Naturally Occurring Pest Bioregulators - American Chemical Society

Chapter 19

Insecticidal Constituents of Azadirachta indica and Melia azedarach (Meliaceae) 1

2

3

S. Mark Lee , James A. Klocke , Mark A. Barnby , R. Bryan and Manuel F. Balandrin

4

Yamasaki ,

5

Downloaded by PRINCETON UNIV on June 7, 2013 | http://pubs.acs.org Publication Date: January 9, 1991 | doi: 10.1021/bk-1991-0449.ch019

National Product Sciences, Inc., University of Utah Research Park, 417 Wakara Way, Salt Lake City, U T 84108

The insecticidal constituents of the Indian neem tree (Azadirachta indica) and the related chinaberry tree (Melia azedarach) were investigated using bioassay-guided fractionation and isolation techniques. Azadirachtin was isolated as the principal insecticidal and antifeedant constituent of A. indica seeds. In addition, 25 volatile compounds were identified as constituents of crushed neem seeds. The major volatile constituent identified, di-n -propyl disulfide, was shown to be larvicidal to three species of insects. Furthermore, two new insecticidal compounds,1-cinnamoylmelianoloneand 1-cinnamoyl-3,11-dihydroxymeliacarpin, were isolated from the fruit of M. azedarach. The insecticidal activities of these new compounds, compared with those of azadirachtin and several of its derivatives, suggest structure -activity relationships and a mode of action that may be useful in the design of synthetic analogs.

The neem tree. Azadirachta indica A. Juss., is a tropical and subtropical species indigenous to India and Southeast Asia (1) which is now widely distributed in many tropical and subtropical regions of both the Old and New Worlds (2-4). The chinaberry tree, Melia azedarach L , is a native of tropical Asia (§), but is now also widely distributed in drier regions of the southern and western United States (§) (e.g., Texas, Arizona, southeastern

1

Current address: Chemistry Laboratory Services, California Department of Food and Agriculture, 3292 Meadowview Road, Sacramento, C A 95832

2

Current address: Division of Entomology and Parasitology, College of Natural Resources, University of California, Berkeley, C A 94720

3

Current address: Department of Entomology, University of Georgia, Athens, GA 30602

4

Current address: SERES Laboratories, Inc., 3331 Industrial Drive, Santa Rosa, C A 95403

5

Current address: Natural Product Sciences, Inc., University of Utah Research Park, 420 Chipeta Way, Salt Lake City, U T 84108 0097-6156/91Α)449-0293$06.00Λ) © 1991 American Chemical Society In Naturally Occurring Pest Bioregulators; Hedin, P.; ACS Symposium Series; American Chemical Society: Washington, DC, 1991.


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NATURALLY OCCURRING PEST BIOREGULATORS

