Browsing by Autor "Alfredo Usubillaga"

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A New ent-kaurene Diterpenoid Isolated from Leaves of Espeletia semiglobulata Cuatrec. and its Potential Antimicrobial Activity
(Sunan Kalijaga Islamic University, 2023) Andrés Márquez; Alida Pérez-Fodich; Luís B. Rojas; Rosa Aparicio; Freddy A. Ramos; Ysbelia Obregón; Alfredo Usubillaga
The fraction of the neutral extraction of the leaves of Espeletia semiglobulata Cuatrec. was subjected to chromatographic separation, it yielded four ent-kaurene type diterpenoids: three known [ent-kaur-16-en-19-al (I), ent-kaur-18-nor-16-en-4-ol (III), ent-kaur-16-en-19-ol (IV)] and a new one elucidated as ent-kaur-3-acetoxy-15-ene (II), based on the physicochemical and spectroscopic data of FTIR, GC-MS, and 1D and 2D NMR. These compounds were subjected to antimicrobial bioassay studies. This new ent-kaurene showed a significant inhibition potential against the growth of gram negative bacterial strains [Escherichia coli (ATCC 25922): 8 mm, Klebsiella pneumoniae (ATCC 23357): 10 mm, Pseudomonas aeruginosa (ATCC 27853): 8 mm], it also showed inhibition against the growth of fungal strain (Candida krusei: 8 mm), at a 2 mg/mL concentration. The compounds (I), (III) and (IV) failed to show any significant results in the antimicrobial screening against five bacterial strains [Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Klebsiella pneumoniae (ATCC 23357), Escherichia coli (ATCC 25922) y Pseudomonas aeruginosa (ATCC 27853)] and one fungal strain [Candida krusei (ATCC 6558)]. These results reveal a remarkable natural structure-activity relationship of the ent-kaurene core regarding the C-3 position (A ring of perhydrophenanthrene unit), whose oxygenation or addition of a hydrogen bond acceptor or donor group, improves the antimicrobial activity.
Actividad antimicrobiana de los extractos polares de tres especies de solanum: s. hypomalocophyllum bitter, s. mamosum l y s.sycophanta dunal et dc de Venezuela
(2019) Libia del Valle Alarcón Pineda; Alexis Eduardo Peña Rangel; Alfredo Usubillaga; Judith Velasco
In this study antibacterial activity of three species of Solanum, collected in the Venezuelan Andes is reported. Antibacterial activity was measured by the diffusion in agar method using bacteria and yeasts of international reference for comparison. Hydroalcoholic extracts of roots, stems and leaves of S. mamosum L. showed respectively a CIM of 420, 260 and 120 mg/ml of activity against Staphylococcus aureous (ATCC 25923). If S. aureus was resistant to meticilina SARM 525 only stems and and leaves were active and showed CIM of 180 and 90 mg/ml respectively. A crude butanolic extract of the green berries (MDA) of S. hypomalacophyllum Bitter showed activity against SARM 525, with CIM of 30 mg/ml. On the other hand desacetoxy-solafi lidine (3) was active with a CIM of 20 mg/ml. Regarding antifungic activity MDA and compound 3 presented activity against Candida crusei (ATCC 6258), but MDA (CIM 25mg/ml) performed better than compound 3, which means that activity of MDA is associated to sinergism. Solanum sycophanta extracts were not active.
Activity of acnistins against Leishmania mexicana, Trypanosoma cruzi and Plasmodium falciparum
(2009) Bernardo Chataing; Antoine Hocquette; S.B. Díaz; Alexis Valentin; Alfredo Usubillaga
Acnistin A and E, two withanolides with a bicyclic side-chain at C-17, isolated from the leaves of Acnitus arborescens (L) Schlecht that grows in the Venezuelan Andes inhibited the growth of Leishmania mexicana and Trypanosoma cruzi in cultured medium. On the other hand acnistins A, E, and L, also inhibited the growth of a chloroquine-resistant strain and a chloroquine-sensitive strain of Plasmodium falciparum in cultured medium. Data indicated that acnistins exerted a higher inhibitory activity upon these parasites that ketoconazole, mevastatin and lapachol in the same conditions of assay.
