Diterpenes and phenolic compounds from Sideritis pullulans

Phytochemical investigation of Sideritis pullulans aerial part and root extracts allowed to isolate six ent-kaurane diterpenes, two phenylpropanoids, and one coumarin, identified as 1α,3α,7β,18-tetrahydroxy-ent-kaur-16-ene (sideripullol A) (1), 3α,11α,18-trihydroxy-ent-kaur-16-ene (sideripullol B) (2), 3α,7β,18-trihydroxy-17-nor-ent-kauran-16-one (sideritone A) (3), 3α,7β-dihydroxy-18-acetyloxy-17-nor-ent-kauran-16-one (sideritone B) (4), 3α,7β,16α,17-tetrahydroxy-18-acetyloxy-ent-kaurane (sideripullol C) (5), 7β,16α,17,18-tetrahydroxy-ent-kaurane (sideripullol D) (6), β-(3-methoxy-4-hydroxyphenyl)-ethyl-O-α-l-arabinopiranosyl-(1→2)-α-l-rhamnopyranosyl-(1→3)-6-O-t-feruloyl-β-d-glucopyranoside (sideritiside A) (7), β-(3,4-dihydroxyphenyl)-ethyl-O-α-l-arabinopiranosyl-(1→2)-α-l-rhamnopyranosyl-(1→3)-6-O-t-feruloyl-β-d-glucopyranoside (sideritiside B) (8), and 7-demethyl-8-methoxycoumarsabin (9), respectively. Twenty known compounds, including phenolics, flavonol glycosides, iridoids, diterpenes, sesquiterpenes, lignans, coumarins, and phenylpropanoids were also isolated and characterized. All diterpenes were evaluated for their cytotoxic activity.