Antifeedant and mosquitocidal compounds from Delphinium x cultorum cv. Magic Fountains flowers

Article abstract of DOI:10.1021/jf990354d

Six volatile compounds, ethylmethylbenzene (1), 1-isopentyl-2,4,5- trimethylbenzene (2), 2-(hex-3-ene-2-one)phenylmethyl ketone (3), E and Z isomers of 3-butylidene-3H-isobenzofuran-1-one (4 and 5), and 2-penten-1- ylbenzoic acid (6), were isolated from the mosquitocidal hexane extract of Delphinium x cultorum cv. Magic Fountains flowers. In addition, the ethyl acetate extract, which displayed corn earworm antifeedant activity, yielded 4-hydroxybenzoic acid (7) and bis(4-hydroxyphenyl)methanol (8). However, compounds 7 and 8 were not biologically active.

Full text of DOI:10.1021/jf990354d

J. Agric. Food Chem. 2000, 48, 503−506
503
An tifeed a n t a n d Mosqu itocid a l Com p ou n d s fr om Delph in iu m ×
cu ltor u m Cv. Ma gic F ou n ta in s F low er s
J ennifer E. C. Miles, Russel S. Ramsewak, and Muraleedharan G. Nair*
Bioactive Natural Products Laboratory, Department of Horticulture and National Food Safety and
Toxicology Center, Michigan State University, East Lansing, Michigan 48824
Six volatile compounds, ethylmethylbenzene (1), 1-isopentyl-2,4,5-trimethylbenzene (2), 2-(hex-3-
ene-2-one)phenylmethyl ketone (3), E and Z isomers of 3-butylidene-3H-isobenzofuran-1-one (4 and
5
), and 2-penten-1-ylbenzoic acid (6), were isolated from the mosquitocidal hexane extract of
Delphinium × cultorum cv. Magic Fountains flowers. In addition, the ethyl acetate extract, which
displayed corn earworm antifeedant activity, yielded 4-hydroxybenzoic acid (7) and bis(4-hydroxy-
phenyl)methanol (8). However, compounds 7 and 8 were not biologically active.
INTRODUCTION
min. The ionization energy was 70 eV. All solvents were ACS
reagent grade and were purchased from Aldrich Chemical Co.,
Inc. Statistical analyses were performed on the larval anti-
feedant data using the F test and least significant difference
(LSD).
Traditionally, plants from the genus Delphinium have
been used as poisons and insecticides and for medicinal
purposes. These activities are linked to the alkaloids
present in these plants. Diterpenoid alkaloids isolated
from Delphinium spp. demonstrated acute mammalian
toxicity (Aiyar et al., 1979) in addition to insecticidal
P la n t Ma ter ia l. Delphinium × cultorum cv. Magic Foun-
tains dark blue/white bee seeds were donated by Bodger Seed,
Ltd., South El Monte, CA. The seeds were germinated in high
porosity, peat-based growing mix in Styrofoam trays (4 in. ×
(
J ennings et al., 1986), antibiotic (Atta-ur-Rahman et
6
in. × 2 in.) and grown until the first leaf appeared. The
al., 1997), antifungal (Atta-ur-Rahman et al., 1997), and
allelopathic (Waller and Burstrom, 1969) activities.
Research on Delphinium has focused primarily on the
isolation of diterpenoid alkaloids. The few reports that
have mentioned nonalkaloids from Delphinium included
fatty acids from Delphinium iliense and Delphinium
ajacis L. (Dong et al., 1991; Hasan and Osman, 1993).
The seed oil of D. ajacis contained a high percentage of
linoleic acid (Hasan and Osman, 1993). Delphinium
peregrinium and Delphinium carolinianum were specif-
ically investigated for nonalkaloid compounds, and
several flavonoids were isolated (Mericli et al., 1991).
