Antimicrobial indole alkaloids from Tabernaemontana corymbosa

Four unreported monoterpene indole alkaloids, tabernaecorymines B–E (1–4), together with twenty-one known indole alkaloids (5–25) were obtained from the stem bark of Tabernaemontana corymbosa. Their structures and absolute configurations were elucidated by extensive spectroscopy, quantum chemical calculations, DP4+ probability analyses and Mo2(OAc)4-induced electronic circular dichroism experiment. The antibacterial and antifungal activities of these compounds were evaluated and some of them showed significant activity against Staphylococcus aureus,Bacillus subtilis, Streptococcus dysgalactiae and Candida albicans.