Antibacterial and cytotoxic activities of naphthoquinone pigments from Onosma visianii Clem.

In this study, the antibacterial and cytotoxic activities of isolated compounds from the roots of were investigated. By using different chromatographic techniques and appropriate spectroscopic methods, the seven naphthoquinones were described: deoxyshikonin ( ), isobutyrylshikonin ( ), α-methylbutyrylshikonin ( ), acetylshikonin ( ), β-hydroxyisovalerylshikonin ( ), 5,8--dimethyl isobutyrylshikonin ( ) and 5,8--dimethyl deoxyshikonin ( ). Among the tested compounds, and exhibited the highest antibacterial activities toward all tested bacterial species (MIC and MIC for gram positive bacteria: 6.40 μg/mL-12.79 μg/mL and 6.82 μg/mL-13.60 μg/mL, respectively; for gram negative bacteria: 4.27 μg/mL-8.53 μg/mL and 4.77 μg/mL-9.54 μg/mL, respectively). Also, naphthoquinones and exhibited strong cytotoxic activity against MDA-MB-231 cells (IC values 86.0 μg/mL and 80.2 μg/mL, respectively), while compounds , , and significantly decreased viability of HCT116 cells (IC values of 97.8 μg/mL, 15.2 μg/mL, 24.6 μg/mL and 30.9 μg/mL, respectively). Our results indicated that all tested naphthoquinone pigments are potential candidates for clinical uses as antibacterial and cytotoxic agents.