Research Article: DNA barcoding and TLC as tools to properly identify natural populations of the Mexican medicinal species Galphimia glauca Cav

Date Published: May 28, 2019

Publisher: Public Library of Science

Author(s): Reinier Gesto-Borroto, Alexandre Cardoso-Taketa, Jessica P. Yactayo-Chang, Karina Medina-Jiménez, Claudia Hornung-Leoni, Argelia Lorence, Maria Luisa Villarreal, Branislav T. Šiler.


Galphimia glauca is a plant that is endemic to Mexico and has been commonly used since pre-Hispanic times to treat various illnesses, including central nervous system disorders and inflammation. The first studies investigating a natural population of G. glauca in Mexico showed that the plant has anxiolytic and sedative activities in mice and humans. The plant’s bioactive compounds were isolated and identified, and they belong to a family of nor-secofriedelanes called galphimines. The integration of DNA barcoding and thin-layer chromatography analysis was performed to clarify whether the botanical classification of the populations in the study, which were collected in different regions of Mexico, as G. glauca was correct or if the populations consist of more than one species of the genus Galphimia. We employed six DNA barcodes (matK, rbcL, rpoC1, psbA-trnH, ITS1 and ITS2) that were analyzed individually and in combination and then compared each other, to indicate differences among the studied populations. In the phylogenetic analysis, ITS1 and ITS2 markers as well as the combination of all DNA regions were the most efficient for discriminating the population studied. The thin-layer chromatography analysis exhibited four principal chemical profiles, one of which corresponded to the populations that produced galphimines. DNA barcoding was consistent and enabled us to differentiate the populations that produce galphimines from those that do not. The results of this investigation suggest that the studied populations belong to at least four different species of the genus Galphimia. The phylogenetic analysis and the thin-layer chromatography chemical profiles were convenient tools for establishing a strong relationship between the genotype and phenotype of the studied populations and could be used for quality control purposes to prepare herbal medicines from plants of the genus Galphimia.

Partial Text

Galphimia glauca Cav. (Malpighiaceae), is a plant that is endemic to Mexico and has been traditionally used to treat different ailments, including central nervous system disorders and inflammation [1]. G. glauca is widely distributed in Mexico [2]; however, scientific investigations of the phytochemical and pharmacological properties of this plant have been limited to populations growing in specific localities of the country. The first studies were conducted in natural populations growing in Doctor Mora, Guanajuato, and showed that the plant has anxiolytic and sedative activities in both mice [3] and humans [4]. The bioactive compounds were isolated and identified, and they correspond to a family of nor-secofriedelanes known as galphimines [5,6]. Subsequently, two metabolomic analyses were carried out in seven populations of the plant collected in the states of Chiapas, Jalisco, Morelos and Querétaro. The results of these investigations showed that only two populations produce galphimines [3,7] exhibiting anxiolytic and sedative activities in mice; however, all of them had anti-inflammatory activity in mice [7]. These results indicate that although these plants are morphologically similar, they are different in respect to their biological activity and metabolic profile; these differences may be observed due to divergent environmental conditions or because the plants consist of different botanical species.

Eight populations botanically classified as G. glauca (six individuals per population) were analyzed using a molecular approach by DNA barcodes and phytochemical analysis by TLC. Individuals from four of these populations (GM, MC, MM and QJ) were studied previously by our group [30]. In this new research, we considered these four populations because three new DNA barcodes (psbA-trnH, ITS1 and ITS2) were introduced in the molecular analysis and to compare the actual chemical profiles by TLC analysis of individuals collected in the four abovementioned localities six years previously.