Alkannin

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)