Actividad antiviral contra el virus de la fiebre amarilla, cepa vacunal 17D, de extractos de hojas de Taraxacum officinale GH Weber ex Wiggers / Phytochemicaland antiviral activity against yellow fever virus, 17D vaccine strain, of extracts from leaves of Taraxacum officinale GH Weber ex Wiggers

Taraxacum officinale leaves were collected at two and 5 months of growth, for antiviral activity against flavivirus, using the 17D vaccine strain of yellow fever virus as a model. Using spectroscopy technique, a total of twelve (12) compounds were identified in the chloroform (C) and hexane (H) extracts of two and five months (2M and 5M) of recollection., The antiviral activity against the yellow fever 17D virus was evaluated with the plaque assay and the concentrations used (50 - 1,5 ug/mL) were no cytotoxic to Vero cells as determined using the MTT(3-(4,5-Dimetiltiazol-2yl)-2,4-difenilbromuro de tetrazolium) assay. The phytochemical composition of leaves growing for 5 months is different and more complex than leaves growing for 2 months. From the four extracts, only C5M inhibited the viral replication in a dose depend manner, with 100 percent viral inhibition at 50 ug/mL (p=0,0124) and the effective doses 50 (ED50: 10,2 +/- 8,7 ug/mL), meanwhile, ED50 of C2M extract was 93,5 +/- 23,5 ug/mL, thus, the extract C5M is 8 times more effective than extract C2M. The identified compounds in extract C5M were: Psi taraxasteryl acetate, cafeic acid, taraxasteryl acetate, taraxerol, taraxerilo acetate and Psi-taraxasterol. One of these compounds or the combinations of them is responsible for the reported high antiviral activity.

Las hojas de Taraxacum officinale fueron colectadas a dos y cinco meses de crecimiento, para determinar actividad antiviral contraflavivirus, utilizando como modelo el virus de fiebre amarilla cepa vacunal 17D. Se identificaron por métodos espectroscópicos, un total de doce (12) compuestos provenientes de los extractos de hexano (H) y cloroformo (C) a dos y cinco meses (2M y 5M) de recolección La actividad antiviral se determinó mediante un ensayo de placa y las concentraciones de extractos utilizadas (50-1,5 ug/mL) fueron no citotóxica en células Vero, determinadas por el método colorimétrico del MTT (3-(4,5-Dimetiltiazol-2yl)-2,4-difenilbromuro de tetrazolio). La composición fitoquímica de los extractos de 5 meses es distinta y más compleja que la de dos meses de crecimiento. De los cuatro extractos sólo el C5M inhibió la replicación del virus en una manera dosis dependiente, con una inhibición del 100 por ciento a 50 ug/mL (p=0,0124) y una dosis efectiva 50 (DE50) de 10,2 +/- 8,7 ug/mL, mientras que el DE50 del extracto C2M es de 93,5 +/- 23,5 ug/mL, lo que hace al extracto clorofórmico de 5 meses aproximadamente 8 veces más efectivo que el C2M. Los compuestos presentes en el extracto C5M son Psi taraxasterilo, ácido cafeíco, acetato de taraxasterilo, taraxerol, acetato de taraxerilo y Psi-taraxasterol. Uno o más de estos compuestos son responsables de alta actividad antiviral reportada.

Actividad biológica de extractos de tres plantas sobre bacterias patógenas para el humano / Biological activity of extracts from three plants over bacteria pathogenic for human beings

El objetivo de esta investigación fue determinar la actividad biológica de extractos de tres plantas sobre bacterias patógenas para el humano. Se determinó la citotoxicidad de extractos y fracciones de Parinari sprucei, Couepia paraensis y Lantana camara L. y se evaluó su actividad antibacteriana mediante el ensayo colorimétrico del 3-(4,5-dimetiltiazol-2yl)-2,4-difenilbromuro de tetrazolio (MTT), utilizando sólo concentraciones inocuas en todos los ensayos realizados. La CMI se determinó con el ensayo de micro dilución MTT y se evaluó la actividad de los posibles agentes antimicrobianos por el método de difusión en agar de Kirby-Bauer. La CMI de los extractos metanólico de C. paraensis y diclorometano/etanol de P. sprucei sobre Staphylococcus aureus fue 25 µg/mL, mientras que la CMI con el extracto etanólico de P. sprucei fue 50 µg/mL. La CMI de la fracción 19 de L. camara L. sobre Acinetobacter haemolyticus y S. aureus fue 50 µg/mL. Los halos de inhibición obtenidos con los extractos metanólico de C. paraensis, y diclorometano/etanol y etanólico de P. sprucei sobre S. aureus fueron de 8, 9 y 7 mm, respectivamente. Los extractos de la familia Verbenaceae no presentaron actividad antibacteriana, mientras que los de la familia Chrysobalanaceae inhibieron la replicación de bacterias grampositivas.

