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Papers by Sylvia Copaja
Journal of the Chilean Chemical Society, Jun 1, 2023
Journal of The Chilean Chemical Society, Nov 1, 2022
Annals of Applied Biology, Jun 1, 1993
SummaryThe effects of DIMBOA in cultivars of wheat on aphid antibiosis and tolerance to the insec... more SummaryThe effects of DIMBOA in cultivars of wheat on aphid antibiosis and tolerance to the insecticide deltamethrin were investigated for the aphid Sitobion auenae. Over 48 hours the mean relative growth rate differed significantly between nymphs of S. auenae reared on wheat cultivars containing different levels of DIMBOA. Nymphs on the resistant cv. Altar showed a significantly greater susceptibility to deltamethrin, with nearly a three‐fold increase in the relative toxicity of deltamethrin, compared with the susceptible cv. Dollarbird. The LC50, adjusted for weight, was reduced by 91% for nymphs reared on the high DIMBOA cultivar. The potential for the enhancement of predation under a reduced pesticide régime is discussed in relation to this research.
Journal of The Chilean Chemical Society, Sep 1, 2022
Chemischer Informationsdienst, May 17, 1983
Journal of The Chilean Chemical Society, Sep 1, 2019
Journal of The Chilean Chemical Society, Mar 1, 2018
Journal of The Chilean Chemical Society, 2023
Chemischer Informationsdienst, 1985
Revista Latinoamericana De Quimica, 2003
A test with the microalga Chlorella vulgaris was used to evaluate the allelopathic potential acti... more A test with the microalga Chlorella vulgaris was used to evaluate the allelopathic potential activity of indole alkaloids present in cereals. Gramine, the main indole alkaloid present in barley shows the highest toxicity. A model mechanism of action for auxin was used to analyze the structural effect on the observed toxicity.
Herbicides - Advances in Research, 2013
Phosphorus and Sulfur and the Related Elements, 1985
ABSTRACT A series of alkoxythioamines, R2NSOR' (NR2=morpholino. piperidino and diethylami... more ABSTRACT A series of alkoxythioamines, R2NSOR' (NR2=morpholino. piperidino and diethylamino: R′ = Me, Et, i-Pr), has been prepared by the alcoholysis of N, N′-thiobisamines induced by the presence of CuCl2 and HCl. The products were characterized by their IR. H-NMR spectra and elemental analyses.
Zeitschrift für Naturforschung C, 2004
Secondary metabolites, DIBOA, HBOA, 7-OH-HBOA and BOA, were isolated and quantified from S. dulce... more Secondary metabolites, DIBOA, HBOA, 7-OH-HBOA and BOA, were isolated and quantified from S. dulce (Nees), a native species in Chile belonging to the Acanthaceae family. The highest DIBOA and HBOA contents were determined in leaves (9.25 mmol kg-1 fr. wt) and root (6.81 mmol kg-1 fr. wt), respectively. Aglycones, 7-OH-HBOA and HBOA, were isolated together from root extracts of Acanthaceae species. Both, HBOA and 7-OH-HBOA should be direct precursors in the biosynthesis of DIBOA and DIMBOA, respectively.
Wood Science and Technology, 2003
Systematic HPLC analysis of aqueous extracts from bark and woody parts of Quillaja saponaria Mol.... more Systematic HPLC analysis of aqueous extracts from bark and woody parts of Quillaja saponaria Mol. ('quillay') growing at three different localities in Central Chile, showed that saponin contents in 100 g of dried plant material ranged from 2.3 g to 15.8 g depending on the extraction method (soxhlet or maceration), the part of the plant analysed and the site of collection. Twigs and barks afforded in most cases extracts with higher levels of saponins as compared to those obtained with woody parts of the same specimen.
Phosphorus, Sulfur, and Silicon and the Related Elements, 1991
Journal of the Chilean Chemical Society, Jun 1, 2023
Journal of The Chilean Chemical Society, Nov 1, 2022
Annals of Applied Biology, Jun 1, 1993
SummaryThe effects of DIMBOA in cultivars of wheat on aphid antibiosis and tolerance to the insec... more SummaryThe effects of DIMBOA in cultivars of wheat on aphid antibiosis and tolerance to the insecticide deltamethrin were investigated for the aphid Sitobion auenae. Over 48 hours the mean relative growth rate differed significantly between nymphs of S. auenae reared on wheat cultivars containing different levels of DIMBOA. Nymphs on the resistant cv. Altar showed a significantly greater susceptibility to deltamethrin, with nearly a three‐fold increase in the relative toxicity of deltamethrin, compared with the susceptible cv. Dollarbird. The LC50, adjusted for weight, was reduced by 91% for nymphs reared on the high DIMBOA cultivar. The potential for the enhancement of predation under a reduced pesticide régime is discussed in relation to this research.
Journal of The Chilean Chemical Society, Sep 1, 2022
Chemischer Informationsdienst, May 17, 1983
Journal of The Chilean Chemical Society, Sep 1, 2019
Journal of The Chilean Chemical Society, Mar 1, 2018
Journal of The Chilean Chemical Society, 2023
Chemischer Informationsdienst, 1985
Revista Latinoamericana De Quimica, 2003
A test with the microalga Chlorella vulgaris was used to evaluate the allelopathic potential acti... more A test with the microalga Chlorella vulgaris was used to evaluate the allelopathic potential activity of indole alkaloids present in cereals. Gramine, the main indole alkaloid present in barley shows the highest toxicity. A model mechanism of action for auxin was used to analyze the structural effect on the observed toxicity.
Herbicides - Advances in Research, 2013
Phosphorus and Sulfur and the Related Elements, 1985
ABSTRACT A series of alkoxythioamines, R2NSOR' (NR2=morpholino. piperidino and diethylami... more ABSTRACT A series of alkoxythioamines, R2NSOR' (NR2=morpholino. piperidino and diethylamino: R′ = Me, Et, i-Pr), has been prepared by the alcoholysis of N, N′-thiobisamines induced by the presence of CuCl2 and HCl. The products were characterized by their IR. H-NMR spectra and elemental analyses.
Zeitschrift für Naturforschung C, 2004
Secondary metabolites, DIBOA, HBOA, 7-OH-HBOA and BOA, were isolated and quantified from S. dulce... more Secondary metabolites, DIBOA, HBOA, 7-OH-HBOA and BOA, were isolated and quantified from S. dulce (Nees), a native species in Chile belonging to the Acanthaceae family. The highest DIBOA and HBOA contents were determined in leaves (9.25 mmol kg-1 fr. wt) and root (6.81 mmol kg-1 fr. wt), respectively. Aglycones, 7-OH-HBOA and HBOA, were isolated together from root extracts of Acanthaceae species. Both, HBOA and 7-OH-HBOA should be direct precursors in the biosynthesis of DIBOA and DIMBOA, respectively.
Wood Science and Technology, 2003
Systematic HPLC analysis of aqueous extracts from bark and woody parts of Quillaja saponaria Mol.... more Systematic HPLC analysis of aqueous extracts from bark and woody parts of Quillaja saponaria Mol. ('quillay') growing at three different localities in Central Chile, showed that saponin contents in 100 g of dried plant material ranged from 2.3 g to 15.8 g depending on the extraction method (soxhlet or maceration), the part of the plant analysed and the site of collection. Twigs and barks afforded in most cases extracts with higher levels of saponins as compared to those obtained with woody parts of the same specimen.
Phosphorus, Sulfur, and Silicon and the Related Elements, 1991