Phenolic compounds such as 2,5,6-trihydroxypiperonylic
acid (Mericli et al., 1991), a new benzoxepine derivative,
oxformasine (Mericli et al., 1996), and 3-hydroxy-2-
methyl-4H-pyran-4-one (Atta-ur-Rahman et al., 1997)
were isolated from Delphinium venulosum, Delphinium
formosum, and Delphinium denudatum, respectively.
No biological activity has been reported for any of these
nonalkaloids. In this paper, we report the isolation of
several nonalkaloid compounds from the biologically
Fa co t ui vn et a ei nx st r. act of Delphinium × cultorum cv. Magic
seedlings were then transplanted into pots (4 in. × 4 in. × 6
in.) and then into large clay pots (10 in. × 6 in. × 10 in.) and
were grown until maturity. The plants were raised in the
Bioactive Natural Products Laboratory Greenhouses, Michigan
State University. The plants were subjected to a 12 h photo-
period, watered once daily, and maintained at 75 °F. Plant
parts were harvested when 75-80% of the florets were fully
expanded on each raceme and stored at -20 °C.
Extr a ction . The frozen flower material was weighed and
spread evenly into three stainless steel lyophilizer trays (29
cm × 31.5 cm × 3.4 cm) and lyophilized using a bulk tray
lyophilizer (model TD-3B, FTS Systems, Inc., Stone Ridge, NY)
at 5 °C for 48 h. The dried flower material was macerated into
a fine powder in a commercial Waring blender. The water
content of the fresh D. × cultorum flowers was approximately
8
0%. Sequential extraction of the lyophilized flower parts (409
g) with hexane and ethyl acetate (3.5 and 2.0 L × 3,
respectively) yielded 8.6 and 3.6 g, respectively.
GC-MS Ch a r a cter iza tion of Com p ou n d s 1-6 in th e
Mosqu itocid a l Ba n d II. The hexane extract (4 g) was
subjected to liquid-liquid extraction with hexane (200 mL ×
3
) and aqueous MeOH (90%, 300 mL). This yielded hexane
soluble and aqueous MeOH soluble fractions weighing 3.7 g
and 283 mg, respectively. The mosquitocidal components from
the aqueous MeOH soluble fraction (283 mg) from the hexane
extract were isolated using preparative TLC on silica gel GF254
glass plates (20 cm × 20 cm; 500 mm thickness; Analtech Inc.,
Newark, DE) developed with CHCl3. The plates were viewed
under UV light (254 and 366 nm) and eluted with MeOH,
yielding bands I-V with weights of 3.4, 4.6, 9.9, 3.4, and 177.4
mg, respectively. Compounds 1-6 were identified using GC-
EIMS from the mosquitocidal band II.
Isola tion of Com p ou n d s 7 a n d 8. The ethyl acetate
extract (1.2 g) was subjected to liquid-liquid extraction with
hexane (200 mL × 3) and aqueous MeOH (90%, 300 mL). This
yielded hexane soluble and aqueous MeOH soluble fractions
weighing 395 mg and 703 mg, respectively. The aqueous
MeOH soluble fraction (2 g) accumulated from several liquid-
liquid extractions of the ethyl acetate extract was fractionated
MATERIALS AND METHODS
Gen er a l Exp er im en ta l P r oced u r es. 1H and 13C NMR
spectra were recorded on a Varian INOVA 300 MHz spectrom-
eter at ambient temperature. GC-EIMS was performed at the
Michigan State University Mass Spectrometry Facility on a
J EOL-J MS-AX505H mass spectrometer configured with a 30
m DB5 column (0.32 mm × 0.25 mm). The carrier gas was
He, and the solvent was acetone. The column temperature was
set at 50 °C and programmed to increase to 190 °C at 10 °C/
*
Phone: (517) 353-2915. Fax: (517) 432-2310. E-mail:
nairm@pilot.msu.edu.
