Francisco Camps

Synthesis of dienic fluorinated analogs of insect sex pheromones

Abstract Synthesis of fluorinated analogs of some dienic insect sex pherormones through a stereocontrolled Wittig reaction of β-fluorinated aldehydes with the appropriate ω-functionalized ylides is reported. Some features of the 1H and 19F NMR spectra of these analogs are also discussed.

Insect allelochemicals from Ajuga plants

Abstract Clerodane diterpenoids and phytoecdysteroids with potential insect antifeedant and moulting hormone activities, respectively, have been isolated from Ajuga plants. Some clerodanes were active against larvae of Egyptian cotton leafworm, Spodoptera littoralis , when present in the diet at 3 ppm doses. Structure-antifeedant activity relations were established. Likewise, first stage larvae of the greenhouse whitefly, Trialeurodes vaporariorum , exhibited complete mortality when fed on A. reptans . This effect was mainly originated by 29-norsengosterone and ajugalactone, two phytoecdysteroids occurring in this plant. For biotechnological production of phytoecdysteroids its total content in different parts of normally grown or in vitro micropropagated A. reptans plants was studied. Great quantitative and qualitative differences were observed. For comparison of these qualitative differences, a dealkylation ratio (Dr=C 28 /C 29 phytoecdysteroid content) and a C-5 hydroxylation ratio (5Hr = 5-OH/5-H phytoecdysteroid content) were established. The 5Hr values appeared to be quite constant ranging from 0.2 to 0.4, whereas Dr values oscillated from 2.3 in whole plants to 12 in root cultures. Production of phytoecdysteroids was highest (⋍5000 ppm/dry wt) in cultures of roots in an hormone supplemented solid medium.

Insect antifeedant activity of clerodane diterpenoids against larvae ofSpodoptera Littoralis (Boisd.) (Lepidoptera)

Antifeedant activities of nine clerodane diterpenoids, isolated in this laboratory from different species ofAjuga plants, have been studied against larvae of Egyptian cotton leafwormSpodoptera littoralis (Boisd.) (Lepidoptera) by application of the leaf disk method. Evaluation of activity was carried out by calculating, at different time intervals, the feeding ratio (FR) from the relationship between the consumed areas of treated disks (CTD) and control disks (CCD); for comparison purposes a FR50 defined as the FR at a CCD of 50% was established. Some compounds exhibited activity at a 0.01 μg/cm2 dose (0.3 ppm). Structure-activity relationships are discussed

Development of a highly sensitive enzyme-linked immunosorbent assay for atrazine Performance evaluation by flow injection immunoassay

Specific polyclonal antibodies to the herbicide atrazine (6-chloro-N-ethyl-N′-isopropyl-1,3,5-triazine-2,4-diamine) have been raised by immunizing three New Zealand rabbits. With the antisera (As) a highly sensitive enzyme-linked immunosorbent assays (ELISA) has been developed to determine atrazine in water samples. Several usable competitive immunoassays have been obtained by screening a battery of nine enzyme tracers (ETs) and three antisera. The optimized ELISA presents an IC50 of 0.28 nM (60 ng l−1) and a detection limit of 0.043 nM (9 ng l−1). Cross-reactivity studies have proved that the immunoassay is specific for atrazine while other triazine compounds are only detected on a minor extent. The flow injection immunoanalysis (FIIA) method has an IC50 of 2 nM (0.47 μg l−1) reaching a detection limit of 0.35 nM (75 ng l−1). The performance of both methods has been evaluated by analyzing water samples containing mixtures of atrazine and other pesticides at the ppb level. For this purpose two candidate reference materials have been used (A and B) and a spiked sample stored on Empore disks (sample C). A close correspondence was found between the results obtained with both immunochemical techniques.

