Structural, histochemical, and phytochemical characterization of Mikania cordifolia (L. f.) Willd. (Asteraceae) in a coastal dune environment

Abstract

Coastal dune is a habitat that presents determining and often limiting factors for plant development. Species of Asteraceae, such as Mikania cordifolia, are commonly found in this environment, including occupying frontal dunes, where winds, salinity, and soil represent severe environmental conditions. Asteraceae is recognized for its different secretory structures and for containing species with potential for bioprospecting. Mikania cordifolia is a species with a voluble habit, wide geographic distribution, and records of medicinal use. However, no studies in the literature cover the anatomical, histochemical, and chemical investigation of all vegetative organs of the mentioned species. In this sense, this study evaluated the anatomical organization of the vegetative organs of M. cordifolia, including secretory structures, as well as the chemical composition of the extract of each organ. For this, diaphanization, microtomy, histochemistry, and phytochemistry techniques were used. Our results showed that the vegetative organs have several adaptations to the coastal dunes environmental conditions, among them the presence of four types of secretory structures – secretory canals and cavities, trichomes and hydathodes. Histochemical analyzes indicated sesquiterpene lactones, pectic and phenolic compounds, lipophilic substances, flavonoids, coumarins, starch and tannins. Nuclear magnetic resonance analyzes showed kaurane diterpenes, steroids, fatty acids, phenolic derivatives, and methoxylated substances. Our results contribute to the understanding of the structure and phytochemistry of the genus Mikania, the adaptations of the species to the coastal dune environment, and the occurrence and distribution of secretory structures in the genus, promoting knowledge and justifying the conservation of the coastal dunes flora.