Morfoanatomia, atividade alelopática e potencial antimicrobiano do extrato bruto e frações das folhas de Piper callosum Ruiz & Pav. (Piperaceae)

Abstract

Piper has great medicinal importance, has a high species richness and holds great commercial value, due to the characteristics of its essential oils. Given the ethnopharmacological evidence for the numerous popular medicinal uses attributed to Piper callosum and the pharmacological potential of its phytochemicals, this species is considered a promising medicinal plant for the development of phytopharmaceuticals. This study aims to characterize the morphology and analysis of the allelopathic and antimicrobial activities of the crude extract and fractions of the leaves of Piper callosum. The leaves were submitted to morphological and histochemical techniques with classic techniques. The allelopathic potential of the extract and fractions was investigated by germination and increasing measures. The leaves of P. callosum are morphologically characterized as: hypoestomatic and elliptic, have glandular trichomes in the epidermis, have mesophyll composed of chlorophyllic parenchyma. The presence of hypodermis on both sides of its leaves was recorded. They have secretory idioblasts that are distributed in the mesophyll and present positive histochemical results for the detection of essential oils. The crude extract (FEB) and its fractions were tested for allelopathic potential in relation to the seeds of Lactuca sativa (lettuce) and Allium cepa (onion), confirming the ability of the extract and fractions to interfere directly in germination, germination speed, growth, hypocotyl and radicle during the bioassay. The fraction of ethyl acetate (FAC) and chloroform fraction (FCLO) affected all parameters evaluated for lettuce and, FAC, hexane fraction (FHEX) and FEB affected growth for onions. The antibacterial tests were submitted to the agar diffusion method and indicated that the leaves of P. callosum did not present antimicrobial activity for the tested microorganisms.