Estudo fitoquímico de três espécies pertencentes à família Rhamnaceae: Discaria americana, Colletia paradoxa e Gouania ulmifolia

Abstract

The present work describes the phytochemistry study and antimicrobial activity of the aerial parts and bark root of three species from Rhamnaceae family: Discaria americana Gilles & Hook, Colletia paradoxa Sprengel and Gouania ulmifolia Hook & Arnott. Four new cyclopeptide natural, discarene C (154), discarene D (155), discarine M (156), discarine N (157) and nine cyclopeptide alkaloids, adoutine Y (92), adoutine Y' (47), franganine (66), frangulanine (67), discarine A (59), discarine B (58), discarine C (100), discarine D (101) and myrianthine A (105), a pentacyclic triterpenoid, acid betulinic (192) and three sterols, β-Sitosterol (195), β-sitosterol-3-O-6-β-D-glucopyranoside (196) and β-sitosterol-3-O-6-stearoyl-β-D-glucopyranoside (197), were isolated of the bark root of D. americana, along with three compounds already described 192, 195, 196, two pentacyclic triterpenoids, ursolic acid (194) and ceanotic acid (193) and an ester derived from ferulic acid (198) of the aerial parts. From the aerial parts of C. paradoxa it was isolated a new compound, called seco-3,4-germanicone (205), along with the known compounds ursolic acid (194), lupeol (199), betulinic acid (192), ceanothic acid (193), taraxerol (200), taraxerone (201), seco-3,4-taraxerone (202), germanicol (203), germanicone (204), β-sitosterol (195) and β-sitosterol-3-O-6-β-D-glucopyranoside (196). From the bark root it was isolated zizyberenalic acid (206), along with compounds 192, 193, 194, 195 and 196. The extracts of the aerial parts of Gouania ulmifolia, two new pentacyclic triterpenoids were isolated, 2-hydroxy-2-nor-20(29)-lupen-27,28-dioic acid (208)and 24-hydroxy-A(1)-nor-2,20(29)-lupadien-27,28-dioic acid (209), along with the known compounds lupeol (199), betulinic acid (192), alphitolic acid (207), β-sitosterol (195) and β-sitosterol-3-O-6-β-D-glucopyranoside (196). All compounds are being described for the first time in the species. Additionally, antimicrobial activity of extracts, fractions and isolated compounds of Discaria americana, Colletia paradoxa and Gouania ulmifolia was analyzed, through the bioautography technique, measuring the inhibitory activity of the growth on different microorganisms, three Gram positive bacteria (Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis) and four Gram negative bacteria (Klebsiella pneumonia, Salmonella setubal, Escherichia coli and Pseudomona aeruginosa) and the fungus (Saccharomyces cerevisiae and Candida albicans).