Screening of Venezuelan plants for anti-inflammatory activity. Results from an in vitro nitric oxide assay

Abstract

Due to its geographical location in the north of South America, Venezuela is considered to be one of the richest and varied countries in terms of plant diversity. Estimates of the total flora of Venezuela near 30,000 species, of which more than 1,500 are used for medicinal purposes by indigenous and local communities. However, only a relatively small proportion of these have been evaluated in terms of their anti-inflammatory activity. Our botanical database (MedPlant) now contains over 4,000 collections representing over 2,000 species. Most of the plants were collected in three states of Venezuela, Amazonas, Bolívar and Cojedes, from 1999 to the present. In this study, we evaluated 165 extracts from 92 species for inhibition of nitric oxide production (Griess assay) by the LPS- stimulated monocyte/macrophage cell line RAW 264.6, as a possible indicator of anti-inflammatory activity. The most promising extracts (50% inhibition of NO at < 40 µg/ml, without cytotoxic effect) were from Tapirira guianensis, Jacaranda copaia, Oxycaryum cubense, Croton cuneatus, Cochlosperm vitifolium, Datura inoxia, Hamelia patens, Ipomoea carnea, Machaerium madeirense, Euterpe precatoria and Costus scaber. Some of these have reported anti-inflammatory activity (Croton cuneatus, Cochlosperm vitifolium, Hamelia patens), while others, such as Datura inoxia, Tapirira guianensis and Oxycaryum cubense have not been reported to show such activity until now. A selection of these plants is now under study using bioassay-guided fractionation.