Silvana Santin - Academia.edu (original) (raw)

Papers by Silvana Santin

Planta Daninha, 2019

Allelopathy is the term used to define any process involving secondary metabolites produced by pl... more Allelopathy is the term used to define any process involving secondary metabolites produced by plants and microorganisms that influence growth and development of agrobiological systems. Currently, it is sought to find allelochemicals of interest and know how to apply them in bio-herbicides to combat weeds. In this study, the effects of the crude leaf extract and fractions of Machaerium hirtum (Vell.) Stellfeld were analyzed on Euphorbia heterophylla L. (wild poinsettia) and Ipomoea grandifolia (Dammer) O'Donell (morning glory), as well as the occurrence of morphoanatomical changes. For this, 0.04 g of the crude extract and fractions were solubilized and diluted (50 mL) to concentrations of 0.1, 0.2, 0.4, and 0.8 g L-1 (m/v). Initial growth tests were performed on Petri dishes containing two paper sheets and seedlings of weed species with the respective treatments, being maintained in a germination chamber for 48 hours at 25 o C. Distilled water was used as a control. Shoot and root length was assessed in the initial growth. The percentage of inhibition was calculated based on the values obtained in the initial growth bioassays. Morphologically altered wild poinsettia seedlings were fixed and sectioned transversely for anatomical analysis. The results indicated significant changes in length, being wild poinsettia seedlings more sensitive when compared to those of morning glory. Morphologically altered seedlings presented root necrosis as the most frequent symptom. Anatomically, parenchymatic cells of the hypocotyl and roots of wild poinsettia seedlings presented smaller and irregularly shaped cells when compared to the control, causing significant reductions in the measured parameters.

Brazilian Journal of Development, 2020

The crude extract and fractions of aerial parts from Psychotria cupularis, collected at Camacan (... more The crude extract and fractions of aerial parts from Psychotria cupularis, collected at Camacan (Brazil), were tested for anti-inflammatory and antiproliferative activity. A phytochemical screening indicated the presence of tannins, anthraquinones, triterpenes, steroids and flavonoids. The crude extract and fractions inhibited the ear oedema in mice between 50.2 to 87.2% and the myeloperoxidase enzyme activity between 51.6 to 97.1%. The butanolic and ethyl acetate fractions was active against glioma, breast, ovary, kidney, colon and leukaemia cell line (IG50 = 4.3 to 16.9 μg/mL).

Natural Product Research, Jun 23, 2017

The crude extract and fractions from the branches of Ixora brevifolia, a tree found in the Brazil... more The crude extract and fractions from the branches of Ixora brevifolia, a tree found in the Brazilian Cerrado, were tested for anti-inflammatory and in vitro antiproliferative effects. The crude extract and n-hexane fraction exhibited significant inhibition of ear oedema in mice, while n-hexane-precipitated and chloroform fractions strongly inhibited the myeloperoxidase activity in ear tissue. The n-hexane and n-hexaneprecipitated fractions showed strong growth inhibition for glioma cell line and the hydromethanolic fraction inhibited the growth of leukaemia cell line.

Natural Product Research, Sep 1, 2013

Journal of the Brazilian Chemical Society, 2019

Sol-gel synthesis is commonly used to modify the surface of mesoporous silica nanoparticles (MSN)... more Sol-gel synthesis is commonly used to modify the surface of mesoporous silica nanoparticles (MSN) with organic groups through the co-condensation method. The template removal, and the site-controlled addition of organic groups and their partial occlusion inside the framework walls are still a challenge in the one-pot synthesis. Here, we optimize the synthesis of amino-modified MSN by the combination of efficient template removal methodology with the precise time of the amino precursor addition to achieve superb mesoporous material. The addition after the growth process produces a sample with a significantly higher amount of NH 2 on the external surface when compared to the standard procedure. The template removal by reflux with isopropanol/H + eliminated ca. 90% of cetyltrimethylammonium bromide (CTAB), and preserved the mechanical and thermal properties, even with thin walls (2.1 nm). The synthesized nanoparticles possess stability, appropriate size, and a positive surface. This makes them excellent nanocarriers, especially in the biomedical field.

