Growth inhibition of human colon carcinoma cells by sesquiterpenoids and tetralones of Zygogynum calothyrsum

Bioassay-guided phytochemical investigation of Zygogynum calothyrsum using the human colon carcinoma cell lines COLO205 and KM12 led to the isolation of three new drimane-type sesquiterpenoids, 1β-p-hydroxy-E-cinnamoyldrimeninol (1), 1β-p-hydroxy-E-cinnamoyl-5α-hydroxydrimeninol (2), and methyl ether of 1β-p-hydroxy-E-cinnamoyl-12α-methoxydrimeninol (3). Also isolated was the known 1β-p-coumaroyloxypolygodial (4) together with two new tetralones, 3'-deoxyisozygolone A (5) and calothyrlone A (9), three known tetralones, isozygolone A (6), zygolone A (7), and 4'-O-methylzygolone A (8), and a known cinnamolide (10). Compounds 1, 7, and 8 demonstrated higher cytotoxicity against COLO205 (GI50 18, 17, and 11 μM, respectively) and KM12 (GI50 14, 14, and 17 μM, respectively) than the Other compounds.