Nevada, and southwestern Utah). The two species are closely related taxonomically, with both belonging to the same subfamily (MeliokJeae) and tribe (Melieae) in the family Meliaceae (mahogany family) (7-9). Recent phytochemical studies have also illustrated the close similarities which exist between their secondary metabolites, especially with regard to their insecticidal tetranortriterpenoid limonoid constituents (meliacins) (7-11). Both plant species have long been recognized for their medicinal (12-16) and insecticidal properties (11.15.17.18). Indeed, these two species have long been recognized as possessing among the most outstanding antifeedant and insecticidal activities among members of the Meliaceae (17-20). In this chapter, our recent studies on the insecticidal constituents from these two plant species will be presented, concentrating first on the volatile organosulfur compounds recently isolated from neem seeds (21), and then on the azadirachtin-type tetranortriterpenoid limonoids present in both species (22-26). Our recent studies on the insecticidal meliacins of the azadirachtin type suggest structure-activity relationships and a mode of action which may be useful in the design of synthetic analogs. Volatile Organosulfur Compounds of Crushed A. indica Seeds Crushed and/or ripening neem tree fruits and expressed neem seed oil give off a strong alliaceous (garlic-like) odor. This characteristic alliaceous odor has also been reported to be present in the leaves, inner bark, timber, and heartwood of this tree species (1.14.21). Some of the reputed medicinal properties of neem seed oil have been attributed to the sulfurous compounds that it contains. Although the presence of sulfur-containing compounds in neem oil had previously been reported (12.14). no detailed chemical studies of neem volatile organosulfur compounds had been reported prior to our recent study (21). The volatiles from crushed neem seeds were purged with nitrogen, trapped onto Amberlite XAD-4 resin traps at room temperature, recovered and concentrated into diethyl ether using a Kuderna-Danish evaporative concentrator at 30°C, and analyzed by means of capillary gas chromatography/mass spectrometry (GC/MS). For comparative purposes, similar volatile concentrates were prepared from freshly chopped onion bulbs and garlic cloves, and blank controls were simultaneously prepared for each of the three test samples. A total of 25 compounds were identified by GC/MS analysis as constituents of the crushed neem seed volatile concentrate, 22 of which were organosulfur compounds. Most of the sulfur-containing compounds were either aliphatic disulfides (eight in all) or higher polysulfides (nine trisulfides and three tetrasulfides). A number of the di- and polysulfides present in the neem seed volatile concentrate were mixed unsymmetrical aliphatic alky! (methyl, propyl, and butyl) and alkenyl (propenyl) containing derivatives. However, no monosulfides or dimethyl polysulfides (often observed in onion and garlic extracts) were found among the neem seed volatiles, and onion-type lachrymatory factors were also absent. Nevertheless, apart from these exceptions, the neem seed volatile constituents were found to generally closely resemble those of onions (21). Most of the neem seed volatiles identified (19 out of 25) were present in concentrations of less than 1% of the total area detected in the GC/MS total ion chromatogram. Many of these minor components (e.g., isomeric dimethylthiophenes and various polysulfides (i.e., tri- and tetrasulfides)) are probably heat-generated artifacts produced upon GC/MS analysis of thermolabile precursors. The major volatile constituents of crushed neem seeds were identified by means of G C / M S as di-n-propyl disulfide (75.74% of the total area detected), n-propyl-trans-1 -propenyl disulfide (9.67%), and n-propyl^js-1-propenyl disulfide (2.76%) (Figure 1). Together, these three closely eluting compounds accounted for 88.17% of the total area detected (all of the 25 compounds identified accounted together for 98.74% of the total area detected). The corresponding trisulfides (2.19, 4.22, and 2.20%, respectively) were the next most abundant group of compounds detected. However, as previously alluded to above, they probably

In Naturally Occurring Pest Bioregulators; Hedin, P.; ACS Symposium Series; American Chemical Society: Washington, DC, 1991.


L E E ET A L

Insecticidal Constituents of A. indica & M . azedarach

n-Propyl-cis-l-propenyl

disulfide

Figure 1. Chemical structures of the principal volatile organosulfur compounds isolated from crushed neem (Azadirachta indica) seeds.


296


represent heat-generated artifacts. Furthermore, the principal neem seed volatiles (i.e., the disulfides) identified by GC/MS are probably artifacts generated from nonvolatile precursor substrates by enzymatic activity when the seeds are crushed, as is the case with onion and garlic tissues (21.27). The neem seed volatiles may be responsible for the reputed insect repellent properties attributed to neem seeds. For example, neem seeds have been reported to repel (generally at a distance, without contact) various types of insects, including book mites, locusts, planthoppers, white ants, cockroaches, moths, mosquitoes, cattle flies, post-harvest insects, and stored-products pests (1.12.14.21). We found that the major volatile component of crushed neem seeds, i.e., di-n-propyl disulfide, exhibited larvicidal properties in bioassays against the larvae of three species of insects, i.e., the yellow fever mosquito (Aedes aegvoti; 5 0 Oethal concentration necessary to kill 50% of the treated insects), 66 ppm), the tobacco budworm (Heliothis virescens: L C ^ , 1000 ppm), and the corn earworm (H. zga; L C ^ , 980 ppm) (21). The most probable chemical-ecological explanation for the presence of biologically active volatile organosulfur compounds in neem seeds is that these compounds, like many other plant secondary metabolites, may play a role in chemical defense mechanisms against herbivorous insects, higher herbivorous predators, and invading microorganisms. Because of their extreme volatility and pungency, these compounds may serve as repellents to attacking insects (27) before they can cause significant injury to neem trees, their leaves, or their seeds. In addition, the neem seed volatiles (and/or their nonvolatile precursors) may be responsible, at least in part, for some of the reputed medicinal properties attributed to neem seeds (21).


