Alejandro Urzua - Academia.edu (original) (raw)
Papers by Alejandro Urzua
Contribuciones científicas y tecnológicas, 1970
RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de... more RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de Chile conocido por los nombre de pelú y pilo. pilo, que se asemeja mucho desde el punto de vista morfológico a las especies neozelandesas S. tetraptera J. Mill. Y S. microphylla Ait. Un estudio preliminar de los alcaloides de las semillas de esta planta chilena permitió aislar citisina, metilcitisina y matrina en proporciones que apoyan la separación taxonómica del pelú de las especies nativas de Nueva Zelandia. SUMMARY-Sophora tetraptera, sensu R,eiche, is the scientific name assigned to a southem Chilean tree known by the names pelú and pilopilo, which closely resembles the N ew Zealand species S. tetraptera J. Mill. and S. microphylla Ait. from a morphological viewpoint. A preliminalj' study of the seed alkaloids of this Chilean plant yielded cytisine, methylcytisine, and matrine in a ratio which supports the taxonomic segregation of the pelú from the species native to New Zealand.
Frontiers in Pharmacology, Nov 30, 2020
free catechol function is necessary for the enzyme inhibition. In addition, the fractions of phen... more free catechol function is necessary for the enzyme inhibition. In addition, the fractions of phenols and phenol-acid compounds showed inhibitory activity against 15-sLOX and the AE, showed a good inhibition against 5-hLOX. These results would be in agreement with the use of L. caustica, as an anti-inflammatory in Mapuche ethnomedicine.
Molecules, Jun 23, 2017
In the present study, the antibacterial activity of several ent-labdane derivatives of salvic aci... more In the present study, the antibacterial activity of several ent-labdane derivatives of salvic acid (7α-hydroxy-8(17)-ent-labden-15-oic acid) was evaluated in vitro against the Gram-negative bacterium Escherichia coli and the Gram-positive bacteria Staphylococcus aureus and Bacillus cereus. For all of the compounds, the antibacterial activity was expressed as the minimum inhibitory concentration (MIC) in liquid media and minimum inhibitory amount (MIA) in solid media. Structure activity relationships (SAR) were employed to correlate the effect of the calculated lipophilicity parameters (logP ow) on the inhibitory activity. Employing a phospholipidic bilayer (POPG) as a bacterial membrane model, ent-labdane-membrane interactions were simulated utilizing docking studies. The results indicate that (i) the presence of a carboxylic acid in the C-15 position, which acted as a hydrogen-bond donor (HBD), was essential for the antibacterial activity of the ent-labdanes; (ii) an increase in the length of the acylated chain at the C-7 position improved the antibacterial activity until an optimum length of five carbon atoms was reached; (iii) an increase in the length of the acylated chain by more than five carbon atoms resulted in a dramatic decrease in activity, which completely disappeared in acyl chains of more than nine carbon atoms; and (iv) the structural factors described above, including one HBD at C-15 and a hexanoyloxi moiety at C-7, had a good fit to a specific lipophilic range and antibacterial activity. The lipophilicity parameter has a predictive characteristic feature on the antibacterial activity of this class of compounds, to be considered in the design of new biologically active molecules.
Boletin De La Sociedad Chilena De Quimica, 1984
Molecules, Apr 10, 2017
In this study, we tested eight naturally-occurring flavonoids-three flavanones and five flavones-... more In this study, we tested eight naturally-occurring flavonoids-three flavanones and five flavones-for their possible antibacterial properties against four Gram-positive and four Gram-negative bacteria. Flavonoids are known for their antimicrobial properties, and due their structural diversity; these plant-derived compounds are a good model to study potential novel antibacterial mechanisms. The lipophilicity and the interaction of antibacterial compounds with the cell membrane define the success or failure to access its target. Therefore, through the determination of partition coefficients in a non-polar/aqueous phase, lipophilicity estimation and the quantification of the antibacterial activity of different flavonoids, flavanones, and flavones, a relationship between these parameters was assessed. Active flavonoids presented diffusion coefficients between 9.4 × 10 −10 and 12.3 × 10 −10 m 2 /s and lipophilicity range between 2.0 to 3.3. Active flavonoids against Gram-negative bacteria showed a narrower range of lipophilicity values, compared to active flavonoids against Gram-positive bacteria, which showed a wide range of lipophilicity and cell lysis. Galangin was the most active flavonoid, whose structural features are the presence of two hydroxyl groups located strategically on ring A and the absence of polar groups on ring B. Methylation of one hydroxyl group decreases the activity in 3-O-methylgalangin, and methylation of both hydroxyl groups caused inactivation, as shown for 3,7-O-dimethylgalangin. In conclusion, the amphipathic features of flavonoids play a crucial role in the antibacterial activity. In these compounds, hydrophilic and hydrophobic moieties must be present and could be predicted by lipophilicity analysis.
