, 500 MHz) δ: 6.06 (s, 2H, Ar-H), 5.54 (t, J=5.8 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 2.63 (s, 1H, -OH), 2.12 (m, 2H, -CH2-), 1.54 (m, 2H, -CH2-CH3), 0.90 (t, J=6.7 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.0 (C), 160.7 (C), 101.9 (C), 92.6 (CH), 57.5 (CH), 55.9 (CH3), 55.5 (CH3), 42.7 (CH2), 19.0 (CH2), 13.9 (CH3); IR (CHCl3, cm−1) ν: 3360, 2982, 1061; anal. calcd (%) for C13H20O4: C 64.98, H 8.39; found: C 64.87, H 8.29; yield, 82.2%. 39: 1H NMR (CDCl3, 500 MHz) δ: 6.02 (s, 2H, Ar-H), 5.60 (t, J=5.4 Hz, 1H, -CH-OH), 3.72 (s, 3H, -OCH3), 3.67 (s, 6H, -OCH3), 3.25 (s, 1H, -OH), 2.22 (m, 2H, -CH2-), 1.42 (m, 4H, -(CH2)2-), 0.85 (t, J=7.1 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.0 (C), 160.6 (C), 99.4 (C), 92.5 (CH), 59.1 (CH), 55.9 (CH3), 55.5 (CH3), 39.8 (CH2), 27.7 (CH2), 22.6 (CH2), 13.9 (CH3);IR (CHCl3, cm−1) ν: 3410, 2914, 1065; anal. calcd (%) for C14H24O4: C 66.12, H 8.72; found: C 66.11, H 8.62; yield, 80.6%. 40: 1H NMR (CDCl3, 500 MHz) δ: 6.04 (s, 2H, Ar-H), 5.59 (t, J=5.5 Hz, 1H, -CH-OH), 3.71 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 3.15 (s, 1H, -OH), 2.15 (m, 2H, -CH2-), 1.41 (m, 6H, -(CH2)3-), 0.91 (t, J=6.2 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.9 (C), 160.2 (C), 99.7 (C), 92.5 (CH), 59.4 (CH), 55.9 (CH3), 55.5 (CH3), 39.4 (CH2), 30.6 (CH2), 26.3 (CH2), 22.7 (CH2), 13.9 (CH3); IR (CHCl3, cm−1) ν: 3390, 2956, 1065; anal. calcd (%) for C15H24O4: C 67.14, H 9.01; found: C 67.02, H 8.96; yield, 79.9%. 41: 1H NMR (CDCl3, 500 MHz) δ: 6.01 (s, 2H, Ar-H), 5.50 (t, J=5.6 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 2.51 (s, 1H, -OH), 2.13 (m, 2H, -CH2-), 1.34 (m, 8H, -(CH2)4-), 0.90 (t, J=7.2 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.1 (C), 160.4 (C), 99.6 (C), 91.8 (CH), 55.9 (CH), 55.5 (CH3), 55.3 (CH3), 39.2 (CH2), 32.2 (CH2), 29.1 (CH2), 26.0 (CH2), 22.8 (CH2), 14.1 (CH3); IR (CHCl3, cm−1) ν: 3360, 2962, 1102; anal. calcd (%) for C16H26O4: C 68.06, H 9.28; found: C 68.11, H 9.17; yield, 73.8%. 42: 1H NMR (CDCl3, 500 MHz) δ: 6.00 (s, 2H, Ar-H), 5.57 (t, J=5.5 Hz, 1H, -CH-OH), 3.71 (s, 3H, -OCH3), 3.65 (s, 6H, -OCH3), 2.49 (s, 1H, -OH), 2.14 (m, 2H, -CH2-), 1.30 (m, 10H, -(CH2)5-), 0.85 (t, J=7.0 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.5 (C), 160.1 (C), 99.6 (C), 91.8 (CH), 56.7 (CH), 55.9 (CH3), 55.5 (CH3), 39.3 (CH2), 31.9 (CH2), 29.5 (CH2), 29.3 (CH2), 25.7 (CH2), 22.6 (CH2), 14.1 (CH3); IR (CHCl3, cm−1) ν: 3395, 2990, 1066; anal. calcd (%) for C17H28O4: C 68.89, H 9.52; found: C 68.76, H 9.41; yield, 78.2%. 43: yield, 68.9%; 1H NMR (CDCl3, 500 MHz) δ: 5.95 (s, 2H, Ar-H), 5.56 (t, J=5.3 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.67 (s, 6H, -OCH3), 2.51 (s, 1H, -OH), 2.15 (m, 2H, -CH2), 1.25 (m, 12H, -(CH2)6-), 0.86 (t, J=7.0 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.4 (C), 160.1 (C), 98.8 (C), 91.8 (CH), 56.7 (CH), 55.9 (CH3), 55.4 (CH3), 39.1 (CH2), 32.2 (CH2), 29.4 (CH2), 29.2 (CH2), 28.1 (CH2), 25.8 (CH2), 22.9 (CH2), 13.6 (CH3); IR (CHCl3, cm−1) ν: 3391, 2864, 1100; anal. calcd (%) for C18H30O4: C 69.64, H 9.74; found: C 69.55, H 9.55; yield, 68.9%. 44: 1H NMR (CDCl3, 500 MHz) δ: 6.92 (dd, J1=9.5 Hz, J2=6.8 Hz, 1H, Ar-H), 6.88 (d, J=6.8 Hz, 1H, Ar-H), 6.82 (d, J=6.8 Hz, 1H, Ar-H), 6.46 (dd, J1=16.2 Hz, J2=1.1 Hz, 1H, Ar-CH=CH-), 6.17 (dq, J1=16.2 Hz, J2=6.2 Hz, 1H, Ar-CH=CH-), 3.86 (s, 6H, -OCH3), 1.95