LC

Insecticidal Tetranortrfterpenoids of A. indica and M. azedarach The potent tetranortriterpenoid limonoids of A. indica (neem) and M. azedarach (chinaberry) (i.e., meliacins) are considered to be among the most promising and interesting of the plantderived insecticidal compounds yet discovered (17). Azadirachtin (Figure 2) is considered to be the prototype compound for this class of feeding deterrent (antifeedant) and insecticidal substances (17.18.28-31). Azadirachtin and Derivatives. The potent and specific effects of azadirachtin against a wide variety of insects, including a number of economically important species of insect pests, have warranted its evaluation as both a source of and a model for new commercial insect control agents. The potential of azadirachtin lies in its several advantages, which include its potency, which is comparable to that of the most potent conventional synthetic insecticides. Furthermore, azadirachtin has a high degree of specificity (affecting behavioral, developmental, and biochemical processes peculiar to insects), it is non-mutagenic (in the Ames test) (32.33). it is biodegradable, and it has systemic activity in plants, being translocated throughout the plant following absorption through the leaves Q4) and/or root system (2QJ. Azadirachtin has several effects on susceptible insects, including potent feeding deterrency, growth inhibition, and ecdysis inhibition (disruption of the molting process) (17.34). Several analogs of azadirachtin (both natural and semi-synthetic) have been shown to exhibit activities comparable to those of the parent compound. For example, two semi synthetic derivatives of azadirachtin, i.e., 22,23-dihydroazadirachtin and 2\3*,22,23tetrahydroazadirachtin, were prepared and tested as growth inhibitors and toxicants against i t virescens larvae (22.26). and as antifeedants against Spodoptera frugiperda (fall armyworm) Q§). The two hydrogenated derivatives proved to be as active as azadirachtin itself in all of these bioassays (22.26.35). Furthermore, 22,23-dihydroazadirachtin also had activity comparable to that of azadirachtin against Epilachna varivestis (Mexican bean beetle) (20. In addition, other related derivatives, such as the semi-synthetic 3-deacetylazadirachtin,


19.

L E E ET A L


l-OH


R 0 3

OH

CH, '

Azadirachtin

Ac

C0 CH

l-Cinnamoyl-3,11-dihydroxymeliacarpin

H

CH

R,0

0

2

3

3

H

Tig Cinn

1-Cinnamoylmelianolone

H

H

Cinn

3-Acetyl-l-cinnamoylmelianolone 3,19-Diacetyl-l-cinnamoylmelianolone 1-Decinnamoylmelianolone

Ac

H

Cinn

Ac

Ac

Cinn

H

H

Cinn C

Tig C II

Figure 2. Stereostructures of some natural and derivatized insecticidal tetranortriterpenoids isolated from Azadirachta indica and Melia azedarach.


