Chemical composition and antioxidant, antibacterial and antiproliferative activities of Macrolobium latifolium Vogel (Fabaceae) stem bark

•The genus Macrolobium has 70–80 species worldwide, which 36 are found in Brazil.•Polyphenols and triterpenoids are suggested as major components in M. latifolium.•Ethyl acetate fraction of M. latifolium acts as antiproliferative and antibacterial.•Phytochemicals of M. latifolium might activate the Nrf2 pathway.•M. latifolium can be source for bioactive molecules on large scale. Macrolobium latifolium Vogel belongs to the Fabaceae family and ethnopharmacological investigations have shown that some species from this family have been popularly used for treatment of chronic diseases. M. latifolium is widely distributed in semi-arid Bahia (Brazil) but reports on its biological activity and chemical composition are absent. In this context, our aim was to evaluate the preliminary chemical constitution and biological activity of M. latifolium stem bark. Overall, ethyl acetate fraction of M. latifolium stem bark (EAFML) was the most effective in reducing DPPH• (2,2-diphenyl-1-picrylhydrazyl radical) and ABTS•+ (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid cation radical) radicals in vitro (IC50 = 8.4 and 4.6 μg/mL, respectively) and protecting H2O2-exposed Raw 264.7 macrophages against cell death. Similarly, EAFML enhanced the heme oxygenase activity of Raw 264.7 macrophages in concentration-dependent manner, suggesting the involvement of Nrf2 pathway. EAFML demonstrated the highest antibacterial activity on Staphylococcus aureus (MIC = MBC = 250 µg/mL), Staphylococcus epidermidis (MIC = 50 µg/mL and MBC = 100 µg/mL), Klebsiella pneumoniae (MIC = MBC = 100 µg/mL), and Proteus mirabilis (MIC = MBC = 100 µg/mL) when compared among other fractions. In addition, proliferation of HepG2 (human hepatocellular carcinoma), MCF7 (human breast carcinoma), and HCT116 (human colon carcinoma) tumor cells were significantly reduced by EAFML (IC50 = 26.4, 19.9, and 22.1 μg/mL, respectively), with no evidence of toxicity against non-tumor cells (MCR5, human fibroblast) and Raw 264.7 macrophages. Classical phytochemical assays and UPLC-MS/MS analysis revealed the presence of quercetin-type flavonols and oleanane-type triterpenoids in the EAFML, which may be related to its biological activities. In conclusion, this study demonstrated the variety of biological properties of M. latifolium stem bark, indicating its therapeutic potential as source of molecules for treatment of oxidative and infectious disorders, as well as cancer.