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(d, J=6.8 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 150.4 (C), 147.9 (C), 130.7 (CH), 129.7 (C), 123.6 (CH), 122.8 (CH), 110.9 (CH), 110.5 (CH), 55.9 (CH3), 55.5 (CH3), 20.5 (CH3); IR (CHCl3, cm−1) ν: 3022, 1611, 974; anal. calcd (%) for C11H14O2: C 74.13, H 7.92; found: C 74.15, H 8.01; yield, 74.9%. 45: 1H NMR (CDCl3, 500 MHz) δ: 7.01 (s, 1H, Ar-H), 6.75 (d, J=5.9 Hz, 1H, Ar-H), 6.60 (d, J=5.9 Hz, 1H, Ar-H), 6.32 (dd, J1=15.8 Hz, J2=1.5 Hz, 1H, Ar-CH=CH-), 6.09 (dq, J1=15.8 Hz, J2=6.2 Hz, 1H, Ar-CH=CH-), 3.90 (s, 3H, -OCH3), 3.87 (s, 3H, -OCH3), 1.85 (dd, J1=6.2 Hz, J2=1.5 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 155.0 (C), 133.6 (CH), 128.8 (CH), 118.9 (CH), 111.4 (C), 104.0 (CH), 55.9 (CH3), 20.5 (CH3); IR (CHCl3, cm−1) ν: 3017, 1130, 973; anal. calcd (%) for C11H14O2: C 74.13, H 7.92; found: C 73.75, H 7.86; yield, 82.1%.
2.2 Biological assay The results of antifeedant activity of synthesized and commercially available compounds against Coleoptera are presented in Table 1. The full details of the biological assay are published in our earlier work [15,16]. The insects used for the tests – Sitophilus granarius L. (Coleoptera: Curculionidae) adults, Tribolium confusum Duv. (Coleptera: Tenebrionidae) adults and larvae, Trogoderma granarium Ev. (Coleoptera: Dermestidae) – were reared in the laboratory at 26±1°C and 60±5% relative humidity on wheat grain (Sitophilus granarius L.) or a whole wheat meal diet (Tribolium and Trogoderma species). The compounds were tested as 1% ethanol solutions. Choice and no-choice tests were conducted using the wheat wafer discs bioassay described previously [17]. The wafer discs (1 cm diameter × 1 mm thick) were saturated by dipping in either solvent only (control) or in 1% pure ethanol solutions of the compounds. After the evaporation of the solvent (30 min of air-drying), the discs were weighed and placed in plastic boxes to provide three experiments: (1) two discs dipped in ethanol (CC; control), (2) two discs dipped in compound solution (EE; no-choice test) and (3) one disc dipped in ethanol and one in tested compound solution (CE; choice test). The wafers used in the experiments were made of wheat flour and water and baked in an oven at 80°C. The discs were offered for a 5-day period to three adults of S. granarius, 20 adults or 10 larvae of T. confusum, or 10 larvae of T. granarium. The number of individual insects used depended on their normal rate of food consumption. Unsexed, 7–10-day-old adults and 5–30-day-old larvae were used for experiments. Each experiment was replicated five times. Alpha-asarone and azadirachtin were used as reference substances. After the completion of the experiments the wafer discs were reweighed. Based on the amount of food consumed, the three coefficient of deterrence (relative R, absolute A, and total T ) were calculated using the formulae from Nawrot et al. [17]. R¼ A¼
CE 100 CþE
ðchoice testÞ
CC EE 100 ðno-choice testÞ CC þ EE
C, CC – amount of food from the control discs consumed. E, EE – amount of food treated with tested compound consumed.
