TAILIEUCHUNG - Three minor ent-kaur-16-ene-type diterpene from croton tonkinensis gagnep

Three diterpenoids with ent-kaur-16-ene skeleton, namely, ent-11 -acetoxy-7,14 - dihydroxykaur-16-en-15-one, ent-18-hydroxykaur-16-ene and ent-kaur-16-en-15-oxo-18-oic acid were isolated from the MeOH extract of the dried leaves of Croton tonkinensis Gagnep. (Euphorbiaceae) by successive chromatographic separation on silica gel, ODS gel and HPLC on ODS. Their structures were established on the basis of spectroscopic analyses. | Journal of Chemistry Vol. 43 2 P. 263 - 264 2005 THREE MINOR ENT-KAUR-16-ENE-TYPE DITERPENE FROM CROTON TONKINENSIS Gagnep. Received PHAN MINH GIANG1 HIDEAKI OTSUKA2 PHAN TONG SON1 1Faculty of Chemistry College of Natural Science Vietnam National University Hanoi 2Graduate School of Biomedical Sciences Hiroshima University Hiroshima Japan SUMMARY Three diterpenoids with ent-kaur-16-ene skeleton namely ent-11 a-acetoxy-7f 14a-dihydroxykaur-16-en-15-one ent-18-hydroxykaur-16-ene and ent-kaur-16-en-15-oxo-18-oic acid were isolated from the MeOH extract of the dried leaves of Croton tonkinensis Gagnep. Euphorbiaceae by successive chromatographic separation on silica gel ODS gel and HPLC on ODS. Their structures were established on the basis of spectroscopic analyses. Keywords Croton tonkinensis Euphorbiaceae ent-kaur-16-ene diterpenoid. The leaves of the endemic Vietnamese medicinal plant Croton tonkinensis Gagnep. Euphorbiaceae has been used in the treatment of gastric and duodenal ulcers 1 . In our first attempt to investigate the phytochemical constituents of this plant the main compound was isolated as a new ent-kaur-16-en-15-one 2 . Later the acting mechanism of the herbal remedy was discovered by us at least in part through the ability of this compound to inhibit the activation of the transcription factor nuclear factor kappa B NI - B 3 . Guided by the activity toward the inhibition of NF-A B further new ent-kauranoids were isolated and structurally determined 3 4 . In addition long-chain alkyl alcohols 5 and flavonoid glucosides 6 were isolated and structurally identified. Our continuous search for the other ent-kauranoids from this plant led to the isolation of three minor diterpenoids 1-3 the structure elucidation of which is described in this paper. The extraction and isolation procedures were carried out as described previously 3 4 . Preparative HPLC on ODS columns using MeOH in water as solvent systems was demonstrated to be an efficient .

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• Three minor ent kaur 16 ene type diterpene
• Croton tonkinensis gagnep
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