Alkannin is a naphthoquinone and enantiomer of shikonin that has been found in A. tinctoria and has diverse biological activities.1,2,3,4,5 It inhibits tumor-specific pyruvate kinase M2 (PKM2; IC50 = 0.3 μM) with 20- and 10-fold selectivity over PKM1 and pyruvate kinase L (PKL), respectively.1 Alkannin inhibits proliferation of HCT116 and SW480 colorectal cancer cells with IC50 values of 2.38 and 4.53 μM, respectively.2 It halts the cell cycle at the G1 phase and induces apoptosis in HCT116 cells when used at a concentration of 3 μM. Alkannin (1 μM) increases levels of Hsp70 in untreated and UVB-irradiated HaCaT cells as well as inhibits UVB-induced DNA fragmentation and caspase-3 activity in HaCaT cells.3 It is active against methicillin-sensitive and -resistant S. aureus (MICs = 6.25 μg/ml) as well as vancomycin-sensitive and -resistant E. faecalis (MICs = 50 and 25 μg/ml, respectively).4 Alkannin scavenges 2,2-diphenyl-1-picrylhydrazyl radicals in a cell-free assay (EC50 = 22 ppm).5
1.Chen, J., Xie, J., Jiang, Z., et al.Shikonin and its analogs inhibit cancer cell glycolysis by targeting tumor pyruvate kinase-M2Oncogene30(42)4297-4306(2011) 2.Huu Tung, N., Du, G.-J., Wang, C.-Z., et al.Naphthoquinone components from Alkanna tinctoria (L.) Tausch show significant antiproliferative effects on human colorectal cancer cellsPhytother. Res.27(1)66-70(2013) 3.Yoshihisa, Y., Hassan, M.A., Furusawa, Y., et al.Alkannin, HSP70 inducer, protects against UVB-induced apoptosis in human keratinocytesPLoS One7(10)e47903(2012) 4.Shen, C.-C., Syu, W.-J., Li, S.-Y., et al.Antimicrobial activities of naphthazarins from Arnebia euchromaJ. Nat. Prod.65(12)1857-1862(2002) 5.Assimopoulou, A.N., and Papageorgiou, V.P.Radical scavenging activity of Alkanna tinctoria root extracts and their main constituents, hydroxynaphthoquinonesPhytother. Res.19(2)141-147(2005)