Potential antioxidant and toxicological activity of the essential oil of Rhaphiodon echinus (Nees & Mart) Schauer (Lamiaceae): morphoanatomy and polyphenolic composition of its extracts

• Published in: Phyton (Buenos Aires) 2018, Vol.87 (1), p.79-86
• Main Authors: Costa A, Rodrigues, Pereira, PS, Alves de Sousa, MK, Rodrigues, FC, Duarte Mendes, VR, Rodrigues Lima, KR, Marivando Barros, L, Rocha Sousa, CM, Alc鈔tara, MS, Leite Cavalcante, AB, Cruz Macedo, R, Kamdem, JP, Duarte, AE
• Format: Article
• Language: English
• Subjects: Acids; Anatomy; Antioxidants; Artemia; Ascorbic acid; Caffeic acid; Chemical composition; Creep (materials); Emulsions; Essential oils; Free radicals; Gallic acid; High-performance liquid chromatography; Liquid chromatography; Metabolites; Morphology; Oils & fats; Quercetin; Rhaphiodon; Scavenging; Secondary metabolites; Species; Toxicity; Toxicity testing; Toxicology
• ISSN: 1851-5657; 0031-9457; 1851-5657
• DOI: 10.32604/phyton.2018.87.079

The species Rhaphiodon echinus, known as betonica or creeping mint, is considered an infesting plant species, typical of the caatinga biome. Morphoanatomy is a very important tool to study the structure of plants, both its external and internal morphology, opening the knowledge about the production of secondary metabolites. These compounds are of great importance for scientific research, which may present themselves as the best antioxidants. Taking into account a lack of data in the literature on the essential oil of R. echinus, this study aimed to demonstrate its antioxidant activity and toxicity. In order to test this hypothesis, tests were carried out by the DPPH method, its toxicological activity on Artemia salina microcrustacean, as well as studies involving cuts of plant anatomy of leaf structures of the species. The vegetal material was collected at URCA and the essential oil was obtained by hydrodistillation, in a type of Clevenger. The HPLC profile of the extract revealed caffeic acid (62.45 mg/g), gallic acid (15.36 mg/g), Quercetin (9.02 mg/g) as the major compounds in the morning, while quercetin (4.15 mg/g) and caffeic acid (2.03 mg/g) were the major compounds in afternoon. DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical was used to assess the radical scavenging ability of the oil. The results demonstrated that the oil exhibited IC50 of 297.7 μg/mL in emulsions with ascorbic acid 73.07 μg/mL. The A. salinalethality assay showed that the oil was toxic at concentrations above 50 μg/mL, with an LC50 of 2.4 μg/mL compared to the positive control, LC50 was 11.50 μg/mL. Regarding the results of the research in Plant Anatomy, some peculiarities for R. echinus are described. Up to date, studies on the toxicity of this plant have not been published.