Abstract

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Abstract

Abstract

Abstract

Abstract

From the leaves and stems of Kadsura longipedunculataFinet et Gagnep (Schisandraceae), a new triterpenoid, schisanlactone E (1), and two new lignans, 9-(β-D-glucopyranosyloxy)-3′-methoxy-3,4-(methylenedioxy)-7,9′-epoxylignan-4′-ol (3) and 3-methoxy-3′,4′-(methylenedioxy)-9,9′-epoxylignan-4,7′-diol (4), together with seven known compounds, were isolated. Their structures were elucidated by analysis of spectroscopic evidence including extensive 2D-NMR data.

Two new 6,7-seco-ent-kaurane diterpenoids, isojaponins A (1) and B (2), together with 18 known ent-kaurane diterpenoids were isolated from the aerial parts of Isodon japonicus. The structures of the two new compounds were elucidated by extensive 1D- and 2D-NMR spectroscopic methods in combination with MS experiments.

Four new, highly oxygenated nortriterpenoids with the unique schisanartane skeleton, propindilactones A–D (1–4), were isolated from the aerial parts of Schisandra propinqua var. propinqua, together with four known schisanartane-type compounds. The structures of the new plant constituents were established on the basis of extensive spectroscopic methods.

Seven new highly oxygenated nortriterpenoids, rubriflorins D–J (1–7), were isolated from the leaves and stems of Schisandra rubriflora, and their structures were elucidated on the basis of extensive analysis of spectroscopic data. These new compounds feature the opening of ring A compared with related known nortriterpenoids isolated from the genus Schisandra and showed weak activity against HIV-1.

A phytochemical study of secondary metabolites produced by Schisandra chinensis has led to the isolation of six novel highly oxygenated nortriterpenoids, wuweizidilactones A–F (1–6). Compounds 3–6 possess an unprecedented 3,4-seco-18(1314)-abeo-artane skeleton. Interestingly, structures 3–6 have a β-oriented methyl group at the C-14 position. This structural feature corroborates the biogenetic pathway proposed for the formation of 18-norschiartane-type compounds 1 and 2. The structures of these novel metabolites were established on the basis of their detailed spectroscopic analysis. The structure of 1 was also confirmed by single-crystal X-ray diffraction analysis. For the first time, the absolute configuration of these nortriterpenoids was determined by using a modified Mosher method.

Three new ent-kaurane diterpenoids, parvifoline Z (1), parvifoline AA (2), and parvifoline AB (3), together with 14 known compounds, were isolated from the leaves of Isodon parvifolius. The structures of the new compounds were elucidated by 1D- and 2D-NMR spectroscopy and mass spectrometry, and by comparison with known compounds. These three new diterpenoids included three types of ent-kauranoids, namely, C(20)-non-oxygenated-ent-kauranoid, 7,20-cyclo-ent-kauranoid and 6,7-seco-ent-kauranoid-7,20-olide. Compounds 1 and 2 exhibited significant cytotoxicities against A549, HT-29, and K562 cell lines (Table 2).

Two new ent-kaurane-derived diterpene derivatives, phyllostacins A (1) and B (2), were isolated from the aerial parts of Isodon phyllostachys, together with two known compounds, irroratin A (3) and serrin B (4). Both 1 and 2 were found to be present as diastereoisomers. In the case of 1, the corresponding diastereoisomeric diacetates 5 and 6 were prepared and separated. The structures of the new compounds were elucidated by extensive 1D- and 2D-NMR spectroscopic methods, in combination with MS experiments. In (D₅)pyridine solution, the two epimers of 1 are present in equal amounts, but in CDCl₃ or CD₃OD, the (S)-epimer predominates in the mixture of hemiacetals.

Three new terpenoids, pubinernoids A–C (1–3), together with six known sesquiterpenoids, were isolated from the leaves and stems of Schisandra pubescens var. pubinervis. The structures of the new compounds were established on the basis of extensive spectroscopic analyses, including application of 2D-NMR spectroscopic techniques. A plausible formation of the sesquiterpenoid 2 is proposed (Scheme 2), starting from guaianediol (4) as the biogenetic precursor, which was also present in the extract.

Five new ent-kaurane diterpenoids, epi-maoecrystal N (1), eriocalyxin G (2), maoecrystal W (3), maoecrystal X (4), and maoecrystal Y (5), along with 22 known ones, were isolated from Isodon eriocalyx (Dunn.) Hara., and their structures were determined by spectroscopic methods. All diterpenoids, except for 3 and 13, were evaluated for inhibition of the K562, T-24, Me180, QGY-7701, and BIU87 cell lines (Table 2).

Two unusual 18,19-secoursane glycosides, bodiniosides A (1) and B (2), and two known triterpenoids, hypadienic acid (3) and 2,3,19-trihydroxyurs-12-en-28-oic acid (4), were isolated from the whole plants of Elsholtzia bodinieri. The structures of 1 and 2 were determined by intensive interpretation of spectral data. This is the first report of E-secoursane glycosides. In addition, the biogenetic relationships among these four triterpenoids are discussed.

