Morfologia, anatomia, histoquímica e fitoquímica de espécies do gênero Hypenia (Mart . ex Benth.) R. Harley (Lamiaceae) ocorr entes no Cerr ado de Goiás

Abstract

The genus Hypenia belongs to the family Lamiaceae and has approximately 27 species, with the center of diversity in the Cerrado biome in the state of Goias, Brazil. The leaf blades and stems of 13 species of this genus were analyzed at morphological, anatomical, histochemical, and phytochemical levels. The leaf blade shape varied from suborbicular, ovate, oblong, elliptic, lanceolate to deltoid, with penninerved venation, of the types craspedodromous, semi-craspedodromous, and craspedodromous with evident primary venation and uniformly spaced secondary venation. In transverse sections, the main differences among species were: primary venation shape – ranging from concave to convex; shape of the vascular system of the primary vein and petiole; cuticle with or without ornamentations; cuticular extensions; position of the druses, as they can occur in the epidermis, in the central zone of the primary venation, and between the secondary veins; proportion of intercellular spaces in the spongy parenchyma; and presence of hydathodes at the leaf margins. We observed two types of glandular trichomes – peltate and capitate – and unicellular and multicellular epidermal trichomes. In the histochemical tests we detected: lipophilic compounds, phenolic compounds, starch, and proteins in practically all the leaf tissues, and silica in the basal cells of the epidermal trichomes and some of the glandular trichomes. The photochemical analyses revealed the presence of anthraquinone, cardioactive, and saponinic heterosides; flavonoids; tannins; and coumarins. Alkaloids were found only in Hypenia aristulata, H. paradise, and H. subrosea. In the analysis of the essential oil, we identified 91 compounds common to all species, which were grouped into 22 main components taking into consideration the ones with highercontent of accumulated oil. According to the constituents detected in the essential oil, among the 13 species of Hypenia studied we observed that some of them are chemically related, which corroborated our anatomical and morphological data. The present study represents the first step of a thorough analysis of a genus that has its center of diversity in the Cerrado of the state of Goias. Additional biological assays are still necessary in order to assess whether the compounds of the essential oil isolated from Hypenia species present pharmacological, genotoxic, and cytotoxic activities.