In Tehuacán-Cuicatlán valley (Mexico), studies have been carried out on the essential oils of medicinal plants with antimicrobial activity and it was found that they present compounds in common such as: α-pinene, β-pinene, carvacrol, eugenol, limonene, myrcene, ocimene, cineole, methyl salicylate, farnesene, and thymol. The goal of this study was to assess the antimicrobial activity of essential oils’ compounds. The qualitative evaluation was carried out by the Kirby Baüer agar diffusion technique in Gram-positive bacteria (11 strains), Gram-negative bacteria (18 strains), and yeasts (8 strains). For the determination of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), the agar dilution method was used. All the evaluated compounds presented antimicrobial activity. The compounds eugenol and carvacrol showed the largest inhibition zones. Regarding yeasts, the compounds ocimene, cineole, and farnesene did not show any activity. The compounds eugenol, carvacrol, and thymol presented the lowest MIC; bactericidal effect was observed at MIC level for S. aureus 75MR, E. coli 128 MR, and C albicans CUSI, for different compounds, eugenol, carvacrol, and thymol. Finally, this study shows that the essential oils of plants used by the population of Tehuacán-Cuicatlán valley share compounds and some of them have antibacterial and fungicidal activity.

El Valle de Tehuacán-Cuicatlán (Puebla) es una zona de gran importancia florística por su amplia diversidad de especies vegetales. Dentro de esta riqueza se encuentra Dalea carthagenensis, que es utilizada por los habitantes del Valle como desinflamatorio y para tratar infecciones gastrointestinales. El objetivo del presente trabajo fue evaluar la actividad antimicrobiana diferencial de flores y tallos de D. carthagenensis a partir de extractos de distinta polaridad, y determinar su composición química general. Se obtuvieron los extractos hexánico, acetónico y metanólico de flores y tallos, mediante el método de maceración. Se evaluó la actividad antibacteriana y antifúngica por los métodos de difusión en agar, inhibición de crecimiento radial y dilución en agar. La composición química de la especie se determinó mediante pruebas cualitativas para fenoles, terpenos, alcaloides, taninos, glucósidos y saponinas. Los extractos hexánicos mostraron la mayor actividad antibacteriana y antifúngica. Staphylococcus aureus ATCC 29213 fue la cepa bacteriana más susceptible al extracto hexánico de flores (CMI = 0.125 mg/mL), así como al de tallo (CMI = 0.5 mg/mL). En la evaluación de la actividad antifúngica, Candida albicans ATCC 14065, C. albicans 17MR, C. albicans 18MR, C. albicans cc y C. tropicalis HA fueron las más susceptibles al extracto hexánico de flores (CMI = 0.125 mg/mL). De los hongos filamentosos, Trychophyton mentagrophytes fue la cepa más susceptible a los extractos hexánicos y acetónicos de flores y tallos, con porcentaje de inhibición del crecimiento radial mayor a 90 % en la concentración de 0.125 mg/mL. En los extractos se detectó la presencia de terpenos, fenoles, saponinas y taninos. Los resultados validan el uso medicinal de D. carthagenensis para el tratamiento de enfermedades de posible origen infeccioso.

Ethnopharmacological relevance Verbesina crocata (Cav.) Less. (Arnica or Capitaneja) is an endemic plant from Mexico restricted to the western part of the country. The aerial parts are used in traditional medicine for the treatment of wounds and burns. The objective of this investigation was to carry out a pharmacognostic study of V. crocata and establish markers that allow for the recognition of the characteristics of the plant and validate its traditional use. The study includes anatomical and chemical characteristics of the plant as well as evaluations of its antioxidant capacity and wound healing ability in a murine model. Materials and methods An anatomical study of V. crocata was performed on the middle part of the leaf and stem. A methanolic extract of this species (VcME) was obtained by methanolic maceration of the aerial parts. Subsequently, a partition of the VcME was made to obtain a hexanic fraction (VcH). The phytochemical preliminary screening and characterization by high-performance liquid chromatography/mass spectrometry (HPLC-ESI/MS) of the VcME and VcH were performed. The antioxidant activity and total phenolic content were quantified. The wound healing capacity of the methanolic extract was determined in CD-1 mice by the healing rate, the tensiometric method, and histological analysis. Results The anatomical study of V. crocata showed the presence of two types of secretory structures and their position on the leaves. In addition, the characteristics of the middle vein and trichomes are potentially useful for recognition of the species. Chemical compounds detected by HPLC-ESI/MS reveal the presence of sitosterol glycoside and catechin derivatives as principal constituents of V. crocata . The VcME showed low antioxidant capacity and total phenolic. V. crocata had a similar healing effect to Recoveron® in the tensiometric method, but the rate of healing was higher. According to the histological analysis, the treatment of V. crocata promoted the remodelling phase 15 days after the incisional wound. Conclusion This is the first pharmacognostic study of this species that covers the plant anatomy, chemical content and biological properties related to its traditional use. V. crocata favours wound healing according to physical and histological evaluations. In addition, the characteristics of the middle vein, trichomes and catechin glycosides are potentially useful for the recognition of this species.