Química Nova, 2009

TERPENES ISOLATED OF Coussarea platyphylla Müll. Arg. (RUBIACEAE). The phytochemical investigatio... more TERPENES ISOLATED OF Coussarea platyphylla Müll. Arg. (RUBIACEAE). The phytochemical investigation of Coussarea platyphylla led to the isolation of triterpenes betulonic and betulinic acid, monoterpenes monotropein and monotropein salt, the diterpene trans-phytol and esteroids. The structures of the isolated compounds were assigned on the basis of spectroscopic data, including two-dimensional NMR methods. The antiproliferative properties against human cancer cell lines and molluscicidal activity against Biomphalaria glabrata of the crude methanolic extract and of its fractions were investigated.

Química Nova, 2004

Recebido em 25/2/03; aceito em 5/1/04; publicado na web em 27/05/04 POLAR CONSTITUENTS OF THE LEA... more Recebido em 25/2/03; aceito em 5/1/04; publicado na web em 27/05/04 POLAR CONSTITUENTS OF THE LEAVES OF Machaonia brasiliensis (RUBIACEAE). Chemical investigation of the MeOH extract of the leaves of Machaonia brasiliensis (Rubiaceae) resulted in the isolation and identification of 3β-O-β-glucopyranosyl stigmasterol, 3β-O-β-glucopyranosyl sitosterol, secologanoside, 7-O-β-glucopyranosyl quercetagetin, 4,5-O-dicaffeoylquinic acid and 5-O-caffeoylquinic acid. The structures of these compounds were established by spectroscopic analysis, including 2D NMR experiments. The chemotaxonomic relevance of the isolation of secologanoside is discussed.

Química Nova, 2008

Recebido em 21/11/07, aceito em 17/3/08, publicado na web em 23/4/08 CHEMICAL CONSTITUENTS OF THE... more Recebido em 21/11/07, aceito em 17/3/08, publicado na web em 23/4/08 CHEMICAL CONSTITUENTS OF THE ROOTS OF Guettarda pohliana Müll. Arg. (RUBIACEAE). The phytochemical investigation of Guettarda pohliana roots led to the isolation of 28-O-β-D-glycopyranosyl-3-O-β-D-quinovopyranosyl quinovic acid, 28-O-β-D-glycopyranosyl-3-O-β-D-glycopyranosyl quinovic acid, 3-O-β-D-glycopyranosyl quinovic acid, 28-O-β-Dglycopyranosyl-3-O-β-D-glycopyranosyl cincholic acid along with quinovic acid, daucosterol and 4,5-O-dicaffeoyl quinic acid. The structures of the isolated compounds were assigned on the basis of spectroscopic data, including two-dimensional NMR methods. The antiradical activity of the crude methanolic extract and of its fractions was evaluated.

Biochemical Systematics and Ecology, 2012

Química Nova, 2018

A simple and low cost experiment is proposed to chemistry students associating the Photodynamic A... more A simple and low cost experiment is proposed to chemistry students associating the Photodynamic Activity involving Chemical and Biochemical concepts. The inclusion of this experiment in undergraduate courses in Chemistry promotes interdisciplinarity and contextualization, combining current and relevant topics to the teaching of program content. The experiment used the Methylene Blue and Erythrosine B as dyes to demonstrate the photodynamic action of these photosensitizers in the inhibition of microbial growth. Both dyes presented satisfactory results against environmental microorganisms. The growth inhibition was caused exclusively by the photochemical processes undergone by the dye/light/oxygen, with LED light exposure.

Chemical Engineering Transactions, 2018

The acyl-homoserine lactones (AHL) are compounds used in intercellular chemical signaling process... more The acyl-homoserine lactones (AHL) are compounds used in intercellular chemical signaling processes by Gram-negative bacteria in a phenomenon known as quorum-sensing. This process makes the microorganisms able to sense and respond to stimuli of individuals of the same species, or even cause physiological changes in the surrounding bacterial populations. In recent years, there is a growing interest in the effect that these compounds might have on higher organisms, such as inter-kingdoms communication mechanisms or physiological and morphological changes in host. In this regard, the study of the effects of these metabolites in plants has gained particular attention. Recently, it was shown that N-(3-oxo-octanoyl)-HL is present in the extract obtained from the leaves and stalks of sugarcane cultivated in Brazil, and that this compound can stimulate the growth of roots and shoots of the plant at low concentrations. Interestingly, it was found that both enantiomers (R) and (S) can acceler...

