The antioxidant activity of the crude n-hexane, dichloromethane, and methanol extracts from 25 species belonging to the Asteraceae, Euphorbiaceae, Rubiaceae, and Solanaceae families collected at natural reserves from the Eje Cafetero Ecorregión Colombia, were evaluated by using the spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging method.The strongest antioxidant activities were showed by the methanol and dichloromethane extracts from the Euphorbiaceae, Alchornea coelophylla (IC 50 41.14 mg/l) and Acalypha platyphilla (IC 50 111.99 mg/l), respectively. These two species had stronger DPPH radical scavenging activities than hydroquinone (IC 50 151.19 mg/l), the positive control. The potential use of Colombian flora for their antioxidant activities is discussed.Key words: Asteraceae -1,1-diphenyl-2-picrylhydrazyl (DPPH) -Euphorbiaceae -radical-scavenging -Rubiaceae -Solanaceae ternative, once it has been suggested that there is an inverse relationship between dietary intake of antioxidants and the incidence of diseases caused by the deficiency on these substances (Antolovich et al. 2002). In recent years, synthetic antioxidants such as buthylated hydroxyanisole (BHA) and buthylated hydroxytoluene (BHT) are added to food preparations because they are good free radical scavengers, even though there are some experimental evidences that they induce DNA damage (Sasaki et al. 2002). Therefore, there is an increasing interest in searching antioxidants from natural origin to scavenge free radicals to prevent human body from oxidative stress produced by ROS and RNS species (Gonçalves et al. 2005).According to Hostettmann and Terreaux (2000), the estimated number of higher plant species in the world is of 400,000, the fact that plant secondary metabolites are characterized by an enormous chemical diversity and that currently one-fourth of all prescribed pharmaceuticals compounds in developed countries are directly or indirectly (semi-synthetic) derived from plants. Then, the above statement in conjunction with the great Colombian biodiversity can make possible to discover new important antioxidant agents from such plethora of plant resources.As plants produce a huge amount of antioxidants they can represent a source of new compounds with antioxidant activities (Cuendet et al. 2000, Bassman 2004. From this point of view, the main goal of this research was to study the antioxidant activities through the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging method of the crude n-hexane, dichloromethane, and methanol extracts from 25 plant species belonging to four botanical families (Asteraceae, Euphorbiaceae, Rubiaceae, and Solanaceae) collected from natural reserves on the Eje Cafetero Ecorregión (ECE), Colombia.The ECE is an area constituted by the departments of Caldas, Quindío, and Risaralda, which are located on the Central Andean Colombian mountain chain, with an extension of 13.873 km 2 . Most of the ECE area is constituted by mountains with high mountain valleys, high pluviosity, and ...

Thirty crude extracts of eight plants belonging to Asteraceae and two to Rubiaceae families collected at different places from the Regional Natural Park Ucumarí (RNPU), Colombia, were tested for their antibacterial activity against two Gram-positive and two Gram-negative bacteria and three fungi. Both the antibacterial and the antimycotic activities were tested by the agar well diffusion method. The cytotoxic activity on the same plant extracts was determined through the brine shrimp lethality bioassay. The extracts from the Asteraceae family were more bioactive against Bacillus subtilis and Staphylococcus aureus. The extracts of both families studied were bioactive against the fungi Candida albicans and Fusarium solani. In addition, the extracts of Asteraceae species displayed the greatest cytotoxic activities. However, the most important specie in this research was Gonzalagunia rosea Standl (Rubiaceae) because of the strong and moderate activities of the methanol and dichloromethane extracts against C. albicans and F. solani, respectively; as well as the strong cytotoxic activity of the methanol extract. None of these ten plants has previously been reported for their biological activities.

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As concentrações de diosgenina em uma coleção de tubérculo de Dioscorea polygonoides do Eje Cafetero (EC, Colombia) foram determinadas por cromatografia líquida de alta eficiência. Os teores obtidos variaram de 0,02 a 2,64%. A maior concentração de diosgenina (2,64%) foi obtida de um tubérculo coletado perto de Salento (Quindio). A média de recuperação desta foi de 97%. A identificação foi feita por cromatografia gasosa-espectrometria de massas (CG-EM) e por coeluição com o padrão autentico. Os resultados destes estudos foram importantes uma vez que os teores de diosgenina obtidos se mostraram superiores quando comparados aqueles relatados para outras espécies medicinais de Dioscorea, tornando Dioscorea polygonoides uma fonte potencial de diosgenina.The diosgenin concentrations in a Dioscorea polygonoides tuber collection from the Eje Cafetero (EC, Colombia) were determined by HPLC and their percentages ranged from 0.02 to 2.64%. The highest diosgenin concentration (2.64%) was obtained in a tuber collected near Salento (Quindío). The average of diosgenin recovery was 97%. Diosgenin was identified by gas chromatography-mass spectrometry (GC-MS) and by coelution with authentic diosgenin standard in both HPLC and GC-MS techniques. The results of this study are important since comparatively they are higher than most of those reported on other medicinal Dioscorea species, making Dioscorea polygonoides a potential new source of diosgenin.

The alkaloids lycorine, 1-O-acetyllycorine and ismine were isolated from the basic dichloromethane- soluble fraction of Crinum x powellii “Album” bulbs. The alkaloid structures were established by physical and spectroscopic analyses, including 1D NMR techniques and GCMS analysis. The three alkaloids are reported for the first time for this hybrid. Additionally, the three alkaloids isolated were tested against a mechanism-based bioassay utilizing genetically engineered mutants of the yeast Saccharomyces cerevisiae strains RAD+, RAD52Y and RS321 where lycorine was the only alkaloid that displayed moderate topoisomerase I inhibitory activity.