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
Hylurgus ligniperda is one of the most important quarantine forest insects associated to pine (Pi... more Hylurgus ligniperda is one of the most important quarantine forest insects associated to pine (Pinus radiate D. Don) logs exported from Chile. Methyl bromide fumigation has been the prominent control method. As the use of this synthetic insecticide leads to serious environmental problems, research to find alternative treatments is urgently needed for the Chilean forestry sector. Hence, plant secondary metabolites have been considered as an alternative for its control. Therefore, the objective of this work was to assess the feeding behavior of H. ligniperda through the artificial diet supplemented with organic fractions obtained from Cestrum parqui leaves. Organic extracts were obtained using a Soxhlet extraction. Non-choice tests were developed for testing the antifeedant activity shown by the organic fractions on adults, and 5th and 6th instar larvae of H. ligniperda. All the extracts tested elicited a decrease in the weight of unsexed H. ligniperda adults, and the effects were dose-dependent. Male beetle weight gain was reduced strongly by chloroform extracts and ethyl acetate elicited a weight increase of female and from the fifth and sixth instar larvae weight. Saponin extract elicited a reduction of the weight in male and female. Finally, the weight of both instar larvae was reduced by chloroform and saponin extract. C. parqui leaf extracts show a great potential for being used for controlling H. ligniperda and thus to diminish the use of harmful synthetic pesticide.
Ciencia e investigación agraria, 2019
M. Chacón-Fuentes, A. Mutis, L. Bardehle, I. Seguel, A. Urzúa, and A. Quiroz. 2019. Decrease of f... more M. Chacón-Fuentes, A. Mutis, L. Bardehle, I. Seguel, A. Urzúa, and A. Quiroz. 2019. Decrease of flavonol synthase enzymatic activity in Ugni molinae Turcz due to the domestication process. Cien. Inv. Agr. 46(1): 30-39. Flavonoid biosynthesis may be affected by plant domestication, with flavonoid production being reduced in proportion to the degree of domestication. In this context, kaempferol (3,4´,5,7-tetrahydroxyflavone) has been identified in the leaves of wild and cultivated Ugni molinae, a berry endemic to Chile. The biosynthetic pathway of kaempferol production begins with naringenin (4´,5,7-trihydroxyflavanone), which is converted to dihydrokaempferol (3,4´,5,7-tetrahydroxyflavanone), catalyzed by flavanone 3ß-hydroxylase (FHT) and then converted to kaempferol by a bifunctional enzyme called flavonol synthase (FLS). Therefore, our study aims to evaluate how FLS activity is affected in murtilla plants that are subjected to the domestication process. Kaempferol was quantified from methanolic extracts of leaf samples collected from both cultivated and wild U. molinae plants using high-performance liquid chromatography, and enzyme extraction was performed to determine FLS activity. The results showed that kaempferol concentration in wild plants from the Soloyo (0.14 μg g-1), Mehuín (0.18 μg g-1) and Queule (0.25 μg g-1) sampling areas was higher than in their cultivated counterparts. Our data are consistent with the FLS activity detected in samples obtained from Manzanal Alto (134.79 pKatal, Soloyo (96.48 pKatal), and Mehuín (119.97 pKatal). These samples also exhibited higher enzymatic activity than their cultivated counterparts. Together, these data suggest that FLS activity is negatively affected by the domestication process.
Frontiers in Microbiology, 2019
Sesquiterpenes as Potential NorA Pump Inhibitors assays, indicated that all combinations between ... more Sesquiterpenes as Potential NorA Pump Inhibitors assays, indicated that all combinations between DCME, epi-cubenol and 15-copaenol, and tested antibiotics showed a synergistic effect in wild type, norA ++ and norA strains. Moreover, those were not toxic for the HeLa cell line at concentrations in which the synergistic effect and inhibitory activity of efflux pumps was determined. Other extracts and compounds obtained from P. uviferum did not display EtBr efflux-inhibiting activity against the evaluated S. aureus strains.
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, ...
