Efecto citotóxico de diterpenos derivados del ácido ent-kaureno aislados de Coespeletia moritziana (Sch. Bip. ex Wedd.) Cuatrec / Cytotoxic effect of ent-kaurene acid-derived diterpenes isolated from Coespeletia moritziana (Sch. Bip. Ex Wedd.) Cuatrec

The objective of the work was to study the cytotoxic effect of ent-kaurene acid derivatives obtained from Coespeletia moritziana (Sch. Bip. Ex Wedd.) Cuatrec., After analysis by GC/MS, IR and NMR. Isolating: kaurenic acid (I), grandifloric acid (II), 15-α-hydroxy kaurenic acid (III), 15 α-acetoxy-kaur 16-en-19-oic acid (IV), Kaurenol (V); and by hemisynthesis: 15,16-epoxy-17-acetoxy-kauran 19-oic acid (VI), 15-oxo-ent-kaur-16-en-19-oic acid (VIII), ester 2,3,4,6 -15-oxo-kaur-16-en-19-oic acid acetyl α-D-pyranosyl tetra-tetra (VII). Cytotoxicity was tested in human cancer cell lines: uterus (HeLa), lung (A-549), breast (MCF-7), African green monkey kidney non-tumor line (Vero) and human peripheral blood mononuclear cells (CMPS). Compound (I) was active against HeLa, A-549 and Vero. Compounds (II and VIII) showed moderate and good (IC50 ≤ 9 µM) cytotoxicity, respectively, against the five cell lines. Compound (V) showed moderate activity against A-549 and compound (VII), slight cytotoxicity against HeLa and A-549. Results that show the cytotoxic specificity of the isolated kaurenes and derivatives of Coespeletia moritzianaand their therapeutic potential.

El objetivo del trabajo fue estudiar el efecto citotóxico de derivados del ácido ent-kaureno obtenidos de Coespeletia moritziana (Sch. Bip. ex Wedd.) Cuatrec., previo análisis mediante GC/MS, IR y RMN. Aislandose: ácido kaurénico(I), ácido grandiflorénico (II), ácido 15-α-hidroxi kaurénico(III), ácido 15 α-acetoxi-kaur 16-en-19-oico (IV), Kaurenol (V); y por hemisíntesis: ácido 15,16-epoxi-17-acetoxi-kauran 19-oico (VI), ácido15-oxo-ent-kaur-16-en-19-oico (VIII), éster 2,3,4,6-tetra acetil α-D-piranosilo del ácido 15-oxo-kaur-16-en-19-oico (VII). La citotóxicidad fue ensayada en líneas celulares cancerosas humanas: útero (HeLa), pulmón(A-549), mama (MCF-7), línea no tumoral de riñón de mono verde africano (Vero) y células mononucleares humanas de sangre periférica (CMPS). El compuesto (I) resultó activo frente a HeLa, A-549 y Vero. Los compuestos (II y VIII), mostraron moderada y buena (IC50≤9µM) citotoxicidad respectivamente, frente a las cinco líneas celulares. El compuesto (V) presentó moderada actividad frente a A-549 y el (VII), leve citotoxicidad frente a HeLa y A-549. Resultados que evidencian la especificidad citotóxica de los kaurenos aislados y derivados de Coespeletia moritzianay su potencial terapéutico.

Caracterización química y actividad antimicrobiana del aceite esencial de las hojas de Libanothamnus neriifolius (Asteraceae) / Chemical characterization and antimicrobial activity of the essential oil of the leaves of Libanothamnus neriifolius (Asteraceae)