The phytochemical study of <i>Laelia marginata</i> (Lindl.) L. O. Williams (Orchidace... more The phytochemical study of <i>Laelia marginata</i> (Lindl.) L. O. Williams (Orchidaceae) led to the isolation of a new natural product named crispoic acid <b>(1)</b>, together with six other known compounds (<b>2</b>–<b>7</b>). The new natural product was identified as a dimer of eucomic acid and was structurally characterised based upon 1D and 2D NMR and HRMS data. Biological assays with plant crude extract, fractions and isolated compounds were performed against two human cancer cell lines (Hela and Siha), and the tropical parasites <i>Trypanosoma cruzi</i> and <i>Leishmania (Leishmania) amazonensis</i>. The phenantrenoid 9,10-dihydro-4-methoxyphenanthren-2,7-diol <b>2</b> was active against Hela and Siha cells (CC₅₀ 5.86 ± 0.19 and 20.78 ± 2.72 μg/mL, respectively). Sub-lethal concentrations of the flavone rhamnazin <b>4</b> were not able to rescue the viability ...

The crude extract and fractions from the branches of <i>Ixora brevifolia</i>, a tree ... more The crude extract and fractions from the branches of <i>Ixora brevifolia</i>, a tree found in the Brazilian Cerrado, were tested for anti-inflammatory and <i>in vitro</i> antiproliferative effects. The crude extract and <i>n</i>-hexane fraction exhibited significant inhibition of ear oedema in mice, while <i>n</i>-hexane-precipitated and chloroform fractions strongly inhibited the myeloperoxidase activity in ear tissue. The <i>n</i>-hexane and <i>n</i>-hexane-precipitated fractions showed strong growth inhibition for glioma cell line and the hydromethanolic fraction inhibited the growth of leukaemia cell line.

Biochemical Systematics and Ecology, 2020

Abstract Phytochemical study of Machaerium brasiliense leaves extract afforded three hopane trite... more Abstract Phytochemical study of Machaerium brasiliense leaves extract afforded three hopane triterpenes 3,4-seco-21β-H-hop-22 (29)-en-3-oic acid (1), hopenone B (2), hopene B (3). In addition, lupeol (4), stigmasterol (5), β-sitosterol (6), daucosterol (7), uracil (8), allantoin (9) and trans-4-hydroxy-N-methylproline (10) were isolated. The structures of these compounds were established based on spectroscopic data in comparison to those described in literature. Considering the chemotaxonomic relevance of the isolated compounds, this is the first report of triterpenes 1, 2 and 3 in Fabaceae family and compounds 7, 8 and 9 in the genus Machaerium. Besides, preliminary screening on antiproliferative and antioxidant activities was performed for MBEB and its fractions.

Natural Product Research, 2019

Journal of Chemical Ecology, 2020

It is known that plant and associated bacteria coevolved, but just now the roles of chemical sign... more It is known that plant and associated bacteria coevolved, but just now the roles of chemical signaling compounds in these intricate relationships have been systematically studied. Many Gram-negative bacteria produce N-acyl-L-homoserine lactones (AHL), chemical signals used in quorum-sensing bacterial communications mechanisms. In recent years, it has been shown that these compounds may also influence the development of plants, acting as allelochemicals, in still not well understood eukaryot-prokaryot interactions. In the present work, a quorum-sensing molecule produced by the tomato associated bacterium Pseudomonas sp. was characterized and its effects on germination and growth of tomato seedlings were accessed. The chemical study of the bacterium extract led to the identification of N-3-oxo-dodecanoyl-L-homoserine lactone (1), using gas chromatography coupled to electron impact mass spectrometry (GC-MS), and ultra-high resolution Qq-time-of-flight mass spectrometry (UHR-QqTOF-MS) equipped with an electrospray ionization source (ESI). The synthetic compound was tested at different concentrations in tomato to evaluate its effects on seed germination and seedlings root growth. Inhibition of tomato seed germination and root growth were observed in the presence of micromolar concentrations of the compound 1. Scanning electron microscopy evidenced morphological alterations on roots in the presence of the compound, with reduction of growth, impaired root hairs development and cracks in the rhizodermis.

