The carbonyl compounds can add to the polarity somewhat. I'm not sure how you have drawn it, as I can't see your structures; but the long carbon chain off the ester is the hydrophobic/non-polar area (just a bunch of C-C and C-H bonds), and the tetrapyrrole ring system is a major source of the molecule's polarity. There are two negatively charged nitrogen atoms tied up with the magnesium as well as two other pyrroles (the two imines in the 5 membered rings) which add polarity significantly, I would think.
Remember a basic way to think of polarity is the difference between the atoms electronegativities, and a shift in electron density towards the more polar atom. I try to remember the Pauling values for electronegativity and use those as guidelines (even though they are not completely accurate). Carbon has a value of 2.6 versus nitrogen with 3, so there is going to be some polarization of that bond. Also, as you speculated, the same goes for the C=O bond, (Oxygen with a value of 3.4).