Roberto Pinzón

Argentine plants as potential source of insecticidal compounds

CH2Cl2 and MeOH extracts of 15 Argentine plants used locally as insecticides, were evaluated for their insecticidal activity. Chenopodium multifidum L. (Chenopodiaceae); Flaveria bidentis (L.) O.K. (Compositae); Aristolochia argentina Gris. (Aristolochiaceae) and Tagetes erecta L. (Compositae) showed a significant activity against Sitophilus oryzae.

Value of the ethnomedical information for the discovery of plants with antifungal properties. A survey among seven Latin American countries.

ETHNOPHARMACOLOGICAL RELEVANCE This study reports the antifungal evaluation of 327 plant species (92 families and 251 genera) from seven Latin American countries which were selected on the basis of their reported ethnomedical uses and compared them with plants selected at random. AIM OF THE STUDY (a) The main aim of this study was to investigate whether the probability of detecting antifungal plants is higher when plants have reports of ethnopharmacological uses related to fungal infections (PAU group) than when they are selected at random (PNAU group). (b) The second objective was to determine, within the PAU group, whether the probability of obtaining a positive result will be higher when the plants are tested against dermatophytes, than against yeasts or Aspergillus spp. (c) The third goal was to investigate, within all MICs<or=1000 microg/mL, if the MICs displayed by the PAU group are comparatively lower than MIC values of the PNAU group; that is to say, if they can be expected more potent antifungal plants within the group of plants that have a history of traditional use related to fungal infections than when they do not have one. MATERIALS AND METHODS A five-stage process of documentation, evaluation and analysis of results was conducted: (1) selection of words that could describe the ethnopharmacological use related to fungal infections; (2) a survey of specialized literature in each country; (3) collection and preparation of an extract of each plant; (4) antifungal evaluation of the selected plants and (5) statistical analysis of the results. For the antifungal evaluation, the microbroth dilution assay recommended by the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) was used against a panel of eleven human opportunistic and pathogenic fungi. For the statistical analysis the Pearsons Chi Square test and the Scores test were used. RESULTS (a) A significantly higher probability of detecting plants with antifungal activity against at least one fungus was found within the PAU (40.3%) than the PNAU group (21.3%) (p<0.01). (b) A similar higher probability than in (a) (39.6% vs. 20.8%) was found when plants were tested against dermatophytes (p<0.01) but not against yeasts or Aspergillus spp. (p>0.05). (c) Within the detected antifungal plants from both groups, plants of the PAU group displayed higher activities (lower MICs) than those of PNAU group against dermatophytes (p<0.05) but not against yeasts or Aspergillus spp. CONCLUSIONS Considering that dermatophytes are the cause of superficial fungal infections, which can be easily detected and followed by traditional healers, our findings suggest that the ethnopharmacological approach is useful in guiding the detection of antifungal plants in Latin America mainly for infections in which the pathological expression is obvious and, therefore, the cure can be clearly observed.

Screening of Latin American Plants for Cytotoxic Activity

Abstract The SRB cytotoxicity assay was used to screen plant extracts, in a collaborative multinational OAS project involving Argentina, Bolivia, Colombia, Costa Rica, Guatemala, Nicaragua and Panama, against breast (MCF-7), lung (H-460), and central nervous system (SF-268) human cancer cell lines. Out of 310 species tested, 23 (7.4%) plants showed cytotoxic activity at GI50 values ≤10 µg/ml. The most active plants were Thevetia ahouai., Physalis viscosa., Piper jacquemontianum., Piper barbatum., Senna occidentalis., Tovomita longifolia., and Lippia cardiostegia.. Blepharocalyx salicifolius. and Senna occidentalis. were selectively active against one cell line, SF-268 or MCF-7, respectively. Within the framework of this project, 14 compounds have been isolated, 5 new (4 benzophenones, coumarin) and 9 known to the literature. But only the bioassay-guided fractionation of the active extract of Piper barbatum. leaves, which led to the isolation of three known compounds: (2′E., 6′E.)-2-farnesyl-1,4-benzoquinone (1), (2′E., 6′E.)-2-farnesylhydroquinone (2), and dictyochromenol (3), is reported here. The chemical structures of 1 and 2 were determined by spectral means (1D, 2D NMR, MS) and chemical data. Among these three, (2′E., 6′E.)-2-farnesyl-1,4-benzoquinone was the most active (MCF-7 GI50 = 1.8 µg/ml; H-460 GI50 = 4.8 µg/ml; SF-268 GI50 = 3.5 µg/ml).

