Sesquiterpenoids are widely distributed in the genus Dysoxylum (Meliaceae) and have attracted attention because of their diverse biological activities, including antibiofilm properties. This study aimed to isolate and characterize sesquiterpenoids from the n-hexane extracts of Dysoxylum acutangulum Miq. and Dysoxylum cauliflorum Hiern twigs, followed by evaluation of their antibiofilm activity against Streptococcus mutans. Chromatographic separation of the n-hexane extract of D. acutangulum afforded spathulenol (1), β-caryophyllene oxide (3), and a mixture of epimeric sesquiterpenoids consisting of 10-oxo-isodauc-3-en-15-al (2a, major) and sinulin A (2b, minor), while humulene diepoxide A (4) was isolated from D. cauliflorum. Structural elucidation was carried out using MS, IR, and extensive NMR spectroscopic analyses, and by comparison with reported data. The major and minor epimers of compound 2 were distinguished based on diagnostic NMR signal intensities and comparison with literature data. Notably, all isolated compounds are reported herein for the first time from their respective Dysoxylum species. Compound 1, the epimeric mixture 2a/2b, and compound 4 exhibited weak antibiofilm activity against S. mutans, with minimum biofilm inhibitory concentration (MBIC) values ranging from 250 to 500 µg/mL, whereas chlorhexidine exhibited superior antibiofilm activity at 62.5 µg/mL. Molecular docking against Sortase A and GtfB revealed moderate binding affinities and suggested plausible interactions with biofilm-associated targets. These findings provide additional chemotaxonomic information on Dysoxylum species and preliminary insight into the antibiofilm potential of their sesquiterpenoids, particularly for compounds with limited previous antibiofilm reports.
Anwar et al. (Mon,) studied this question.