Two new 3,4-seco-ent-kaurenes, caracasine (1) and caracasine acid (2), were isolated from non-polar extracts of the flowers of Croton caracasana (Euphorbiaceae), together with six known terpenes, stigmasterol (4), stigmastenone (5), 2,6-dimethylocta-3,7-diene-2, 6-diol (6), spathulenol (7), caryophyllene oxide (8), and aromadendrene (9), and the flavonoid tribuloside (10). The chemical structures were determined by spectroscopic means and chemical correlations. All isolated compounds are being described for the first time for this species.

Fuiidacio'n lnstituto Bota'nico de Venezuela, Apto. 21 56,101 0-A Caracas, Venezueh AbstractThe chemical composition of the leaf oil of Lepechinin snlzjinefolin (Kunth) Epl. was determined by means of GC and GC/MS. Plant material from 60 individual plants was investigated and the quantitative oil data were analyzed by a multivariate statistical analysis revealing two chemotypes. The major constituents ofthe palustrol-type (28 samples) were (-)-palustrol (19.1%), p-phellandrene (13.8%), borneol (11.8%) and camphene (7.2%). The oil of the premnaspirodiene-type (Xsamples) was dominated by p-phellandrene (13.3%), borneol(12.3%), (-)-premnaspirodiene (9.4%) and cainphene (8.5%). The presence of a third chemotype (5 samples) with 6-3-carene (12.9%), T-cadinol (9.1%) and borneol(8.4%) became evident but has to be substantiated by analysis of further samples of plant material.

Flavonoids are present in practically all plants and many biological activities have been described for them. The flavonoid quercetin is a common molecule for which anti-HIV activity has been demonstrated. Avicularin and guajaverin are derivatives of quercetin with a glycoside substituent in their structure. In this work, a mixture of both derivatives was purified from an extract of Psidium guinense. The mixture exhibited activity against HIV-1 in vitro, with an IC50 of approximately 8.5 μg/mL, which compares favorably with the IC50 of 53 μg/mL of quercetin. The mixture also inhibited HIV-1 reverse transcriptase (RT), with an IC50 of 7.2 μM, compared to 0.6 μM for quercetin. These results are in agreement with the in silico prediction for the interaction of these flavonoids with RT and suggest that the glycosylic moiety could favor the transport of the compound into the cell. However, the glycosidic moiety might be cleaved intracellularly, being the resultant quercetin responsible for the antiviral activity.

No abstract

La nefropatía es una de las complicaciones más importantes de la diabetes, la cual puede conducir a la muerte. Las kinasas activadas por mitógenos (MAPK) son conocidos mediadores del daño renal en la diabetes, cuya activación (fosforilación) se encuentra asociada al aumento de la síntesis de proteínas de la matriz extracelular (colágeno, fibronectina, entre otras) y a la fibrosis renal. Recientemente, se ha establecido a la planta Ruellia tuberosa L. como antioxidante, antiinflamatoria, antidiabética y nefroprotectora en varios modelos experimentales. En este trabajo se evaluó el efecto del tratamiento con 10 mg/kg/día, p.o, del extracto acuoso de la raíz de R. tuberosa (RT) durante cuatro semanas, sobre la fosforilación de la ERK 1/2 en la corteza renal de ratas control y con diabetes tipo I inducida por la estreptozotocina y se vinculó con los marcadores de la fibrosis renal tales como el aumento del peso del riñón, contenido de proteínas totales y de colágeno I. Los resultados demuestran que el tratamiento con RT previno el aumento de la fosforilación de las ERK 1/2, del peso del riñón, y del contenido de proteínas y de colágeno I renal por en la diabetes inducida por ETZ. Los hallazgos contribuyen a la elucidación de los mecanismos por los cuales R. tuberosa protege al riñón frente a la diabetes, estableciéndose así la actividad antifibrótica de esta especie utilizada en la medicina popular venezolana.