Screening of Latin American plants for antiparasitic activities against malaria, Chagas disease, and leishmaniasis.

In order to explore rationally the medical potential of the plant biodiversity of the Central and South American region as a source of novel antiparasitic molecules, a multinational Organization of American States (OAS) project, which included the participation of multidisciplinary research centers from Argentina, Bolivia, Colombia, Costa Rica, Guatemala, Nicaragua and Panama, was carried out during the period 2001-2004. This project aimed at screening organic plant extracts for antitrypanosomal, antileishmanial and antimalarial activities and subsequently isolating and characterizing bioactive molecules. Plants for antiparasitic screening were selected from a database of ethnomedical uses of Latin American plants (PlanMedia) based on the amount of biological and chemical information available in the literature. We report here the evaluation of 452 extracts from 311 plant species in vitro screens against Plasmodium falciparum, Leishmania mexicana, and Trypanosoma cruzi. Out of 311 species tested, 17 plants (5.4%) showed antiparasitic activities at IC50 values ≤ 10 µg/mL. The most active plants were Acnistus arborescens (L.) Schltdl. (Solanaceae) (leaf, EtOH, IC50: 4 µg/mL) Monochaetum myrtoideum Naudin (Melastomataceae) (leaf, MeOH, IC50: 5 µg/mL) and Bourreria huanita (Lex.) Hemsl. (Boraginaceae) (branch, EtOH, IC50: 6 µg/mL). These were selectively active against P. falciparum, L. mexicana and T. cruzi, respectively.

Antinociceptive and uterine relaxant activities of Viburnum toronis alive (Caprifoliaceae)

Petroleum ether, ethyl acetate and methanolic leaf extracts of Viburnum toronis Killip et Smith were studied. From the petroleum ether extract, fatty acids of methyl esters such as methyl myristate, methyl palmitate, methyl stearate and methyl araquidonate were identified by means of GC-MS. From the ethyl acetate extract, 2-methylbutanoic, 2-methyl-2-butenoic, 3-methylbutanoic acids and 4-hydroxy-4-methylpentanone were identified by means of GC-MS. Through the isolated organ technique, uterine relaxant was verified; and through the method of writhings induced by acetic acid, the antinociceptive activity of methanolic extracts and the extract in ethyl acetate were verified. It was found that the extract in ethyl acetate showed the greatest in both uterine relaxant and antinociceptive activity at doses of 250 mg/kg.

Subcutaneous antifungal screening of Latin American plant extracts against Sporothrix schenckii and Fonsecaea pedrosoi

Context: Subcutaneous mycoses are chronic infections caused by slow growing environmental fungi. Latin American plants are used in folk medicine to treat these afflictions. Moreover, the potential of the rich Latin American biodiversity for this purpose has not been fully explored. Objectives: The aim of the study was to screen Latin American plant extracts against two species of subcutaneous fungi: Sporothrix schenckii and Fonsecaea pedrosoi. Materials and methods: One hundred ninety-five organic extracts from 151 Latin American plants were screened against two subcutaneous fungi by the agar dilution method at a concentration of 100 µg/mL, and minimum inhibitory concentrations (MICs) of active extracts were determined. Positive (amphothericin B) and negative (50% ethanol) controls were used. Results and discussion: Twenty eight extracts showed activity at ≤100 µg/mL. Of these, four extracts from Gnaphalium gaudichaudianum DC (Asteraceae), Plumeria rubra L (Apocynaceae), Tecoma stans (L.) Juss. ex Kunth. (Bignoniaceae), and Trichostigma octandum (L.), H. Walter showed activity against F. pedrosoi at MIC 12.5 µg/mL; and, four extracts from Bourreria huanita (Lex.) Hemsl. (Boraginaceae), Phytolacca bogotensis Kunth (Phytolaccaceae), Monnina xalapensis Kunth (Polygalaceae) and Crataegus pubescens (C. Presl) C. Presl (Rosaceae) against S. schenckii. This is the first report on antifungal activity of the Latin American plants against these two subcutaneous fungi. Conclusion: S. schenkii and F. pedrosoi were inhibited by B. huanita (MIC: 12.5 and 25 µg/mL), G. gaudichaudianum (MIC: 50 and 12.5 µg/mL) and T. triflora (MIC: 25 µg/mL).

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.