El aceite esencial de las hojas frescas de Libanothamnus neriifolius (B. ex H) Ernst., fue obtenido por el método de hidrodestilación utilizando la trampa de Clevenger, obteniendo 1.8 mL (rendimiento 0.087%). El aceite esencial se caracterizó por el método de cromatografía de gases acoplado a espectrometría de masas (CG-EM), identificando como compuestos principales β-felandreno (29.04%), α-felandreno (19.86%), α-pineno (13.57%) y α-tujeno (12.35%). La actividad antimicrobiana se determinó por el método de difusión en agar con discos, frente a bacterias y levaduras de referencia internacional (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 23357, Pseudomonas aureginosa ATCC 27853, Candida albicans CDC-B385, Candida krusei ATCC 6258). El aceite esencial inhibió el desarrollo de S. aureus, C. albicans y C. Krusei, con un valor de Concentración Inhibitoria Mínima (CIM) de 50 μL/mL, 700 μL/mL y 500 μL/mL, respectivamente. Este es el primer reporte sobre actividad antimicrobiana para L. neriifolius y para el género Libanothamnus.

The essential oil of the fresh leaves of Libanothamnus neriifolius (B. ex H) Ernst. was obtained by the hydrodistillation method using the Clevenger trap, obtaining 1.8 mL (0.087% yield). The essential oil was characterized by the method of gas chromatography coupled to mass spectrometry (GC/MS), identifying as main compounds, that β-phelandrene (29.0%), α-phelandrene (19.9%), α-pinene (13.6%), and α-tujene (12.4%) were the most abundant constituents. Antimicrobial activity of the oil was tested Staphylococcus aureus ATCC25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 23357, Pseudomonas aureginosa ATCC 27853, Candida albicans CDC-B385, Candida krusei ATCC 6258 by the agar difusion method. It showed activity against S. aureus with MIC of 50 μL/mL. With respect to antifungic activity it was active against C. albicans and C. krusei with MIC of 700 μL/mL and 500 μL/mL respectively. This is the first report on the antimicrobial activity of this L. neriifolius and for the genere Libanothamnus.

Antimalarial Activity of some Kaurenes.

The antirnalarial activity of sixteen ent-kaurenes was assayed on male albino mice infected with Plasmodium berghei. Ent-kaur-16-en-19-oic acid (kaurenic acid), l5iα-hydroxy- ent-kaur-16-en-19-oic acid, 15α-acetoxy- ent-kaur-16-en-19-oic acid, and ent-kaur-9(11)16-en-19-oic acid, natural kaurenes isolated from two species of Espelletiinae, were modified by semisynthesis to obtain methyl esters, glucopyranosyl esters, epoxides, 17-hydroxy, and isokaurenes (compounds with a 15,16-double bond). The kaurenes were first submitted to an in vitro test to measure their capacity to inhibit the formation of ß-hematin. Compared with chloroquine (95.7%), the best effect was shown by 16,17-epoxy-ent-kauran-19-oic acid α-D- glucopyranosyl ester (2a), which produced 92.6% inhibition. Three other kaurenes showed good inhibition levels: ent-kaur- 16-en-I 9-oic acid (1a, 73.5%), 17-hydroxy- ent-kaur- I5-en-19-oic acid methyl ester (3b, 76.5%), and 15-oxo-16,17-epoxy-ent-kaur-16-en-19-oic acid (X-D-glucopyranosyl ester (4b,76.1%). These four compounds were assayed in a four day suppressive test in vivo (Peters' test) using chloroquine as a positive control. Two hours after infection the mice received the first treatment and then every 24 hours during four consecutive days. Blood smears from the tails were prepared on the fourth day and parasitemia was determined microscopically. Survivals were followed up to the 30th day post-infection, Once again compound 2a performed best, showing 4.5% of parasitemia on the fourth day post-infection (chloroquine 0.2%) and a survival time of 25.5 days (chloroquine 29.5 days; la 18.8 days, 4b 12.7 days and 3b 10.3 days). A comparative examination of the effect of all compounds on the in vitro test permitted the inference that the presence of a C- 19 carboxylic moiety was a requirement for the antimalarial activity and that a 16,17 epoxy group enhanced such activity.

On the Allylic Oxidation of Ent-kaurenic Acid Methyl Ester with Lead Tetra-acetate.

