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Two new triterpenoids, 21 beta-hydroxyolean-12-en-3-one (1) and a seco-dinor derivative of pristimerine named dzununcanone (2), were isolated from the root bark of Hippocratea excelsa. Their structures were assigned on the basis of spectroscopic evidence, mainly 1H and 13C 1D and 2D NMR including DEPT, COSY, ROESY, HSQC, and HMBC experiments, as well as EIMS and HREIMS. The known 21alpha-hydroxy-3-oxofriedelane (3), a compound new to the species, and the known methide quinones pristimerine (4) tingenone (5), and xuxuarine Ebeta (7) were also isolated. The antiprotozoal activities were determined against Giardia intestinalis. Pristimerine and tingenone were the most active antigiardial compounds, with IC50 values of 0.11 and 0.74 microM, respectively, compared with metronidazole, the current drug of choice (IC50 1.23 microM).

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Banned or restricted organochlorine pesticides in many countries worldwide are still in use in developing countries for agricultural and livestock activities, as well as for vector control in public health campaigns. The present study was conducted to map estimated concentrations of organochlorine pesticides in a karstic region in the Yucatan Peninsula, Mexico, known as ‘Ring of Cenotes’. Water samples from 20 sinkholes (‘cenotes’) were collected during the dry and rainy seasons in 2010–11, analysed by gas chromatography and maps of pesticide concentrations were produced using geographical information system. Results show the presence of banned pesticides, all of them exceeding the limits stated by the Mexican Official Norm. The number and concentration of pesticides during the dry season were qualitatively and quantitatively higher than in the rainy season. The spatial distribution of pesticide concentrations shows that causes of pesticide pollution in the aquifer of the Ring of Cenotes are multifactorial.