Thymohydroquinone is a quinone that has been found in N. sativa seeds and has diverse biological activities.1,2 It scavenges 2,2-diphenyl-1-picrylhydrazyl free radicals in a cell-free assay (IC50 = 2.4 μg/ml) and has a Trolox equivalent value of 2.6 in an oxygen radical absorbance capacity (ORAC) assay when used at concentrations ranging from 1.6 to 6.4 μg/ml.1 Thymohydroquinone inhibits growth of A2780, OVCAR-8, and CIS-A2780 ovarian cancer cells (IC50s = 3.1, 8.9, and 9.8 μM, respectively), as well as immortalized human ovarian epithelial cells (IC50 = 14 μM).2 It is also active against P. falciparum in vitro (IC50 = 15.9 μM).

References
1. Tesarova, H., Svobodova, B., Kokoska, L., et al. Determination of oxygen radical absorbance capacity of black cumin (Nigella sativa) seed quinone compounds. Nat. Prod. Commun. 6(2), 213-216 (2011).
2. Johnson-Ajinwo, O.R., Ullah, I., Mbye, H., et al. The synthesis and evaluation of thymoquinone analogues as anti-ovarian cancer and antimalarial agents. Bioorg. Med. Chem. Lett. 28(7), 1219-1222 (2018).