297


298


also have activity comparable to that of azadirachtin as growth inhibitors and toxicants against the larvae of H. virescens (22) and E. varivestis (36). In a recent study (2§), it was found that radioactively labelled (tritiated) 22,23dihydroazadirachtin administered orally to fifth (last) instar larvae of H. virescens was rapidly absorbed through the midgut and into the hemocoel, and that excretion of the compound was slow. Data obtained by thin-layer chromatographic (TLC) analysis indicated that metabolism of the dihydroazadirachtin to a more polar form(s) probably occurred following absorption through the midgut (25). Azadirachtin disrupts the normal growth and development of a variety of insect pests, possibly by functioning as a molting hormone (ecdysteroid) analog (17.25.34.36-38). In several species of insects treated with azadirachtin, ecdysis was prevented possibly by the disruption of the molting hormone titre (17.20.36). Azadirachtin was found to be tightly bound to binding proteins in the insect body, and its action is irreversible, one dose (1 JJQ) being sufficient to disrupt subsequent developmental and/or reproductive stages (25.36). For example, development to the pupal stage was disrupted by such doses (25). Insecticidal Constituents of M. azedarach. Azadirachtin has previously been reported to be a constituent of both A. indica and M. azedarach (9.17.18.39.40). However, recent, more detailed investigations suggest that azadirachtin has never been isolated from or identified in authentic M. azedarach. and that it has so far been shown to occur only in A. indica (7.8.10.11.28.31). We found that methanolic extracts of chinaberry (M. azedarach) fruits from southwestern Utah possessed insecticidal potency comparable or equivalent to that of A indica seed extracts and/or to that of azadirachtin (19.23). However, after a thorough search by means of TLC and high-pressure liquid chromatography (HPLC), we were unable to detect the presence of azadirachtin in these chinaberry extracts. Instead, in an effort to isolate and identify the principal active constituents of M. azedarach. we isolated and characterized two new potent insecticidal tetranortriterpenoid limonoids. The first of these was a novel meliacin termed 1 -cinnamoylmelianolone. It possesses a novel structure (skeletal arrangement) not previously observed among the azadirachtin-like meliacins (23). The second compound was a new derivative of meliacarpin (11.31). i.e., 1-cinnamoyl-3,11dihydroxymeliacarpin (Figure 2). The insecticidal activities of these two new compounds, plus two acetylated derivatives of 1-cinnamoylmelianolone (Figure 2) were compared to those of azadirachtin and several of its derivatives using two species of lepidopterous insects. H. virescens (Table I) and S. frugiperda (Table II). Green chinaberry (M. azedarach) fruits were collected during late September of 1986 from trees growing in Hurricane, Utah. (We have observed that chinaberries allowed to ripen and become yellow tend to ferment, giving off malodorous products) (§). Methanolic extracts of the fresh chinaberry fruits (5.7 kg fresh weight) were prepared, concentrated, and filtered. The aqueous methanolic filtrate was partitioned successively, first with hexane and then with methylene chloride. The methylene chloride partitionfraction was concentrated in vacuo at 40°C yielding an extract weighing 6.6 g which was then subjected to flash column chromatography on silica gel using a step-gradient elution involving n-hexane, ethyl acetate, isopropanol, and methanol. Effluents from this column were monitored by means of thin-layer chromatography (TLC). The fraction containing the compounds of interest (2.5 g) was rechromatographed on a low-pressure column using 60% aqueous methanol as eluting solvent system. Monitoring of collected fractions by TLC revealed the fractions containing the two compounds (meliacins) of interest (yield, 1.38 g). Further purification of this fraction was accomplished by means of droplet counter-current chromatography (DCCC) using a solvent system (mixture) incorporating chloroform-toluene-methanol-water (41), finally affording c&. 200 mg of 1cinnamoylmelianolone and £a. 300 mg of 1-cinnamoyl-3,11-dihydroxymeliacarpin. Final purification of the compounds was accomplished by means of normal- and reversed-phase


19.

L E E ET A L


Table I. Growth-Inhibitory and LarvickJal Effects of Natural and Derlvatized Tetranortriterpenoids from Azadirachta Indica and Melia azedarach Fed in Artificial Diet to First-lnstar Larvae of Heliothis virescens.