A new member of the PBAN family in Spodoptera littoralis: molecular cloning and immunovisualisation in scotophase hemolymph

In this article, we report evidence suggesting that the immunoreactive factor previously detected in Spodoptera littoralis scotophase hemolymph is PBAN, which supports a humoral route of the hormone to the pheromone gland. Western blot after native-PAGE of prepurified scotophase hemolymph extracts yielded an immunoreactive band with the same mobility as S. littoralis Br-SOG factor and the expected mobility for a noctuid PBAN. This band was not detected in photophase hemolymph extract. The identity of S. littoralis Br-SOG factor as PBAN was obtained from cDNA cloning using RT-PCR strategy. This allowed us to deduce the amino acid sequence of Spl-PBAN, which is highly homologous to other known PBANs. Moreover, we found that the PBAN encoding cDNA also encoded four other putative amidated peptides (Spl-DH homologue, Spl-alpha-NP, Spl-beta-NP and Spl-gamma-NP) that are identical or highly conserved among noctuids, and two non amidated peptides of unknown function. This cDNA organization is common to all known cDNAs encoding PBANs, leading to the release of different peptides after putative enzymatic cleavage of the preprohormone.

Improved oxidation procedure with aromatic peroxyacids

Abstract The application of the m -Chloroperbenzoic acid-potassium fluoride system in the Baeyer-Villiger oxidation of aromatic aldehydes and in the epoxidation of olefins has been studied.

Control of the sex pheromone biosynthetic pathway in Thaumetopoea pityocampa by the pheromone biosynthesis activating neuropeptide

Abstract This study shows that the pheromone biosynthesis activating neuropeptide (PBAN) is involved in the regulation of sex pheromone biosynthesis in Thaumetopoea pityocampa . In vitro incubation of pheromone glands with PBAN resulted in a dose-dependent increase in pheromone titer. The formation of labeled pheromone from deuterated 11-hexadecynoic acid was stimulated in pheromone glands upon in vitro incubation with PBAN. However, no differences were found between PBAN-treated glands and controls in the amounts of labeled intermediates. In vivo experiments with deuterated (Z)-11-hexadecenoic acid and 11-hexadecynoic acid showed that 12,13-methylenehexadec-12-enoic acid inhibited both the δ-11 desaturation of (Z)-11-hexadecenoic acid and the Z-13 desaturation of 11-hexadecynoic acid. The amounts of natural pheromone produced by pheromone glands topically treated, in vivo , with 12,13-methylenehexadec-12-enoic acid and further incubated, in vitro , with PBAN were similar to those found in glands that had not been administered the inhibitor. Topical application of (Z)-13-hexadecen-11-yn-l-ol to pheromone glands in vivo resulted in the formation of the corresponding acetate. All these results indicate that PBAN controls pheromone biosynthesis in the processionary moth by regulating a step involved in the transformation of the enyne acyl intermediate into the enynol.

Composition and location of phytoecdysteroids in Ajuga reptans in vivo and in vitro cultures

Abstract The location and concentration of phytoecdysteroids in Ajuga reptans have been studied in different normally grown or in vitro micropropagated plants. Some callus cultures were also studied. The relationship of phytoecdysteroid relative concentration with growing conditions and source of tissue are discussed. The ratio of C 28 /C 29 phytoecdysteroids was established amongst the four major compounds (29-norsengosterone and 29-norcyasterone as C 28 , and cyasterone and ajugalactone as C 29 ) which between them account, on average, for 92% of the total phytoecdysteroid content. This ratio was found to be less than one in all types of leaves from wild material, slightly higher than one in the roots of wild plants, and in the range from three to five in greenhouse and in vitro plants. Micropropagated plants had an extremely low phytoecdysteroid content in leaves, whereas that in roots was the highest detected in our experiments. Callus cultures obtained from leaves or roots completely lost their capacity to produce ecdysteroids.

Regiospecific reduction of unsaturated conjugated ketones with sodium dithionite under phase transfer catalysis

Abstract Selective double bond reduction of unsaturated conjugated ketones has been achieved in excellent yields by use of sodium dithionite in a two phase benzene-water system with Adogen as phase transfer catalyst. However, this reduction was unsatisfactory for hydrophilic ketones; in this case, competitive reactions led to the predominant formation of water soluble sulfur derivatives, similar to those obtained in the reaction of unsaturated conjugated ketones with sodium dithionite in aqueous dimethylformamide.

Tetrabutylammonium biflouride: A versatile and efficient flourinating agent

Abstract The use of tetrabutylammonium, biflouride as stable and easily available source of flouride ion in nucleophilic substitution process with different substrates is reported.