91.3
83.0o 77.4no 70.3mn 22.4h 59.6l 80.5o 64.9lm 0.4c 37.9j 8.7de 18.7fg 49.8k 41.0j -47.4a 33.8ij 12.2ef 37.9j -28.6b 21.8gh 7.7cde 30.4ij 4.6cd 19.5fg 28.4hi 7.7cde 2.8cd 8.8de 8.2de p
6.7c 97.1ij 96.6ij 93.3ij 93.9ij 95.8ij 54.6f 71.4g 82.2gh 86.4hi 95.3ij 72.3g 28.2d 22.4d -25.3b 20.2d 82.2fg 1.0c 19.4d 28.2d 41.1e -39.5a 20.9d 21.1d 47.6ef -0.9c 42.5e 96.0ij j
98.2
A
R
189.5
89.7g 174.5kl 166.9jk 115.7hi 153.5j 176.3kl 119.5hi 71.7f 120.2hi 95.1g 114.0hi 122.1i 69.2f -25.1a 8.5b 32.4c 120.2hi -27.6a 41.2bcd 35.9cd 71.5f -34.9a 40.4cde 49.5cde 55.3ef 1.9b 51.3de 104.2gh l
T
98.2
95.4mn 94.8mn 88.1lmn 91.7lmn 73.9jk 85.0lm 68.8j 45.6i 93.0lmn 83.5kl 71.9j 86.4lm 34.2h -10.5cd 32.5h -8.6cd 6.9fg -66.4a -4.6de -2.5def 3.0efg 12.7g -33.5b 29.2h -17.7c -5.2de 26.5h 95.2mn n
R
93.1
71.2k 73.1k 60.5i 62.6ij 84.9l 90.7lm 6.2ef 19.2g -0.9cde 31.7h 11.5fg 8.7f 8.8f 17.9g 70.2jk -8.6bc -13.2ab 0.3de -2.5cd -16.8a -11.1ab -17.9a 11.5fg -16.3a -10.8ab 13.9fg -16.1ab 92.3lm m
A
191.3
166.6no 167.9no 148.6n 154.3mn 158.8mno 175.7op 75.1hi 64.8h 92.1ijk 115.1l 83.5ij 95.1jk 43.0g 7.4def 102.7kl -17.1bc -6.4cde -66.2a -7.1cd -19.3bc -8.1cd -5.2cde -22.0bc 12.8f -28.5b 8.7def 10.3ef 187.5p p
T
Trogoderma granarium Ev. larvae
97.0
77.8n 97.4o 97.2o 95.7o 97.3o 97.9o 63.9lm 71.4mn 96.2o 59.5kl 96.6o 53.0kl 20.8gh -33.5a 20.8gh 5.6def 12.6fg -22.3b -0.3de -23.6ab -14.0bc 22.3ghi 32.0ij 7.0ef -4.2cd 25.4ijk 34.2k 93.1o o
R
86.0
91.6l 31.4g 39.0hi -6.1ab 10.3f 29.0g 41.0i 34.1gh 55.5j 59.8j 66.7k 33.8gh 7.5def 1.0cd 7.5def -3.0bc -2.5bc 2.8cde -3.0bc 8.0de -7.8ab -10.5a -2.3bg 6.2def 1.3cd -10.5a 8.8ef 88.1l l
A
183.0
169.4rs 128.8mno 136.2no 89.6jk 107.6l 126.9mn 104.9kl 105.6kl 151.7op 119.3lm 163.3pr 86.8j 28.3ghi -32.6a 28.3ghi 2.5ef 10.2ef -19.5abc -3.3cde -15.6bcd -21.7ab 11.8ef 29.6hi 13.1efg -2.9de 14.8fg 43.0i 181.2s s
T
Tribolium confusum Duv. adult
Values followed by the same letter within a column are not significantly different at the p
SAR and QSAR in Environmental Research Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gsar20
Synthesis, antifeedant activity against Coleoptera and 3D QSAR study of alphaasarone derivatives a
a
b
c
B. Łozowicka , P. Kaczyński , T. Magdziarz & A.T. Dubis a
Institute of Plant Protection - National Research Institute, Bialystok, Poland b
University of Silesia, Department of Organic Chemistry, Katowice, Poland c
University of Bialystok, Institute of Chemistry, Bialystok, Poland Published online: 07 Mar 2014. To cite this article: B. Łozowicka, P. Kaczyński, T. Magdziarz & A.T. Dubis (2014) Synthesis, antifeedant activity against Coleoptera and 3D QSAR study of alpha-asarone derivatives, SAR and QSAR in Environmental Research, 25:3, 173-188, DOI: 10.1080/1062936X.2013.875061 To link to this article: http://dx.doi.org/10.1080/1062936X.2013.875061
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
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SAR and QSAR in Environmental Research, 2014 Vol. 25, No. 3, 173–188, http://dx.doi.org/10.1080/1062936X.2013.875061
Synthesis, antifeedant activity against Coleoptera and 3D QSAR study of alpha-asarone derivatives B. Łozowickaa*, P. Kaczyńskia, T. Magdziarzb and A.T. Dubisc
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a
Institute of Plant Protection - National Research Institute, Bialystok, Poland; bUniversity of Silesia, Department of Organic Chemistry, Katowice, Poland; cUniversity of Bialystok, Institute of Chemistry, Bialystok, Poland (Received 20 August 2013; in final form 19 November 2013) For the first time, a set of 56 compounds representing structural derivatives of naturally occurring alpha-asarone as an antifeedants against stored product pests Sitophilus granarius L., Trogoderma granarium Ev., and Tribolium confusum Duv., were subjected to the 3D QSAR studies. Three-dimensional quantitative structure–activity relationships (3D-QSAR) for 56 compounds, including 15 newly synthesized, were performed using comparative molecular field analysis s-CoMFA and SOM-CoMSA techniques. QSAR was conducted based on a combination of biological activity (against Coleoptera larvae and beetles) and various geometrical, topological, quantum-mechanical, electronic, and chromatographic descriptors. The CoMSA formalism coupled with IVE (CoMSA–IVE) allowed us to obtain highly predictive models for Trogoderma granarium Ev. larvae. We have found that this novel method indicates a clear molecular basis for activity and lipophilicity. This investigation will facilitate optimization of the design of new potential antifeedants. Keywords: 3D QSAR; CoMSA; antifeedant activity; stored product pests; alpha asarones derivatives; synthesis
