Varioskan Flash microplate reader (Thermo Scientific). Fourier-transform infrared (FTIR) spectroscopy was recorded using an IRSpirit FTIR spectrophotometer in a transmission mode. The data acquisition was performed using a Labsolutions IR software (version 2.25) (all from Shimadzu, Kyoto, Japan). The 1 H NMR spectra were obtained at 500 MHz using a Varian VNMRS500 spectrometer between 80 and -5 Procedures for hemin esterification reaction: This was performed according to , with some modifications. To a freshly prepared solvent mixture of CH3OH (20 mL) and H2SO4 (2 mL), solid hemin (100 mg, 0.154 mmol., 1.0 eq.) was added and dissolved. The mixture was stirred for 20 minutes at room temperature under the exclusion of light. This period was sufficient for the fraction of the diester to reach its maximum, as evidenced by TLC employing a solvent system of petroleum ether:CH2Cl2:CH3OH (1:1:0.3). The reaction was then quenched by the addition of a mixture of ethyl acetate (125 mL) and H2O (500 mL) and stirring for 30 min at room temperature. Next, the hemins, including the unmodified hemin, mono and diester were repeatedly extracted from the aqueous phase with ethyl acetate and then chloroform. The hemin-containing solutions were characterized by a reddish colour and a characteristic Soret band at 398 nm. These solutions were then mixed with anhydrous sodium sulphate for 3 hours for drying, followed by filtration and solvent removal in vacuo. the solid was dissolved in the previously mentioned petroleum ether: CH2Cl2:CH3OH solvent mixture and separation of the diester was performed using a silica gel column. Moreover, the monoester and unmodified hemin were eluted with petroleum ether: CH3OH solvent mixtures of the ratios 3:1 and 1:1, respectively, and all remaining solvents were removed in vacuo. In some experiments, and to slow down the rate of reaction, freshly distilled THF (200 mL) was added to the previously mentioned CH3OH:H2SO4 mixture, and the reaction was allowed to proceed for one hour. The final reddish-brown solid before the chromatographic purification and the separated hemin powders were characterized by HPLC, UV-vis, 1 H-NMR, FTIR, and LC-MS.