Test Compound

c,d

Azadirachtin 22,23-Dihydroazadirachtin 2',3',22,23-Tetrahydroazadirachtin 3-Deacetylazadirachtin 1 -Detigloyl-22,23-dihydroazadirachtin Deacetylazadirachtinol d

d

d

d

0

6

1 -Cinnamoylmelianolone 3-Acety1-1 -cinnamoyl melianolone 3,19-Diacetyl-1 -cinnamoyl melianolone 1 -Cinnamoyl-3,11 -dihydroxymeliacarpin 6

a

(ppm)

(ppm)

0.07

0.80

0.08

0.47

0.08 0.09

0.30 0.37

0.59 0.17

2.40 0.80

0.12

1.50

0.15

1.50

0.12

1.50

0.18

3.50

EC5Q is the effective concentration in ppm of additive necessary to reduce larval growth to 50% of the control values.

b

LC5Q is the lethal concentration in ppm of additive necessary to kill (usually by inhibiting ecdysis, the final stage of the molting process) 50% of the treated insects.

c

Naturally occurring compound isolated from Azadirachta indica.

d

Similar preliminary results were obtained against the corn earworm ( K zea) and the fall armyworm (S. frugiperda) (see Table II).

e

Naturally occurring compound isolated from Melia azedarach.


299

300



Table II.

Growth-Inhibitory and LarvlckJal Effects of Natural and Derivatlzed Tetranortriterpenolds from Azadirachta Indica and Melia azedarach Fed in Artificial Diet to First-lnstar Larvae of Spodoptera frugiperda.

Test Compound

Azadirachtin

b

0

d

1 -Cinnamoy1melianolone 3-Aceryl-1 -cinnamoyl melianolone 3,19-Dlacetyl-1 -cinnamoyl melianolone 1 -Cinnamoyl-3,11 -dihydroxymeliacarpin d

a

(ppm)

LC5o (ppm)

0.08

1.0

0.04

1.3

0.06

2.4

0.04

2.5

0.04

1.6

EC5o is the effective concentration in ppm of additive necessary to reduce larval growth to 50% of the control values.

b

LC5o is the lethal concentration in ppm of additive necessary to kill (usually by inhibiting ecdysis, the final stage of the molting process) 50% of the treated insects.

c

Naturally occurring compound isolated from Azadirachta indica.

d

Naturally occurring compound isolated from Melia azedarach.


19.

LEEETAL.


301

HPLC methods previously described (22.24.26.42). The cinnamoyl ester-bearing compounds were detected by ultraviolet (UV) monitoring at 280 nm. Structure elucidation of the purified compounds was carried out by means of infrared (IR) and UV spectrophotometry, proton and carbon-13 nuclear magnetic resonance (NMR) spectroscopy, and electron impact (EI-) and fast-atom bombardment mass spectrometry (FAB-MS). The structures of the two new isolates and three of their derivatives were established on the basis of spectroscopic data and spectral evidence obtained on comparison with azadirachtin (23). The two new meliacins showed general TLC chromatographic properties similar to those of azadirachtin, including giving characteristic colors typical of azadirachtin after spraying with a vanillin-H S0 -etnanol solution followed by heating. However, unlike azadirachtin, the two new compounds showed the strong UV absorptions (in methanol) at 280 nm typical of an ^-unsaturated, unsubstituted aromatic group, i.e., a trans-cinnamovl group. This identification was corroborated by IR, El- and FAB-MS, and proton and carbon13 NMR spectra (11.23.31). Downloaded by PRINCETON UNIV on June 7, 2013 | http://pubs.acs.org Publication Date: January 9, 1991 | doi: 10.1021/bk-1991-0449.ch019

