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Papers by Alejandro Urzua
Frontiers in Pharmacology, Nov 30, 2020
Boletin De La Sociedad Chilena De Quimica, 1984
Boletin De La Sociedad Chilena De Quimica, 1996
Revista Latinoamericana de Química, 1997
Molecules, 2021
Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the ma... more Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadi...
Revista Chilena de Historia Natural, 2020
Background Endophytic fungi are diverse and ubiquitous in nature, yet studies simultaneously comp... more Background Endophytic fungi are diverse and ubiquitous in nature, yet studies simultaneously comparing endophyte communities in above- and below-ground plant tissues are relatively scarce. The main goal of our study was to compare the diversity and community composition of endophytic fungi associated with above- and below-ground tissues of the plant Aristolochia chilensis in an arid ecosystem. Endophytic fungi were isolated from healthy leaves and roots of A. chilensis, and the internal transcribed spacer (ITS) region was sequenced for phylogenetic and taxonomic analysis. Results A combined total of 457 fungal isolates were cultured from leaf and root tissues, belonging to 54 operational taxonomic units (OTUs). The genera Fusarium, Penicillium, Phialemonium and Trichoderma were the most representative endophyte taxa identified in A. chilensis tissues; nevertheless, Fusarium was significantly more dominant in the below-ground community, while foliar endophyte community was dominated ...
Journal of Soil Science and Plant Nutrition, 2020
Ciencia e investigación agraria, 2019
Frontiers in Microbiology, 2019
The use of plant secondary metabolites has been incorporated as key part of integrated pest manag... more The use of plant secondary metabolites has been incorporated as key part of integrated pest management and as an alternative to the use of pesticides. This may even be more relevant regarding domiciliary pest insects, capable of vectoring pathogens to humans. In these environments control its more difficult due to its possible effect on non-target organisms and human health. Here we evaluated the use of the resinous exudate of Chile’s endemic bushHaplopappus platylepis(Asteraceae) as a sticky trap for crawling pest insects. We usedBlatta orientalisLinneus (oriental cockroach), a cosmopolitan synanthropic pest, as test organism. We compared effectiveness on cockroach-trapping ofH. platylepis’ resin versus a commercially available sticky trap, and analyzed these two sticky substances using UHPLC-DAD-MS and GC-MS. We found thatH. platylepisresin was as effective as the commercial adhesive on trappingB. orientalis. Plant resinous exudate was composed by a mixture of flavonoids, labdane ...
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](Molecules (Basel, Switzerland), Jan 27, 2018
The beetle Marsham (Coleoptera: Curculionidae), endemic to Europe and Northern Africa, is one of ... more The beetle Marsham (Coleoptera: Curculionidae), endemic to Europe and Northern Africa, is one of the most important red clover pests in Chile. As commercial insecticides are less effective against this pest, plant secondary metabolites have been considered as an alternative for its control. Here, we have investigated the chemical composition of essential oil (EO), petroleum ether extract (PEE), and dichloromethane extract (DCME) from heartwood. Additionally, the effects of EO and extracts on the feeding behavior (% of weight shift) of have been evaluated. The composition of EO, PEE, and DCME were analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The results showed the presence of a similar mixture of sesquiterpenes in the essential oil and in both of the extracts, which accounted for circa 60% of the total mixture. Sesquiterpenes were further isolated using chromatographic methods and were structurally characterized by optical rotation, GC⁻MS, ...
Boletin De La Sociedad Chilena De Quimica, 1984
Molecules (Basel, Switzerland), Jan 13, 2015
In this communication, we report the springtime variation of the composition of aristolochic acid... more In this communication, we report the springtime variation of the composition of aristolochic acids (AAs) in Aristolochia chilensis leaves and stems. The dominant AA in the leaves of all samples, which were collected between October and December, was AA-I (1), and its concentration varied between 212.6 ± 3.8 and 145.6 ± 1.2 mg/kg and decreased linearly. This decrease occurred in parallel with the increase in AA-Ia (5) concentration from 15.9 ± 0.8 mg/kg at the beginning of October to 96.8 ± 7.8 mg/kg in mid-December. Both acids are enzymatically related by methylation-demethylation reactions. Other AAs also showed important variations: AA-II (2) significantly increased in concentration, reaching a maximum in the first two weeks of November and subsequently decreasing in mid-December to approximately the October levels. The principal component in the AA mixture of the stems was also AA-I (1); similar to AA-II (2), its concentration increased beginning in October, peaked in the second ...
