Chang-Ji Zheng

The escalating threat of antibiotic-resistant bacteria and fungi underscores an urgent need for new antimicrobial agents. This study aimed to synthesize and evaluate the antimicrobial activities of two series of 3-alkylidene-2-indolone derivatives. We synthesized 32 target compounds, among which 25 exhibited moderate to high antibacterial or antifungal activities. Notably, compounds 10f, 10g, and 10h demonstrated the highest antibacterial activity with a minimum inhibitory concentration (MIC) of 0.5 μg/mL, matching the activity of the positive control gatifloxacin against three Gram-positive bacterial strains: Staphylococcus aureus ATCC 6538, 4220, and Methicillin-resistant Staphylococcus aureus ATCC 43300. Moreover, the three most active compounds 10f, 10g, and 10h were evaluated for their in vitro cytotoxicity in the HepG2 cancer cell line and L-02; only compound 10h was found to exert some level of cytotoxicity. These findings suggest that the synthesized 3-alkylidene-2-indolone derivatives hold potential for further development as antibacterial agents.

Five compounds including three triterpenoids and two sesquiterpenes were isolated from Alimatis rhizoma. Their chemical structures were determined to be alisol B 23-acetate (1), alisol C 23-acetate (2), alisol B (3), alismol (4) and alismoxide (5) by various spectroscopic analysis, including ¹H-NMR, ¹³C-NMR, HMBC and MS spectra. Compounds 1–5 were evaluated for their antibacterial potential against 6 strains of bacteria including three drug-resistant bacteria (one methicillin-resistant Staphylococcus aureus strain CCARM 3506, two quinolone-resistant Staphylococcus aureus strains CCARM 3505 and CCARM 3519), two G⁺ bacteria (Streptococcus mutans KCTC 3289 and Staphylococcus aureus KCTC 209) and one G⁻ bacterium (Escherichia coli KCTC 1924). Compounds 1–5 showed strong antibacterial effect against S. mutans KCTC 3289, their MIC values were 2, 64, 16, 32 and 32 μg/mL, respectively. The antibacterial activity results of compounds 1–5 against these bacteria were reported for the first time. The results indicate that Alimatis rhizoma are potential sources of new antibacterial material.