Molecules, 2016
The weevil Aegorhinus superciliosus Guérin (Coleoptera: Curculionidae), which is endemic to Centr... more The weevil Aegorhinus superciliosus Guérin (Coleoptera: Curculionidae), which is endemic to Central-Southern Chile and Argentina, is one of the major berry pests in Chile and the most important pest in the La Araucanía Region (38˝44 1 9"S, 72˝35 1 25"W). Due to the poor effectiveness and problems surrounding the implementation of the traditional control methods using organophosphate and carbamate insecticides, new strategies for controlling this pest are needed. In this communication, we evaluated the behavioral responses of male and female A. superciliosus to volatile compounds released from the essential oil (EO) obtained from the heartwood of Pilgerodendron uviferum (D. Don) Florin using olfactometric bioassays. The composition of the EO was analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). According to these analyses, δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the principal components of the EO. The Pilgerodendron uviferum EO, which is almost exclusively composed of sesquiterpenes (99.5%), exhibited a repellent effect against A. superciliosus adults, regardless of the sex or concentration used (56.6 mg/cm 3 and 1.58ˆ10´2 mg/cm 3). The EO has low volatility and greater persistence than the EOs composed of monoterpenes and is considered a good model in the search for raspberry weevil repellents.
Boletin De La Sociedad Chilena De Quimica, 1984
Molecules, 2016
Berberis microphylla is a native plant that grows in Patagonia and is commonly used by aboriginal... more Berberis microphylla is a native plant that grows in Patagonia and is commonly used by aboriginal ethnic groups in traditional medicine as an antiseptic for different diseases. The present study evaluated the antibacterial and synergistic activity of alkaloid extracts of B. microphylla leaves, stems and roots used either individually or in combination with antibiotics against Gram-positive and Gram-negative bacteria. The in vitro antibacterial activities of leaf, stem and root alkaloid extracts had significant activity only against Gram-positive bacteria. Disc diffusion tests demonstrated that the root extract showed similar activity against B. cereus and S. epidermidis compared to commercial antibiotics, namely ampicillin and cephalothin, and pure berberine, the principal component of the alkaloid extracts, was found to be active only against S. aureus and S. epidermidis with similar activity to that of the root extract. The minimum inhibitory concentrations (MICs) of the alkaloid extracts ranged from 333 to 83 µg/mL, whereas minimum bactericidal concentrations (MBCs) varied from 717 to 167 µg/mL. In addition, synergistic or indifferent effects between the alkaloid extracts and antibiotics against bacterial strains were confirmed.
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 ...
Contribuciones científicas y tecnológicas, 1970
RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de... more RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de Chile conocido por los nombre de pelú y pilo. pilo, que se asemeja mucho desde el punto de vista morfológico a las especies neozelandesas S. tetraptera J. Mill. Y S. microphylla Ait. Un estudio preliminar de los alcaloides de las semillas de esta planta chilena permitió aislar citisina, metilcitisina y matrina en proporciones que apoyan la separación taxonómica del pelú de las especies nativas de Nueva Zelandia. SUMMARY-Sophora tetraptera, sensu R,eiche, is the scientific name assigned to a southem Chilean tree known by the names pelú and pilopilo, which closely resembles the N ew Zealand species S. tetraptera J. Mill. and S. microphylla Ait. from a morphological viewpoint. A preliminalj' study of the seed alkaloids of this Chilean plant yielded cytisine, methylcytisine, and matrine in a ratio which supports the taxonomic segregation of the pelú from the species native to New Zealand.
Frontiers in Pharmacology, Nov 30, 2020
free catechol function is necessary for the enzyme inhibition. In addition, the fractions of phen... more free catechol function is necessary for the enzyme inhibition. In addition, the fractions of phenols and phenol-acid compounds showed inhibitory activity against 15-sLOX and the AE, showed a good inhibition against 5-hLOX. These results would be in agreement with the use of L. caustica, as an anti-inflammatory in Mapuche ethnomedicine.
