Aspectos químicos do estudo interdisciplinar (químico, farmacológico, botânico e agronômico) de Egletes viscosa Less

Abstract

The flower buds of Egletes viscosa Less. ("macela" or "macela-da-terra") are used in folk medicine for the treatment of gastric disturbances. Due to the widespread use they can be easily found in herbal stores throughout the Northeast of Brazil. A study of the volatile chemical constitution with different specimens of E. viscosa led to the characterization of two chemotypes for this species. One chemotype is characterized by the presence of transpinocarvyl acetate, as the major constituent while the other presents another acetylated monoterpene designated trans-isopinocarvyl acetate. The later is repported for the first time in the literature. Several other volatile constituents were also identified from both oils. The chloroform extract from the flower buds of E. viscosa yielded, besides the already know non-volatile constituents centipedic acid, ternatin, and lactone, reported previously for this species, five other diterpene not yet reported for the species. Four of them are furan derivatives: 12-epi-bacchotricuneatin A, barbatol, tarapacol and the new monocyclic diterpene 15,20-epoxy-9,10-seco-4,9(10),13(20),14-labdatetraene-18-o1; the other one is a novel y-lactone m onocyclic d iterpene 9 ,10-seco-4,9(10),13(14)-labdatriene-15,20-olid-18-ol. Scopoletin was also isolated. The large amount of the isolated diterpenes: lactona and 12-epi-bacchotricuneatin A allowed the preparation of four, nitrogenated and oxigenated, derivatives by Michael addition of specific amine and alcohols to the diterpenes. Structure determination was performed by spectroscopic analysis (NMR, IR, MS) including two-dimensional NMR and gas chromatography coupled to mass spectrometry.