Characterization of<i>Coleus aromaticus</i>essential oil and its major constituent carvacrol for<i>in vitro</i>antidiabetic and antiproliferative activities

Abstract

Coleus aromaticus leaf essential oil and its purified constituent, carvacrol, were studied for their inhibition activity of diabetic linked α-amylase and α-glucosidase, and the antiproliferative activity and cytotoxicity on human melanoma cancer (A375) cells; its effect on cell cycle arrest, DNA fragmentation and apoptosis by the cleavage of poly-(ADPribose)-polymerase (PARP) and Bcl-2 gene expression was examined. The essential oil and its constituent carvacrol exhibited inhibitory activities against α-amylase and α-glucosidase. The IC50 values for α-amylase (34.64 ± 1.09; 152.3 ± 1.21 µg mL−1) and α-glucosidase (29.29 ± 1.05; 94.02 ± 0.78 µg mL−1) were obtained for the essential oil and carvacrol respectively. Carvacrol inhibited the growth of A375 cells by inducing apoptosis as evidenced by acridine orange/ethidium bromide staining and flow cytometry analyses. The A375 cells treated with carvacrol for 24 h induced apoptosis by the cleavage of PARP and reduced Bcl-2 gene expression. Carvacrol may induce apoptosis by direct activation of the mitochondrial pathway, which plays a vital role in the anticancer effect.