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Structure-Activity Relationships of Azadirachtin and Its Analogs and Derivatives The insecticidal activities of the two new meliacins, two acetylated derivatives of 1 -cinnamoyl melianolone, and azadirachtin and several of its analogs and derivatives tested against _K virescens and S. frugiperda are shown in Tables I and II, respectively. These data, together with other findings on the insecticidal activities of closely related compounds (20.22.25.26.35.36.43). suggest that specific ester groups are not required at positions 1 and 3 in the azadirachtin nucleus in order to maintain a high level of insecticidal activity. However, the presence of certain ester groups (e.g., tigloyl, cinnamoyl) at these positions may provide a favorable hydrophilic/lipophilic balance necessary for optimum transport across various membranes and physiological compartments as these molecules make their way to their target sites or receptors. It seems probable that the ester groups at positions 1 and 3 in ring A are hydrolyzed off enzymatically in vivo (e.g., by esterases) to afford the more polar deesterrfied metabolites which are the true ultimate molecular species involved in interaction with the appropriate receptor(s) at the molecular level. A number of metabolic and physiological studies (17.25.34.36) strongly suggest that azadirachtin and related compounds act at hormonal (physiological) concentrations rather than at the more usual pharmacological or toxicological concentration levels (36). Furthermore, it has previously been observed that the effects of azadirachtin on susceptible insects (such as the disturbance of hormonal systems giving rise to ecdysis (molting) inhibition) are similar to those produced by the administration of certain plant-derived ecdysteroid analogs (phytoecdysones) such as ponasterone A (Figure 3) (34.44.45). In addition, recent studies with synthetic ecdysone agonists have produced hormonal disturbances and molting cycle (ecdysis) failures (46.47) similar to those observed upon administration of azadirachtin and/or the phytoecdysones (such as ponasterone A). These observations suggest that azadirachtin and related compounds may be acting as ecdysteroid (molting hormone) analogs, thus interfering with insect development by causing profound hormonal disturbances. In this regard, azadirachtin and related compounds may be acting either as ecdysteroid agonists or antagonists (or as a combination of both at various different receptors), either directly or indirectly (e.g., by negative feedback inhibition of hormone biosynthesis or metabolism, or related mechanisms). A comparison of the chemical structure of the deesterrfied derivative of azadirachtin with that of the insect molting hormone, ecdysterone (Figure 3), shows several structural similarities, especially with regard to the spatial disposition of the hydroxy! groups at C-3 in the A rings and in the oxygenation pattern in the B and D rings and adjacent moieties in both molecules. It is noteworthy that although the A / B ring junction is trans in azadirachtin and related compounds (with the 3-OH in the axial position) and.cjs. in the ecdysteroids (with the 3-OH in the equatorial position) (2§), the hydroxyl groups of both molecules at position



302


Azadirachtin skeleton, deesterified (1,3-dideacylated)



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L E E ET A L


303

C-3 occupy the same relative spatial relationship with regard to the rest of the structure (skeletal carbon framework) in both types of molecules (Figure 3). Thus, there may be two alternative carbon frameworks which can hold the C-3 hydroxyl oxygens in space in such a way that appropriate receptor interactions can occur. Also noteworthy is the equatorial (or pseudoequatorial) disposition of the oxygen functionalities at C-6 in the B rings and the axial (or pseudoaxial) disposition of the oxygen functionalities at C-14 in the D rings of both molecules. These observations, both with regard to biological (insecticidal) activities and chemical structures, suggest that considerable portions of the azadirachtin structure may be required in order to elicit the hormonal disturbances previously observed. Rembold has suggested a minimum structure required to elicit the desired biological activities in this class of compounds (insecticidal tetranortriterpenoids) (2S). The proposed ecdysteroid-analog mode of action and structure-activity relationships may be useful and important considerations in the design of synthetic analogs of these natural and biorational insecticides. Acknowledgments This work was supported in part by a grant awarded to J.A.K. by the U.S. National Science Foundation (PCM-8314500). We thank Ms. Deborah Camomile for typing this manuscript. Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

12. 13. 14. 15.

16. 17.

18.

