Insights into the mechanism of Na+,K+-ATPase inhibition by 2-methoxy-3,8,9-trihydroxy coumestan.

The molecular mechanisms involved in Na+,K+-ATPase inhibition by 2-methoxy-3,8,9-trihydroxy coumestan were investigated. We show that this compound decreases the free sulfydryl groups present in the enzyme and that its inhibitory effect is prevented by dithiothreitol and other two sulfydryl containing reagents. We propose a redox cycle culminating with the irreversible oxidation of sulfydryl groups essential for the catalytic activity of this enzyme and of two other related P-type ATPases.

Medicinal plants from open-air markets in the State of Rio de Janeiro, Brazil as a potential source of new antimycobacterial agents.

ETHNOPHARMACOLOGICAL RELEVANCE: Several medicinal plants are traditionally traded in open-air markets in Rio de Janeiro State (Brazil) to treat tuberculosis (TB) and related symptoms. AIMS OF THE STUDY: Conduct a survey in the open-air markets of 20 cities of Rio de Janeiro State to find medicinal plants that are popularly used to treat tuberculosis and other related diseases and assess their in vitro antimycobacterial activity. MATERIALS AND METHODS: We used direct observation and semi-structured interviews and asked herbalists to list species (free listing) in order to gather data about the plant species most commonly used for lung problems. We calculated a Salience Index and acquired two species of "erva-de-passarinho" (mistletoe), Struthanthus marginatus and Struthanthus concinnus (Loranthaceae), commonly used to treat tuberculosis for a bioassay-guided isolation of the antimycobacterial active principles. Extracts, fractions and isolated compounds of both species were assayed in vitro against susceptible (H37Rv) and rifampicin-resistant (ATCC 35338) Mycobacterium tuberculosis strains. RESULTS: From the interviews, we generated a list of 36 plant species belonging to 12 families. The mistletoes Struthanthus marginatus and Struthanthus concinnus showed high Salience Index values among plants used to treat tuberculosis. Bioassay-guided fractionation of hexane extracts from both species led to the isolation and/or identification of steroids and terpenoids. The Minimum Inhibitory Concentration (MIC) of the extracts and isolated compounds ranged from 25 to 200 µg/mL. Some of the isolated compounds have been previously assayed against Mycobacterium tuberculosis, others are reported here for the first time (obtusifoliol: MIC H37Rv 50 µg/mL, MIC ATCC 35338 12.5 µg/mL; 3-O-n-acil-lup-20(29)-en-3ß,7ß,15α-triol: MIC H37Rv 200 µg/mL, MIC ATCC 35338 100 µg/mL). CONCLUSIONS: This study demonstrated the importance of ethnobotanical surveys in markets as a source for new drugs and also for scientific validation of folk medicine.

Medicinal plants traded in the open-air markets in the State of Rio de Janeiro, Brazil: an overview on their botanical diversity and toxicological potential

Medicinal plants have been used for many years and are the source of new active substances and new drugs of pharmaceutical interest. The popular knowledge contained in the open-air markets is studied through urban ethnobotany, and is a good source of information for ethnobotanical research. In this context, we surveyed the literature on works concerning open-air markets in the State of Rio de Janeiro to gather knowledge of the commercialized plants therein. A literature search resulted in ten studies with 376 listed species, distributed in 94 families and 273 genera. Asteraceae family had the greater representation, followed by Lamiaceae and Fabaceae. Solanum was the most frequent genus. Two hundred and twenty four species could be considered potentially toxic or potentially interact with other drugs/medicines. Eighteen species are referred as "not for use during pregnancy", and 3 "not for use while nursing". These results are a source of concern since in Brazil, as it is worldwide, there is the notion that plants can never be harmful. The results for the Sørensen Coefficient showed greater similarity between works performed in very close study areas. Other studies presented low similarity, mainly because of the difficulty in plant identification or a very specific focus in methodology.

Structure-activity relationship of wedelolactone analogues: structural requirements for inhibition of Na+, K+ -ATPase and binding to the central benzodiazepine receptor.

Coumestans 2a-i, bearing different patterns of substitution in A- and D-rings, were synthesized and evaluated as inhibitors of kidney Na+, K+ -ATPase and ligands for the central benzodiazepine (BZP) receptor. The presence of a hydroxyl group in position 2 favours the effect on Na+, K+ -ATPase but decreases the affinity for the BZP receptor, allowing the design of more selective molecules than the natural wedelolactone. On the other hand, the presence of a catechol in ring D is important for the effect on both molecular targets.

Urban ethnobotany in Petrópolis and Nova Friburgo (Rio de Janeiro, Brazil) / Etnobotânica urbana em Petrópolis e Nova Friburgo (Rio de Janeiro, Brasil)

The main goal of this paper was the study of the useful plants sold in the open-air fairs of Petrópolis and Nova Friburgo, Rio de Janeiro, Brazil. Data collection was obtained through participant observation, semi structured interviews and free listing with four herbalist informants. From the interviews, 115 species (belonging to 49 families) were recorded: 94 for medicinal purposes, 12 with religious application, and 9 for ornamental purposes. Thirty percent of the species were native, and 72 percent herbaceous. The most representative families were Asteraceae (26 species) and Lamiaceae (10 species). The medicinal species related to diseases of the respiratory system were more common during the winter and autumn. "Espinheira-santa" (Clarisia cf. ilicifolia) had the highest Relative Importance (1.8) and collocation in all seasons using the Preference Ranking, although its effectiveness or toxicity levels have not been established. The importance of the study is to gather knowledge from local herbalists about commercialized species in open-air fairs and popular markets in the Rio de Janeiro State, which represent valuable resources for bioprospection.

O principal objetivo desse trabalho foi estudar as plantas úteis comercializadas em feiras livres em Petrópolis e Nova Friburgo, Rio de Janeiro, Brasil. Os dados foram coletados utilizando as técnicas de observação participante, entrevistas semi-estruturadas e listagem livre com quatro comerciantes de plantas medicinais. A partir dessas entrevistas, 115 espécies (pertencentes a 49 famílias) foram relacionadas: 94 com uso medicinal, 12 com uso religioso e 9 com uso ornamental. Trinta por cento das espécies são nativas e 72 por cento possuem hábito herbáceo. As famílias mais representativas foram Asteraceae (26 espécies) e Lamiaceae (10 espécies). As espécies medicinais indicadas para o tratamento de doenças do sistema respiratório foram mais freqüentes durante o outono e inverno. A espécie denominada como Espinheira-santa (Clarisia cf. ilicifolia) obteve o valor mais alto de Importância Relativa (1,8) e a mais alta colocação em todas as estações do ano utilizando o cálculo Preference Ranking, embora seus níveis de eficiência e toxidez não tenham sido ainda estabelecidos. O estudo se mostrou relevante, pois visa reunir o conhecimento dos informantes sobre as espécies que comercializam em feiras livres e mercados populares no estado do Rio de Janeiro, que representa uma valiosa fonte para a bioprospecção.