The empirical treatment of different diseases with plant extracts is of worldwide distribution ^(1,2). There are a large number of compounds present in vegetable matter, the flavonoids being an important group among them. The flavonoids are polyphenols that constitute part of the non-energetic diet of humans ⁽³⁾; they are absorbed at the intestine level, metabolized, and later on, eliminated by the bile, feces and/or urine as degraded products. Estrada et al. ⁽⁴⁾ have reported the presence of several flavonoids in B. megalandra leaves.

The digestion and intestinal absorption of flavonoids greatly depend on their chemical characteristics in particular on the presence of sugars and in their esterification with different acids ^(5,6). In general the flavonoids are deglycosylated before being absorbed although some of them can get intact into the enterocyte and once into the cell can undergo chemical modifications such as: methylation, sulphation and/or glucuronidation ⁽⁷⁾, via the circulation they reach the liver where they are further metabolized ⁽³⁾. The flavonoids that are not absorbed by the small intestine reach the colon, where they can be metabolized by the intestinal bacteria producing more simple phenolic compounds such as: acids phenylacetic, phenylpropionic, hydoxibenzoic and lactones⁽⁸⁾. The absorbed polyphenol compounds can reach the liver, may go back to the intestine, by the bile, as a different chemical from that ingested and eliminated in the feces. Some flavonoids or their metabolites can reach the kidney and are eliminated by the urine.

At present, there are not evidences of the intestinal absorption of the secondary metabolites present in B. megalandra leaves aqueous extract; in consequence we investigate the appearance of compounds present in the urine of rats that drink B. megalandra leaves aqueous extract that were not present in the urine of control animals in order to show a direct evidence of the intestinal absorption of the compounds present in the plant extract.