Three Novel Quinoline Alkaloids From Tetradium glabrifolium and Their Antibacterial Activities

Three novel quinoline alkaloids, tetradiunitiside A (1), tetradiunitiside B (2), and glycohaplopine-6-O-α-l-rhamnopyranoside (3), along with eight known ones (4-11), were isolated from the fruits of Tetradium glabrifolium. Their structures were inferred by IR, 1D NMR and 2D NMR, and HR-ESI-MS spectra. All the isolated compounds were evaluated for their antibacterial activities. Compounds 1-11 had potential antibacterial activities against Bacillus gasoformans, Bacillus subtilis, Pseudomonas solanacearum, and Pseudomonas aeruginosa, with minimum inhibitory concentration (MIC) values ranging from 100 to 3.125 µg/mL. Among them, compound 6 showed the most significant antibacterial activity against four strains of bacteria. These findings elucidated the pharmacological substance basis for the antibacterial activity of T. glabrifolium to some extent.