The structural elucidation and antimicrobial activities of two new sesquiterpenes from Syringa pinnatifolia Hemsl.

AIM: To study the chemical constituents of Syringa pinnatifolia Hemsl. and their antibacterial and antifungal activities. METHODS: The CHCl3-soluble fraction was separated by chromatography, and the structures of the new compounds were elucidated by spectral experiments. Antimicrobial activity of the compounds was evaluated against various bacteria and fungi. RESULTS: Two new sesquiterpenes, guai-9-en-4-ol (1) and 14, 15-dinorguai-1, 11-dien-9, 10-dione (2) were isolated from the stem of Syringa pinnatifolia Hemsl. var. alashanensis. Compound 1 is more active against Bacillus coagulas, while being less active against Proteus vulgaris. Compound 2 shows good activity against Escherichia coli, and is less active against Staphylococcus aureus. CONCLUSIONS: Compounds 1 and 2 are new compounds, and when evaluated against various bacteria showed good results.