New triterpenoids from the stem bark of Hypodaphnis zenkeri.
A new pentacyclic triterpenoid and three new derivatives based on the taraxer-14-ene skeleton with a C-28 attached a carboxylic acid group have been isolated from the stem bark of Hypodaphnis zenkeri, together with six known compounds. The new product was identified as 2α,3α-dihydroxytaraxer-14-en-28-oic acid (1). Its derivatives, 2α,3α-diacetyltaraxer-14-en-28-oic acid (2), 2α,3α-di-O-carbonyl-2α,3α-dihydroxytaraxer-14-en-28-oic acid (3) and 2α,3α-dipropionyltaraxer-14-en-28-oic acid (4) were obtained by semisynthesis. The known compounds were identified as 3β-hydroxytaraxer-14-en-28-oic acid or aleuritolic acid (5) (McPhail, A.T., McPhail, D.R., Wani, M.C., Wall, M.E. & A.W., Nicholas, A.W. (1989). Identity of maprounic acid with aleuritolic acid. Revision of the structure of maprounic acid: X-ray crystal structure of p-bromobenzyl acetylmaprounate. Journal Natural Products, 52, 212), 3α-hydroxytaraxer-14-en-28-oic acid or isoaleuritolic acid (6), 3α-acetyltaraxer-14-en-28-oic acid acetate or aleuritolic acid acetate (7) (Chaudhuri, S.K., Fullas, F., Brown, D.M., Wani, M.C., Wall, M.E., Cai, L., … Kinghorn, A.D. (1995). Isolation and structural elucidation of pentacyclic triterpenoids from Maprounea africana. Journal of Natural Products, 58, 1-9), 3-oxo-taraxer-14-ene or taraxerone (8) β-sitosterol (9) and stigmasterol (10) (Kamboj & Saluja, 2011), together with fatty acids. Their structures were established on the basis of spectroscopic studies and chemical transformations.
T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T1 T20 T21 T22 T2 T3 T4 T5 T6 T7 T8 T9
CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
2α,3α-dipropionyltaraxer-14-en-28-oic acid 3β-hydroxytaraxer-14-en-28-oic acid aleuritolic acid pentacyclic triterpenoid taraxer-14-ene maprounic acid aleuritolic acid maprounic acid p-bromobenzyl acetylmaprounate 3α-hydroxytaraxer-14-en-28-oic acid aleuritolic acid acetate isoaleuritolic acid 3α-acetyltaraxer-14-en-28-oic acid acetate triterpenoids carboxylic acid 3-oxo-taraxer-14-ene taraxerone β-sitosterol stigmasterol 2α,3α-dihydroxytaraxer-14-en-28-oic acid 2α,3α-diacetyltaraxer-14-en-28-oic acid 2α,3α-di-O-carbonyl-2α,3α-dihydroxytaraxer-14-en-28-oic acid