Molecules, Jun 23, 2017
In the present study, the antibacterial activity of several ent-labdane derivatives of salvic aci... more In the present study, the antibacterial activity of several ent-labdane derivatives of salvic acid (7α-hydroxy-8(17)-ent-labden-15-oic acid) was evaluated in vitro against the Gram-negative bacterium Escherichia coli and the Gram-positive bacteria Staphylococcus aureus and Bacillus cereus. For all of the compounds, the antibacterial activity was expressed as the minimum inhibitory concentration (MIC) in liquid media and minimum inhibitory amount (MIA) in solid media. Structure activity relationships (SAR) were employed to correlate the effect of the calculated lipophilicity parameters (logP ow) on the inhibitory activity. Employing a phospholipidic bilayer (POPG) as a bacterial membrane model, ent-labdane-membrane interactions were simulated utilizing docking studies. The results indicate that (i) the presence of a carboxylic acid in the C-15 position, which acted as a hydrogen-bond donor (HBD), was essential for the antibacterial activity of the ent-labdanes; (ii) an increase in the length of the acylated chain at the C-7 position improved the antibacterial activity until an optimum length of five carbon atoms was reached; (iii) an increase in the length of the acylated chain by more than five carbon atoms resulted in a dramatic decrease in activity, which completely disappeared in acyl chains of more than nine carbon atoms; and (iv) the structural factors described above, including one HBD at C-15 and a hexanoyloxi moiety at C-7, had a good fit to a specific lipophilic range and antibacterial activity. The lipophilicity parameter has a predictive characteristic feature on the antibacterial activity of this class of compounds, to be considered in the design of new biologically active molecules.
Boletin De La Sociedad Chilena De Quimica, 1984
Molecules, Apr 10, 2017
In this study, we tested eight naturally-occurring flavonoids-three flavanones and five flavones-... more In this study, we tested eight naturally-occurring flavonoids-three flavanones and five flavones-for their possible antibacterial properties against four Gram-positive and four Gram-negative bacteria. Flavonoids are known for their antimicrobial properties, and due their structural diversity; these plant-derived compounds are a good model to study potential novel antibacterial mechanisms. The lipophilicity and the interaction of antibacterial compounds with the cell membrane define the success or failure to access its target. Therefore, through the determination of partition coefficients in a non-polar/aqueous phase, lipophilicity estimation and the quantification of the antibacterial activity of different flavonoids, flavanones, and flavones, a relationship between these parameters was assessed. Active flavonoids presented diffusion coefficients between 9.4 × 10 −10 and 12.3 × 10 −10 m 2 /s and lipophilicity range between 2.0 to 3.3. Active flavonoids against Gram-negative bacteria showed a narrower range of lipophilicity values, compared to active flavonoids against Gram-positive bacteria, which showed a wide range of lipophilicity and cell lysis. Galangin was the most active flavonoid, whose structural features are the presence of two hydroxyl groups located strategically on ring A and the absence of polar groups on ring B. Methylation of one hydroxyl group decreases the activity in 3-O-methylgalangin, and methylation of both hydroxyl groups caused inactivation, as shown for 3,7-O-dimethylgalangin. In conclusion, the amphipathic features of flavonoids play a crucial role in the antibacterial activity. In these compounds, hydrophilic and hydrophobic moieties must be present and could be predicted by lipophilicity analysis.
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
Hylurgus ligniperda is one of the most important quarantine forest insects associated to pine (Pi... more Hylurgus ligniperda is one of the most important quarantine forest insects associated to pine (Pinus radiate D. Don) logs exported from Chile. Methyl bromide fumigation has been the prominent control method. As the use of this synthetic insecticide leads to serious environmental problems, research to find alternative treatments is urgently needed for the Chilean forestry sector. Hence, plant secondary metabolites have been considered as an alternative for its control. Therefore, the objective of this work was to assess the feeding behavior of H. ligniperda through the artificial diet supplemented with organic fractions obtained from Cestrum parqui leaves. Organic extracts were obtained using a Soxhlet extraction. Non-choice tests were developed for testing the antifeedant activity shown by the organic fractions on adults, and 5th and 6th instar larvae of H. ligniperda. All the extracts tested elicited a decrease in the weight of unsexed H. ligniperda adults, and the effects were dose-dependent. Male beetle weight gain was reduced strongly by chloroform extracts and ethyl acetate elicited a weight increase of female and from the fifth and sixth instar larvae weight. Saponin extract elicited a reduction of the weight in male and female. Finally, the weight of both instar larvae was reduced by chloroform and saponin extract. C. parqui leaf extracts show a great potential for being used for controlling H. ligniperda and thus to diminish the use of harmful synthetic pesticide.