In this paper, results obtained upon treatment of the methyl ester of ent-kaur-16-en-19-oic acid (1b) with lead tetra-acetate under reflux in glacial acetic acid solution and an argon atmosphere are described. After 30 minutes reflux, GC-MS analysis of the product indicated the presence of three substances, the initial compound (1b, 7 %), the methyl ester of ent-kaur-16-en-15-O-acetyl-19-oic acid (2a, C23H3004, 45 %), and its isomer, the methyl ester of ent-kaur-15-en-17- 0-acetyl-19-oic acid (3a, 47 %). Flash chromatography over silica gel containing 20% AgNO3 yielded 2b (456 mg), which was identified by direct comparison with an authentic sample, and 3a (472 mg), whose structure was established by uni- and bi-dimensional NMR analysis. Hydrolysis of 3a with dry ammonia in MeOH yielded the methyl ester of ent-kaur-15-en-17-hydroxy-19-oic acid (3b, C21H32 03); treatment of this compound with chromic acid/pyridine complex rendered the aldehyde (4).

Evaluación fitoquímica preliminar y actividad hipoglicemiante aguda del extracto acuoso de la raíz de Ruellia tuberosa L. en ratas con diabetes experimental / Preliminary phytochemical screening and acute hypoglycemic effects of the aqueous extract of Ruellia tuberosa L. root in experimental diabetes in rats

La diabetes es uno de los principales problemas de la salud pública mundial. En Venezuela se utilizan varias plantas para el tratamiento de la diabetes, sin embargo, los estudios farmacológicos de estas especies han sido insuficientes. Ruellia tuberosa L. (Acanthaceae) es una de estas plantas de uso en la medicina tradicional. En los últimos años, he mos estudiado la farmacología del extracto acuoso de la raíz de la R. tuberosa (RT) demostrando su actividad an ti - inflamatoria, antioxidante y protectora frente al daño renal inducido por la diabetes. El tratamiento subcrónico con este extracto fue capaz de inhibir el aumento de la glucosa sanguínea en ratas con diabetes inducida por la es - treptozotocina (ETZ). En este trabajo se evaluó el perfil fitoquímico preliminar y el contenido de polifenoles totales del extracto de RT, así como también sus efectos agudos sobre la glicemia en ratas diabéticas. Los resultados muestran que el RT produjo un efecto hipoglicemiante tanto en los animales controles como en las ratas con diabetes inducida por la ETZ, con porcentajes de variación de la glicemia comparables con el hipoglicemiante oral de referencia, la glibenclamida. Este extracto mostró la presencia de un alto contenido de polifenoles, lo que posiblemente se encuentre asociado con su actividad antidiabética y antioxidante, reflejada a través de la reacción del RT con el radical 2,2- difenil-1-picrilhidrazil (DPPH). Todos estos hallazgos contribuyen con la validación del RT como un extracto antidiabético, el cual involucran la disminución de la glicemia y el decremento del estrés oxidativo. Asimismo, sienta las bases para el aislamiento y caracterización de los componentes responsables de su actividad farmacológica.

Essential Oil Composition and Antibacterial Activity of Hyptis colombiana from the Venezuelan Andes.

Hyptis colombiana is an aromatic shrub native to the Colombian and Venezuelan Andes. Aerial parts were collected in Mérida State at about 3100 m above sea level in February 2005, and May and October 2006. The essential oil was found to contain germacrene D and ß-caryophyllene as main constituents (about 50%). The February 2005 and October 2006 oils were found to have antibacterial activity against Staphylococcus aureus, but not the May 2006 oil, probably due to the lack of some minor constituent.

Chemical composition of the essential oil of Gynoxys meridana from Mérida, Venezuela.

The volatile components from the fresh leaves of Gynoxys meridana Cuatrec. were obtained by hydrodistillation and analyzed by GC/MS. A total of 25 compounds, representing 99.3% of the oil, were identified. The dominant compounds were γ-curcumene (31.9%), fukinanolide (22.3%), ß-pinene (9.5%), α-phellandrene (7.1%) and α-pinene (5.7%).

