Avaliação morfoanatômica de órgãos vegetativos de Bixa orellana L.: contribuições para a padronização farmacognóstica

Abstract

Bixa orellana L. (annatto) has notable cultural, nutritional, and medicinal relevance. Despite its broad use as a natural dye, no official monograph exists. This study characterized the morphology and anatomy of the leaves, stem, and root of B. orellana to provide data supporting species standardization. Samples were collected in São Luís, Maranhão (Brazil), between April and July 2025. Morphological traits were analyzed macroscopically. Anatomical features were examined through freehand paradermal and transverse sections, bleaching with sodium hypochlorite, staining with toluidine blue, and light microscopy to identify diagnostic structures. The leaves are simple, alternate, membranous, and deltoid, with an oblique base and cuspidate apex. Anatomically, they are amphistomatic, showing sinuous epidermal cells and anomocytic stomata. Additional features include a concave–convex midrib, an open-arc collateral vascular bundle with a continuous sclerenchymatic sheath, dorsiventral mesophyll, calcium oxalate crystals, and secretory cavities. The stem exhibits an ectophloic siphonostele, crystal-bearing idioblasts, and secretory cavities, while the root presents an active cambium, sclerenchymatic fibers associated with the phloem, and parenchymatic rays. These results provide diagnostic parameters useful for authenticating the plant drug and emphasize the need for further studies to support regulation and ensure the safe use of the species.