Contribuição ao conhecimento químico de plantas do nordeste do Brasil: Bauhinia ungulata L. (Leguminoseae)

Abstract

The Bauhinia genus possess 300 species distributed in tropical area of the planet. Species of this genus have been used in popular medicine on the diabetes treatment. Preliminary pharmacological studies showed hypoglicemic action of Bauhinia ungulata L. [1], popularly known on the northeast of Brazil as “pata-de-vaca”, however, no phytochemical study has been reported yet [2]. This work reports the isolation and structural charactherization of the volatile and non-volatile constituents from the leaves of Bauhinia ungulata, for the accomplishment of pharmacological tests with the isolated compounds. A circadian study of the chemical composition of the leaves of B. ungulata was carry out with its essential oil. The main constituents were: (E)- -caryophyllene (1), - humulene (2), germacrene D (3), cariilene (4), -copaene (5), germacrene B (6), - cadimene (7) e byciclogermacrene (8). Changes were observed at 9:00 to 12:00 a.m. with the increase of contents of the constituents 4 and 8, and reduction of contents of compounds 2, 3, 5, 6, 7, besides of appearance of oxygenated terpenes only at 12:00 a.m. The phytochemical study of the non-volatile constituents was accomplished by the investigation of the hexane (EHBU) and ethanol (EEBU) extracts. From the EHBU traicontanol was obtained in high contents. Sucessive chromatographies from the EEBU yielded 4 metabolites charactherized as the flavonoids quercetine, quercetine-3- O-arabinofuranoside and quercitrine, besides the methoxy inositol 3-O-metil- D-pinitol. The alkaloid fraction yielded the -carbolines harmane e eleagnine. XIX The identification of the volatile compounds was done by GLC/MS. Structure charactherization of the non-volatile was made by spectroscopic methods such as IR and two and one dimensional ¹H and ¹³C NMR (COSY, HMQC, HMBC),