3d image of alkannin skeletal formula

alkannin natural red 20 alkanet extract anchusaic acid anchusin dye pigment paint indicator borage alkanna tinctoria food colouring cosmetics additive food adjuvants ingredient agent ins number e103 r-enantiomer shikonin racemic mixture shikalkin biosynthesis molecule molecular formula skeletal structural structure geometry ball stick tautomer isomer stereoisomer orbital structure activity relationship sar racemate naphthoquinone roots red-purple red 3d chemistry