1
0.1021/jf990354d CCC: $19.00 © 2000 American Chemical Society
Published on Web 12/31/1999

504 J. Agric. Food Chem., Vol. 48, No. 2, 2000
Miles et al.
using a Waters Sep-Pak C18 cartridge (1.0 mL capacity; Waters
Chromatography Division, Millipore Corp., Milford, MA) eluted
with aqueous MeOH (90%, 1.25 mL × 4), MeOH (5 mL), and
(RO) water in an incubator at 26 °C for 3 days. Next, 10-12
fourth instar larvae were placed in 980 mL of RO water in
test tubes. Twenty microliters of test material dissolved in
DMSO, to give a concentration of 250 mg 20 mL , was added
to each tube. A 20 mL aliquot of DMSO was used as a control.
Treatments and controls were run in triplicate and were
covered and left at room temperature. Larval mortality was
recorded at 2 h intervals, up to and including 24 h (Nair et
al., 1989; Roth et al., 1998).
Cor n Ea r w or m An tifeed a n t Assa y. Corn earworm eggs,
Helicoverpa zea Boddie (Lepidoptera:Noctuidae) and dry corn
earworm diet was purchased from North Carolina State
Insectory, Department of Entomology, North Carolina State
University, Raleigh, NC. The eggs were hatched in an incuba-
tor at 27 °C. The dry diet was dispensed into scintillation vials
-
1
CHCl
3
(3 mL). This yielded fractions I-VI with weights of
1
012, 174, 79, 48, 399, and 156 mg, respectively. The corn
earworm growth-inhibitory fractions I-IV were combined (1.2
g) and further separated using preparative HPLC on two
J aigel GS310-F columns in tandem (i.d. 20 mm × 300 mm),
eluted with aqueous MeOH (90%) at a flow rate of 5 mL/min
and detected using UV 210 nm. This yielded fractions I-VI
weighing 22, 324, 621, 10,0.6, and 123 mg, respectively. The
antifeedant fraction, VI, was further separated by preparative
HPLC on two J aigel S-343-15 ODS columns in tandem (i.d.
2
0 mm × 250 mm), eluted with aqueous MeOH (70%) at a
flow rate of 5 mL/min and detected using UV 210 nm. This
yielded fractions I-VI weighing 5, 24, 10, 50, 4, and 2 mg,
respectively. Fractions II and IV were purified under the same
conditions with the exception of the eluting solvent, which was
aqueous MeOH (60%), and a flow rate of 3 mL/ min. Com-
pounds 7 (14 mg) and 8 (26 mg) were purified from fractions
(940 mg) for each treatment. Test material was dissolved in
DMSO to give a concentration of 1250 mg 25 mL-1, unless
otherwise stated. Next, 25 mL of the test solution was mixed
thoroughly with the portions of dry diet. An aliquot of 25 mL
of DMSO was used as a control. Agar solution (1.4%) was
mixed and autoclaved for 5 min at 15 psi and 125 °C to melt
the agar. This solution was held in a water bath at 50 °C, and
added to the dry diet until the total diet weighed 5 g. The final
concentration of test extracts and compounds was 250 mg/mL.
The wet diet was mixed thoroughly, and 3-4 drops of diet were
dispensed into 3.5 mL polystyrene vials. The freshly poured
portions of diet were allowed to cool and dry for at least 1 h.
After drying, one neonate larva was placed in each vial, and
the vials were capped. The treatment and control vials were
held in a growth chamber at a photoperiod of 16 h day and 8
h night with day temperature at 28 °C and night temperature
at 24 °C. Each treatment had 15 replicates. The treatments
were arranged in a completely randomized design. Larvae were
weighed (mg) after 6 days (Zhang et al., 1997).