Kunkel, G. Flowering Trees in Subtropical Gardens; Dr. W. Junk: The Hague-BostonLondon, 1978; p 258. Ahmed, S.; Grainge, M. Econ. Bot. 1986,40,201-209. Lewis, W.H.; Elvin-Lewis, M.P.F. Econ. Bot.1983,37,69-70. Ahmed, S.;Bamofleh,S.; Munshi, M. Econ. Bot. 1989,43,35-38. Munz, P.A.; Keck, D.D. A California Flora and Supplement; University of California: Berkeley, 1973; p 999. Duffield, M.R.; Jones, W.D. Plants for DryClimates;H.P. Books: Tucson, 1981; p 118. Taylor, D.A.H. In Chemistry and Chemical Taxonomy of the Rutales; Waterman, P.G.; Grundon, M.F., Eds.; Academic: New York, 1983; pp 353-375. Silva, M.F. das G.F. da; Gottlieb, O.R.; Dreyer,D.L.Biochem. Syst. Ecol.1984,12, 299-310. Silva, M.F. das G.F. da; Gottlieb, O.R. Biochem. Syst. Ecol. 1987,15,85-103. Taylor, D.A.H. Prog. Chem. Org. Nat. Prod. 1984,45,1-102. Kraus, W. In New Trends in Natural Products Chemistry 1986; Atta-ur-Rahman; Le Quesne, P.W., Eds.; Studies in Organic Chemistry, Vol. 26; Elsevier Science: Amsterdam, 1986; pp 237-256. Nadkarni, K.M.; Nadkarni, A.K. Indian Materia Medica, 3rd ed.; Popular Book Depot: Bombay, India, 1954; Vol. 1, pp 776-784. Chopra, R.N.; Nayar, S.L.; Chopra, I.C. Glossary of Indian Medicinal Plants; Council of Scientific and Industrial Research: New Delhi, 1956; pp 31-32, 163-164. Dey, K.L.; Mair, W. The Indigenous Drugs of India, 2nd ed.; Pama Primlane, Chronica Botanica: New Delhi, 1973; pp 186-188. Perry, L.M.; Metzger, J. Medicinal Plants of East and Southeast Asia: Attributed Properties and Uses; Massachusetts Institute of Technology: Cambridge, Massachusetts, 1980; pp 260-262. Kapoor, L.D. Handbook of Ayurvedic Medicinal Plants; CRC: Boca Raton, Florida, 1990; pp 59-60, 225-226. Schmutterer, H. In CRC Handbook of Natural Pesticides, Vol. III, Insect Growth Regulators, Part B; Morgan, E.D.; Mandava, N.B., Eds.; CRC: Boca Raton, Florida, 1987; pp 119-170. Warthen, J.D., Jr.; Morgan, E.D. In CRC Handbook of Natural Pesticides, Vol. VI, Insect Attractants and Repellents; Morgan, E.D.; Mandava, N.B., Eds.; CRC: Boca Raton, Florida, 1990; pp 23-134.



304 19.

20.

21. 22. 23. 24.


25. 26. 27. 28. 29. 30. 31. 32.

33. 34. 35.

36.

37. 38. 39. 40.

41. 42. 1986, 43. 44.

45.

46. 47.