1. Introduction The threat of destruction of stored grain products and their infection by pests of stored products necessitates the application of a chemical method of crop protection. In recent years, the number of registered pest control products has been reduced, which is the result of negative evaluation of their active substances during a review conducted by the European Commission directive 91/414/EEC. This creates a risk that individuals resistant to applied insecticides will appear [1]. Thus, intensive scientific studies are being conducted with the purpose of finding new, selective, environmentally friendly and non-toxic pesticides. A current trend is to limit insect populations, not to completely destroy them, through the application of compounds acting on the taste organs of insects, called deterrents [2–5]. To date, several hundred compounds of plant origin that naturally protect crops against pests have been tested; however, they are expensive to produce. An alternative option is to synthesize chemical analogues of active substances of plant origin, called semi-compounds [6]. QSAR, the quantitative study of the dependence of biological activity on chemical structure, is a powerful method that has been routinely employed in the design of new drugs and the understanding of toxicity [7]. This strategy is also applied more and more often in *Corresponding author. Email: [email protected] © 2014 Taylor & Francis
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pesticide chemistry [8–12]. This means that QSAR is beginning to play a significant role in the process of rational pesticide design [11–13], which also encompasses semi-compounds with deterrent action. The recognition and understanding of the effects of their action depending on structure and physicochemical properties makes it possible to effectively reduce the time necessary for developing new substances. One promising direction of studies on finding substances which limit the populations of stored products pests is the synthesis of chemical isomers, analogues or derivatives of alphaasarone. Asarone is a natural compound isolated from calamus roots (Acorus calamus L.) and asarabacca roots (Asarum europaeum L.), and it is a growth inhibitor and antifeedant for Peridroma saucia Hubner larvae [14]. Our previous studies concerned the synthesis of positional isomers of alpha-asarone [15] and of its analogues [16]. All synthesized alpha-asarone derivatives, as well as a group of commercially available compounds structurally similar to asarone, were used for studies of deterrent action against Sitophilus granarius L., Trogoderma granarium Ev. and Tribolium confusum Duv. larvae and beetles. Thus, the goal of this study was to conduct 3D-QSAR analysis for 57 compounds of specific deterrent activity against three species of stored product pests with the application of comparative molecular surface analysis (CoMSA) for determination of quantitative dependencies between the structure and the studied biological activity based on determined chromatographic parameters of lipophilicity and computational physicochemical descriptors.
2. Methods 2.1 Compounds Structures of tested synthesized (1–45) and commercially available (46–57) compounds are presented in Figure 1. The synthesis of compounds 1–30 was described in our previous publications [15,16]. Compounds 46–57 are commercially available. The synthesis and characteristics of compounds 31-45 are described below. 2.1.1 Synthesis In 50 mL THF, 0.2 mol of alkyl bromide (1-bromoethane, 1-bromopropane, 1-bromobutane, 1-bromopentane, 1-bromohexane, 1-bromoheptane or 1-bromooctane) was added dropwise to the mixture (5 g, 0.21 mol) of magnesium turnings in 50 mL THF. The solution of 2,4,6-trimethoxybenzaldehyde or 3,4-trimethoxybenzaldehyde or 2,6-trimethoxybenzaldehyde (0.05 mol) in 50 mL of THF was added dropwise after the formation of Grignard reagent. The solution was stirred for 2 h at room temperature and monitored by thin-layer chromatography (TLC). After the completion of the reaction, 50 mL of methanol was added to the reaction mixture and extracted with ethyl ether (3 × 50 mL). The combined extract was washed with water and dried over anhydrous magnesium sulphate (VI) and filtered. The filtrate was evaporated, and the crude product was purified via silica gel column chromatography using mixture of hexane and ethyl ether (4:6 v/v) as the eluting solution. A solution of 1-(2,4,6-trimethoxyphenyl)alkan-1-ol or 1-(3,4-dimethoxyphenyl)propan-1-ol or 1-(2,6-dimethoxyphenyl)propan-1-ol 0.04 mol in 50 mL of dry toluene was treated with 0.05 mol of anhydrous CuSO4. The reaction mixture was heated for 2 h at reflux and monitored by TLC. After completion of the reaction, the mixture was filtered and evaporated. The
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Figure 1.
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Structures of tested compounds.
crude product was purified via silica gel column chromatography using mixture of hexane and ethyl ether (3:7 v/v) as the eluting solution. 2.1.2 Instruments Melting points were determined on a Köffler apparatus of the Böetius type and uncorrected. 1 HNMR and 13CNMR spectra were recorded on a Bruker Avance II spectrometer using CDCl3 solution with TMS as internal standard (chemical shifts in δ ppm). IR spectra were recorded on a Nicolet IS10 FTIR spectrometer in chloroform solutions. The reaction products were isolated by column chromatography or flash chromatography performed on silica gel
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70–230 mesh ASTM (Merck, Darmstad, Germany). Thin-layer chromatograms were developed on aluminium TLC sheets pre-coated with silica gel F254 (Merck, Darmstadt, Germany). The spots were visualized with 50% sulphuric acid after heating. All the solvents were dried and freshly distilled prior to use. Starting materials and reagents were purchased from SigmaAldrich (Steiheim, Germany) or Merck (Darmstadt, Germany).