Composición química de los aceites esenciales de Piper dilatatum L.C. Rich. y Piper tuberculatum Jacq. de Mérida, Venezuela
(2008) Flor Mora; Jhon Peña; Luís B. Rojas; Alfredo Usubillaga; Pablo Meléndez
La composición química del aceite esencial de las especies Piper dilatatum L.C. Rich. y Piper tuberculatum Jacq., provenientes de dos localidades del estado Mérida, Venezuela, fue determinada. Los aceites esenciales fueron obtenidos por hidrodestilación de las hojas frescas de la planta y analizados por espectrometría de gases-masa. En el aceite de P. dilatatum se identificaron 23 componentes que constituyen el 86,9% del aceite, de los cuales se encuentran en mayor proporción el b-Pineno (17,2 %), el a-Pineno (10,8%) y el cis-Ocimeno (10,3%). En el aceite esencial P. tuberculatum se identificaron un total de 11 compuestos que conforman el 96,6% de la muestra, siendo el fenil propanoide dilapiol el componente mayoritario (72,4%). Esta especie representa una variedad quimiotaxonómica diferente a las reportadas en la literatura
COMPOSICIÓN QUÍMICA Y ACTIVIDAD ANTIBACTERIANA DEL ACEITE ESENCIAL DE Zingiber officinale DEL MUNICIPIO INDEPENDENCIA ESTADO TÁCHIRA
(2010) Libia Alarcón; Aránzazu Peña; Judith Velasco; Alfredo Usubillaga
Elpresente trabajo comprende elestudiodela composicion quimica y actividad antibacteriana del aceite esencial de las hojas de Zingiber officinale, plantaquecreceenelestadoTachira(Venezuela).El aceite fue obtenido por hidrodestilacion usando una trampa deClevenger yfueanalizado porCGyCG- MS. Se logro identificar 21 compuestos que representan el 97,8% del total del contenido volatil. Loscompuestosencontradosmasabundantesfueron: 1,8-cineole (16, 9%), geraniol (15,1%), canfeno (12,6%),neral(11,6)yborneol(11,1%).Seevaluola actividad antibacteriana in vitro del aceite por el metodo de difusion en agar con discos, contra Staphylococcusaureus(ATCC25923), Enterococcus faecalis (ATCC 29212), Klebsiella pneumoniae (ATCC 23357), Escherichia coli (ATTC 25922) y Pseudomonas aeruginosa (ATTC 27853). El aceite deZ.officinalemostroposeeractividadcontratodos los microorganismos ensayados, con un rango de CIM entre 20 y 240 μg/ml. La actividad antibacteriana del aceite esencial deZ.officinale abajas concentraciones, esuna opcion que ofrece la medicinanaturalcontracepasbacterianas querepresentan unproblemadesaludimportante.
Composición Química y Evaluación de la Actividad Antimicrobiana del Aceite Esencial de Espeletia Schultzii Wedd (Asteraceae) Recolectada en el Estado Trujillo – Venezuela
(2016) Libia del Valle Alarcón Pineda; Alexis Peña; Judith Velasco; Alfredo Usubillaga; Billmary Z. Contreras Moreno; Luís B. Rojas; Deisy Ramírez; Rosa Aparicio
The essential oil of fresh leaves Espeletia schultzii Wedd (Asteraceae) obtained by hydrodistillation was rich in hydrocarbon monoterpenes. The analysis of its volatile components by chromatography gas-mass spectrometry (GC-MS) allowed the identification of 13 components, which constituted 100% of essential oil of which the majority were α-pinene (50.11%), β-pinene (16.28%) and β-myrcene (14.71%). The antibacterial activity of the essential oil was assessed using methods agar diffusion and broth microdilution discs against Staphylococcus aureus (ATCC 25923) Enterococcus faecalis (ATCC 29212), Salmonella typhi (CDC57), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 23357) and Pseudomonas aeruginosa (ATCC 27853) and antifungal activity against Candida albicans (CDC-B385) and Candida krusei (ATCC 6258). This oil showed only activity antibacterial, with variation in the results according to the method used by the diffusion method agar disk inhibited by Gram positive bacteria (S. aureus and E. faecalis) with inhibition halos of 7 to 9 mm in diameter and minimum inhibitory concentration values (MIC) ranging between 280 and 580 mg / mL, using the broth microdilution method, inhibited the development of all microorganisms tested at concentrations of 10 to 100 ug / mL. These results revealed that the sensitivity of the method plays an important role in the evaluation of this oil as an antibacterial, It is more sensitive the broth microdilution method. This is the first report of the activity antibacterial essential oil obtained from the leaves of this species.