Biochemical Systematics and Ecology, 2020

Orchidaceae are one of the largest families of flowering plants. In this work, the first phytoche... more Orchidaceae are one of the largest families of flowering plants. In this work, the first phytochemical study of the non-flowering parts of the South American species Stanhopea lietzei (Regel) Schltr. is reported. It led to the isolation of nine compounds, including the rare dimeric compound 2,2′,7,7′-tetramethoxy-4,4′,6,6′-tetrahydroxy-(1,1′)-biphenanthrene (1). This compound was tested for the first time against HeLa human cancer cells, with IC 50 16.9 ± 0.9 μg/mL. Biological assays against neotropical parasites, virus and other human cancer cell lines are also reported. Finally, the relevance of biphenanthrenes, flavonoids, and C-glycosylated phenolic compounds for chemophenetics relationships within neotropical species of the Cymbidieae tribe and Oncidiinae, Maxillariinae, Cyrtopodiinae and Stanhopeinae subtribes was also discussed.

Journal of the Brazilian Chemical Society, 2020

A new bis-iridoid glucoside minutifloroside (1) was isolated from Palicourea minutiflora, togethe... more A new bis-iridoid glucoside minutifloroside (1) was isolated from Palicourea minutiflora, together with asperuloside, (−)-epicatechin, catechin, quercetin, rutin, ursolic acid, oleanolic acid, daucosterol and two monoterpenic indole alkaloids strictosidinic acid and vincosamine. Structural characterization of the compounds was established on their spectral data basis, mainly mass spectrometry (MS) and 1D and 2D nuclear magnetic resonance (NMR). The bis-iridoid showed high activity against Candida albicans strain and antioxidant activity.

Planta Daninha, 2019

Allelopathy is the term used to define any process involving secondary metabolites produced by pl... more Allelopathy is the term used to define any process involving secondary metabolites produced by plants and microorganisms that influence growth and development of agrobiological systems. Currently, it is sought to find allelochemicals of interest and know how to apply them in bio-herbicides to combat weeds. In this study, the effects of the crude leaf extract and fractions of Machaerium hirtum (Vell.) Stellfeld were analyzed on Euphorbia heterophylla L. (wild poinsettia) and Ipomoea grandifolia (Dammer) O'Donell (morning glory), as well as the occurrence of morphoanatomical changes. For this, 0.04 g of the crude extract and fractions were solubilized and diluted (50 mL) to concentrations of 0.1, 0.2, 0.4, and 0.8 g L-1 (m/v). Initial growth tests were performed on Petri dishes containing two paper sheets and seedlings of weed species with the respective treatments, being maintained in a germination chamber for 48 hours at 25 o C. Distilled water was used as a control. Shoot and root length was assessed in the initial growth. The percentage of inhibition was calculated based on the values obtained in the initial growth bioassays. Morphologically altered wild poinsettia seedlings were fixed and sectioned transversely for anatomical analysis. The results indicated significant changes in length, being wild poinsettia seedlings more sensitive when compared to those of morning glory. Morphologically altered seedlings presented root necrosis as the most frequent symptom. Anatomically, parenchymatic cells of the hypocotyl and roots of wild poinsettia seedlings presented smaller and irregularly shaped cells when compared to the control, causing significant reductions in the measured parameters.

Brazilian Journal of Development, 2020

The crude extract and fractions of aerial parts from Psychotria cupularis, collected at Camacan (... more The crude extract and fractions of aerial parts from Psychotria cupularis, collected at Camacan (Brazil), were tested for anti-inflammatory and antiproliferative activity. A phytochemical screening indicated the presence of tannins, anthraquinones, triterpenes, steroids and flavonoids. The crude extract and fractions inhibited the ear oedema in mice between 50.2 to 87.2% and the myeloperoxidase enzyme activity between 51.6 to 97.1%. The butanolic and ethyl acetate fractions was active against glioma, breast, ovary, kidney, colon and leukaemia cell line (IG50 = 4.3 to 16.9 μg/mL).

