Secondary metabolites from the root of Ehretia longiflora and their biological activities

Bioassay-guided fractionation of the methanolic extract of the root of Ehretia longiflora (Boraginaceae) afforded eight compounds, ehretiquinone (1), ehretiolide (2), ehreticoumarin (3), ehretilactone A (4), ehretilactone B (5), ehretiamide (6), ehretine (7), and ehretiate (8), together with 12 known compounds (9–20). The relative configuration of 1 was determined by single crystal X-ray diffraction. Among the isolates, 1 and prenylhydroquinone (14) showed antitubercular activity against Mycobacterium tuberculosis strain H37Rv with MIC values of 25.0 and 26.2μg/mL, respectively. Moreover, 1 exhibited inhibitory effects on N-formylmethionylleucylphenylalanine (fMLP)-induced superoxide production, with IC50 value of 0.36±0.03μM.