Chemical composition and antibacterial activity of the essential oil of Ruilopezia bracteosa.

The essential oil from the leaves ofRuilopezia bracteosa was obtained by hydrodistillation, and analyzed by GC-MS. Eighteen components, which made up 99.6% of the oil were identified, the most abundant being ß-myrcene (34.2%), α-pinene (24.3%), 7-epi-α-selinene (9.1%), ß-pinene (8.5%) and 6,9-guaiadiene (4.4%). Antibacterial activity was tested against Gram-positive and Gram-negative bacteria using broth microdilution and disk agar diffusion methods. MIC values found presented significant differences between both methods, which may be due to diffusion factors.

Volatile Constituents from the Flowers of Spathodea campanulata from the Venezuelan Andes.

The chemical composition is reported of the essential oil obtained by hydrodistillation of Spathodea campanulata P. Beauv. (Bignoniaceae) flowers collected in the Andes region of Venezuela. Thirty compounds were characterized, representing 96.5% of the total oil composition; benzyl benzoate (17.5%) was the major constituent. Others major components were a mixture of geranyl acetone with a-humulene (12.7%), ß-caryophyllene (9.5%), farnesyl acetone (6.0%), aromadendrene (4.3%), α-gurjunene (3.9%) and tricosane (3.7%). This is the first report related to the chemical composition of the essential oil of S. campanulata flowers.

Chemical composition of the essential oil of Erechtites valerianaefolia from Mérida, Venezuela.

The volatile components from the leaves of Erechtites valerianaefolia (Wolf) DC. were obtained by hydrodistillation and analyzed by GC/MS. A total of 12 compounds, representing 99.8% of the oil, were identified. The dominant compounds were limonene (56.7%), myrcene (12.7%), trans-beta-farnesene (10.2%) and l-phellandrene (8.7%).

Chemical composition of the essential oil from the leaves of Carapa guianensis collected from Venezuelan Guayana and the antimicrobial activity of the oil and crude extracts.

The essential oil obtained by hydrodistillation of Carapa guianensis Aubl. (Meliaceae) leaves was analyzed by GC-FID and GC-MS. Twenty-three components were identified, which made up 93.7% of the oil. The most abundant constituents were bicyclogermacrene (28.5%), alpha-humulene (17.2%), germacrene B (11.9%), and trans-beta-caryophyllene (9.9%). Antimicrobial activity of the essential oil, as well as the crude extracts of the leaves obtained by refluxing the dried leaves with n-hexane, dichloromethane, and methanol, was determined using the disc diffusion assay. Activity against Staphylococcus aureus ATCC 29923 and Enterococcus faecalis ATCC 29212 was only found for the essential oil and the methanolic extract, at minimal inhibitory concentrations (MIC) of 400 microg/mL and 50 microg/mL.

Steroidal saponins from the fruits of Solanum torvum.

Seven steroidal glycosides have been isolated from the fruits of Solanum torvum Swartz. Their structures were established by 2D NMR spectroscopic techniques ((1)H,(1)H-COSY, TOCSY, NOESY, HSQC, and HMBC) and mass spectrometry as (25S)-26-(ß-D-glucopyranosyloxy)-3-oxo-5α-furost-20(22)-en-6α-yl-O-ß-D-xylopyranoside (1), (25S)-26-(ß-D-glucopyranosyloxy)-3-oxo-22α-methoxy-5α-furostan-6α-yl-O-ß-D-xylopyranoside (2), (25S)-26-(ß-D-glucopyranosyloxy)-3ß-hydroxy-22α-methoxy-5α-furostan-6α-yl-O-α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside (3), (25S)-3ß-hydroxy-5α-spirostan-6α-yl-O-ß-D-xylopyranoside (4), (25S)-3-oxo-5α-spirostan-6α-yl-O-ß-D-xylopyranoside (5), (25S)-3ß-hydroxy-5α-spirostan-6α-yl-O-ß-D-glucopyranoside (6), (25S)-3ß,27-dihydroxy-5α-spirostan-6α-yl-O-ß-D-glucopyranoside (7).