Gyp sy Moth Ca ter p illa r An tifeed a n t Assa y. Gypsy
moth eggs, Lymantria dispar L. (Lepidoptera:Lymantriidae)
were obtained from the Insect Production Unit of the Canadian
Forest Service, Sault Ste. Marie, Canada. The dry diet was
mixed in the Bioactive Natural Products Laboratory, Depart-
ment of Horticulture, Michigan State University, and consisted
of wheat germ (36 g), casein (7.5 g), Wesson’s salt mix (2.4 g),
sorbic acid (0.6 g), methylparaben (p-hydroxybenzoic acid
methyl ester) (0.3 g), and Hoffman-La Roche 26862 vitamin
mixture (Hoffman-La Roche, Inc., Nutley, NJ ; 3.0 g). The eggs
were hatched in an incubator at 27 °C. The dry diet was
dispensed into scintillation vials (845 mg) for each treatment.
The rest of this assay was identical to that of the corn earworm
assay (Zhang et al., 1997).
1
II and IV, respectively, and were identified by using H and
1
3
C NMR spectra.
Com p ou n d 1: ethylmethylbenzene. GC-EIMS 70 eV, m/z
+
values (rel intensity): 120 [M ] (28.75), 105 [M - 15] (100),
9
1 [M - 29] (12.5).
Com p ou n d 2: 1-isopentyl-2,4,5-trimethylbenzene. GC-
+
EIMS 70 eV, m/z values (rel intensity): 190 [M ] (10.63), 133
[M - 57] (100).
Com p ou n d 3: 2-(hex-3-ene-2-one)phenylmethyl ketone. GC-
+
EIMS 70 eV, m/z values (rel intensity): 216 [M ] (47.5), 201
(18.75), 173 (2.5), 145 (2.5), 132 (21.25), 119 (67.5), 105 (8.75),
9
7 (7.5), 91 (12.5), 83 (100), 77 (3.75), 65 (2.5), 55 (16.25).
Com pou n d 4: (E)-3-butylidene-3H-isobenzofuran-1-one. GC-
+
EIMS 70 eV, m/z values (rel intensity): 188 [M ] (28.75), 159
[
M - 29] (100), 146 [M - 42] (30).
Com pou n d 5: (Z)-3-butylidene-3H-isobenzofuran-1-one. GC-
+
EIMS 70 eV, m/z values (rel intensity): 188 [M ] (28.75), 159
[
M - 29] (100), 146 [M - 42] (30).
Com p ou n d 6: 2-penten-1-ylbenzoic acid. GC-EIMS 70 eV,
+
m/z values (rel intensity): 190 [M ](72.5), 161 [M - 29] (100),
1
48 [M - 42] (78.75).
Com p ou n d 8: bis(4-hydroxyphenyl)methanol. H NMR (300
MHz, d -DMSO): δ 3.72 (1H, s, H-1), 6.67 (4H, d, J ) 8.4,
H-2, H-2′, H-6, H-6′), 7.74 (4H, d, J ) 8.4, H-3, H-3′, H-5, H-5′).
1
6
1
3
C NMR (75 MHz, d -DMSO): δ 55.6 (s, C-7), 114.2 (s, C-2,
6
C-2′, C-3, C-3′, C-5, C-5′, C-6, C-6′), 131.3 (s, C-1, C-1′), 159 (s,
C-4, C-4′).
Meth yla tion of Com p ou n d 8. Diazomethane was pre-
pared by dissolving 0.5 of N-nitroso-N-methylurea in 10% KOH
solution (50 mL) with ether (50 mL) over an ice bath. The
mixture was stirred gently for a few minutes and poured into
a 250 mL separatory funnel. The KOH solution layer was
removed, and the diazomethane solution was then washed
with 25 mL of ice-cold water. The diazomethane solution was
poured into a brown bottle containing KOH pellets and stored
at -20 °C. The diazomethane solution and a small amount of
MeOH was added to a sample of compound 8 (8 mg). The
sample was capped and allowed to sit in the fume hood for 2
RESULTS AND DISCUSSION
The flowers of D. × cultorum were separated from the
stems, lyophilized, and macerated into a fine powder
prior to the sequential extraction with hexane and ethyl
acetate. These crude extracts were tested at 250 mg/
mL concentrations for antifungal, antibacterial, topo-
isomerase inhibitory, mosquitocidal, and larval anti-
feedant activities. The hexane extract showed 93% and
h. The ether was evaporated with N
removed in vacuo at 30 °C to yield compound 9 (8.9 mg): 1
NMR (300 MHz, d -DMSO) δ 3.72 (1H, s, H-1), 3.84 (6H, s),
2
gas, and the MeOH
H
5
9% growth inhibition against H. zea and L. dispar,
respectively. In addition, it produced 100% mortality at
0 mg/mL concentration in A. aegyptii larvae at 2 h.
