Structural Characterization, Antimicrobial Activity, and In Vitro Cytotoxicity Effect of Black Seed Oil

Figure 3

Chemical structures of thymoquinone (a), dithymoquinone (b), thymohydroquinone (c), and thymol (d). The green color arrows exhibit that the bond can undergo free rotation without a significant energy cost, rendering compounds very flexible and with more conformations.

(a)

(b)

(c)

(d)