Effect of some ent-kaurenes on the viability of human peripheral blood mononuclear cells.

The possible cytotoxic activity of some ent-kaurenes on human mononuclear cells, obtained from peripheral blood, was studied having in mind future studies on their antitumor activity. The cells were obtained using the Ficoll-Hypaque method, adjusted to 2 x 10(6) cells/mL, and incubated with kaurenes for 48 hours at 3 x 10(-5), 30 x 10(-5), 300 x 10(-1) and 3000 x 10(-5) micromol/well. Ent-kaurenic acid showed no toxicity at all concentrations studied. The least toxic of all the kaurene derivatives studied was ent-15,16-epoxy-17-acetoxy-(-)-kauran-19-oic acid, with a cellular viability of 99% at 3 x l0(-5) micromol/well, and 94% at 30 x 10(-1) micromol/well. Another compound that showed low toxicity was the 2,3,4,6-tetra-acetyl-alpha-D-pyranosyl ester of ent-15-oxo-(-)-kaur-16-en-19-oic acid with 44% viability at 3000 x 10(-5) micromol/well. The most toxic compounds at all concentrations tested were ent-kaur-16-en-19-ol acetate and ent-16alpha-hydroxy-(-)-kauran-19-oic acid. On the other hand, ent-kaur-9(11)16-dien-19-oic acid, ent-kauran-19-oic acid, and ent-kaur-16-en-19-ol were toxic only at the highest concentration studied. According to these results, and considering the concentrations employed, ent-kaur-16-en-19-oic acid and ent-15,16-epoxy-17-acetoxy-(-)-kauran-19-oic acid could be used for in vivo experiments and possibly for therapeutic purposes on humans, without much risk.

Chemical composition and antibacterial activity of the essential oil of Espeletia nana.

The essential oil of the leaves of Espeletia nana Cuatrec., obtained by hydrodistillation, was analyzed by GC-MS, which allowed the identification of 24 components, which made up 99.9% of the oil. The most abundant compounds were a-pinene (38.1%), beta-pinene (17.2%), myrcene (15.0%), spathulenol (4.2%), bicyclogermacrene (4.0%), a-zingiberene (4.0%), and gamma-himachalene (3.7%). Antibacterial activity was tested against Gram-positive and Gram-negative bacteria using the agar disk diffusion method. Activity was observed only against Gram-positive bacteria. MIC values were determined for Staphylococcus aureus ATCC 25923 (200 microg/mL) and Enterococcusfaecalis ATCC 29212 (600 microg/mL).

On the isomerization of ent-kaurenic acid.

Kaurenic acid (1a) is a tetracyclic diterpene that has an exocyclic double bond at delta16. Isokaurenic acid (2a) has an endocyclic delta15double bond. This compound has been isolated from Espeletia tenore (Espeletinae), a resinous plant from the Venezuelan Andes, but its occurrence is rare. In order to obtain a larger amount of 2a, the isomerization of la, which is easily obtained from other Espeletinae, was tried. Kaurenic acid methyl ester (1b) was treated with dil. HCl in CH3Cl/EtOH, after 6 h under reflux a yield of 41.5% isokaurenic acid methyl ester (2b) was obtained but 35.7% 16alpha-ethoxy-kauran-19-oic acid methyl ester (3b) had formed as a byproduct. Treating 1b with CF3COOH in refluxing CH2Cl2 permitted to obtain a yield of 66.6% of 2b in 4 h and only traces of 16alpha-hydroxy-kauran-19-oic acid methyl ester (3a) as a byproduct. Both isomers were separated on a silica gel column impregnated with 20% AgNO3. Treating 2b with KOH in refluxing DMSO yielded pure isokaurenic acid, no back isomerization was observed.