The citotoxicity of extracts and fractions obtained from three plants was determined, and their antibacterial activity was evaluated through a colorimetric assay with tetrazolium 3-(4,5-dimethilthiazol-2yl)-2,4-diphenilbromide (MTT)), using only innocuous concentrations in all the assays carried out. The MIC was determined by the MTT micro dilution assay, and the activity of the possible antimicrobial agents by the Kirby-Bauer agar diffusion test. The MIC of a methanol extract from Couepia paraensis, and a dichloromethanol/ethanol from Parinari sprucei over S. aureus was 25 µg/mL, while the MIC with the ethanol extract from P. sprucei was 50 µg/mL. The MIC of fraction 19 of Lantana camara L. over A. haemolyticus and S. aureus was 50 µg/mL. The inhibition halos obtained with the C. paraensis methanol extracts, and the P. sprucei over S. aureus dichloromethanol/methanol and ethanol extract, were 8, 9 and 7 mm respectively. The Verbenaceae family extracts did not present any antibacterial activity, while those of the Chrysobalanaceae family inhibited replication of gram positive bacteria.

Couepia paraensis: estudio fitoquímico, ensayos de citotoxicidad y de inhibición de la glucosa-6-fosfatasa / Couepia paraensis: phytochemical study, cytotoxicity assays and inhibition of glucose-6-phosphatase

From the cholroform extract of the aerial parts of Couepia paraensis the triterpenes beta-sitosterol1, betulinic acid acetate 2, and oleanolic acid acetate 3, were isolated. Six triterpenes from the chloroform-methanol, acids: oleanolic 4, pomolic 5, ursolic 6, betulinic 7, 6-beta-hydroxybetulínic 8. Additionally from the methanolic extract three flavonoids were isolated: mricetin 9, quercetin 10 y rutina 11. The chloroform and chloroform-methanol extracts were not citotoxic at concentration of 2,5 and 3,1 ug/ml respectively after 24 hours of incubation. The methanol extract was found to be harmless to a concentration of 50 ug/ml, both at 24 hours (LD50 = 10.77 ug/ml) and 120 hours (LD50 = 28.86 ug/ml) of incubation. Only the methanol extract showed significant inhibition (41 percent) of the activity of G-6-Pase in intact microsomes without affecting the activity of the enzyme in microsomes broken.

Se aislaron e identificaron tres triterpenos: beta-sitosterol 1, acetato del ácido betulínico, 2 y acetato del ácido oleanólico 3 del extracto clorofórmico. Seis triterpenos del extracto cloroformo: metanol (9:1) que fueron identificados como ácidos: oleanólico 4, pomólico 5, ursólico 6, betulínico 7, 6-beta-hidroxibetulínico 8. Mientras que del extracto metanólico se identificaron 3 flavoniodes: miricetina 9, quercetina 10 y rutina 11. Los extractos de cloroformo y cloroformo /metanol resultaron inocuos hasta las concentraciones de 2,5 y 3,1ug/ml respectivamente, después de 24 horas de incubación. El extracto metanólico es inocuo hasta una concentración de 50 ug/ml, tanto a 24 horas (LD50 = 10,77 ug/ml) como a 120 horas (LD50 = 28,86 ug/ml) de incubación. Solamente el extracto metanólico mostró una inhibición significativa (41 por ciento) de la actividad de la G-6-Pasa de microsomas intactos sin afectar la actividad de la enzima en microsomas rotos.

Effect of flavonoids from Exellodendron coriaceum (Chrysobalanaceae) on glucose-6-phosphatase.

From the n-butanol extract of the aerial parts of Exellodendron coriaceum (Benth.) Prance the flavonoids quercetin-3-O-beta-D-galactopyranoside (1), quercetin-3-O-alpha-L-arabinopyranoside (2), quercetin-3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-rhamnopyranoside (3), and quercetin-3-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-galactopyranoside (4) were isolated. Additionally from this extract three flavonoids were isolated and partially characterized as quercetin glycosides. All these compounds were tested for their hypoglycemic activity using the glucose-6-phosphatase microsomal hepatic system. The flavonoids inhibited the activity of the enzyme when intact microsomes were used, the highest percentage of inhibition being 65%. To the best of our knowledge, this is the first report of chemical and biological activity of E. coriaceum.

