Adonirubin

The quantification of carotenoids (Structure: Supplementary Figure S2) was performed as previously described [42 (link)]. Standards were used for standard calibration curves using lycopene (ExtraSynthese, Genay, France), β-carotene (Sigma-Aldrich, St. Louis, MA, USA), canthaxanthin (VWR, Darmstadt, Germany), echinenone (Sigma-Aldrich, St. Louis, MA, USA), adonirubin (CaroteNature, Münsingen, Switzerland), 3-hydroxyechinenone (CaroteNature, Münsingen, Switzerland) and astaxanthin (Sigma-Aldrich, St. Louis, MA, USA).

Carotenoids were extracted as described before^{45 (link)}. The Agilent 1200 series system (Agilent Technologies, Waldbronn, Germany) was used with a reversed phase precolumn (LiChrospher 100 RP18 EC-5, 40 × 4 mm) (CS-Chromatographie, Langerwehe, Germany) and a reversed phase main column (LiChrospher 100 RP18 EC-5, 125 × 4 mm) (CS-Chromatographie, Langerwehe, Germany) and methanol:water (9:1) (A) and methanol (B) were used as mobile phases. Carotenoids were detected with a diode array detector (DAD) through recording of the UV/visible (Vis) spectrum. The injection volume was 50 µL and a gradient at a flow rate of 1.5 mL min⁻¹ was used as the following; 0 min B: 0%, 10 min B: 100%, 32.5 min B: 100%. For quantification the signal of the extract at wavelength λ_max 471 nm was used. Standard calibration curves were generated with lycopene (ExtraSynthese, Genay, France), β-carotene (Sigma-Aldrich, St. Louis, USA), canthaxanthin (VWR, Darmstadt, Germany), zeaxanthin (ExtraSynthese, Genay, France), echinenone (Sigma-Aldrich, St. Louis, USA), adonirubin (CaroteNature, Münsingen, Schwitzerland), adonixanthin (CaroteNature, Münsingen, Schwitzerland) and astaxanthin (Sigma-Aldrich, St. Louis, USA) to quantify carotenoid titers. All standards were dissolved in chloroform according to their solubility and diluted in methanol:acetone (7:3) containing 0.05% BHT.