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.     

Three New Sesquiterpene Pyridine Alkaloids from Euonymus fortunei

Three new macrocyclic β‐dihydroagarofuran‐type sesquiterpene pyridine alkaloids, fortuneines A ( 1 ), B ( 2 ), and C ( 3 ), together with the four known alkaloids wilfornine E ( 4 ), aquifoliunine E‐I ( 5 ), euoverrine B ( 6 ), and euojaponine I ( 7 ), were isolated from the aerial parts of Euonymus fortunei. Their structures were elucidated by spectroscopic methods, including HR‐ESI‐MS, ¹H‐ and ¹³C‐NMR, DEPT, ¹H,¹H‐COSY, HSQC, HMBC, and ROESY. This is the first isolation of the above sesquiterpene pyridine alkaloids from this plant, except for compound 6 .     

Pregnane‐Type Steroidal Alkaloids of Sarcococca saligna: a New Class of Cholinesterase Inhibitors

Phytochemical investigation of Sarcococca saligna by extensive bioassay‐guided fractionation resulted in the isolation of the pregnane‐type steroidal alkaloids 1 – 15 , i.e. of the five new compounds 1 – 5 and the ten known alkaloids 6 – 15 . The structures of the new alkaloids salignenamide C ( 1 ), salignenamide D ( 2 ), 2β‐hydroxyepipachysamine D ( 3 ), salignenamide E ( 4 ), and salignenamide F ( 5 ) were elucidated with the help of modern spectroscopic techniques, while the known alkaloids axillarine C ( 6 ), axillarine F ( 7 ), sarcorine ( 8 ), N³‐demethylsaracodine ( 9 ), saligcinnamide ( 10 ), salignenamide A ( 11 ), vaganine A ( 12 ), axillaridine A ( 13 ), sarsalignone ( 14 ), and sarsalignenone ( 15 ) were identified by comparing their spectral data with those reported earlier. Inhibition of electric‐eel acetylcholinesterase (EC 3.1.1.7) and horse‐serum butyrylcholinesterase (EC 3.1.1.8) by alkaloids 1 – 15 were investigated. These new cholinesterase inhibitors may act as potential leads in the discovery of clinically useful inhibitors for nervous‐system disorders, particularly by reducing memory deficiency in Alzheimer's disease patients by potentiating and effecting the cholinergic transmission process. These compounds were found to inhibit both enzymes in a concentration‐dependent fashion with the IC₅₀ values ranging from 5.21–227.92 μM against acetylcholinesterase and 2.18–38.36 μM against butyrylcholinesterase.     

Amaryllidaceae Alkaloids from Lycoris radiata

A phytochemical investigation on bulbs of Lycoris radiata resulted in the isolation of three new Amaryllidaceae alkaloids, named 5,6‐dehydrodihydrolycorine ( 1 ), 6β‐acetoxycrinamine ( 2 ), and (+)‐8‐O‐acetylhomolycorine α‐N‐oxide ( 3 ), together with eleven known alkaloids, 4 – 14 . The structures of the new alkaloids were established by means of spectroscopic methods, and the known compounds were identified by comparison of their data with those in the literature. Compound 2 showed cytotoxicity against HL‐60, A‐549, and MCF‐7 cells, with IC₅₀ values of 8.1, 24.3, and 15.0 μM , respectively.     

Alkaloids from the Stems of Glycosmis pentaphylla

A new simple carbazole alkaloid, 4‐(7‐hydroxy‐3‐methoxy‐6‐methyl‐9H‐carbazol‐4‐yl)but‐3‐en‐2‐one ( 1 ), and two new dimeric carbazole alkaloids, bisglybomine B ( 2 ) and biscarbalexine A ( 3 ), together with seven known alkaloids, were isolated from the stems of Glycosmis pentaphylla. Their structures were elucidated by spectroscopic methods, especially 2D‐NMR techniques.     

New Alkaloids from Hippeastrum papilio (Ravenna) Van Scheepen

A new phytochemical study of the indigenous Brazilian species Hippeastrum papilio is reported herein. Three novel Amaryllidaceae alkaloids were isolated, including hippapiline ( 1 ), papiline ( 2 ), and 3‐O‐demethyl‐3‐O‐(3‐hydroxybutanoyl)haemanthamine ( 3 ). Their structures were determined by physical and spectroscopic methods. In addition, the known alkaloids, haemanthamine ( 4 ), galanthamine ( 5 ), narwedine ( 6 ), 11β‐hydroxygalanthamine ( 7 ), apogalanthamine ( 8 ), and 9‐O‐demethyllycosinine B ( 9 ) were identified. The unusual cis‐B/C‐ring fusion for the new homolycorine representative hippapiline was ratified by NMR and CD spectroscopy.     