6
6
8
.67 (4H, d, J ) 8.4, H-2, H-2′, H-6, H-6′), 7.74 (4H, d, J )
.4, H-3, H-3′, H-5, H-5′).
1
The ethyl acetate extract showed 88% growth inhibition
against H. zea. Both extracts were subjected to liquid-
liquid extraction with hexane and aqueous MeOH as a
preliminary means of separation.
Bioassay-directed fractionation of the hexane extract
was conducted using fourth instar A. aegyptii and H.
zea neonates. Both the hexane soluble and aqueous
MeOH soluble fractions exhibited LD100 in 2 h at 100
mg/mL concentration when tested against A. aegyptii.
Similarly, these fractions showed significant antifeedant
activity against H. zea and L. dispar; however, the
Acetyla tion of Com p ou n d 9. To compound 9 (8.9 mg) was
added a solution of pyridine (2 mL) and acetic anhydride (1
µL). The clear solution was allowed to sit for 2 days in the
dark with constant stirring. The solvent was removed in vacuo
1
at 50 °C to yield compound 10 (10.2 mg): H NMR (300 MHz,
6
d -DMSO) d 2.35 (3H, s), 3.72 (1H, s, H-1), 3.84 (6H, s), 6.67
4H, d, J ) 8.4, H-2, H-2′, H-6, H-6′), 7.74 (4H, d, J ) 8.4,
H-3, H-3′, H-5, H-5′).
Mosqu itocid a l Assa y. First instar mosquito larvae, Aedes
aegyptii (Dipera:Culicidae), were provided by Drs. Alexander
Raikel and Alan Hays, Department of Entomology, Michigan
State University. The larvae were raised in reverse osmosis
(

Antifeedant and Mosquitocidal Compounds
J. Agric. Food Chem., Vol. 48, No. 2, 2000 505
F igu r e 2. Antifeedant assay of fractions I-VI from C18 Sep-
Pak separation of ethyl acetate extract from D. X cultorum
flower parts on H. zea at 250 mg/mL concentration after 6
days; p e 0.01.
(Ogawa et al., 1995; Watanabe et al., 1993). However,
we could not assign which peak corresponded to which
isomer; we did not have standards, and the GC-MS of
these compounds are not reported. TIC peak 6 showed
+
M at m/z 190 and fragment ions at m/z 161, indicating
loss of an ethyl moiety, and at m/z 148, suggesting a
McClafferty rearrangement followed by cleavage of a
propyl group. Compound 6 was identified from these
diagnostic ions as 2-penten-1-ylbenzoic acid (Li et al.,
F igu r e 1. Compounds characterized by GC-MS analysis of
the mosquitocidal fraction, band II, from the hexane extract.
aqueous MeOH soluble fraction was the most active.
Separation of the aqueous MeOH soluble fraction was
conducted by preparative TLC, yielding bands I-V. All
five bands were assayed against A. aegyptii. Band II
produced 100% mortality at 1 mg/mL concentration in
1
993). As a result of the volatility of the mosquitocidal
band II containing compounds 1-6 (Figure 1), the yield
was very low and did not allow further bioassays to be
conducted on the pure compounds or the isolation of
further biologically active components.
