Evaluation of the antibacterial synergism of two plant extracts belonging to Bignoniaceae family and development of a topical formulation

Abstract Fridericia caudigera and Cuspidaria convoluta (Bignoniaceae) species, which grow in the northwest of Argentina, have shown antibacterial effect against strains isolated from skin infections, and each one displayed synergism with commercial antibiotics. The aims of this work were to evaluate the antibacterial activity and toxicity of the combination of these two plant species, and to design a stable gel for topical use including the blend of extracts. The combination of extracts was evaluated for synergistic effects (chequerboard assay), genotoxicity (Ames test) and cytotoxicity (Artemia salina test). A gel was subsequently formulated with the combination of extracts using carboxymethylcellulose as a polymer. The following physico- chemical characteristics of the gel formulation: pH, viscosity, spreadability and total phenol content, as well as resistance to severe temperature changes, biological activity (diffusion in agar), in vitro permeation (Franz cells) and primary dermal irritation (Draize test) were analyzed. The combination of extracts showed a synergistic effect on pathogenic bacteria and was not toxic in the in vitro tests. The gel was stable and retained the antimicrobial activity of the original extracts. The formulation proposed in this work could constitute an alternative for primary skin infections since it proved to be safe for topical administration.

Phytochemical composition and biological screening of two Lophophytum species / Composición fitoquímica y cribado biológico de dos especies de Lophophytum

Lophophytum species are holoparasites that grow on tree roots. The objectives of the work were to explore the chemical composition of the tubers of two Lophophytum species and to analyze the antioxidant, anti-inflammatory and antilithiatic activity of their extracts using in vitro methods. The chemical composition was determined by histochemical, phytochemical and TLC tests. In addition, the profile of phenolic compounds was determined by HPLC-MS. The presence of secondary metabolites of recognized activity was demonstrated. The results of the HPLC-MS/MS allowed the tentative identification of catechin, luteolin and glycosides of eriodictyol, naringenin and luteolin in the extract of Lophophytum leandriand eriodictyol, naringenin, luteolin and their glycosylated derivatives in Lophophytum mirabile. The extracts showed promising antioxidant (DPPH, ABTS and ß-carotene-linoleic acid), anti-inflammatory (inhibition of 5-LOX) and anti-urolytic (by bioautographic TLC) activity. It is noteworthy that these are the first results of the phytochemical composition and biological activity of L. mirabile. However, in vivo studies are required to corroborate these activities.

Las especies de Lophophytumson holoparásitas que crecen en raíces de árboles. Los objetivos del trabajo fueron explorar la composición química del túber de dos especies de Lophophytum y analizar la actividad antioxidante, antiinflamatoria y antilitiásica de sus extractos usando métodos in vitro. La composición química se determinó mediante pruebas histoquímicas, fitoquímicas y por TLC. Además, se determinó el perfil de compuestos fenólicos por HPLC-MS/MS. Se demostró presencia de metabolitos secundarios de reconocida actividad. Los resultados del HPLC-MS/MS permitieron identificar tentativamente catequina, luteolina y glucósidos de eriodictiol, naringenina y luteolina en el extracto de Lophophytum leandriy eriodictiol, naringenina, luteolina y sus derivados glicosilados en Lophophytum mirabile. Los extractos mostraron prometedora actividad antioxidante (DPPH, ABTS y ß-caroteno-ácido linoleico), antiinflammatoria (inhibición de la 5-LOX) y antiurolitiásica (por TLC bioautográfica). Es de destacar que estos son los primeros resultados de composición fitoquímica y actividad biológica de L. mirabile. Sin embargo, se requieren estudios in vivo para corroborar dichas actividades.

Antibacterial activity of essential oils of aloysia polystachya and lippia turbinata (Verbenaceae) / Actividad antibacteriana de los aceites esenciales de aloysia polystachya y lippia turbinata (Verbenaceae)

Aloysia polystachya and Lippia turbinata are medicinal and aromatic plants. Nevertheless, there are few reports in literature concerning the biological properties of species that grow in northeastern Argentina. The antibacterial activity and the chemical composition of both essential oils were evaluated in this work. The extraction was performed by steam distillation and their volatile compounds were determined by gas chromatography/mass spectrometry. The antibacterial activity was evaluated by disc diffusion and broth microdilution assay. The main compounds were carvone (78.9 percent) and limonene (14.2 percent) in A. polystachya and carvone (80.77 percent), limonene (8.73 percent), beta- caryophyllene (2.13 percent) and 1,8-cineole (1.70 percent) in L. turbinata. Both essential oils were bactericide against Escherichia coli ATCC 35218 and clinical isolates of Enterobacter cloacae and Klebsiella pneumoniae. Essential oil of A. polystachya was also bactericide against Staphylococcus aureus ATCC 29212, S. aureus ATCC 25923 and clinical strain of S. aureus methicillin susceptible.

Aloysia polystachya y Lippia turbinata son plantas medicinales y aromáticas. Hay pocos informes en la literatura sobre las propiedades biológicas de especies que crecen en el nordeste de Argentina. La actividad antibacteriana y la composición química de ambas especies se evaluaron en este trabajo. La extracción se realizó por destilación con vapor y sus compuestos se determinaron por cromatografía gaseosa/espectrometría de masa. La actividad antibacteriana fue evaluada por difusión en discos y microdilución en caldo. Los principales compuestos fueron carvona (78.9 por ciento) y limoneno (14.2 por ciento) en A. polystachya y carvona (80.77 por ciento), limoneno (8.73 por ciento), beta-cariofileno (2.13 por ciento) y 1,8-cineol (1.70 por ciento) en L. turbinata. Ambos aceites esenciales fueron activos contra Escherichia coli ATCC 35218 y aislamientos clínicos de Enterobacter cloacae y Klebsiella pneumoniae. El aceite esencial de A. polystachya fue bactericida contra Staphylococcus aureus ATCC 29212, S. aureus ATCC 25923 y aislamientos clínicos de S. aureus sensible a meticilina.