Anti-proliferative and antibacterial homoisoflavonoids from Pterolobium punctatum

Twelve homoisoflavonoids, including five new mimosin-type ones (1-5) and a new sappanin-type one (6), were isolated from the MeOH extract of the branches and stems of Pterolobium punctatum. Their structures were elucidated by comprehensive spectroscopic interpretation. The isolates were evaluated for their anti-proliferative activity (against JIMT-1 cells) and antibacterial activity (against methicillin-resistant Staphylococcus aureus, Acinetobacter baumannii, and Bacillus cereus). Notably, compound 3 (IC₅₀ = 5.70 μM) exhibited promising antiproliferative activity against JIMT-1 cells, while compound 10 (MIC = 32 μg/mL) showed broad-spectrum antibacterial activity against the above-mentioned bacterial strains. Preliminary structure-activity relationship (SAR) analysis of these homoisoflavonoids revealed that the α,β-unsaturated fragments are crucial for both activities.