ABSTRACT Castor bean (Ricinus communis L.) is an oleaginous plant of economic importance due to its different industrial applications. Edaphic characteristics are used to determine the viability of places considered as suitable to obtain castor oil. The objectives of this study were to determine the edaphic characteristics and oil content of R. communis, and to evaluate elicitation with salicylic acid (SA) in El Marqués, Querétaro, Mexico. Sampling was carried out in a direct way, selecting sites where castor bean plants were found. Samples of 1.5 kg of soil were taken and 3 clusters of castor bean in a mature state were collected from 21 accessions. The physicochemical characteristics of the soil and oil content of seeds were determined. Finally, 300 plants of the Guanajuatoil variety were planted and elicitated with different SA concentrations under greenhouse conditions in order to determine oil content. The physical analysis of the soil samples indicated dark-colored soils, Mollisol and Vertisol types, with different textures: clay, clay loam, sandy clay loam and sandy loam. Soil chemical analyses showed the following soil characteristics: pH 7.22; electrical conductivity 0.52 dS m-1; organic matter 7.17%; cation exchange capacity 26.77; calcium 38.62, magnesium 6.81, sodium 13.41and potassium 6.97 cmol kg-1; and nitrogen and phosphorus contents of 16.32 and 54 mg kg-1, respectively. Castor oil content was higher in clay soils (41.46%). The plants elicited with SA presented oil contents ranging from 28.99% to 52.9%, obtained with 100 and 900 ^M. In conclusion, elicitation with SA is an adequate method to increase oil content in castor bean seeds. The locality of El Marqués has good potential for the production of castor oil.

Abstract Many medicinal herbs are used in folk medicine without taking into account their toxicity. Hamelia patens Jacq. (Rubiaceae), a Mexican endemic species, is used for the empirical treatment of pain. The aim of this work was to evaluate the toxicity and antinociceptive effects of ethanolic extracts of H. patens leaves. The toxicity of H. patens leaves (500–5000 mg/kg) was evaluated in acute (14 days) and subacute (28 days) assays. In the subacute assay, a blood analysis (both hematology and chemistry) was carried out. The antinociceptive effects of H. patens leaves (50–200 mg/kg) were evaluated using thermal-induced nociception (hot plate) and the chemical-induced nociceptive tests (acid acetic and formalin). In the acute toxicity test, the LD50 estimated for H. patens leaves was 2964 mg/kg i.p. and >5000 mg/kg p.o., whereas in the subacute test HPE did not affect hematological or biochemical parameters. In chemical-induced nociception models, H. patens (100 and 200 mg/kg p.o.) showed antinociceptive effects with similar activity than 100 mg/kg naproxen. In the hot plate test, HPE at 100 mg/kg (17%) and 200 mg/kg (25%) showed moderate antinociceptive effects. HPE could be a good source of antinociceptive agents because of its good activity and low toxicity.