Lee, S.M.; Stone, G.A.; Klocke, J.A. 190th American Chemical Society National Meeting, Chicago, Illinois, September 8-13, 1985; American Chemical Society: Washington, DC, 1985; Agrochemicals Division Abstract No. 76. Klocke, J.A. InAllelochemicals:Role in Agriculture and Forestry; Waller, G.R., Ed.; ACS Symposium Series No. 330; American Chemical Society: Washington, DC, 1987; pp 396-415. Balandrin, M.F.; Lee, S.M.; Klocke, J.A. J.Agric.Food Chem. 1988, 36, 1048-1054. Yamasaki, R.B.; Klocke, J.A. J. Agric. Food Chem.1987,35,467-471. Lee, S.M.; Klocke,J.A.;Balandrin, M.F. Tetrahedron Lett. 1987, 28, 3543-3546. Klocke, J.A.; Barnby, M.A.; Yamasaki, R.B.; Lee, S.M.; Balandrin, M.F. Proc. 31st Internat. Congr. Pure Appl. Chem., Section 4, Chemistry and Biotechnology of Biologically Active Substances of Medical and VeterinaryImportance,1987, pp 150169. Barnby, M.A.; Klocke, J.A.; Darlington, M.V.; Yamasaki, R.B. Entomol. Exp. Appl. 1989, 52, 1-6. Barnby, M.A.; Yamasaki, R.B.; Klocke, J.A. J. Econ. Entomol. 1989, 82, 58-63. Block, E. Scient. Am. 1985,252(3),114-119. Taylor, D.A.H. Tetrahedron 1987, 43, 2779-2787. Turner, C.J.; Tempesta, M.S.; Taylor, R.B.; Zagorski, M.G.; Termini, J.S.; Schroeder, D.R.; Nakanishi, K. Tetrahedron1987,43,2789-2803. Bilton, J.N.; Broughton, H.B.; Jones, P.S.; Ley, S.V.; Lidert, Z.; Morgan, E.D.; Rzepa, H.S.; Sheppard, R.N.; Slawin, A.M.Z.; Williams, D.J. Tetrahedron 1987, 43, 2805-2815. Kraus, W.; Bokel, M.; Bruhn, A.; Cramer, R.; Klaiber, I.; Klenk,A.;Nagl, G.; Pöhnl, H.; Sadlo, H.; Vogler, B. Tetrahedron 1987, 43 2817-2830. Jacobson, M. In Natural Pesticides from the Neem Tree (Azadirachta indica A. Juss.); Schmutterer, H.; Ascher, K.R.S.; Rembold, H., Eds.; German Agency for Technical Cooperation: Eschborn, Germany, 1980; pp 33-42. Jongen, W.M.F.; Koeman, J.H. Environ. Mutagen.1983,5,687-694. Kubo, I.; Klocke, J.A. Agric. Biol. Chem. 1982, 46, 1951-1953. Klocke, J.A.; Balandrin, M.F.; Barnby, M.A.; Yamasaki, R.B. In Insecticides of Plant Origin; Arnason, J.T.; Philogène, B.J.R.; Morand, P., Eds.; ACS Symposium Series No. 387; American Chemical Society: Washington, DC, 1989; pp 136-149. Rembold, H. In Insecticides of Plant Origin; Arnason, J.T.; Philogène, B.J.R.; Morand, P., Eds.; ACS Symposium Series No. 387; American Chemical Society: Washington, DC, 1989; pp 150-163. Ruscoe, C.N.E. Nature New Biol. 1972, 236, 159-160. Leuschner, K. Naturwissenschaften1972,59,217-218. Morgan, E.D.; Thornton, M.D.Phytochemistry1973, 12, 391-392. Morgan, E.D.; Wilson, I.D. In CRC Handbook of Natural Pesticides:Methods,Vol. II, Isolation and Identification; Mandava, N.B., Ed.; CRC: Boca Raton, Florida, 1985; pp 3-81. Lee, S.M.; Klocke, J.A. J. Liq.Chromatogr.1987,10,1151-1163. Yamasaki, R.B.; Klocke, J.A.; Lee, S.M.; Stone, G.A.; Darlington, M.V. J. Chromatogr. 356, 220-226. Kubo, I.; Matsumoto, A.; Matsumoto, T.; Klocke, J.A. Tetrahedron 1986, 42 489-496. Kubo, I.; Klocke, J.A. In Plant Resistance to Insects; Hedin, P . A ., Ed.; ACS Symposium Series No 208; American Chemical Society: Washington, DC, 1983; pp 329-346. Kubo, I.; Klocke, J.A. In Natural Resistance of Plants to Pests: Roles of Allelochemicals; Green, M.B.; Hedin, P.A., Eds.; ACS Symposium Series No. 296; American Chemical Society: Washington, DC, 1986; pp 206-218. Wing, K.D. Science 1988, 241, 467-469. Wing, K.D.; Slawecki, R.A.; Carlson, G.R. Science 1988, 241, 470-472.

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