Triterpenoid saponins from Campsiandra guayanensis.

Thirteen new triterpenoid saponins (1-13) were isolated from the aerial parts of Campsiandra guayanensis. Their structures were elucidated by 1D and 2D NMR experiments including 1D-TOCSY, DQF-COSY, ROESY, HSQC, and HMBC spectroscopy, as well as ESIMS analysis. The aglycon moieties of 1-10 were assigned as oleanane derivatives and those of 11-13 as lupane derivatives.

Evaluation of flavonoids from Bauhinia megalandra leaves as inhibitors of glucose-6-phosphatase system.

From the methanol extract of Bauhinia megalandra fresh leaves, eight flavonoids were isolated and evaluated by rat liver microsomal glucose-6-phosphatase (G-6-Pase) bioassay, which might be a useful methodology for screening antihyperglycaemic substances. All the flavonoids assayed showed an inhibitory effect on the intact microsomal G-6-Pase: quercetin and kaempferol exhibited the lowest effect; astilbin, quercetin 3-O-alpha-rhamnoside, kaempferol 3-O-alpha-rhamnoside and quercetin 3-O-alpha-arabinoside an intermediate effect. The highest inhibitory activity was shown by quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''galloyl)rhamnoside. None of the flavonoids mentioned above showed an inhibitory effect on the disrupted microsomal G-6-Pase. Quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''-galloyl)rhamnoside exhibited the lowest IC50 of all the flavonoids assayed. Also, the phlorizin IC50 is reported.

A new kaurane diterpene dimer from Parinari campestris.

A new kaurane diterpene dimer, 15-oxozoapatlin-13alpha-yl-10'alpha,16'alpha-dihydroxy-9'alpha-methyl-20'-nor-kauran-19'-oic acid gamma-lactone-17'-oate (1), together with the known 13-hydroxy-15-oxozoapatlin (2), 10alpha,13alpha,16alpha,17-tetrahydroxy-9alpha-methyl-15-oxo-20-nor-kauran-19-oic acid gamma-lactone (3), 2alpha,10alpha,13alpha,16alpha,17-pentahydroxy-9alpha-methyl-15-oxo-20-nor-kauran-19-oic acid (19,10)-lactone (4), 3alpha,10alpha,13alpha,16alpha,17-pentahydroxy-9alpha-methyl-15-oxo-20-nor-kauran-19-oic acid gamma-lactone (5), and 1beta,16alpha,17-trihydroxy-ent-kaurane (6) were isolated from the leaves of Parinari campestris and identified on the basis of detailed spectral analysis, including 2D NMR spectrometry and ESI-MS.

Inhibition of hepatic neoglucogenesis and glucose-6-phosphatase by quercetin 3-O-alpha(2''-galloyl)rhamnoside isolated from Bauhinia megalandra leaves.

In intact microsomes, quercetin 3-O-alpha-(2''-galloyl)rhamnoside (QGR) inhibits glucose-6-phosphatase (G-6-Pase) in a concentration-dependent manner. QGR increased the G-6-Pase K(m) for glucose-6-phosphate without change in the V(max). The flavonol did not change the kinetic parameters of disrupted microsomal G-6-Pase or intact or disrupted microsomal G-6-Pase pyrophosphatase (PPase) activity. This result allowed the conclusion that QGR competitively inhibits the glucose-6-phosphate (G-6-P) transporter (T1) without affecting the catalytic subunit or the phosphate/pyrophosphate transporter (T2) of the G-6-Pase system.QGR strongly inhibits the neoglucogenic capacity of rat liver slices incubated in a Krebs-Ringer bicarbonate buffer, supplemented with lactate and oleate saturated albumin. The QGR G-6-Pase inhibition might explain the decrease in the liver slice neoglucogenic capacity and, in turn, could reduce glucose levels in diabetic patients.

Structure of kaurane-type diterpenes from Parinari sprucei and their potential anticancer activity.

