Fig 5. Effects of borneol and menthol on viability of human corneal epithelial (HCE) cells and TRPM8-expressing HEK293 cells.

(A) Both borneol and menthol at 1 mM significantly reduced the viability of HCE cells. (B) Borneol at 0.1–1000 μM did not affect the viability of TRPM8-HEK293 cells, while menthol at 100 and 1000 μM showed strong inhibition on cell viability. (*** P<0.001 vs control; ^## P<0.01, ^### P<0.001 between indicated columns; n = 8 in each column).