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2.1.3 Characteristics of the compounds 31: 1H NMR (CDCl3, 500 MHz) δ: 6.61 (s, 2H, Ar-H), 6.36 (d, J=15.9 Hz, 1H, Ar-CH=CH-), 6.22 (dt, J1=15.9 Hz, J2=5.8 Hz, 1H, Ar-CH=CH-), 3.87 (s, 6H, -OCH3), 3.84 (s, 3H, -OCH3), 2.25 (m, 2H, -CH2-CH3), 1.11 (t, J=7.2 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.3 (C), 159.9 (C), 141.5 (CH), 123.5 (CH), 105.2 (C), 91.1 (CH), 55.6 (CH3), 55.2 (CH3), 24.8 (CH2), 13.8 (CH3); IR (CHCl3, cm−1) ν: 3065, 1625, 961; anal. calcd (%) for C13H18O3: C 70.24, H 8.16; found: C 70.22, H 8.11; yield, 74.6%. 32: 1H NMR (CDCl3, 500 MHz) δ: 6.63 (s, 2H, Ar-H), 6.32 (d, J=15.4 Hz, 1H, Ar-CH=CH), 6.28 (dt, J1=15.4 Hz, J2=6.3 Hz, 1H, Ar-CH=CH-), 3.86 (s, 6H, -OCH3), 3.80 (s, 3H, -OCH3), 2.11 (m, 2H, -CH=CH-CH2-), 1.52 (m, 2H, -CH2-CH3), 0.96 (t, J=7.1 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.5 (C), 106.4 (C), 142.5 (CH), 118.3 (CH), 105.4 (C), 91.6 (CH), 55.6 (CH3), 55.2 (CH3), 33.6 (CH2), 24.5 (CH2), 13.0 (CH3); IR (CHCl3, cm−1) ν: 3025, 1115, 963; anal. calcd (%) for C14H20O3: C 71.16, H 8.53; found: C 71.20, H 8.48; yield, 72.1%. 33: 1H NMR (CDCl3, 500 Mz) δ: 6.52 (s, 2H, Ar-H), 6.43 (d, J=16.0 Hz, 1H, Ar-CH=CH-), 6.29 (dt, J1=16.0 Hz, J2=6.2 Hz, 1H, Ar-CH=CH-), 3.88 (s, 6H, -OCH3), 3.87 (s, 3H, -OCH3), 2.12 (m, 2H, -CH=CH-CH2-), 1.43 (m, 4H, -(CH2)2-), 0.91 (t, J=6.0 Hz, 3H, -CH3); 13 C NMR (CDCl3, 50 MHz) δ: 161.8 (C), 160.2 (C), 139.8 (CH), 118.3 (CH), 105.6 (C), 91.5 (CH), 55.6 (CH3), 55.2 (CH3), 34.2 (CH2), 31.2 (CH2), 22.0 (CH2), 13.8 (CH3); IR (CHCl3, cm−1) ν: 3025, 1135, 973; anal. calcd (%) for C15H22O3: C 71.97, H 8.86; found: C 71.76, H 8.79; yield, 77.5%. 34: 1H NMR (CDCl3, 500 Mz) δ: 6.63 (s, 2H, Ar-H), 6.28 (d, J=16.1 Hz, 1H, Ar-CH=CH-), 6.11 (dt, J2=16.1 Hz, J1=6.4 Hz, 1H, Ar-CH=CH-), 3.88 (s, 6H, -OCH3), 3.84 (s, 3H, -OCH3), 2.11 (m, 2H, -CH=CH-CH2-), 1.38 (m, 6H, -(CH2)3-), 0.90 (t, J=6.4 Hz, 3H, -CH3); 13 C NMR (CDCl3, 50 MHz) δ: 160.8 (C), 160.2 (C), 141.5 (CH), 123.2 (CH), 105.5 (C), 90.8 (CH), 55.6 (CH3), 55.2 (CH3), 34.2 (CH2), 32.2 (CH2), 29.0 (CH2), 23.1 (CH2), 14.4 (CH3); IR (CHCl3, cm−1) ν: 3018, 1139, 962; anal. calcd (%) for C16H24O3: C 72.69, H 9.15; found: C 72.58, H 9.11; yield, 73.2%; mp, 38–39°C. 35: 1H NMR (CDCl3, 500 Mz) δ: 6.67 (s, 2H, Ar-H), 6.44 (d, J=15.9 Hz, 1H, Ar-CH=CH-), 6.28 (dt, J1=15.9 Hz, J2=6.3 Hz, 1H, Ar-CH=CH-), 3.89 (s, 6H, -OCH3), 3.85 (s, 3H, -OCH3), 2.12 (m, 2H, -CH=CH-CH2-), 1.40 (m, 8H, -(CH2)4-), 0.95 (t, J=6.1 Hz, 3H, -CH3); 13 C NMR (CDCl3, 50 MHz) δ: 160.8 (C), 159.5 (C), 141.5 (CH), 122.4 (CH), 105.4 (C), 90.8 (CH), 55.6 (CH3), 55.2 (CH3), 33.0 (CH2), 31.6 (CH2), 29.6 (CH2), 28.2 (CH2), 22.2 (CH2), 13.5 (CH3); IR (CHCl3, cm−1) ν: 3028, 1117, 969; anal. calcd (%) for