A novel asymmetric ent-kaurane dimer, xindongnin P (1), was isolated from Isodon rubescens var. rubescens. Its structure was elucidated by detailed spectroscopic analysis. Compound 1 contains a tetrahydrofuran moiety whose formation leads to inversion of configuration at C(16). This differentiates 1 from known related dimers, which were isolated before from the Isodon genus. A likely biogenetic pathway from the alleged monomer precursor 3 is proposed.

Four new, highly oxygenated nortriterpenoids with unique schisanartane skeletons, micrandilactones D–G (1–4), have been isolated from the leaves and stems of Schisandra micrantha, and their structures have been elucidated on the basis of extensive spectral studies. The postulated biogenetic sequences of sixteen highly oxygenated nortriterpenoids and bisnortriterpenoids with new skeletons from three Schisandra species are discussed and have been compared from a chemotaxonomic standpoint.

The tow novel ent-abietane diterpenoids 1 and 2, named xerophilusins R and S, respectively (=(11β)-6,11-dihydroxy-7,20-dioxo-ent-abieta-5,8(14),15(17)-trien-16-oic acid δ-lactone and (11β,15S)-6,11,17-trihydroxy-7,20-dioxo-ent-abieta-5,8(14)-dien-16-oic acid δ-lactone, resp.), were isolated from Isodon xerophilus (C. J. Wu et H. W. LI) H. Hara. Their structures were established by spectroscopic means.

Three new ent-clerodane diterpenoids, isoscoparin A, B, and C (1–3), were isolated from Isodon scoparius. Their structures were determined by NMR-spectra analysis. The biogenetic implication of the diterpenes from Isodon genus is discussed.

A new ursane-type nortriterpenoid, adenanthusone (=(11α,12α)-4-demethyl-11,12-epoxy-3,13-dihydroxy-2-oxoursa-3,20(30)-diene-28-oic acid γ-lactone; 1) was isolated from Isodon adenanthus. Its structure was determined by NMR spectra and X-ray crystallographic diffraction analysis. The biogenetic implication of the nortriterpene is discussed.

Six new ent-abietane diterpenoids, rubescensins I–M (1–5) and P (6), along with two related acetonide derivatives (7 and 8), were isolated from Isodon rubescens. Their structures were elucidated by detailed spectroscopic analysis. Compound 5 is the first N-containing diterpenoid from the genus Isodon, exhibiting notable cytotoxicity against human tumor K562 cells.

Two new diterpenoids, rubescensin S (=(1α,6β,14β)-7α,20-epoxy-1,7,14-trihydroxy-16-oxo-15,16-seco-ent-kauran-6,15-olide; 1) and rubescensin T (=(1α,6β,11β,20S)-7α,20-epoxy-1,6,7-trihydroxy-20-methoxy-8,15-seco-ent-kaur-16-en-11,15-olide; 2) were isolated from the Chinese medicinal herb Isodon rubescens var. taihangensis. Compound 1 possesses a unique, unprecedented 15,16-seco-ent-kaurane skeleton. Both compounds exhibited cytotoxic activities against K562 human leukemia cells.

The phytochemical investigation on the ethanolic extracts of the barks of Taxus yunnanensis (Taxaceae) led to the isolation of two new neo-lignans, named taxuyunins A (1) and B (2), a-long with the known diterpenolignan, brevitaxin (3). Their structures were elucidated on the basis of spectroscopic and chemical evidences. Compound 1 is a neo-lignan xyloside while compound 2 belongs to the rare neo-lignan possessing a ramified C₃side chain.

Further investigation on the leaves of Isodon sculponeatus afforded two new ent-kaurane diterpenoids, sculponeatins J and K. Their structures were elucidated on the basis of their spectral properties, as well as X-ray crystallographic analysis. The cytotoxicities of these two new compounds against human tumor cells K562 and T24 were also tested, and sculponeatin J showed significant inhibitory effects with IC₅₀ values less than 1.0 μg/mL.

Further investigation on the aerial parts of Isodon enanderianus afforded a novel asymmetric ent-kauranoid dimer, enanderinanin J (1). The structure of the dimer was elucidated by means of spectroscopic methods (including 2D NMR techniques). Enanderinanin J was a dimer of xerophilusin A and probably formed by [4 + 2] cycloaddition.

Further investigation on the leaves of Isodon xerophilus afforded three novel ent-kaurane diterpenoids, xerophilusins D-F (1–3), together with seven known compounds, phyllostachysin A (4), oleanolic acid, caffeic acid, rosmarinic acid, rutin, quercetin-3-O-β-D-glucopyranoside, and quercetin. Structures of 1–3 were elucidated on the basis of their spectral properties and X-ray crystallographic analysis. Compound 1 showed broad spectra inhibiting human tumor cells and significant cytotoxicity.