Natural Product Research, Jun 23, 2017

The crude extract and fractions from the branches of Ixora brevifolia, a tree found in the Brazil... more The crude extract and fractions from the branches of Ixora brevifolia, a tree found in the Brazilian Cerrado, were tested for anti-inflammatory and in vitro antiproliferative effects. The crude extract and n-hexane fraction exhibited significant inhibition of ear oedema in mice, while n-hexane-precipitated and chloroform fractions strongly inhibited the myeloperoxidase activity in ear tissue. The n-hexane and n-hexaneprecipitated fractions showed strong growth inhibition for glioma cell line and the hydromethanolic fraction inhibited the growth of leukaemia cell line.

Natural Product Research, Sep 1, 2013

Journal of the Brazilian Chemical Society, 2019

Sol-gel synthesis is commonly used to modify the surface of mesoporous silica nanoparticles (MSN)... more Sol-gel synthesis is commonly used to modify the surface of mesoporous silica nanoparticles (MSN) with organic groups through the co-condensation method. The template removal, and the site-controlled addition of organic groups and their partial occlusion inside the framework walls are still a challenge in the one-pot synthesis. Here, we optimize the synthesis of amino-modified MSN by the combination of efficient template removal methodology with the precise time of the amino precursor addition to achieve superb mesoporous material. The addition after the growth process produces a sample with a significantly higher amount of NH 2 on the external surface when compared to the standard procedure. The template removal by reflux with isopropanol/H + eliminated ca. 90% of cetyltrimethylammonium bromide (CTAB), and preserved the mechanical and thermal properties, even with thin walls (2.1 nm). The synthesized nanoparticles possess stability, appropriate size, and a positive surface. This makes them excellent nanocarriers, especially in the biomedical field.

Química Nova, 2009

TERPENES ISOLATED OF Coussarea platyphylla Müll. Arg. (RUBIACEAE). The phytochemical investigatio... more TERPENES ISOLATED OF Coussarea platyphylla Müll. Arg. (RUBIACEAE). The phytochemical investigation of Coussarea platyphylla led to the isolation of triterpenes betulonic and betulinic acid, monoterpenes monotropein and monotropein salt, the diterpene trans-phytol and esteroids. The structures of the isolated compounds were assigned on the basis of spectroscopic data, including two-dimensional NMR methods. The antiproliferative properties against human cancer cell lines and molluscicidal activity against Biomphalaria glabrata of the crude methanolic extract and of its fractions were investigated.

Química Nova, 2004

Recebido em 25/2/03; aceito em 5/1/04; publicado na web em 27/05/04 POLAR CONSTITUENTS OF THE LEA... more Recebido em 25/2/03; aceito em 5/1/04; publicado na web em 27/05/04 POLAR CONSTITUENTS OF THE LEAVES OF Machaonia brasiliensis (RUBIACEAE). Chemical investigation of the MeOH extract of the leaves of Machaonia brasiliensis (Rubiaceae) resulted in the isolation and identification of 3β-O-β-glucopyranosyl stigmasterol, 3β-O-β-glucopyranosyl sitosterol, secologanoside, 7-O-β-glucopyranosyl quercetagetin, 4,5-O-dicaffeoylquinic acid and 5-O-caffeoylquinic acid. The structures of these compounds were established by spectroscopic analysis, including 2D NMR experiments. The chemotaxonomic relevance of the isolation of secologanoside is discussed.