C17H26O3: C 73.34, H 9.41; found: C 73.18, H 9.32; yield, 70.6%; mp, 41–42°C. 36: 1H NMR (CDCl3, 500 MHz) δ: 6.62 (s, 2H, Ar-H), 6.36 (d, J=15.7 Hz, 1H, Ar-CH=CH), 6.29 (dt, J1=15.7 Hz, J2=6.3 Hz, 1H, Ar-CH=CH-), 3.91 (s, 6H, -OCH3), 3.84 (s, 3H, -OCH3), 2.25 (m, 2H, -CH=CH-CH2-), 1.38 (m, 10H, -(CH2)5-), 0.91 (t, J=5.9 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.8 (C), 159.5 (C), 141.5 (CH), 117.2 (CH), 104.2 (C), 90.8 (CH), 55.6 (CH3), 55.2 (CH3), 33.1 (CH2), 31.9 (CH2), 29.7 (CH2), 29.1 (CH2),
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28.8 (CH2), 22.7 (CH2), 14.1(CH3); IR (CHCl3, cm−1) ν: 3033, 1123, 975; anal. calcd (%) for C13H28O3: C 73.93, H 9.65; found: C 73.77, H 9.61; yield, 67.2%; mp, 45–46°C. 37: 1H NMR (CDCl3, 500 MHz) δ: 6.06 (s, 2H, Ar-H), 5.48 (t, J=6.2 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 2.93 (s, 1H, -OH), 1.95 (m, 2H, -CH2-), 0.92 (t, J=7.1 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.7 (C), 160.5 (C), 99.1 (C), 92.1 (CH), 57.9 (CH), 55.9 (CH3), 55.5 (CH3), 32.3 (CH2), 10.0 (CH3); IR (CHCl3, cm−1) ν: 3392, 2897, 1085; anal. calcd (%) for C12H18O4: C 63.70, H 8.02; found: C 63.90, H 8.12; yield, 83.4%. 38: 1H NMR (CDCl3, 500 MHz) δ: 6.06 (s, 2H, Ar-H), 5.54 (t, J=5.8 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 2.63 (s, 1H, -OH), 2.12 (m, 2H, -CH2-), 1.54 (m, 2H, -CH2-CH3), 0.90 (t, J=6.7 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.0 (C), 160.7 (C), 101.9 (C), 92.6 (CH), 57.5 (CH), 55.9 (CH3), 55.5 (CH3), 42.7 (CH2), 19.0 (CH2), 13.9 (CH3); IR (CHCl3, cm−1) ν: 3360, 2982, 1061; anal. calcd (%) for C13H20O4: C 64.98, H 8.39; found: C 64.87, H 8.29; yield, 82.2%. 39: 1H NMR (CDCl3, 500 MHz) δ: 6.02 (s, 2H, Ar-H), 5.60 (t, J=5.4 Hz, 1H, -CH-OH), 3.72 (s, 3H, -OCH3), 3.67 (s, 6H, -OCH3), 3.25 (s, 1H, -OH), 2.22 (m, 2H, -CH2-), 1.42 (m, 4H, -(CH2)2-), 0.85 (t, J=7.1 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.0 (C), 160.6 (C), 99.4 (C), 92.5 (CH), 59.1 (CH), 55.9 (CH3), 55.5 (CH3), 39.8 (CH2), 27.7 (CH2), 22.6 (CH2), 13.9 (CH3);IR (CHCl3, cm−1) ν: 3410, 2914, 1065; anal. calcd (%) for C14H24O4: C 66.12, H 8.72; found: C 66.11, H 8.62; yield, 80.6%. 40: 1H NMR (CDCl3, 500 MHz) δ: 6.04 (s, 2H, Ar-H), 5.59 (t, J=5.5 Hz, 1H, -CH-OH), 3.71 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 3.15 (s, 1H, -OH), 2.15 (m, 2H, -CH2-), 1.41 (m, 6H, -(CH2)3-), 0.91 (t, J=6.2 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.9 (C), 160.2 (C), 99.7 (C), 92.5 (CH), 59.4 (CH), 55.9 (CH3), 55.5 (CH3), 39.4 (CH2), 30.6 (CH2), 26.3 (CH2), 22.7 (CH2), 13.9 (CH3); IR (CHCl3, cm−1) ν: 3390, 2956, 1065; anal. calcd (%) for C15H24O4: C 67.14, H 9.01; found: C 67.02, H 8.96; yield, 79.9%. 