Biochemical Systematics and Ecology, 2000
Frontiers in Pharmacology, Nov 30, 2020
Boletin De La Sociedad Chilena De Quimica, 1984
Boletin De La Sociedad Chilena De Quimica, 1996
Revista Latinoamericana de Química, 1997
Molecules, 2021
Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the ma... more Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadi...
Revista Chilena de Historia Natural, 2020
Background Endophytic fungi are diverse and ubiquitous in nature, yet studies simultaneously comp... more Background Endophytic fungi are diverse and ubiquitous in nature, yet studies simultaneously comparing endophyte communities in above- and below-ground plant tissues are relatively scarce. The main goal of our study was to compare the diversity and community composition of endophytic fungi associated with above- and below-ground tissues of the plant Aristolochia chilensis in an arid ecosystem. Endophytic fungi were isolated from healthy leaves and roots of A. chilensis, and the internal transcribed spacer (ITS) region was sequenced for phylogenetic and taxonomic analysis. Results A combined total of 457 fungal isolates were cultured from leaf and root tissues, belonging to 54 operational taxonomic units (OTUs). The genera Fusarium, Penicillium, Phialemonium and Trichoderma were the most representative endophyte taxa identified in A. chilensis tissues; nevertheless, Fusarium was significantly more dominant in the below-ground community, while foliar endophyte community was dominated ...
Journal of Soil Science and Plant Nutrition, 2020
Ciencia e investigación agraria, 2019
Frontiers in Microbiology, 2019
The use of plant secondary metabolites has been incorporated as key part of integrated pest manag... more The use of plant secondary metabolites has been incorporated as key part of integrated pest management and as an alternative to the use of pesticides. This may even be more relevant regarding domiciliary pest insects, capable of vectoring pathogens to humans. In these environments control its more difficult due to its possible effect on non-target organisms and human health. Here we evaluated the use of the resinous exudate of Chile’s endemic bushHaplopappus platylepis(Asteraceae) as a sticky trap for crawling pest insects. We usedBlatta orientalisLinneus (oriental cockroach), a cosmopolitan synanthropic pest, as test organism. We compared effectiveness on cockroach-trapping ofH. platylepis’ resin versus a commercially available sticky trap, and analyzed these two sticky substances using UHPLC-DAD-MS and GC-MS. We found thatH. platylepisresin was as effective as the commercial adhesive on trappingB. orientalis. Plant resinous exudate was composed by a mixture of flavonoids, labdane ...
Molecules (Basel, Switzerland), Jan 27, 2018
The beetle Marsham (Coleoptera: Curculionidae), endemic to Europe and Northern Africa, is one of ... more The beetle Marsham (Coleoptera: Curculionidae), endemic to Europe and Northern Africa, is one of the most important red clover pests in Chile. As commercial insecticides are less effective against this pest, plant secondary metabolites have been considered as an alternative for its control. Here, we have investigated the chemical composition of essential oil (EO), petroleum ether extract (PEE), and dichloromethane extract (DCME) from heartwood. Additionally, the effects of EO and extracts on the feeding behavior (% of weight shift) of have been evaluated. The composition of EO, PEE, and DCME were analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The results showed the presence of a similar mixture of sesquiterpenes in the essential oil and in both of the extracts, which accounted for circa 60% of the total mixture. Sesquiterpenes were further isolated using chromatographic methods and were structurally characterized by optical rotation, GC⁻MS, ...
Boletin De La Sociedad Chilena De Quimica, 1984
Molecules (Basel, Switzerland), Jan 13, 2015
In this communication, we report the springtime variation of the composition of aristolochic acid... more In this communication, we report the springtime variation of the composition of aristolochic acids (AAs) in Aristolochia chilensis leaves and stems. The dominant AA in the leaves of all samples, which were collected between October and December, was AA-I (1), and its concentration varied between 212.6 ± 3.8 and 145.6 ± 1.2 mg/kg and decreased linearly. This decrease occurred in parallel with the increase in AA-Ia (5) concentration from 15.9 ± 0.8 mg/kg at the beginning of October to 96.8 ± 7.8 mg/kg in mid-December. Both acids are enzymatically related by methylation-demethylation reactions. Other AAs also showed important variations: AA-II (2) significantly increased in concentration, reaching a maximum in the first two weeks of November and subsequently decreasing in mid-December to approximately the October levels. The principal component in the AA mixture of the stems was also AA-I (1); similar to AA-II (2), its concentration increased beginning in October, peaked in the second ...
Biochemical Systematics and Ecology, 2000