Twenty-three kaurane-type diterpenes 1 - 23, including twenty new natural products 1 - 20, have been isolated from the leaves of Parinari sprucei and their structures elucidated by spectroscopic and chemical analysis. The isolated compounds were tested for their cytotoxic activity towards a panel of cancer cell lines. Compounds 9 and 10 showed activity against all cell lines with ED (50) values in the range of 10 - 20 microg/mL. The previously known 13-hydroxy-15-oxozoapatlin 21 was evaluated in an in vivo hollow fiber test, and found to be active with KB and LNCaP cells at the concentrations used.

Anti-Sindbis activity of flavanones hesperetin and naringenin.

The effect of hesperetin, naringenin and its glycoside form on the Sindbis neurovirulent strain (NSV) replication in vitro was studied. All flavanones tested were not cytotoxic on Baby Hamster cells 21 clone 15 (BHK-21). Antiviral effect was evaluated by a colorimetric assay using MTT (3-(4,5 dimethylthiazol-2-yl)-2,5-dipheyl-tetrazolium bromide) and by plaque reduction assay. Hesperetin and naringenin had inhibitory activity on NSV infection. The 50% inhibitory doses (ID(50%)) of both compounds were 20.5 and 14.9 microg/ml respectively, as established by plaque assay. However their glycosides, hesperidin and naringin did not have inhibitory activity. Implying that the presence of rutinose moiety of flavanones blocks the antiviral effect. Oxygenation on the 3' positions at the B rings on the hesperetin skeleton decrease the anti viral activity at 25 microg/ml.

Antioxidant and free-radical scavenging activity of constituents of the leaves of Tachigalia paniculata.

Two new myricetin glycosides, myricetin 7-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (1) and myricetin 7-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (2), together with the known compounds quercetin 3-O-beta-D-glucopyranoside (3), quercetin 3-O-alpha-L-rhamnopyranoside (4), quercetin 3-O-beta-D-galactopyranoside (5), methyl gallate (6), isovanillin (7), 4-hydroxymethylbenzoate (8), 3,4-dihydroxymethylbenzoate (9), and caffeoyl aldehyde (10) were isolated from the leaves of Tachigalia paniculata. The structures of these compounds were determined by spectroscopic methods. Their antioxidant activity was determined by measuring free-radical scavenging effects using three different assays, namely, the Trolox Equivalent Antioxidant Capacity (TEAC) assay, the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay), and the inhibition of xanthine oxidase activity. Compounds 1, 2, and 6 showed activity in the TEAC test, compounds 5-7 and 10 were moderately active in the autoxidation assay, while compounds 1 and 2 were the most potent of the isolates in the xanthine oxidase test.

Antioxidant activity of flavonoids from Licania licaniaeflora.

In our screening program for antioxidants with DPPH radical scavenging activity we tested several flavonoids isolated from the leaves of Licania licaniaeflora (Chrysobalanaceae family) and identified by spectroscopic evidence, particularly with 1H and 13C NMR. All the isolated compounds exhibited DPPH radical scavenging activity: quercetin derivatives showed the strongest action, while the flavanone 8-hydroxy-naringenin and kaempferol 3-O-alpha-rhamnoside had the lowest.

Actividad antiviral de flavonoides de hirtella castillanum ante los virus herpes simple tipo 2 y encefalitis equina Venezolana / Activity hirtella castillanum in herpes simplex virus type 2 and venezuelan equine encephalitis

Mediante fraccionamientos por solubilidad y métodos cromatográficos del extracto metanólico de las hojas de Hirtella castillanum se aislaron cuatro flavonoides: Quercetina (1), Quercetina-3-ramnósido (2), Miricetina (3) y mirecitina-3- ramnósido (4). De los mismos, solo Quercetina mostró una apreciable actividad antiviral ante el virus herpes simple tipo 2 (VHS-2) y el virus de la encefalitis equina Venezolana (EEV) en ensayos in vitro.

Actividad antiviral de flavonoides aislados de licania pittieri ante el virus de la fiebre amarilla / Antiviral activity of isolated flavonoides of the pittieri licania before to yellow fever viruses

Mediante fraccionamientos por solubilidad y métodos cromatográficos (sephadex LH20 y sílica gel RP-18) del extracto metanólico de las hojas de licania pittieri, se aislaron cinco flavonoides: quercetina (1), quercetina-3-galactósido (2), quercetina-3-rhamnósido (3), quercetina-3-arabinofuranósido (4) y (2R, 3R) taxifolina-3-rhamnósido (5). De los mismos, sólo quercetina mostró apreciable actividad antiviral ante el virus de fiebre amarilla (FA) en ensayos in vitro