41: 1H NMR (CDCl3, 500 MHz) δ: 6.01 (s, 2H, Ar-H), 5.50 (t, J=5.6 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.66 (s, 6H, -OCH3), 2.51 (s, 1H, -OH), 2.13 (m, 2H, -CH2-), 1.34 (m, 8H, -(CH2)4-), 0.90 (t, J=7.2 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 161.1 (C), 160.4 (C), 99.6 (C), 91.8 (CH), 55.9 (CH), 55.5 (CH3), 55.3 (CH3), 39.2 (CH2), 32.2 (CH2), 29.1 (CH2), 26.0 (CH2), 22.8 (CH2), 14.1 (CH3); IR (CHCl3, cm−1) ν: 3360, 2962, 1102; anal. calcd (%) for C16H26O4: C 68.06, H 9.28; found: C 68.11, H 9.17; yield, 73.8%. 42: 1H NMR (CDCl3, 500 MHz) δ: 6.00 (s, 2H, Ar-H), 5.57 (t, J=5.5 Hz, 1H, -CH-OH), 3.71 (s, 3H, -OCH3), 3.65 (s, 6H, -OCH3), 2.49 (s, 1H, -OH), 2.14 (m, 2H, -CH2-), 1.30 (m, 10H, -(CH2)5-), 0.85 (t, J=7.0 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.5 (C), 160.1 (C), 99.6 (C), 91.8 (CH), 56.7 (CH), 55.9 (CH3), 55.5 (CH3), 39.3 (CH2), 31.9 (CH2), 29.5 (CH2), 29.3 (CH2), 25.7 (CH2), 22.6 (CH2), 14.1 (CH3); IR (CHCl3, cm−1) ν: 3395, 2990, 1066; anal. calcd (%) for C17H28O4: C 68.89, H 9.52; found: C 68.76, H 9.41; yield, 78.2%. 43: yield, 68.9%; 1H NMR (CDCl3, 500 MHz) δ: 5.95 (s, 2H, Ar-H), 5.56 (t, J=5.3 Hz, 1H, -CH-OH), 3.70 (s, 3H, -OCH3), 3.67 (s, 6H, -OCH3), 2.51 (s, 1H, -OH), 2.15 (m, 2H, -CH2), 1.25 (m, 12H, -(CH2)6-), 0.86 (t, J=7.0 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 160.4 (C), 160.1 (C), 98.8 (C), 91.8 (CH), 56.7 (CH), 55.9 (CH3), 55.4 (CH3), 39.1 (CH2), 32.2 (CH2), 29.4 (CH2), 29.2 (CH2), 28.1 (CH2), 25.8 (CH2), 22.9 (CH2), 13.6 (CH3); IR (CHCl3, cm−1) ν: 3391, 2864, 1100; anal. calcd (%) for C18H30O4: C 69.64, H 9.74; found: C 69.55, H 9.55; yield, 68.9%. 44: 1H NMR (CDCl3, 500 MHz) δ: 6.92 (dd, J1=9.5 Hz, J2=6.8 Hz, 1H, Ar-H), 6.88 (d, J=6.8 Hz, 1H, Ar-H), 6.82 (d, J=6.8 Hz, 1H, Ar-H), 6.46 (dd, J1=16.2 Hz, J2=1.1 Hz, 1H, Ar-CH=CH-), 6.17 (dq, J1=16.2 Hz, J2=6.2 Hz, 1H, Ar-CH=CH-), 3.86 (s, 6H, -OCH3), 1.95
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B. Łozowicka et al.
(d, J=6.8 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 150.4 (C), 147.9 (C), 130.7 (CH), 129.7 (C), 123.6 (CH), 122.8 (CH), 110.9 (CH), 110.5 (CH), 55.9 (CH3), 55.5 (CH3), 20.5 (CH3); IR (CHCl3, cm−1) ν: 3022, 1611, 974; anal. calcd (%) for C11H14O2: C 74.13, H 7.92; found: C 74.15, H 8.01; yield, 74.9%. 45: 1H NMR (CDCl3, 500 MHz) δ: 7.01 (s, 1H, Ar-H), 6.75 (d, J=5.9 Hz, 1H, Ar-H), 6.60 (d, J=5.9 Hz, 1H, Ar-H), 6.32 (dd, J1=15.8 Hz, J2=1.5 Hz, 1H, Ar-CH=CH-), 6.09 (dq, J1=15.8 Hz, J2=6.2 Hz, 1H, Ar-CH=CH-), 3.90 (s, 3H, -OCH3), 3.87 (s, 3H, -OCH3), 1.85 (dd, J1=6.2 Hz, J2=1.5 Hz, 3H, -CH3); 13C NMR (CDCl3, 50 MHz) δ: 155.0 (C), 133.6 (CH), 128.8 (CH), 118.9 (CH), 111.4 (C), 104.0 (CH), 55.9 (CH3), 20.5 (CH3); IR (CHCl3, cm−1) ν: 3017, 1130, 973; anal. calcd (%) for C11H14O2: C 74.13, H 7.92; found: C 73.75, H 7.86; yield, 82.1%.