2
h. Because of the volatility of this band, isolation of
Bioassay-directed fractionation of the ethyl acetate
extract was conducted using H. zea neonates. The
aqueous MeOH fraction from liquid-liquid extraction
of the ethyl acetate extract was further separated using
a C18 sep-pak cartridge. The resulting fractions I-VI
were tested against H. zea for antifeedant activity, and
fractions I-IV were combined on the basis of their
similar TLC profiles and similar levels of antifeedant
activity as indicated by larval weight reduction by >90%
pure compounds from it was very difficult. Therefore,
this band was analyzed by GC-EIMS. The total ion
current (TIC) profile indicated a total of 15 peaks, six
of which were characterized and assigned structures
(
Figure 1) based on their fragmentation patterns with
Rt values of 3.00, 6.98, 13.11, 13.22, 13.75, and 13.90
min, respectively.
Peak 1, showing M at m/z 120 and fragment ions at
+
m/z 105 and 91, indicating the loss of ethyl and methyl
substituents, respectively, was assigned the structure
identical to 1, an isomer of ethylmethylbenzene (Na-
tional Institute of Science and Technology [NIST], 1998).
(Figure 2).
The combined fractions were purified by preparative
HPLC using a series of size exclusion columns. The
antifeedant compounds were eluted in the last fraction
at Rt ) 46-110 min and further purified by HPLC on
ODS columns. The fraction eluting at Rt ) 52 min was
identified as 4-hydroxybenzoic acid (7) (Mericli et al.,
1991). The fraction that eluted at Rt ) 57 min was
+
Similarly, peak 2 with M at m/z 190 and the fragment
ion at m/z 133 due to the loss of an isobutyl moiety, was
identical to 1-isopentyl-2,4,5-trimethylbenzene (2) (King-
ston et al., 1988). The third peak was the most abundant
+
in the TIC. The M at m/z 216 produced fragment ions
at m/z 201, 173,119, and 83 due to the cleavage of a
methyl, 2-propanone, hex-2-ene-1-one, and phenyl-
methyl ketone, respectively. Peak 3 was characterized
from its EIMS fragmentation pattern as compound 3,
2
-(hex-3-ene-2-one)phenylmethyl ketone. Literature
search revealed that this is the first report of compound
. The MS analysis revealed that TIC peaks 4 and 5
3
+
showed identical fragmentation profiles with an M ion
at m/z 188. The fragment ions at m/z 159 due to cleavage
of an ethyl moiety and 146 suggesting a McClafferty
rearrangement followed by the loss of a propyl group.
Hence, these compounds were identified as isomers of
each other and differed only in retention times. A survey
of the NIST mass spectral database and the literature
revealed that they were the E and Z isomers of 3-but-
ylidene-3H-isobenzofuran-1-one, respectively (4 and 5)
identified as bis(4-hydroxyphenyl)methanol (8) (Elliger,
1985).
Compound 8 gave an AB pair of doublets at δ 6.67
and 7.74 (J ) 8.4 Hz) and each signal integrated for
1
four protons in the H NMR spectrum. This suggested
that 8 is a symmetrical molecule, containing two

506 J. Agric. Food Chem., Vol. 48, No. 2, 2000
Miles et al.
benzene rings that had a 1,4 substitution pattern. A one
Elliger, C. A. Deoxygenation of aldehydes and ketones with
sodium cyanoborohydrate. Synth. Comm. 1985, 14, 1315-
1324.
proton singlet at δ 3.72 further supported the symmetry
in 8. The 13C NMR data of 8 gave signals at δ 55.6 (C-
Gijbels, M. J . M.; Fischer, F. C.; Scheffer, J . J . C. Phthalides
in roots of Apium graveolens, A. graveolens var. rapaceum,
Bifora testiculata and Petroselinum crispum var. tuberosum.
Fitoterapia 1985, 56, 17-23; Chem. Abstr. 1985, 103,
7
) and 159 (C-4, C-4′), which indicated oxygen function-
alities at these positions.
1
3590u.
Hasan, S. Q.; Osman, S. M. Studies on indigenous seed oils.
