Chemical characterization of two morphologically related Espeletia (Asteraceae) species and chemometric analysis based on essential oil components

ABSTRACT In this study, a comprehensive phytochemical characterization of two morphologically related species from the genus Espeletia Mutis ex Bonpl., namely, Espeletia grandiflora Humb. & Bonpl. and Espeletia killipii Cuatrec., Asteraceae, has been performed by gas chromatography coupled to flame ionization detection, gas chromatography coupled to mass spectrometry and ultra-high performance liquid chromatography coupled to ultraviolet and high-resolution mass spectrometry. Analysis of ethanol extracts (70%, v/v) from leaves and concomitant compound dereplication allowed the identification of major peaks, most of them new reports for the genus Espeletia or the subtribe Espeletiinae. Chemical characterization of resins essential oils indicated several similarities and differences between both species and from other members of the subtribe. Chemometric analysis (hierarchical clustering analysis and orthogonal partial least-squares discriminant analysis) applied to the essential oil composition of 31 species from Espeletiinae furthermore allowed the identification of three primary clusters correlated with the taxonomy. Hence, this study underscored qualitative and semiquantitative differences between the chemical composition of leaves and resins of E. grandiflora and E. killipii, provided information on chemotaxonomy and described the presence of different trends in the essential oil composition from species of Espeletiinae.

Actividad antibacteriana de extractos y fracciones de hojas de Siparuna sessiliflora Kunth A. DC. (limoncillo) / Anti-bacterial action of extracts and fractions from Siparuna sessiliflora Kunth A. DC (limoncillo)

Introducción: Siparuna sessiliflora Kunth A. DC. es una especie vegetal comúnmente conocida en Colombia como limoncillo, utilizada por parte de varias comunidades indígenas para tratar diferentes problemas de salud. A pesar de contar con diversos registros de usos etnobotánicos, esta especie ha sido poco estudiada desde el punto de vista fitoquímico o de su actividad biológica. Objetivos: evaluar la actividad antibacteriana de los extractos y las fracciones obtenidos a partir de las hojas de Siparuna sessiliflora sobre Bacillus subtilis, Staphylococcus aureus, Escherichia coli y Pseudomonas aeruginosa. Métodos: el material vegetal fue extraído por maceración en frío con éter de petróleo y etanol 96 por ciento; estos extractos se fraccionaron por métodos cromatográficos y partición líquido/líquido; su actividad antibacteriana se evaluó por el método de difusión en gel por perforación en placa. Posteriormente, se identificaron los principales compuestos responsables de la bioactividad por medio de cromatografía de gases acolada a espectrometría de masas. Resultados: se encontró que las fracciones de alcaloides Alk 1 y Alk 2 presentaron actividad frente a B. subtilis, S. aureus y E. coli. Adicionalmente, la subfracción Alk 2A fue la más activa frente a B. subtilis. Se identificaron sobre todo alcaloides isoquinolínicos y un derivado del ácido cinámico como posibles compuestos responsables de la bioactividad. Conclusiones: se reportó la actividad antibacteriana de S. sessiliflora frente a bacterias grampositivas y gramnegativas, y se generó nuevo conocimiento sobre su fitoquímica que corrobora su uso tradicional en la cura de cuadros infecciosos.

Introduction: Siparuna sessiliflora Kunth A. DC. is a plant species popularly known in Colombia as «limoncillo¼ and used by several indigenous communities for treating different health disorders. Despite the many records of its ethnobotanical uses, this species has been poorly studied from a phytochemical or biological standpoint. Objectives: to evaluate the antibacterial activity of the extracts and fractions obtained from Siparuna sessiliflora´s leaves against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Methods: the plant material was extracted by cold maceration with petroleum ether and 96 percent ethanol. Those extracts were fractionated by chromatographic methods and liquid-liquid partitioning; additionally, its antibacterial activity was assessed by gel diffusion. Subsequently, there were identified the main bioactive compounds by gas chromatography-mass spectrometry. Results: it was found that the alkaloidal fractions Alk 1 and Alk 2 were active against B. subtilis, S. aureus and E. coli. Additionally, the subfraction Alk 2A was the most active against B. subtilis. Isoquinoline alkaloids and a cinnamic acid derivative were identified as possible compounds responsible for bioactivity. Conclusions: the antibacterial activity of S. sessiliflora against Gram positive and Gram negative bacteria was reported, so the new knowledge about its phytochemistry endorses its traditional use in the treatment of infections.