A previously undescribed triterpenoid saponin, 3-O-[α-l-rhamnopyranosyl-(1→2)-{β-d-glucopyranosyl-(1→6)-}β-d-galactopyranosyl-(1→2)-β-d-glucuronopyranosyl]-sophoradiol (1), in addition to twenty-nine known constituents (2-30) were isolated from the aerial parts of Genista numidica Spach. Structures elucidation was performed by comprehensive 1D- and 2D-NMR analyses and HRESIMS. The extracts, fractions and isolated compounds were evaluated for their antibacterial, antioxidant and tyrosinase inhibitory activities. The experimental findings indicated that genistin (16), isosalipurpol (27), and koaburaside (29) have moderate to low antibacterial activity against E. faecalis, S. aureus, S. epidermidis and P. aeruginosa bacteria with MICs ranging from 31.2 to 125 μg/mL. Compounds 19 and 27 exhibited a good antiradical activity potential (IC50 11.8 and 11.1 μg/mL, respectively). Only compounds 23, 27 and 28 exhibited low inhibitory effect against mushroom tyrosinase (IC50 from 90.2 to 225.6 μg/mL).
Keywords: Fabaceae; Triterpenoid saponins; antibacterial activity; antioxidant activity; antityrosinase activity; flavonoids.