Tabernaecorymine A, an 18-normonoterpenoid indole alkaloid with antibacterial activity from Tabernaemontana corymbosa.

Tabernaecorymine A, an 18-normonoterpenoid indole alkaloid with conjugated (E)-3-aminoacrylaldehyde fragment was obtained from the stem bark of Tabernaemontana corymbosa. Its structure was elucidated by extensive spectroscopic data analyses, and further verified by ACD/structure elucidator, electronic circular dichroism (ECD) analyses and density functional theory (DFT) chemical shift predictions. The compound exhibited significant antibacterial bioactivity against Streptococcus dysgalactiae with an MIC value of 3.12 μ g/mL, which is better than the plant drug berberine. [Display omitted] • An 18-normonoterpenoid indole alkaloid was isolated from Tabernaemontana corymbosa. • Tabernaecorymine A (1) was determined by spectral data analysis, ACD/SE, ECD, and DFT synergistic algorithms. • Antibacterial activity of tabernaecorymine A (1) was evaluated. [ABSTRACT FROM AUTHOR]