cis-Clerodane Diterpene Lactones from Amphiachyris dracunculoides. 3

Abstract

Five cis-clerodane lactones, amphiacrolides J (1), K (2), L (3), M (4), and N (5), were isolated from the aerial parts of the composite Amphiachyris dracunculoides. The first four are new compounds, and the fifth was previously reported from another source. All compounds were assigned stereochemical structures based upon spectral and chemical data, including high-field 1D and 2D NMR for complete assignment of 1H- and 13C-NMR spectra. Amphiacrolide N (5) was converted to amphiacrolide J (1) by treatment with MeOH and TFA, and amphiacrolide L (3) was prepared from amphiacrolide B (9) by CrO3 oxidation to ketone 10 followed by its reduction with NaBH4.

Clerodane diterpenes: sources, structures, and biological activities

“…181,210 neo -Clerodane-type diterpenoid 520 from Ajuga decumbens has a C-1/C-19 ether bridge. 211 Compounds 521–525 contain a C-20/C-7 γ-lactone/lactol bridge, 52,212 compounds 526 has a C-18/C-7 δ-lactone bridge, 213 and finally, microdon B ( 527 ) possesses a C-17/C-12 δ-lactone bridge.…”

“…173 Two new neo-clerodane diterpenoids with multiple O-containing rings, compounds 439 and 440, were isolated from an acetone extract of the aerial parts of Scutellaria galericulata. 84,173,[180][181][182][183][184][185][186][187][188][189][190][191] (Table 14 compounds 446-480 found in ESI †). Amphiacrolides A-E, I, J, L, and M (446-454), isolated from Amphiachyris dracunculoides, have an ethyl butenolide side chain attached at C-9, as supported by characteristic MS fragments (m/z 111, 98, and 97) and 1 H and 13 C-NMR peaks.…”

“…Amphiacrolides A-E, I, J, L, and M (446-454), isolated from Amphiachyris dracunculoides, have an ethyl butenolide side chain attached at C-9, as supported by characteristic MS fragments (m/z 111, 98, and 97) and 1 H and 13 C-NMR peaks. [180][181][182] The stereochemistries of the amphiacrolides were established from the chemical correlation of these compounds to gutierolide, a compound with absolute stereochemistry determined by X-ray analysis. [180][181][182] The planar structures of 460 and 461, isolated from different Baccharis species are identical, but the compounds are epimeric at C-8.…”

“…[180][181][182] The stereochemistries of the amphiacrolides were established from the chemical correlation of these compounds to gutierolide, a compound with absolute stereochemistry determined by X-ray analysis. [180][181][182] The planar structures of 460 and 461, isolated from different Baccharis species are identical, but the compounds are epimeric at C-8. 173,186 The absolute stereochemistry (neo-series, 5 : 10 trans, 17 : 20 trans) of gaudichanolide A (461) from B. gaudichaudiana was established by X-ray crystallographic analysis.…”

Diterpenoids

“…The glucoside, rumphioside 51 has been isolated 60 from the Philippine medicinal plant Tinospora rumphii (Menispermaceae), whilst the amphiacrolides, e.g. 52, are lactones which were extracted 61,62 from Amphiachyris dracunuloides. Extraction of the bark of Casearia tremula (Flacourtiaceae) gave 63 the cis-clerodane 53, whilst the relative 54 was obtained 64 from Laetia procera (Flacourtiaceae).…”