Jairo Calle

Chromenes from Ageratum conyzoides

Abstract-Analysis of the aerial part of Ayeratum conyzoides afforded 11 chromenes, sitosterol, (+)-sesamin and caryophyllene oxide. One chromene is new and eight of the others were obtained for the first time from this species. The ‘C NMR spectral data for four of the chromenes have not been published before. INTRODUCIION Over the last two or three decades, great attention has been focused on the biological activity of natural com- pounds of plant origin for their potential as natural pesticides against phytophagous insects. In Colombia, plants have been used for centuries for their insecticidal. repellent or antifeedant properties in the protection of crops from insect attack [I]. Ageratum conyzoides, a widespread weed in Colombia and elsewhere, known to contain precocene I and precocene II [2,3], has been used both in folk medicine and as an insecticide. A study of the insecticidal activity of various fractions of an n-hexane extract of

Methoxyflavones from Ageratum conyzoides

Abstract Nine methoxyflavones were obtained from aerial parts of Ageratum conyzoides , two of which are new: 5,6,8,3′,4′,5′-hexamethoxyflavone and 8-hydroxy-5,6,7,3′,4′,5′-hexamethoxyflavone.

Sesquiterpene lactones from Salvia palaefolia

Abstract The aerial part of Salvia palaefolia yielded (−)-glechomafuran, 1β,10α;4α,5β-diepoxy-8β-hydroxyglechoman-8α,12-olide and the new eudesmanolides: 1α-acetoxy-8α-hydroxy-2-oxo-eudesman-3,7(11)-dien-8,12-olide and 1α,8α-dihydroxy-2-oxo-eudesman-3,7(11)-dien-8,12-olide. The structure of the former new compound was determined from its spectral data and chemical behaviour and its absolute configuration by CD experiments. The absolute configuration of 1β,10α;4α,5β-diepoxy-8β-hydroxyglechoman-8α,12-olide was established by X-ray diffraction analysis.

Minor sesquiterpene lactones from Salvia palaefolia

Abstract Five minor eudesmane constituents of Salvia palaefolia were isolated from the same extract which had earlier yielded the two fully characterized eudesmanolides. The five new natural compounds were identified by spectral studies and comparison with known substances.

A C-methyl chalcone from Dalea caerullea

Abstract A petrol extract of Dalea caerullea yielded the new 4′,6′-dihydroxy-3′,5′-dimethyl-2′-methoxychalcone which was characterized by spectroscopy. Mono- and sesquiterpenes were also obtained from extracts of this plant.

Alterations in the reproduction of mice induced by rapanone

Oral administration of rapanone to a group of female mice at doses of 60 and 120 mg/kg, reduced the percentage of pregnancies compared to control group, suggesting an anovulatory effect. Postcoital administration induced uterine alteration in both the first and second gestation periods. These results seem to indicate inhibition of trophoblast implantation in the first period, and an abortive effect and/or reabsorption in the second. Daily administration of rapanone to a group of male mice resulted in fertility alteration, which is attributed to an antispermatogenic effect. Rapanone did not show acute toxic effects at the doses tested in this research.

Cytotoxic Activities of Colombian Plant Extracts on Chinese Hamster Lung Fibroblasts

Fifty‐one crude extracts from 31 Colombian plants used in traditional medicine have been screened for cytotoxicity in a MTT assay with V79 cells. Eleven extracts (21%) were active, showing a survival percentage below 20% with respect to the controls. The most active were ethanol and dichloromethane extracts from Acnistus arborescens leaves. The IC50 values obtained (6 and 11 μg/mL) encourage a more in depth investigation.