Química Nova, 2008

Recebido em 21/11/07, aceito em 17/3/08, publicado na web em 23/4/08 CHEMICAL CONSTITUENTS OF THE... more Recebido em 21/11/07, aceito em 17/3/08, publicado na web em 23/4/08 CHEMICAL CONSTITUENTS OF THE ROOTS OF Guettarda pohliana Müll. Arg. (RUBIACEAE). The phytochemical investigation of Guettarda pohliana roots led to the isolation of 28-O-β-D-glycopyranosyl-3-O-β-D-quinovopyranosyl quinovic acid, 28-O-β-D-glycopyranosyl-3-O-β-D-glycopyranosyl quinovic acid, 3-O-β-D-glycopyranosyl quinovic acid, 28-O-β-Dglycopyranosyl-3-O-β-D-glycopyranosyl cincholic acid along with quinovic acid, daucosterol and 4,5-O-dicaffeoyl quinic acid. The structures of the isolated compounds were assigned on the basis of spectroscopic data, including two-dimensional NMR methods. The antiradical activity of the crude methanolic extract and of its fractions was evaluated.

Biochemical Systematics and Ecology, 2012

Química Nova, 2018

A simple and low cost experiment is proposed to chemistry students associating the Photodynamic A... more A simple and low cost experiment is proposed to chemistry students associating the Photodynamic Activity involving Chemical and Biochemical concepts. The inclusion of this experiment in undergraduate courses in Chemistry promotes interdisciplinarity and contextualization, combining current and relevant topics to the teaching of program content. The experiment used the Methylene Blue and Erythrosine B as dyes to demonstrate the photodynamic action of these photosensitizers in the inhibition of microbial growth. Both dyes presented satisfactory results against environmental microorganisms. The growth inhibition was caused exclusively by the photochemical processes undergone by the dye/light/oxygen, with LED light exposure.

Chemical Engineering Transactions, 2018

The acyl-homoserine lactones (AHL) are compounds used in intercellular chemical signaling process... more The acyl-homoserine lactones (AHL) are compounds used in intercellular chemical signaling processes by Gram-negative bacteria in a phenomenon known as quorum-sensing. This process makes the microorganisms able to sense and respond to stimuli of individuals of the same species, or even cause physiological changes in the surrounding bacterial populations. In recent years, there is a growing interest in the effect that these compounds might have on higher organisms, such as inter-kingdoms communication mechanisms or physiological and morphological changes in host. In this regard, the study of the effects of these metabolites in plants has gained particular attention. Recently, it was shown that N-(3-oxo-octanoyl)-HL is present in the extract obtained from the leaves and stalks of sugarcane cultivated in Brazil, and that this compound can stimulate the growth of roots and shoots of the plant at low concentrations. Interestingly, it was found that both enantiomers (R) and (S) can acceler...

The phytochemical study of <i>Laelia marginata</i> (Lindl.) L. O. Williams (Orchidace... more The phytochemical study of <i>Laelia marginata</i> (Lindl.) L. O. Williams (Orchidaceae) led to the isolation of a new natural product named crispoic acid <b>(1)</b>, together with six other known compounds (<b>2</b>–<b>7</b>). The new natural product was identified as a dimer of eucomic acid and was structurally characterised based upon 1D and 2D NMR and HRMS data. Biological assays with plant crude extract, fractions and isolated compounds were performed against two human cancer cell lines (Hela and Siha), and the tropical parasites <i>Trypanosoma cruzi</i> and <i>Leishmania (Leishmania) amazonensis</i>. The phenantrenoid 9,10-dihydro-4-methoxyphenanthren-2,7-diol <b>2</b> was active against Hela and Siha cells (CC₅₀ 5.86 ± 0.19 and 20.78 ± 2.72 μg/mL, respectively). Sub-lethal concentrations of the flavone rhamnazin <b>4</b> were not able to rescue the viability ...

The crude extract and fractions from the branches of <i>Ixora brevifolia</i>, a tree ... more The crude extract and fractions from the branches of <i>Ixora brevifolia</i>, a tree found in the Brazilian Cerrado, were tested for anti-inflammatory and <i>in vitro</i> antiproliferative effects. The crude extract and <i>n</i>-hexane fraction exhibited significant inhibition of ear oedema in mice, while <i>n</i>-hexane-precipitated and chloroform fractions strongly inhibited the myeloperoxidase activity in ear tissue. The <i>n</i>-hexane and <i>n</i>-hexane-precipitated fractions showed strong growth inhibition for glioma cell line and the hydromethanolic fraction inhibited the growth of leukaemia cell line.

