Objective To study the chemical constituents of the dried leaves of Callicarpa nudiflora and discover bioactive compounds with anti-methicillin-resistance Staphylococcus aureus (MRSA) effects. Methods A systematic separation of chemical constituents was conducted by comprehensive chromatographic methods, including silica gel, Sephadex LH-20, ODS column chromatography and other chromatographic techniques. The structures of the isolated compounds were determined on the basis of spectroscopic analysis including IR, HR-ESI-MS, ¹H-NMR, ¹³C-NMR, HSQC, HMBC, COSY, etc. The minimum inhibitory concentrations (MICs) of the compounds against Staphylococcus aureus, MRSA, Escherichia coli, and multidrug-resistant E. coli were determined by the nutrient broth dilution method. Results One monoterpene, named (Z)-2-methyl-6-methyleneocta-2,7-dine-1-yl (E)-3-(4-hydroxyphenyl)acrylate (1), and four sesquiterpenoids, named monasuslunin (2), (1S,5R,9R)-10,10-dimethyl-2,6-dimethylenebicyclo [7.2.0] undecan-5-ol (3), 7-epi-eudesm-4(15)-ene-1β,6β-diol (4), sclareolide (5) were isolated and identified. Compound 1 exhibited strong inhibitory effects against S. aureus 29213 and MRSA T144, with MICs of 8 μg/mL for both. The MICs against E. coli 25922 and E. coli B2 were both greater than 8 μg/mL. Conclusion Compound 1 is a new compound named Callinuene A and compounds 3-5 are first isolated within this species. Compound 1 exhibits significant anti-MRSA activity.

Callicarpa nudiflora Hook. et Arn  /  monoterpene  /  sesquiterpenoids  /  (Z)-2-methyl-6-methyleneocta-2,7-dine-1-yl (E)-3-(4-hydroxyphenyl)acrylate  /  callinuene A  /  7-epi-eudesm-4(15)-ene-1β,6β-diol  /  sclareolide  /  anti-MRSA activity