Presencia de ácido láctico y otros compuestos semivolátiles en mieles de meliponini / Presence of lactic acid and other semivolatil compound in meliponini honeys

Durante el estudio de compuestos semivolátiles, se encontró ácido láctico en mieles producidas por cuatro especies de abejas sin aguijón. Además, se identificaron otros compuestos: ácido 2-etil-2-hidroxi-propanoico en mieles de Melipona favosa, 5-(hidroximetil)-2-furancarboxaldehído y a-(fenilmetil)-benceno etanol, en mieles de Scaptotrigona mexicana, 2-butanol, eneicosano y heptacosano en mieles deTrigona carbonaria.

During the study of semivolatile compounds, lactic acid was found in the honey produced by four species of stingless bees. Moreover, other compounds were identified: 2-ethylhydroxy- propanoic acid in Melipona favosa honeys, 5-(hydroxymethyl)-2-furancarboxaldehyde and a-phenylmethyl benzene ethanol in Scaptotrigona mexicana honey, 2-butanol, heneicosane and heptacosane in Trigona carbonaria honey.

Chemical composition of the essential oil from Carramboa littlei (Asteraceae).

The essential oil from the leaves of Carramboa littlei Aristeg. was isolated by hydrodistillation yielding 0.09%, w/v. The chemical composition was determined by GC-FID and GC-MS. Sixteen components were identified by comparison of their mass spectra with Wiley and NIST library data. The major constituents of the oil were germacrene-D (50.0%), bicyclogermacrene (4.8%) and ent-kaur-16-en-19-al (21.8%).

Chemical composition of the essential oil from the bark Bursera tomentosa (Jacq) Tr & Planch / Composición química del aceite esencial de la corteza de Bursera tomentosa (Burseraceae) (Jacq) Tr & Planch

The bark of Bursera tomentosa was collected at full flowering stage in September 2002 at Cabudare, Lara State. The essential oil was isolated by hydrodistillation and it was analyzed by GC and GC/MS. Twenty eight components were identified which made up 90.1 percent of the oil. The main constituents of the essential oil were: spatulenol (11.4 percent, globulol (8.9 percent), epi alpha Cadinol (8.8 percent) and cis-ocimene (7.3 percent).

La corteza de Bursera tomentosa, fue recolectada en estado de floración en el mes de septiembre 2002 en Cabudare, Estado Lara. El aceite esencial fue obtenido por hidrodestilación y analizado por CG y CG/EM. Se identificó veinte y ocho compuestos que constituyen el 90.1por ciento del aceite. Los constituyentes mayoritarios del aceite esencial fueron spatulenol (11.4 por ciento), globulol (8.9 por ciento), epi-alfa-cadinol (8.8 por ciento) y cis-ocimeno (7.3 por ciento).

The volatile constituents of Salvia leucantha.

Salvia leucantha Cav. (Lamiaceae), native to Mexico, is found in Venezuela in parks and gardens. Hydrodistillation of the fresh leaves of this plant yielded 0.05% of essential oil. GC and GC/MS analyses permitted the identification of 30 compounds, which made up 95.9% of the oil. The most abundant constituents were bornyl acetate (24.1%), beta-gurjunene (14.8%), beta-caryophyllene (14.1%), dillapiol (11.0%) and bicyclogermacrene (8.9%).

Chemical composition and larvicidal activity of Eugenia triquetra essential oil from Venezuelan Andes.

The chemical constituents of the essential oil obtained by hydrodistillation of the leaves of Eugenia triquetra O. Berg, collected in Táchira State, Venezuela, were identified by GC-MS analysis. Twenty-six components, which made up 88.5% of the oil, were identified. The major constituents were linalool (17.5%), limonene (16.9%), alpha-pinene (11.6%), beta-pinene (8.7%), and p-cymene (3.7%). The essential oil was tested against third-instar larvae of Aedes aegypti, showing a LC50 value of 64.8 +/- 5.6 ppm.