Hi Raul,
I can't advise you re buying the apartments from the company as that would depend entirely on your brother's tax and personal circumstances. However 11% seems extremely high. I would have though somewhere between 6 and 7% would be more realistic.
What is your brother's repayment capacity like? Are the properties rented or rentable? What is the rent roll?
If your brother has decent repayment capacity then he needs to refinance immediately. With that kind of loan to value and a decent rent roll he should be able to get a better rate.
Best of luck,
Kate.