Two New C20‐Diterpenoid Alkaloids from the Tibetan Medicinal Plant Aconitum naviculare Stapf

Two new C₂₀‐diterpenoid alkaloids named naviculine A ( 1 ) and naviculine B ( 2 ), were isolated from Aconitum naviculare Stapf . Their structures were established by spectral methods, especially 2D‐NMR spectra (¹H,¹H‐COSY, HMQC, HMBC, and NOESY) and DFT methods (at the B3LYP/6‐311++G(2d,p)//B3LYP/6‐31G(d) level), respectively. They were assayed for their anti‐HIV‐1 activity.     

Piepunine,A Novel Bis‐diterpenoid Alkaloid from the Roots of Aconitum piepunense

Further investigation on the roots of Aconitum piepunense led to the isolation of a novel bis‐diterpenoid alkaloid designated as piepunine ( 1 ). Its structure was established by extensive interpretation of its 1D‐ and 2D‐NMR data, high‐resolution ESI‐MS, and IR spectra. Piepunine represents the first example of an atisine–denudatine‐type bis‐diterpenoid alkaloids.     

A New Diterpenoid and a New Diterpenoid Alkaloid from Aconitum coreanum

A new diterpenoid, guan fu diterpenoid A ( 1 ), and a new diterpenoid alkaloid, guan fu base S ( 2 ), were isolated from the Chinese medicinal herb Aconitum coreanum (Lèvl. ) Rapaics , together with five known diterpenoid alkaloids guan fu base P, guan fu base R, guan fu base G, guan fu base F, and guan fu base Z. The structures of the two new compounds were elucidated as ent‐kaurane‐16,20‐diol ( 1 ) and (11β,13S)‐2,3,15,16‐tetradehydro‐16,17‐dihydrohetisan‐11,13,14‐triol 11,13‐diacetate ( 2 ) on the basis of HR‐MS and 2D‐NMR analyses. This is the first report of an ent‐kaurane diterpenoid in Aconitum coreanum.     

A New Alkaloid from the Roots of Aconitum carmichaeli Debx.

A new diterpene alkaloid, 12‐epi‐15‐O‐acetyl‐17‐benzoyl‐16‐hydroxy‐16,17‐dihydronapelline ( 1 ), along with nine known diterpene alkaloids including yunaconitine ( 2 ), neoline ( 3 ), mesaconitine ( 4 ), beiwutine ( 5 ), chasmanine ( 6 ), songorine ( 7 ), 12‐epi‐napelline ( 8 ), foresticine ( 9 ), and 15α‐hydroxyneoline ( 10 ) were isolated from the roots of Aconitum carmichaeli Debx. The structure of compound 1 was elucidated by comprehensive spectroscopic analysis.     

Four New Nor‐Diterpenoid Alkaloids from Aconitum brachypodum

Four new C₁₉‐nor‐diterpenoid alkaloids, named brachyaconitines A–D ( 1 – 4 ), were isolated from the roots of Aconitum brachypodum Diels. Their structures were elucidated as 3‐O‐acetyl‐20‐deethyl‐20‐formylaconitine ( 1 ), 3‐O‐acetyl‐19,20‐didehydro‐20‐deethylaconitine ( 2 ), 3‐O‐acetyl‐8‐de(acetyloxy)‐7,8,17,20‐tetradehydro‐20‐deethyl‐7,17‐secoaconitine ( 3 ), and 1‐O‐methylflavaconitine ( 4 ) by means of MS, IR, 1D‐ and 2D‐NMR analyses. The structure of compound 1 was confirmed by an X‐ray diffraction experiment.     

Five New C19‐Diterpenoid Alkaloids from Aconitum hemsleyanum

Five new C₁₉‐diterpenoid alkaloids, named hemsleyaconitines A–E ( 1 – 5 , resp.), were isolated from Aconitum hemsleyanum Pritz. By UV, IR, MS, 1D‐ and 2D‐NMR analyses, their structures were elucidated as 18‐dehydroxygeniculatine D ( 1 ), 6‐hydroxy‐14‐O‐veratroylneoline ( 2 ), 14‐O‐acetyl‐8‐ethoxysachaconitine ( 3 ), 18‐veratroylkaracoline ( 4 ) and 8‐O‐ethylaustroconitine B ( 5 ).     

C19 and C20 Diterpene Alkaloids from Aconitum toxicum Rchb.

Acotoxinine ( 1 ), a new norditerpene alkaloid, was isolated from the roots of Aconitum toxicum Rchb ., together with the structurally related C₁₉ diterpene alkaloids neoline ( 2 ) and aconitine ( 3 ) and C₂₀ diterpene alkaloids songorine ( 4 ) and songoramine ( 5 ). The structures were elucidated by HR‐MS and advanced NMR methods, including ¹H‐NMR, JMOD, ¹H,¹H‐COSY, HSQC, and HMBC experiments. This is the first report of C₂₀ diterpenoid alkaloids in Aconitum toxicum.     

Secokaraconitine, A New Diterpenoid Alkaloid from Aconitum karacolicum

The known diterpenoid alkaloids karacoline, karakanine, songorine, napelline, 12-acetylnapelline, cammaconine, and a new 7,17-secoalkaloid of the lycoctonine type, secokaraconitine, were isolated from tubers of Aconitum karacolicum. An x-ray structure analysis of the new alkaloid was performed.     

