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Cytotoxic terpenoids from Calocedrus macrolepis var. formosana
Calocetriol (1), diacetylcalocediol (2), abeoabietalignol (3), labdanecaryophyllic acid (4), and ferrugimenthenol (5) were isolated from the bark of Calocedrus macrolepis var. formosana. Compounds 1 and 2 are secoabietane-type diterpenoids, and 3-5 with respective C30, C35, and C30 skeletons are novel meroterpenoids. Their structures were characterized by spectroscopic analysis. Of these compounds identified, 3-5 exhibited significant cytotoxic activities against human oral epidermoid carcinoma KB cells with IC50 values of 8.9±0.1, 9.2±0.4, and 9.0±0.1µM, respectively.