Biochemical Systematics and Ecology, 2020

Abstract Phytochemical study of Machaerium brasiliense leaves extract afforded three hopane trite... more Abstract Phytochemical study of Machaerium brasiliense leaves extract afforded three hopane triterpenes 3,4-seco-21β-H-hop-22 (29)-en-3-oic acid (1), hopenone B (2), hopene B (3). In addition, lupeol (4), stigmasterol (5), β-sitosterol (6), daucosterol (7), uracil (8), allantoin (9) and trans-4-hydroxy-N-methylproline (10) were isolated. The structures of these compounds were established based on spectroscopic data in comparison to those described in literature. Considering the chemotaxonomic relevance of the isolated compounds, this is the first report of triterpenes 1, 2 and 3 in Fabaceae family and compounds 7, 8 and 9 in the genus Machaerium. Besides, preliminary screening on antiproliferative and antioxidant activities was performed for MBEB and its fractions.

Natural Product Research, 2019

Journal of Chemical Ecology, 2020

It is known that plant and associated bacteria coevolved, but just now the roles of chemical sign... more It is known that plant and associated bacteria coevolved, but just now the roles of chemical signaling compounds in these intricate relationships have been systematically studied. Many Gram-negative bacteria produce N-acyl-L-homoserine lactones (AHL), chemical signals used in quorum-sensing bacterial communications mechanisms. In recent years, it has been shown that these compounds may also influence the development of plants, acting as allelochemicals, in still not well understood eukaryot-prokaryot interactions. In the present work, a quorum-sensing molecule produced by the tomato associated bacterium Pseudomonas sp. was characterized and its effects on germination and growth of tomato seedlings were accessed. The chemical study of the bacterium extract led to the identification of N-3-oxo-dodecanoyl-L-homoserine lactone (1), using gas chromatography coupled to electron impact mass spectrometry (GC-MS), and ultra-high resolution Qq-time-of-flight mass spectrometry (UHR-QqTOF-MS) equipped with an electrospray ionization source (ESI). The synthetic compound was tested at different concentrations in tomato to evaluate its effects on seed germination and seedlings root growth. Inhibition of tomato seed germination and root growth were observed in the presence of micromolar concentrations of the compound 1. Scanning electron microscopy evidenced morphological alterations on roots in the presence of the compound, with reduction of growth, impaired root hairs development and cracks in the rhizodermis.

Biochemical Systematics and Ecology, 2020

Orchidaceae are one of the largest families of flowering plants. In this work, the first phytoche... more Orchidaceae are one of the largest families of flowering plants. In this work, the first phytochemical study of the non-flowering parts of the South American species Stanhopea lietzei (Regel) Schltr. is reported. It led to the isolation of nine compounds, including the rare dimeric compound 2,2′,7,7′-tetramethoxy-4,4′,6,6′-tetrahydroxy-(1,1′)-biphenanthrene (1). This compound was tested for the first time against HeLa human cancer cells, with IC 50 16.9 ± 0.9 μg/mL. Biological assays against neotropical parasites, virus and other human cancer cell lines are also reported. Finally, the relevance of biphenanthrenes, flavonoids, and C-glycosylated phenolic compounds for chemophenetics relationships within neotropical species of the Cymbidieae tribe and Oncidiinae, Maxillariinae, Cyrtopodiinae and Stanhopeinae subtribes was also discussed.

Journal of the Brazilian Chemical Society, 2020

A new bis-iridoid glucoside minutifloroside (1) was isolated from Palicourea minutiflora, togethe... more A new bis-iridoid glucoside minutifloroside (1) was isolated from Palicourea minutiflora, together with asperuloside, (−)-epicatechin, catechin, quercetin, rutin, ursolic acid, oleanolic acid, daucosterol and two monoterpenic indole alkaloids strictosidinic acid and vincosamine. Structural characterization of the compounds was established on their spectral data basis, mainly mass spectrometry (MS) and 1D and 2D nuclear magnetic resonance (NMR). The bis-iridoid showed high activity against Candida albicans strain and antioxidant activity.