Pablo Sanchez-Vindas

Insecticidal defenses of Piperaceae from the neotropics.

Insecticidal and growth-reducing properties of extracts of 14 species of American neotropical Piperaceae were investigated by inclusion in diets of a polyphagous lepidopteran, the European corn borer,Ostrinia nubilalis. Nutritional indices suggested most extracts acted by postdigestive toxicity.Piper aduncum, P. tuberculatum, andP. decurrens were among the most active species and were subjected to bioassay-guided isolation of the active components. Dillapiol was isolated from the active fraction ofP. aduncum, piperlonguminine was isolated fromP. tuberculatum, and a novel neolignan fromP. decurrens. The results support other studies on Asian and AfricanPiper species, which suggest that lignans and isobutyl amides are the active defence compounds in this family.

Traditionally-Used Antimalarials from the Meliaceae

A quantitative ethnobotanical approach to antimalarial drug discovery led to the identification of Lansium domesticum Corr. Ser. (Meliaceae) as an important antimalarial used by Kenyah Dyak healers in Indonesian Borneo. Triterpenoid lansiolides with antimalarial activity were isolated from the bark and shown to have activity in both in vitro bioassays with Plasmodium falciparum, and in mice infected with P. berghei. A survey of African and tropical American Meliaceae led to further development of the limonoid gedunin from the traditionally used medicinal plants, tropical cedar, Cedrela odorata L., and neem, Azadirachta indica A. Juss. Gedunin has significant in vitro activity but initially showed poor in vivo activity. In vivo activity was improved by (1) incorporation into an easy to absorb suspension, (2) preparation of a more stable compound, 7-methoxygedunin; and (3) synergism with dillapiol, a cytochrome P450 3A4 inhibitor. The results show the potential for both antimalarial drug and phytomedicine development from traditionally used plants.

Screening of Costa Rican Trichilia species for biological activity against the larvae of Spodoptera litura (Lepidoptera: Noctuidae)

Crude methanolic extracts made from the twigs of 39 plant samples from six species of Trichilia collected in Costa Rica, were incorporated into artificial diet and fed to neonate Spodoptera litura larvae. All six plant species tested significantly reduced larval growth after 7 and 10 days. The most active species was T. americana, reducing growth, on average, to 3.9% of control at 1000ppm fresh weight. The least active, on average, was T. glabra. A twig extract of T. americana proved to be more active than wood, bark or leaf extracts, with the twig extract reducing growth of S. litura larvae by 50% (EC(50)) at a dietary concentration of 17.2ppm. When T. americana wood extract was incorporated into artificial diet (10, 25, 50 and 75ppm) and fed to S. litura larvae throughout larval development, growth was slowed and the final weight of pupae and adults was reduced. At higher extract concentrations (50 and 75ppm) larvae entered one or two supernumerary instars before pupation occurred. This was shown to be due to both starvation and to post-ingestive activity of the extract.

