Seasonal Flavonoid Profile and Kaempferitrin Content in the Leaf Extracts of Bauhinia forficate Subspecies forficate from Two Locations in Southeastern Brazil

The leaves of Bauhinia forficate L. (Fabaceae) are used in Brazilian folk medicine mainly as antidiabetic agent. They are rich in polyphenols, and kaempferitrin and other flavonoids are currently considered as basic chemical criteria for the quality and the effectiveness of extracts and phytopharmaceuticals derived from them. Aiming to expand the scope of current data of the chemical profile of B. forficate subsp. forficate, the present study employed HPLC-DAD and HPLC-DAD-ESI/MS to compare the flavonoid profile and kaempferitrin content in the leaves of specimens collected seasonally during one year, in two different locations in Southeastern Brazil: Rio de Janeiro (RJ) and Sao Paulo (SP) states. The data showed a variation in the flavonoid profile and in the kaempferitrin content depending on the place of collection and the season of the year. The target compound, kaempferitrin, was found to be only a minor constituent in RJ (0.21 - 1.02 μg/mg), and was mostly absent or occurred as trace in SP location (0.00 - 0.12 μg/mg). Some degree of similarity was observed in the flavonoid profiles according to the region of collection. In agreement with some published reports, the low and quite variable kaempferitrin content as well the wide variability of the flavonoid profiles brings into question the dubious matter of using these compounds as chemical markers for this medicinal species.