J . Oil Technol. Assoc. 1993, 25, 47-49.
J ennings, K. R.; Brown, D. G.; Wright, D. P., J r. Methyllyca-
conitine, a naturally occurring insecticide with a high
affinity for the insect cholingenic receptor. Experientia 1986,
4
2, 611-613.
Kingston, E. E.; Eichhozler, J . V.; Lyndon, P.; MacLeod, J . K.
An unexpected γ-hydrogen rearrangement in the mass
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Spectrom. 1988, 23, 42-47.
Li, S.; Wang, Z.; Fang, X.; Li, Y. Synthesis of (Z)-Ligustilide.
Synth. Commun. 1993, 23, 2909-2913.
To confirm the oxygen functionalities, compound 8
was methylated using diazomethane to yield 9. It was
evident from the H NMR of 9 that 8 contained 2-OH
moieties as indicated by a singlet at δ 3.84 that
integrated for six protons. Also, a singlet at δ 3.91 in
compound 9 indicated the presence of a third OH
functionality in 8.
1
Luo, Y.; Pan, J .; Ding, K.; Yan, Z. Anticonvulsive constituents
in the essential oil of Chaxiong (Ligusticum sinense Oliv cv.
Chaxiong). Zhongcaoyao 1996, 27, 456-457; Chem. Abstr.
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996, 125, 309171u.
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loidal constituents of Delphinium peregrinum. Fitoterapia
1991, 62, 460; Chem. Abstr. 1992, 117, 4210a.
Mericli, A. H.; Mericli, F.; Ulubelen, A.; Ilarslan, R. Aromatic
compounds from Delphinium venulosum. Phytochemistry
To confirm the presence of the third hydroxyl group
in 9, it was acetylated using acetic anhydride and
1
pyridine. The H NMR analysis of the product (10) gave
1
991, 30, 4195-4196.
a signal at δ 2.35 that integrated for three protons and
confirmed the presence of a hydroxy group at C-7 in 8.
Hence, the structure of compound 8 was assigned as bis-
Mericli, F.; Mericli, A. H.; Becker, H.; Ulubelen, A. A benzox-
epine derivative from Delphinium formosum. Phytochem-
istry 1996, 42, 1257-1258.
(
4-hydroxyphenyl)methanol. Compounds 7 and 8 did not
Nair, M. G.; Putnam, A. R.; Mishra, S. K.; Mulks, M. H.; Taft,
W. H.; Keller, J . E.; Miller, J . R.; Zhu, P.-P.; Meinhart, J .
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National Institute of Standards and Technology. NIST Chem-
istry Webbook. Available online at http://webbook.nist.gov/
chemistry; 1998.
show antifeedant activity on H. zea at 250 mg/mL
concentration.
This is the first bioassay-directed phytochemical
investigation of the hybrid D. × cultorum and the first
analysis of volatile compounds from Delphinum flowers.
This study yielded compounds 1-6 and 8 new to the
genus Delphinium, of which 3 is novel. In addition, this
is the first report of compounds 1-6 from Delphinium
species. Compounds 1, 2, and 6 have never been
reported from natural sources. E and Z isomers of
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butyrlactones. Heterocycles 1995, 41, 2587-2599.
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3
-butylidene-3H-isobenzofuran-1-one (4 and 5) are com-
monly found in essential oils of Angelica (Dai and Qiu,
996), Apium (Gijbels et al., 1985), and Ligusticum
5
45.
1
Waller, G. R.; Burstrom, H. Diterpenoid alkaloids as plant
growth inhibitors. Nature 1969, 222, 576-578.
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characterizations of their E- and Z-isomers. Heterocycles
species (Luo et al., 1996). Compound 7 has been isolated
previously from D. venulosum Boiss (Mericli et al.,
1
991).
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1
993, 36, 553-563.
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Technology Program, National Center for the Research Re-
sources, National Institutes of Health. The NMR data were
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