A regression analysis of q’eqchi’ Maya medicinal plants from southern Belize

A previous study provided a general quantitative analysis of 169 collected medicinal plants used by the Q’eqchi’ Maya healers of southern Belize. This paper is focused on a statistical analysis of this ethnobotanical information using the method developed by Moerman (1991). The residual values obtained from the regression analysis of the Q’eqchi’ medicinal plant species versus the species listed in the checklist of the vascular plants of Belize (Balick, Nee, and Atha, 2001) placed the Piperaceae, the Rubiaceae, and the Asteraceae in the first three ranks, and the Poaceae, the Cyperaceae, and the Orchidaceae in the last three ranks. The results were compared with three northern temperate regions (Kashmir, Korea, and North America) and three southern neotropical regions (Chiapas, Ecuador, and Veracruz). The coefficients of correlation between the checklist of vascular plants of Belize and the other six floras showed, as expected, high values for regions with similar climatic type. Thus, high correlations were determined between the tropical vegetation of Belize and those of Chiapas, Ecuador, and Veracruz. The coefficients were lower with the three temperate floras but still quite high. The same analysis was done with the medicinal plants only and led to much lower coefficients, but once again, the higher results were obtained for Chiapas and Veracruz. In this case, the last rank for Ecuador demonstrated that the selection of plants in traditional medicine by the indigenous people is a complex phenomenon which depends not only on the composition of the flora but also on culture-specific factors.RésuméUne précédente étude a fourni une analyse quantitative générale de 169 plantes médicinales utilisées par les guérisseurs Maya Q’eqchi’ du sud du Belize. Ce document se concentre sur l’analyse statistique des informations ethnobotaniques selon la méthode développée par Moerman (1991). Les valeurs résiduelles obtenues à partir des analyses de régression des plantes médicinales Q’eqchi’ vis-à-vis des espèces mentionnées dans la liste des plantes vasculaires du Belize (Balick, Nee, et Atha, 2001) ont placé les Piperacées, les Rubiacées et les Asteracées aux trois premières places, et les Poacées, les Cyperacées et les Orchidacées aux trois dernières places. Les résultats ont été comparés avec ceux de trois régions tempérées du nord (Cachemire, Corée, et Amérique du Nord) et de trois régions néotropicales du sud (Chiapas, Équateur, et Veracruz). Les coefficients de corrélation entre les plantes listées dans le manuel des plantes vasculaires du Belize et les six autres flores ont montré comme attendu de hautes valeurs pour les régions possédant un type climatique similaire. Ainsi, une haute corrélation a été démontrée entre la végétation tropicale du Belize et celles du Chiapas, de l’Équateur, et du Veracruz. Les coefficients étaient plus bas avec les trois régions tempérées mais tout de même passablement élevés. La même analyse a été effectuée avec les plantes médicinales et a mené à des coefficients beaucoup plus bas, mais encore une fois, les résultats les plus élevés ont été obtenus pour le Chiapas et le Veracruz. Dans ce cas, la dernière position de l’Équateur a souligné que la sélection des plantes par les indigènes dans la médecine traditionnelle est un phénomène complexe qui dépend non seulement de la composition de la flore mais aussi de facteurs spécifiques à la culture.

Novel steroids from Trichilia hirta as identified by nanoprobe INADEQUATE 2D-NMR spectroscopy

Abstract Two novel steroids, 3-hydroxypregnane-2,16-dione [ 1 ] and 2-hydroxyandrosta-1,4-diene-3,16 dione [ 2 ], were isolated from ethanolic extracts of the wood and bark of Trichilia hirta . The structure of 1 was rigorously determined from 2D-INADEQUATE NMR data that was: 1) acquired with a new higher-sensitivity 13 C probe called a Nano·nmr probe, and; 2) processed with a new NMR-analysis program called FRED, which automatically generated the complete carbon structure (as shown). In this first known application of both a Nanoprobe and FRED software to an unknown compound, the complete carbon skeleton was easily determined using only 11 mg (30 μmoles) of sample.

Inhibition of Bacterial Quorum Sensing and Biofilm Formation by Extracts of Neotropical Rainforest Plants

Bacterial biofilms are responsible for many persistent infections by many clinically relevant pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. Biofilms are much more resistant to conventional antibiotics than their planktonic counterparts. Quorum sensing, an intercellular communication system, controls pathogenesis and biofilm formation in most bacterial species. Quorum sensing provides an important pharmacological target since its inhibition does not provide a selective pressure for resistance. In this study, we investigated the quorum sensing and biofilm inhibitory activities of 126 plant extracts from 71 species collected from neotropical rainforests in Costa Rica. Quorum sensing and biofilm interference were assessed using a modified disc diffusion bioassay with Chromobacterium violaceum ATCC 12,472 and a spectrophotometric bioassay with Pseudomonas aeruginosa PA14, respectively. Species with significant anti-quorum sensing and/or anti-biofilm activities belonged to the Meliaceae, Melastomataceae, Lepidobotryaceae, Sapindaceae, and Simaroubaceae families. IC50 values ranged from 45 to 266 µg/mL. Extracts of these active species could lead to future development of botanical treatments for biofilm-associated infections.

Spirocaracolitone isolated from a new genus and species, Ruptiliocarpon caracolito. The first CD spiro-triterpenoid

Abstract The novel spiro-triterpenoid spirocaracolitone, was isolated from a newly described genus and species, Ruptiliocarpon caracolito Hammel and Zamora (Lepidobotryaceae), a tree from humid lowland tropical rainforest in Costa Rica. Spectroscopic methods allowed for the elucidation of fragments of the molecule but only X-ray diffraction yielded the definitive structure. Spirocaracolitone has a unique, previously unreported CD spiro friedelin skeleton.