Insect Antijuvenile Hormone Research Articles

Essential Oil Composition of Platostoma menthoides (L.) A. J. Paton whole plant

Platostoma menthoides (L.) A. J. Paton (Syn: Geniosporum prostratum (L) Benth. Geniosporum tenuiflorum) is an aromatic annual herb found in India and Sri Lanka belonging to the family Lamiaceae. Hydrodistillation of the plant collected from the North Central province in Sri Lanka, yielded 0. 5% (v/w) of a light yellow colored fragrant oil. The oil was analyzed by GC-FID and GC-MS. A total of 74 components accounting for 85.01 % of the oil were identified by comparison of their mass spectra with those in the NIST and WILEY libraries and their retention indices with published values. These compounds included sesquiterpene hydrocarbons (55.80 %), monoterpene hydrocarbons (14.77 %), oxygenated monoterpenes (8.82 %) and oxygenated sesquiterpenes (17.62 %). The main components of the oil were β-caryophyllene (37.01 %), limonene (8.45 %), bornyl formate (5.57 %), α-humulene (4.70 %) and caryophyllene oxide (5.82 %). It also contained a small amount of the methoxychromene precocene 1 (0.23 %), an insect anti-juvenile hormone which has not been reported widely from the Lamiaceae or the genus Platostoma.

Composition of the essential oils from the leaves of two varieties ofAspilia africana (Pers.) C. D. Adams from Cameroon

Four essential oil samples obtained by hydrodistillation from the leaves of Aspilia africana var. africana and a corresponding sample of A. africana var. ambigua were analysed by GC and GC–MS. The two varieties were poor in essential oil content (<0.1%). The qualitative composition of the essential oils was found to be quite similar, irrespective of the area and date of plant collection. Marked differences were, however, observed in the quantitative composition of the oils from the two varieties. As far as A. africana var. africana is concerned, two oil samples from Bafoussam were rich in sesquiterpenes (88% and 94%) with germacrene-D (45% and 54%) as the major component, while two oil samples from Yaoundé contained mainly monoterpenes (63% and 48%) with α-pinene (39% and 27%) as the most abundant component. The variety A. africana var. ambigua afforded an essential oil rich in monoterpenes (54%) with limonene (23%) and α-pinene (22%) as predominating components. Finally, the insect antijuvenile hormone precocene I was found to be present in all samples of the two varieties. Copyright © 1999 John Wiley & Sons, Ltd.

Insecticidal, anti-juvenile hormone, and fungicidal activities of organic extracts from different Penicillium species and their isolated active components.

Organic extracts from mycelium and culture broth of 21 Penicillium isolates have been tested for insecticidal, insect anti-juvenile hormone (anti-JH), and antifungal activities. Culture broth extracts were the most active, mainly against insects; nearly 25% of them have shown high entomotoxicity (100% mortality at 100 microg/cm(2)). A strong in vivo anti-JH activity against Oncopeltus fasciatus Dallas was detected in the culture broth extracts from P. brevicompactum P79 and P88 isolates. The two new natural products isolated from P79, N-(2-methyl-3-oxodec-8-enoyl)-2-pyrroline (1) and 2-hept-5-enyl-3-methyl-4-oxo-6,7,8,8a-tetrahydro-4H-pyrrolo[2,1-b]-1, 3-oxazine (2), possessed anti-JH and insecticidal activity, respectively, against O. fasciatus. Synthesized natural compound 1 has shown an ED(50) of 0.7 microg/nymph when assayed on newly molted fourth-instar nymphs of O. fasciatus. Promising biological activities have also been detected in the synthetic precursors.

Insect anti-juvenile hormone and juvenile hormone activity from plants in the genusNama

The insect anti-juvenile hormones precocene I and II (7-methoxy-2,2-dimethyl-2H-1-benzopyran and 6,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran) were identified in three of nineNama (Hydrophyllaceae) species. Precocene I occurred inN. lobbii while precocene II occurred inN. hispidum, N. lobbii andN. sandwicense. N. hispidum contained the highest concentration (ca 0.5% dry weight) of precocene II, which was found in the leaves, stems, seed capsules, corolla, glandular trichomes, and seeds. In addition to the anti-juvenile hormone, insect juvenile hormone activity was detected in the organosoluble extracts ofN. rothrockii andN. sandwicense. N. sandwicense is the first plant discovered to contain compounds with both anti- and juvenile hormone activity.