New Diterpenoid Alkaloids from Aconitum liangshanicum

One new C₁₉‐diterpenoid alkaloid, named liangshantine ( 1 ), and three new C₂₀‐diterpenoid alkaloids, liangshansines A–C ( 2 – 4 , resp.), as well as eight known compounds, were isolated from the roots of Aconitum liangshanicum. The structures of these new alkaloids were elucidated by spectroscopic methods.     

Hemsleyaconitines F and G,Two Novel C19‐Diterpenoid Alkaloids Possessing a Unique Skeleton from Aconitum hemsleyanum

Hemsleyaconitines F and G ( 1 and 2 , resp.) were isolated from the EtOH extract of Aconitum hemsleyanum. Their structures were elucidated by extensive analyses of the IR, 1D‐ and 2D‐NMR, and MS data. The two C₁₉‐diterpenoid alkaloids 1 and 2 possess a novel skeleton, featuring a five‐membered D‐ring between C(9), C(13), C(14), C(15), and C(16), which is quite different from the previously isolated six‐membered D‐ring analogs.     

Two New C20‐Diterpenoid Alkaloids from Aconitum carmichaelii

Two new C₂₀‐diterpenoid alkaloids, named aconicarchamines A and B ( 1 and 2 , resp.), were isolated from Aconitum carmichaelii. By UV, IR, MS, and 1D‐ and 2D‐NMR analyses, their structures were elucidated as 14,17‐dihydro‐14,17‐dihydroxyajabicine and 15‐O‐acetyllassiocarpine. Compound 1 is the third C₂₀‐diterpenoid alkaloid with the lycoctine skeleton bearing an exocyclic C‐atom at C(14).     

Three New C19‐Diterpenoid Alkaloids from Aconitum forrestii

A further study of the alkaloid constituents of Aconitum forrestii led to the isolation of three new C₁₉‐diterpenoid alkaloids, named 14‐acetoxy‐8‐O‐methylsachaconitine ( 1 ), 14‐acetoxyscaconine ( 2 ), and 8‐O‐ethylcammaconine ( 3 ). Their structures were determined by UV, IR, and MS, 1D‐ and 2D‐NMR analyses.     

Three New C19‐Diterpenoid Alkaloids from Aconitum hemsleyanum var. circinatum

Further phytochemical investigation of the roots of Aconitum hemsleyanum var. circinatum resulted in the isolation of three new aconitine‐type C₁₉‐diterpenoid alkaloids, hemsleyanines E–G ( 1 – 3 , resp.). The structures of these new alkaloids were elucidated on the basis of spectral data including 2D‐NMR.     

New Diterpenoid Alkaloids from Aconitum recemulosum Franch.

Two new diterpenoid alkaloids, racemulosines A ( 1 ) and B ( 2 ), were isolated from the roots of Aconitum racemulosum Franch . The structures of the new alkaloids were elucidated by analysis of physical and spectroscopic data, and the structure of 1 was further confirmed by a single‐crystal X‐ray diffraction analysis. Furthermore, compound 1 , at 2.25?10^?4 mol/l, showed moderate activity against platelet aggregation induced by PAF (platelet‐activation factor).     

Three New C19‐Diterpenoid Alkaloids from Aconitum transsectum

Three new C₁₉‐diterpenoid alkaloids, named aconitramines A ( 1 ), B ( 2 ), and C ( 3 ), were isolated from Aconitum transsectum. By UV, IR, 1D‐ and 2D‐NMR, and MS analyses, their structures were elucidated as 18‐methoxyvilmoraconitine, 18‐demethoxydolichotine A, and 18‐demethoxydolichotine B. Compound 1 is the second known C₁₉‐diterpenoid alkaloid with a three‐membered ring formed by C(8), C(9), and C(10).     

Habaenines A and B,Two New Norditerpenoid Alkaloids from Aconitum habaense

Two new norditerpenoid alkaloids, habaenine A and B ( 1 and 2 ), together with two known compounds, were isolated from Aconitum habaense. The structures of the new compounds were elucidated on the basis of spectral analyses as (1α,6α,16β)‐8‐(acetyloxy)‐20‐ethyl‐13‐hydroxy‐1,6,16‐trimethoxy‐4‐(methoxymethyl)‐19‐oxoaconitan‐14‐yl 4‐methoxybenzoate ( 1 ) and (1α,6α,16β)‐8‐(acetyloxy)‐13‐hydroxy‐1,6,16‐trimethoxy‐4‐(methoxymethyl)‐aconitan‐14‐yl 4‐methoxybenzoate ( 2 ).     

A New Diterpenoid Alkaloid from Aconitum episcopale

A new diterpenoid alkaloid with an epoxy ring between C(3) and C(17) was isolated from Aconitum episcopale. The structure was elucidated on the basis of spectral and chemical evidence.     

Two New Alkaloids from the Roots of Aconitum sinomontanum Nakai

Two new alkaloids, ranaconidine (=20‐ethyl‐1α,14α,16β‐trimethoxyaconitane‐4,7,8,10‐tetrol; 1 ) and N‐(chloromethyl)taspine (=1‐[2‐(N‐(chloromethyl)‐N,N‐dimethylaminium)ethyl]‐3,8‐dimethoxybenzopyrano[5,4,3‐cde]benzopyran‐5,10‐dione; 2 ), together with two known compounds, i.e., benzethonium chloride ( 3 ) and ranaconine ( 4 ) were isolated from the roots of Aconitum sinomontanum Nakai . The structures of the compounds were elucidated on the basis of spectral evidences and in the comparison with previously published data.