Six known ent-kaurene, a new ent-kaurane and a new pimarane diterpenes were isolated from Sideritis trojana. The structures of new compounds were determined as ent-7alpha-15beta,16beta-epoxykaurane (1), and ent-2alpha-hydroxy-8(14),15-pimaradiene (2) along with the known compounds siderol (3), sideridiol (4), 7-epicandicandiol (5), isocandol B (6), candol A acetate (7) ent-7alpha-acetoxykaur-15-ene (8) by IR, 1D and 2D NMR techniques and HRMS.
The genus Sideritis (Lamiaceae) is represented by 45 species (54 taxa) in Anatolia with high endemism ratio (74%), and Turkey is one of the gene centers of the genus along with Spain. Acetone extract of the aerial parts of Sideritis lycia afforded eight known ent-kaurene diterpenoids, structures of which have been identified as linearol, isolinearol, isosidol, sidol, siderol, sideridiol, 7-epi-candicandiol and foliol through 1 H NMR, 13 C NMR and mass spectroscopic analyses. Cytotoxic and antiviral activities of the acetone extract, linearol, sidol and isosidol were investigated together with insecticidal activity of species. The antiviral index of linearol, isosidol and acetone extract of S. lycia were determined as 2.31, 2.01 and 2.58, respectively, except sidol. 7-Epi-candicandiol was found to be the most active diterpene against a series of cancer cell lines with ED50 values; KB (13.3 µg/mL), COL-2 (11.8 g/mL), LU1 (17.9 g/mL), LNCaP (14.9 g/mL) and A2780 (9.0 g/mL). Activity results of this study indicated that ent-kaurane diterpenes have potential to be considered as antiviral and cytotoxic lead compounds.
Key indicatorsSingle-crystal X-ray study T = 293 K Mean (C-C) = 0.007 Å R factor = 0.072 wR factor = 0.091 Data-to-parameter ratio = 16.9For details of how these key indicators were automatically derived from the article, see
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