Ciencia e investigación agraria, 2019
M. Chacón-Fuentes, A. Mutis, L. Bardehle, I. Seguel, A. Urzúa, and A. Quiroz. 2019. Decrease of f... more M. Chacón-Fuentes, A. Mutis, L. Bardehle, I. Seguel, A. Urzúa, and A. Quiroz. 2019. Decrease of flavonol synthase enzymatic activity in Ugni molinae Turcz due to the domestication process. Cien. Inv. Agr. 46(1): 30-39. Flavonoid biosynthesis may be affected by plant domestication, with flavonoid production being reduced in proportion to the degree of domestication. In this context, kaempferol (3,4´,5,7-tetrahydroxyflavone) has been identified in the leaves of wild and cultivated Ugni molinae, a berry endemic to Chile. The biosynthetic pathway of kaempferol production begins with naringenin (4´,5,7-trihydroxyflavanone), which is converted to dihydrokaempferol (3,4´,5,7-tetrahydroxyflavanone), catalyzed by flavanone 3ß-hydroxylase (FHT) and then converted to kaempferol by a bifunctional enzyme called flavonol synthase (FLS). Therefore, our study aims to evaluate how FLS activity is affected in murtilla plants that are subjected to the domestication process. Kaempferol was quantified from methanolic extracts of leaf samples collected from both cultivated and wild U. molinae plants using high-performance liquid chromatography, and enzyme extraction was performed to determine FLS activity. The results showed that kaempferol concentration in wild plants from the Soloyo (0.14 μg g-1), Mehuín (0.18 μg g-1) and Queule (0.25 μg g-1) sampling areas was higher than in their cultivated counterparts. Our data are consistent with the FLS activity detected in samples obtained from Manzanal Alto (134.79 pKatal, Soloyo (96.48 pKatal), and Mehuín (119.97 pKatal). These samples also exhibited higher enzymatic activity than their cultivated counterparts. Together, these data suggest that FLS activity is negatively affected by the domestication process.
Frontiers in Microbiology, 2019
Sesquiterpenes as Potential NorA Pump Inhibitors assays, indicated that all combinations between ... more Sesquiterpenes as Potential NorA Pump Inhibitors assays, indicated that all combinations between DCME, epi-cubenol and 15-copaenol, and tested antibiotics showed a synergistic effect in wild type, norA ++ and norA strains. Moreover, those were not toxic for the HeLa cell line at concentrations in which the synergistic effect and inhibitory activity of efflux pumps was determined. Other extracts and compounds obtained from P. uviferum did not display EtBr efflux-inhibiting activity against the evaluated S. aureus strains.
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, ...
Molecules, 2016
The weevil Aegorhinus superciliosus Guérin (Coleoptera: Curculionidae), which is endemic to Centr... more The weevil Aegorhinus superciliosus Guérin (Coleoptera: Curculionidae), which is endemic to Central-Southern Chile and Argentina, is one of the major berry pests in Chile and the most important pest in the La Araucanía Region (38˝44 1 9"S, 72˝35 1 25"W). Due to the poor effectiveness and problems surrounding the implementation of the traditional control methods using organophosphate and carbamate insecticides, new strategies for controlling this pest are needed. In this communication, we evaluated the behavioral responses of male and female A. superciliosus to volatile compounds released from the essential oil (EO) obtained from the heartwood of Pilgerodendron uviferum (D. Don) Florin using olfactometric bioassays. The composition of the EO was analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). According to these analyses, δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the principal components of the EO. The Pilgerodendron uviferum EO, which is almost exclusively composed of sesquiterpenes (99.5%), exhibited a repellent effect against A. superciliosus adults, regardless of the sex or concentration used (56.6 mg/cm 3 and 1.58ˆ10´2 mg/cm 3). The EO has low volatility and greater persistence than the EOs composed of monoterpenes and is considered a good model in the search for raspberry weevil repellents.
Boletin De La Sociedad Chilena De Quimica, 1984
Molecules, 2016
Berberis microphylla is a native plant that grows in Patagonia and is commonly used by aboriginal... more Berberis microphylla is a native plant that grows in Patagonia and is commonly used by aboriginal ethnic groups in traditional medicine as an antiseptic for different diseases. The present study evaluated the antibacterial and synergistic activity of alkaloid extracts of B. microphylla leaves, stems and roots used either individually or in combination with antibiotics against Gram-positive and Gram-negative bacteria. The in vitro antibacterial activities of leaf, stem and root alkaloid extracts had significant activity only against Gram-positive bacteria. Disc diffusion tests demonstrated that the root extract showed similar activity against B. cereus and S. epidermidis compared to commercial antibiotics, namely ampicillin and cephalothin, and pure berberine, the principal component of the alkaloid extracts, was found to be active only against S. aureus and S. epidermidis with similar activity to that of the root extract. The minimum inhibitory concentrations (MICs) of the alkaloid extracts ranged from 333 to 83 µg/mL, whereas minimum bactericidal concentrations (MBCs) varied from 717 to 167 µg/mL. In addition, synergistic or indifferent effects between the alkaloid extracts and antibiotics against bacterial strains were confirmed.
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 ...