Bioactive rinderol and cynoglosol isolated from Cynoglossum columnae Ten. in vitro root culture

Abstract Plant in vitro cultures can effectively reduce the overexploitation of natural resources for the efficient production of natural compounds with therapeutic potential, as in case of Boraginaceae family which is well studied for its shikonin/alkannin derivatives production in biotechnological systems. In this study two naphthoquinone derivatives were isolated for the first time from in vitro root cultures of Cynoglossum columnae Ten. The structures of 2-methoxy-5O, 6-(isohex-1-ene-1,2-diyl)-5,8-dihydroxynaphthalene-1,4-dione ( 1 ) and 2-[(2S)-5-methyl-6-oxo-3,6-dihydro-2H-pyran-2-yl]-5,8-dihydroxynaphthalene-1,4-dione ( 2 ) were identified by spectroscopic methods and named as rinderol and cynoglosol, respectively. Both naphthoquinones were examined for their cytotoxicity towards HL-60, HeLa and HCT-116 human cancer cell lines. Rinderol ( 1 ) showed the highest activity towards HL-60 (IC 50 =2.0 μg/mL), while cynoglosol ( 2 ) was selectively active against HL-60 (IC 50 =4.3 μg/mL). Antibacterial activity of rinderol ( 1 ) was noted for Staphylococcus epidermidis ATCC 12228 as MIC=3.91 μg/mL and Staphylococcus epidermidis MRSE 456 as MIC=7.81 μg/mL. These results present Cynoglossum columnae Ten. in vitro root culture as a new biotechnological source of natural compounds with a potential for therapeutic applications.