Antifungal and cytotoxicity activities and new proanthocyanidins isolated from the barks of Inga laurina (Sw.) Willd

The Inga genus comprises approximately 300 species that can be found from Mexico to northern Argentina. In folk medicine, Inga species are used to treat various diseases. The species Inga laurina is widely found in the Brazilian flora; however, there are few studies about its biological activity and chemical composition. The main purpose of this study was to identify and isolate the chemical constituents of Inga laurina barks and to evaluate the antifungal and cytotoxic activities. The total content of phenolics, proanthocyanidins, and flavonoids from the barks of Inga laurina were performed by spectrophotometric methods and the ethyl acetate (EAF) and n-butanol (BF) fractions showed the best results. Eleven compounds were identified in EAF by HPLC-ESI(−)-MS/MS, which showed good antifungal activity with MIC values of 23.4 and 46.8 μg mL−1, evaluated by broth microdilution method. Five new compounds of the genus Inga were isolated for the first time. Three of these compounds were isolated and reported on the literature for the first time: a proanthocyanidin B-type, gallocatechin-(4α→8)-4’-O-methylgallocatechin (XI) and two proanthocyanidins A-type, gallocatechin-(2→O→7,4→8)-4’-O-methylgallocatechin (XII) and gallocatechin-3-O-galloyl-(2→O→7,4→8)-4’-O-methylgallocatechin (XIII). The chemical study of the plant bark showed that this species is rich in phenolic compounds and it has great potential for the discovery of new bioactive compounds.