Two chemicals, methylene blue and azure I, make mouse brain cells produce a lot more hydrogen peroxide — over two and a half times more in some cases — when tested in a lab dish. This suggests they cause the tiny energy factories inside the cells to make more of this potentially harmful substance.

In lab tests on mouse brain cells, methylene blue makes more hydrogen peroxide than azure I, but azure I is more efficient—it creates more of this chemical per bit of oxygen it uses. So even though it makes less overall, it’s more wasteful with oxygen.

The more methylene blue you add, the more hydrogen peroxide the mitochondria make—up to 25 times more at the highest dose tested.

Methylene blue makes mitochondria produce more hydrogen peroxide, but if you block a specific part of the energy chain (Complex III), that extra production stops—meaning methylene blue needs that part to work.

In a lab test with mouse brain cells, a chemical called methylene blue makes the energy-producing parts of the cells work harder without using energy to make ATP, while another chemical called azure I doesn’t do anything. This suggests methylene blue might be messing with how the cells normally control their energy production.

A chemical called Azure I, which comes from methylene blue, doesn’t fix the energy power plants in mouse brain cells—even though it’s better at blocking certain brain enzymes. This means it might work in other ways, not by helping cells make energy.