Methyl rosmarinate is a noncompetitive tyrosinase inhibitor which is isolated from Rabdosia serra, with an IC50 of 0.28 mM for mushroom tyrosinase.Methyl rosmarinate shows antioxidative, and antifungal activities. It has inhibitory activities against tyrosinase, α±-glucosidase, and matrix metalloproteinase-1 (MMP-1).

An initial microtiter dilution assay indicated activity of compounds against S. carnosus LTH1502, whereas esters with chain lengths, RA, n-Methyl rosmarinate (RE1), n-dodecyl rosmarinate (RE12), and n-octadecyl rosmarinate (RE18) were used in a time-kill assay S. carnosus LTH1502. Compounds were added at 0.75 mM in the log phase, 5 mM in the exponential phase, 10 mM in the stationary phase. RA had no effect in the lag and exponential phase but decreased cell counts during the stationary phase. In contrast, RE1 and RE12 decreased cell number in all three phase, will RE12 reducing counts most rapidly. Addition of RE18 did not affect regardless of the growth phase[1]