Contribución al estudio de los componentes del aceite esencial de la Espeletia schultzii
(1986) Alfredo Usubillaga; Glady Castellano
Espeletia schuitzii is a compositae endemic to many Venezuelan paramos. From the resin of this plant the essential oil was obtained by steam distillation. It was inspected by gas chromatography on a carbowax 20M column and showed 34 peaks, two of them represent around 70% of the essence. It was treated on a dry silicagel column and five fraccions of different polarity were obtained. The first fraction contained the two mayor components which were identified by GC MS analysis as a and s-pinene.This finding was confirmed by the C- 13 spectrum of the essential oil . CMR analysis permitted comparison of the essential oils obtained from fresh plants collected at different paramos. No differences in composition were found.
Cytotoxic activity of acnistins upon human cancer cells
(2009) Bernardo Chataing; Alfredo Usubillaga; M César Pérez; Ramón Méndez
The cytotoxic activity against human A375 melanoma, MCF7 breast cancer and K652 leukemia cells of acnistins A, E and L, isolated from the leaves of Acnistus arborescens (L) Schletcht (Solanaceae) and the derivatives, 2,3-5,6-diepoxi-acnistin A and acnistin F, obtained in the laboratory by hemisynthesis, were examined using a microculture tetrazolium (MTT) assay. The objectives were to determine if these compounds have cytotoxic activity against cancer cells; to determine the type of interaction between acnistin A with ketoconazole and a-solamargine as well as the type of interaction between acnistin E with a-solamargine and a-chaconine, two compounds which interfere with neutral lipid metabolism. On the other hand this study was addressed to obtain evidence about acnistin moieties that are important for activity. Results indicated that acnistins A, E and L were cytotoxic to human A375 melanoma cells with IC50 values ranging between 0.19 to 80.5 µM, depending on the time of exposition to the steroidal lactone. Also, acnistins A and E were cytotoxic toward MCF7 breast cancer and K652 leukemia cells, with IC50 values ranging from 10.2 to 134.4 µM. The effectiveness of acnistins A and E against the human A375 melanoma cells was greater than against the other cell lines. The results suggested that presence of an a,b-unsaturated ketone, an epoxy moiety between C-5 and C-6, and an hydroxyl group at C-17 are required for activity.
Estudio de la anatomia y distribucion de las glandulas del minthostachys mollis griseb. Que crece en venezuela
(1994) Alfredo Usubillaga; Luís B. Rojas
Estudio de la Composición Química del Aceite Esencial de Hojas y Tallos de Physalis Peruviana L.
(2018) Marielba Morillo; Virginia Marquina; Luís B. Rojas; Rosa Aparicio; Juan Carmona; Alfredo Usubillaga
Physalis peruviana L. es una especie originaria de los Andes de Sur América perteneciente a la familia\nSolanaceae. El aceite esencial de hojas y tallos de esta planta fue aislado mediante hidrodestilación,\nempleando la trampa de Clevenger, con un rendimiento de 0,01 % y 0,012 % respectivamente. La\ncomposición química de estos aceites fue determinada por cromatografía de gases–masas y mediante\nmedición de los índices de Kovats (GC-FID). En el aceite proveniente de las hojas se identifi caron\n22 componentes, siendo el ácido hexadecanoico (42,8 %), el (-)-epóxido de hexadeceno (28,8 %), el\nfi tol (4,7 %), y el éster metílico del ácido hexadecanoico (2,1 %) los componentes mayoritarios. En el\naceite de los tallos se identifi caron 21 componentes y los mayoritarios fueron el ácido hexadecanoico\n(80,5 %), el ácido pentadecanoico (3,3 %) y el ácido tetradecanoico (2,6 %). Este es el primer reporte\nsobre los constituyentes volátiles presentes en las hojas y tallos de Physalis peruviana L. en Venezuela.
Tratamiento topico del herpes simplex, el herpes zoster y el herpes genital con una mezcla de alcaloides de solanaceas
(1998) Bernardo Chataing; Nersa Buitriago de Cristancho; Alfredo Usubillaga
Editorial. El síndrome TMT y el síndrome TMA. Síntomas, Efectos, Epidemiología, Etiología, Terapia y Contraindicaciones