Atractylenolide II is a sesquiterpene compound isolated from the dried rhizome of Atractylodes macrocephala (Baizhu in Chinese); anti-proliferative activity.IC50 value: 82.3 μM(B16 melanoma cell, 48 h) [1]Target: anticancer natural compoundin vitro: AT-II treatment for 48 h dose-dependently inhibited cell proliferation with an IC(50) of 82.3 μM, and induced G1 phase cell cycle arrest. Moreover, treatment with 75 μM AT-II induced apoptosis. These observations were associated with the decrease of the expression of Cdk2, phosphorylated-Akt, phosphorylated-ERK and Bcl-2, the increase of the expression of phosphorylated-p38, phosphorylated-p53, p21, p27, and activation of caspases-8, -9 and -3. In addition, a chemical inhibitor of p53, PFTα, significantly decreased AT-II-mediated growth inhibition and apoptosis [1]. In B16 and A375 cells, AT-II (20, 40 μm) treatment for 48 h dose-dependently reduced protein expression levels of phospho-STAT3, phospho-Src, as well as STAT3-regulated Mcl-1 and Bcl-xL. Overexpression of a constitutively active variant of STAT3, STAT3C in A375 cells diminished the antiproliferative and apoptotic effects of AT-II [2].in vivo: Daily administration of AT-II (12.5, 25 mg/kg, i.g.) for 14 days significantly inhibited tumor growth in a B16 xenograft mouse model and inhibited the activation/phosphorylation of STAT3 and Src in the xenografts [2].

References:
[1]. Ye Y, et al. Atractylenolide II induces G1 cell-cycle arrest and apoptosis in B16 melanoma cells. J Ethnopharmacol. 2011 Jun 14;136(1):279-82.
[2]. Fu XQ, et al. Inhibition of STAT3 signalling contributes to the antimelanoma action of atractylenolide II. Exp Dermatol. 2014 Nov;23(11):855-7.