Precocene I and Other Constituents of the Essential Oil ofPlatostoma africanum

The essential oil from the herb PLATOSTOMA AFRICANUM was analysed by means of GLC, LSC and GC-MS. So far a large number of its components were identified, among which were 16 sesquiterpene hydrocarbons (43%), seven phenylpropane derivatives (16%), seven oxygen-containing, straight-chain aliphatic compounds (11%), and six oxygen-containing sesquiterpenes (5%). Monoterpenes were present in small amounts only. An estimated 10% of the total oil was made up of diterpenes. The main component of the oil was germacrene-D (19%). An unusual component was found to be the chromene derivative precocene I (11%), which is an insect anti-juvenile hormone. This is, as far as we know, the first detection of a chromene in the family Lamiaceae. The composition of the oil of P. AFRICANUM has not been reported previously. The method of isolation affected the yield, composition, and odour of the oil.

The effect of some furochromene and benzochromene analogues of 2,2‐dimethyl‐7‐methoxychromene (precocene I) and benzofuran precursors on Oncopeltus fasciatus (dallas) and Locusta migratoria migratorioides (R&amp;F)

AbstractAs part of an extensive study on insect antijuvenile hormones (AJH) structurally related to 2,2‐dimethyl‐7‐methoxychromene and 6,7‐dimeth‐oxy‐2,2‐dimethylchromene (precocenes I and II, respectively), four furophenols, six furochromenes, three benzofuran derivatives and two benzochromenes were tested for biological effects on Oncopeltus fasciatus and Locusta migratoria. Exposure to ajar deposit of the chemical was used for O. fasciatus and topical application in acetone for L. migratoria, with precocenes I and II as standards for comparison. All compounds were toxic to O. fasciatus and in some cases, this may have concealed any potential AJH activity, which was not observed for any compound tested. Toxicity to L. migratoria was less evident and three of the furochromene derivatives, allprecocene‐I (PI) analogues, showed AJH activity seven to ten‐fold lower than that of PI. Neither of the benzochromenes tested showed any AJH activity. The results are discussed in terms of the known structure‐activity relationships for precocene‐like AJH activity.

Synthesis of two optical isomers of the insect anti-juvenile hormone agent fluoromevalonolactone(FMev) and their biological activities.

The optical isomers (R)-(-)- and (S)-(+)-tetrahydro-4-fluoromethyl-4-hydroxy-2H-pyran-2-one (fluoromevalonolactone, . FMev) of the insect anti-juvenile hormone were synthesized by using combined enzymatic and chemical methods, and their biological activities were examined by using the silkworm Bombyx mori L. It was found that the observed anti-juvenile hormone and insecticidal activity against Bombyx mori after topical treatment with racemic FMev was due to the (R)-(-)-enantiomer of FMev, the (S)-(+)-enantiomer being inactive.

Synthesis and Anti-juvenile Hormone Activity of 2,2-Dimethyl-1,2-dihydroquinoline Derivatives, Nitrogen Analogues of Precocene I and II

A synthesis of nitrogen analogues of the natural insect anti-juvenile hormones precocene I and II is reported. The crucial step of this synthesis is thermal cyclization of the N-alkynylaniline 3 into the corresponding 1,2-dihydroquinoline when promoted by a copper catalyst. Biological testing of the anti-juvenile hormone activity was carried out against Callosobruchus chinensis by observing the inhibition of eclosion. The 7-methoxy analogue showed higher activity than the 6,7-dimethoxy analogue. However, the former showed lower activity than precocene I.

Design of novel insect anti-juvenile hormones: allylic alcohol derivatives

Three analogues of 3,3-dimethyl-2-propenol (dimethylallyl alcohol) were synthesized and found to possess anti juvenile hormone activity when assayed on lepidopterous insect species (particularly the tobacco hornworm, Manduca sexta). The most active compound of those described, 3,3-dichloro-2-propenyl hexanoate, caused precocious metamorphosis, inhibited juvenile hormone (JH) biosynthesis in vitro, and reduced JH titers in vivo.

Synthesis and anti-juvenile hormone activity of 2,2-dimethl-1,2-dihydroquinoline derivatives. Nitrogen analogues of precocene I and II.

A synthesis of nitrogen analogues of the natural insect anti-juvenile hormones precocene I and II is reported. The crucial step of this synthesis is thermal cyclization of the N-alkynylaniline 3 into the corresponding 1,2-dihydroquinoline when promoted by a copper catalyst. Biological testing of the anti-juvenile hormone activity was carried out against Callosobruchus chinensis by observing the inhibition of eclosion. The 7-methoxy analogue showed higher activity than the 6,7-dimethoxy analogue. However, the former showed lower activity than precocene I.

