Don't know about it's properties as liver protector, but during PTC or cruise it up-regulates the number of androgen receptors in muscle cells as well as L-Carnit-L-Tartrate (yeah, maybe not necessary bc. androgens also up-regulate this number)
Some months ago I was cruising (taking 2 times around 1-2g of NAC and same amount of carnit-tartrate) with less than 100mg/week of testE, and decided to cut a bit (loose some fat) then added 10mg dbol only after training (on training days, 3-4/week) and 3x 10mg/day stanozolol oral for some weeks. I had a bloodwork done at the 3rd week or so, and my liver values were in normal range.
I was not taking liv.52 as I usually do, so cysteine should be the responsible.