Abstract. The trimeric caffeic acid derivative pulcaffeate (1) was isolated from the organic crude extract of the roots of Bourreria pulchra (Boraginaceae). The biosynthesis of 1 appears to involve an intramolecular Diels-Alder reaction between a cyclohexa-1,3-diene intermediate, generated by the oxidation of the aromatic ring of a cinnamic acid unit, and the conjugated double bond of a caffeic acid unit. The structure of the new metabolite was elucidated through a detailed analysis of its 1H and 13C NMR spectroscopic data. This is the first report of a trimeric metabolite occurring in B. pulchra.

Resumen. Pulcafeato (1) un derivado trimérico del ácido cafeico fue aislado del extracto orgánico crudo de las raíces de Bourreria pulchra (Boraginaceae). La biosíntesis de 1 parece llevarse a cabo mediante una reacción intramolecular de Diels-Alder entre un intermediario de cyclohexa-1,3-dieno, generado durante la oxidación del anillo aromático de una unidad de ácido cinámico, y el doble enlace conjugado de una unidad de ácido cafeico. La estructura del nuevo metabolito fue elucidada mediante el análisis detallado de sus datos espectroscópicos de RMN de 1H y 13C. Este es el primer reporte sobre la presencia de un metabolito trimérico en B. pulchra.

ABSTRACT The ethanolic extract of Melipona beecheii Bennett 1831, propolis from Yucatán Mexico was evaluated in vitro for the determination of its phenolic compound content, antioxidant capacity and antifungal activity. The results were compared against those of the ethanolic extract of Apis mellifera propolis. The total phenolic content, flavonoid content and flavanones–dihydroflavonols content were assessed by colorimetric methods. The antifungal activity was assessed in vitro against Candida albicans. For the ethanolic extract of M. beecheii propolis; total phenolic content, was 263.25 ± 8.78 µg/ml, total flavonoid content was 768 ± 204 µg/ml and flavanones–dihydroflavonols content was 335.42 ± 15.08 µg/ml. For antioxidant activity assessed as DPPH scavenging and iron reducing power ethanolic extract of M. beecheii propolis reported IC50 of 32.47 and 1.60 µg/ml of gallic acid equivalent respectively. Regarding antifungal activity against C. albicans, the minimal inhibitory concentration and minimal fungicidal concentration for ethanolic extract of M. beecheii propolis were 1.62 ± 0.33 and 2.50 ± 0.22 µg/ml of dry extract; For both minimal inhibitory concentration and minimal fungicidal concentration, ethanolic extract of M. beecheii propolis required 30% less concentration of dry extract than ethanol extract of A. mellifera propolis to exert the same antifungal actions against C. albicans. To the best of our knowledge, this is the first report about the flavonoid and flavanones–dihydroflavonols content of M. beecheii propolis. Due to the lack of information available about the stingless bee's honeycomb products, the study and conservation of endemic honeybees should remain as an active focus of research.

ABSTRACT Thirteen pentacyclic triterpenes, methyl 3-oxours-12-en-23-oate, marsformosanone, taraxerone, β-amyrenone, α-amyrenone, lupenone, 24-methylencycloartan-3-one, moretenol acetate, β-amyrin acetate, germanicol acetate, 24-methylencycloartanyl acetate, β-amyrin, and α-amyrin were identified in a chloroform-methanol propolis extract from Melipona beecheii. Additionally, were identified in this propolis, hexadecanoic acid, methyl ester, octadecanoic acid, methyl ester and 1-triacontanol. The purification of the propolis extract was carried out using different chromatographic techniques, including vacuum liquid chromatography, gravity column chromatography and gel filtration chromatography Sephadex LH-20. The identification of the metabolites was performed using mass spectrometry.

Two natural isocordoin derivatives, dihydroisocordoin (1) and flemistrictin B (2), were isolated from the root extract of Lonchocarpus xuul. Both metabolites were identified on the basis of their spectroscopic data and by comparing them with those reported in the literature.

Del extracto de la raíz de Lonchocarpus xuul fueron aislados dos derivados naturales de isocordoína, dihidroisocordoína (1) y flemistrictina B (2). Ambos metabolitos fueron identificados con base en sus datos espectroscópicos y por comparación de los mismos con los reportados en la literatura.