Synthesis of precocenes with ionoforic groups

AbstractPreparation of potential insect antijuvenile hormone agents with polyoxyethyl and glycosyl groups at C‐8 position of the 2‐H‐chromene ring of precocenes is described.

Synthesis of 6‐methoxy‐2,2‐dimethyl‐2H‐1‐benzothiopyran and 6,7‐dimethoxy‐2,2‐dimethyl‐2H‐1‐benzothiopyran, sulfur analogues of precocene I and precocene II

AbstractPreparation of title compounds 5, sulfur analogues of the natural insect antijuvenile hormones precocene I and II, is described. The synthetic pathway involves conversion of the appropriate thiophenol 2 into the corresponding thiochroman‐4‐one 4 followed by reduction and dehydration. The 13C nmr data for all the above products are also reported.

Radiosynthesis of high specific activity tritium‐labeled precocene II

AbstractThe insect antijuvenile hormone precocene II (6,7‐dimethoxy‐2,2‐dimethylchromene) was radiosynthesized, incorporating tritium specifically in the gem‐dimethyl group at high specific activity. 7‐Hydroxycoumarin was methylated (CH3I/KOH) and then oxidized at 6‐position (K2S2O8/NaOH). The resulting 6‐hydroxy‐7‐methoxycoumarin was methylated (CH3I/KOH) and reacted with excess C3H3MgI to give precocene II‐[2‐methyl‐3H] at a specific activity of 32 Ci/mmol. This synthetic scheme offers access to radiolabeled preparations of a wide variety of mono‐ and dialkoxy‐substituted analogues of precocene II.

Syntheses of the two optical isomers of the insect anti-juvenile hormone agent ethyl p-[2-(t-Butylcarbonyloxy)butoxy]benzoate (ETB) and their biological activities

The optical isomers (9) and (13) of the insect anti-juvenile hormone, (�)-ethyl p-[2-(t-butylcarbonyloxy)butoxy]benzoate (ETB) (14), have been synthesized and their biological activities examined in the tobacco hornworm Manduca sexta. It was found that the observed anti-juvenile hormone activity at low dose levels and juvenile hormone activity at higher levels in the Manduca sexta, after topical treatment with the racemic mixture (14) is due entirely to the (–)-enantiomer (9), the (+)-enantiomer (13) being completely inactive.

Synthesis of crown‐ether precocenes

AbstractPreparation of potential insect antijuvenile hormone agents with 15‐crown‐5 and 18‐crown‐6 moieties connecting the C‐6 and C‐7 positions of the 2 H‐chromene ring of precocenes is described.

Fluorinated chromenes. III. Synthesis of 3‐fluoro‐2,2‐dimethyl‐2H‐chromenes

AbstractThe reaction of 2‐fluoro‐1,1‐dimethoxy‐3‐methylbut‐2‐ene (3) with phenols in dry pyridine leads to 3‐fluoro‐2,2‐dimethyl‐2H‐chromenes. 3‐Fluoro analogues of the natural insect antijuvenile hormones Precocene I (1a) and II (1b) have been prepared by this method.

Fluorinated chromenes 1: 2,2,2-trifluoroethoxy precocene analogs and their corresponding 3,4-epoxides

Preparation of potential insect antijuvenile hormone agents 2,2-dimethyl-7-(2,2,2-trifluoroethoxy)-2H-chromene ( 3a ), 6-methoxy-2,2-dimethyl-7-(2,2,2-trifluoroethoxy)-2 H -chromene ( 3b ) and 7-methoxy-2,2-dimethyl-6--(2,2,2-trifluoroethoxy)-2 H -chromene ( 3c ) and the corresponding 3,4-epoxides 5a and 5b is reported.

Fluorinated chromenes. Synthesis of 6,7‐dimethoxy‐2‐methyl‐2‐trifluoromethyl‐2H‐chromene

AbstractPreparation of the title compound, a trifluoromethyl analog of the natural insect antijuvenile hormone 6,7‐dimethoxy‐2,2‐dimethyl‐2H‐chromene (precocene II), from 3,4‐dimethoxyphenol and 1,1,1‐trifluoro‐4,4‐dimethoxy‐2‐methyl‐2‐butyl mesylate is described.

ChemInform Abstract: SYNTHESIS OF INSECT ANTIJUVENILE HORMONES

AbstractDie Alkoxyphenole (I) reagieren mit der Dimethylacrylsäure (II) zu den Chromanonen (III), die mit Lithiumaluminiumhydrid in Tetrahydrofuran zu den Chromanolen (IV) reduziert werden.

Radiosynthesis and metabolism of the insect antijuvenile hormone, precocene II

Radiosynthesis and metabolism of the insect antijuvenile hormone, precocene II