Objective: To study the chemical constituents of traditional Mongolian medicine Usnea longissima.
Methods: The compounds were isolated and purified by the methods of solvent extraction and chromatographic technique, and their structures were identified on the basis of the analyses of spectral data.
Results: Three compounds were obtained and identified as 4-hydroxy-2-[ (2-hydroxy-4-methoxy-6-methylbenzoyl) oxy]-6-methylbenzoic acid (1), dibutyl phthalate (2) and diisobutyl phthalate (3).
Conclusion: Compound 1 is a new compound and named as isoevernic acid, compounds 2 and 3 are isolated from Usnea longissima for the first time.