2.2 Biological assay The results of antifeedant activity of synthesized and commercially available compounds against Coleoptera are presented in Table 1. The full details of the biological assay are published in our earlier work [15,16]. The insects used for the tests – Sitophilus granarius L. (Coleoptera: Curculionidae) adults, Tribolium confusum Duv. (Coleptera: Tenebrionidae) adults and larvae, Trogoderma granarium Ev. (Coleoptera: Dermestidae) – were reared in the laboratory at 26±1°C and 60±5% relative humidity on wheat grain (Sitophilus granarius L.) or a whole wheat meal diet (Tribolium and Trogoderma species). The compounds were tested as 1% ethanol solutions. Choice and no-choice tests were conducted using the wheat wafer discs bioassay described previously [17]. The wafer discs (1 cm diameter × 1 mm thick) were saturated by dipping in either solvent only (control) or in 1% pure ethanol solutions of the compounds. After the evaporation of the solvent (30 min of air-drying), the discs were weighed and placed in plastic boxes to provide three experiments: (1) two discs dipped in ethanol (CC; control), (2) two discs dipped in compound solution (EE; no-choice test) and (3) one disc dipped in ethanol and one in tested compound solution (CE; choice test). The wafers used in the experiments were made of wheat flour and water and baked in an oven at 80°C. The discs were offered for a 5-day period to three adults of S. granarius, 20 adults or 10 larvae of T. confusum, or 10 larvae of T. granarium. The number of individual insects used depended on their normal rate of food consumption. Unsexed, 7–10-day-old adults and 5–30-day-old larvae were used for experiments. Each experiment was replicated five times. Alpha-asarone and azadirachtin were used as reference substances. After the completion of the experiments the wafer discs were reweighed. Based on the amount of food consumed, the three coefficient of deterrence (relative R, absolute A, and total T ) were calculated using the formulae from Nawrot et al. [17]. R¼ A¼
CE 100 CþE
ðchoice testÞ
CC EE 100 ðno-choice testÞ CC þ EE
C, CC – amount of food from the control discs consumed. E, EE – amount of food treated with tested compound consumed.
91.3
83.0o 77.4no 70.3mn 22.4h 59.6l 80.5o 64.9lm 0.4c 37.9j 8.7de 18.7fg 49.8k 41.0j -47.4a 33.8ij 12.2ef 37.9j -28.6b 21.8gh 7.7cde 30.4ij 4.6cd 19.5fg 28.4hi 7.7cde 2.8cd 8.8de 8.2de p
6.7c 97.1ij 96.6ij 93.3ij 93.9ij 95.8ij 54.6f 71.4g 82.2gh 86.4hi 95.3ij 72.3g 28.2d 22.4d -25.3b 20.2d 82.2fg 1.0c 19.4d 28.2d 41.1e -39.5a 20.9d 21.1d 47.6ef -0.9c 42.5e 96.0ij j
98.2
A
R
189.5
89.7g 174.5kl 166.9jk 115.7hi 153.5j 176.3kl 119.5hi 71.7f 120.2hi 95.1g 114.0hi 122.1i 69.2f -25.1a 8.5b 32.4c 120.2hi -27.6a 41.2bcd 35.9cd 71.5f -34.9a 40.4cde 49.5cde 55.3ef 1.9b 51.3de 104.2gh l
T
98.2
95.4mn 94.8mn 88.1lmn 91.7lmn 73.9jk 85.0lm 68.8j 45.6i 93.0lmn 83.5kl 71.9j 86.4lm 34.2h -10.5cd 32.5h -8.6cd 6.9fg -66.4a -4.6de -2.5def 3.0efg 12.7g -33.5b 29.2h -17.7c -5.2de 26.5h 95.2mn n
R
93.1
71.2k 73.1k 60.5i 62.6ij 84.9l 90.7lm 6.2ef 19.2g -0.9cde 31.7h 11.5fg 8.7f 8.8f 17.9g 70.2jk -8.6bc -13.2ab 0.3de -2.5cd -16.8a -11.1ab -17.9a 11.5fg -16.3a -10.8ab 13.9fg -16.1ab 92.3lm m
A
191.3
166.6no 167.9no 148.6n 154.3mn 158.8mno 175.7op 75.1hi 64.8h 92.1ijk 115.1l 83.5ij 95.1jk 43.0g 7.4def 102.7kl -17.1bc -6.4cde -66.2a -7.1cd -19.3bc -8.1cd -5.2cde -22.0bc 12.8f -28.5b 8.7def 10.3ef 187.5p p
T
Trogoderma granarium Ev. larvae
97.0
77.8n 97.4o 97.2o 95.7o 97.3o 97.9o 63.9lm 71.4mn 96.2o 59.5kl 96.6o 53.0kl 20.8gh -33.5a 20.8gh 5.6def 12.6fg -22.3b -0.3de -23.6ab -14.0bc 22.3ghi 32.0ij 7.0ef -4.2cd 25.4ijk 34.2k 93.1o o
R
86.0
91.6l 31.4g 39.0hi -6.1ab 10.3f 29.0g 41.0i 34.1gh 55.5j 59.8j 66.7k 33.8gh 7.5def 1.0cd 7.5def -3.0bc -2.5bc 2.8cde -3.0bc 8.0de -7.8ab -10.5a -2.3bg 6.2def 1.3cd -10.5a 8.8ef 88.1l l
A
183.0
169.4rs 128.8mno 136.2no 89.6jk 107.6l 126.9mn 104.9kl 105.6kl 151.7op 119.3lm 163.3pr 86.8j 28.3ghi -32.6a 28.3ghi 2.5ef 10.2ef -19.5abc -3.3cde -15.6bcd -21.7ab 11.8ef 29.6hi 13.1efg -2.9de 14.8fg 43.0i 181.2s s
T
Tribolium confusum Duv. adult
Values followed by the same letter within a column are not significantly different at the p