Alkaloids from Ochrosia borbonica

Ten new monoterpenoid indole alkaloids, ochroborines A and B ( 1 and 2 , resp.), 10‐hydroxyisovallesiachotamine ( 3 ), 10‐hydroxyisositsirikine ( 4 ), 10,11‐dimethoxysitsirikine ( 5 ), 10‐methoxyapoyohimbine ( 6 ), 10‐hydroxyakuammidine ( 7 ), akuammidine 17‐O‐β‐D ‐glucoside ( 8 ), 15α‐hydroxyapparicine ( 9 ), and 15α‐hydroxy‐10‐methoxyapparicine ( 10 ), and 24 known alkaloids were isolated from leaves and twigs of Ochrosia borbonica J. F.Gmel . These structures were elucidated based on 1D‐ and 2D‐NMR, FT‐IR, UV, and MS data. 10‐Hydroxyisovallesiachotamine ( 3 ), ellipticine, and 10‐methoxyellipticine showed cytotoxic activities against five human cancer cell lines.     

Chemical Constituents from the Stems of Mahonia Japonica

A new dihydroberberine alkaloid, 7,8‐dihydro‐8‐methoxyberberine ( 1 ), along with six known compounds including two dihydroberberine alkaloids, 7,8‐dihydro‐8‐hydroxyberberine ( 2 ) and oxyberberine ( 3 ) and four protoberberine alkaloids, berberine ( 4 ), palmatine ( 5 ), jatrorrhizine ( 6 ) and columbamine ( 7 ), were isolated from the stems of Mahonia japonica. These compounds were characterized and identified by physical and spectral evidence.     

Three New Pregnane Alkaloids from Pachysandra terminalis

Three new pregnane alkaloids, pachystermine C ( 1 ), pachysanamine A ( 2 ), and pachysanamine B ( 3 ), together with four known ones, pachystermine B ( 4 ), pachysamine A ( 5 ), (20S)‐20‐(dimethylamino)‐16α‐hydroxy‐3β‐(3′α‐isopropyl)lactam‐5α‐pregnan‐4‐one ( 6 ), and E‐salignone ( 7 ), were isolated from Pachysandra terminalis. The chemical structures of the new alkaloids were elucidated by spectroscopic methods. All the compounds were evaluated for their inhibitory activities against HL‐60, SMMC‐7721, A‐549, MCF‐7, and SW480 cell lines, some of the compounds showed stronger cytotoxicity for the test cell lines, especially compounds 2 , 3 , and 7 .     

Alkaloids from the Roots of Stemona tuberosa

Four new alkaloids, didehydrotuberostemonine A ( 1 ), stemoninone ( 2 ), tuberostemospiroline ( 3 ), and tuberostemonine L ( 4 ), together with seven known alkaloids, were isolated from the roots of Stemona tuberosa. Their structures were elucidated on the basis of spectroscopic analysis. The known alkaloids were identified as 2‐oxostenine ( 5 ), tuberostemonine ( 6 ), sessilifoliamide H ( 7 ), tuberostemonone ( 8 ), didehydrotuberostemonine ( 9 ), bisdehydrostemoninine ( 10 ), and tuberostemoamide ( 11 ).     

Secoleuconoxine and Oxopericine Derivatives from Kopsia

Two new indole alkaloids, viz., arboloscine ( 1 ), the first example of a secoleuconoxine, and pericidine ( 5 ), an oxidized derivative of pericine ( 6 ), were obtained as minor alkaloids from the stem‐bark extract of the Malayan Kopsia species, K. arborea. Their structures were established by spectroscopic analysis.     

A novel synthetic approach for the synthesis of pyridocarbazole alkaloids

The synthesis of 11‐methyl‐6H‐pyrido[4,3‐b]carbazole‐1(2H)‐one (5), which can be important for the synthesis of other pyridocarbazole alkaloids and especially 1‐substituted ellipticines, is described. Construction of the tetracyclic structure was achieved by a new route and two important precursor compounds (4a and 4b) for the synthesis of pyridocarbazole alkaloids and also many new tetrahydrocar‐bazole derivatives (7, 8, 9, 10, 11, 12, 13) were synthesized.     

Two New Aporphine Alkaloids from Litsea glutinosa

Chemical examination of the BuOH extract of the leaves and twigs of Litsea glutinosa collected from Xishuangbanna resulted in the isolation of two new aporphine alkaloids, namely litseglutine A ( 1 ) and B ( 2 ), along with two known aporphine alkaloids, boldine ( 3 ) and laurolitsine ( 4 ). The structures of the new alkaloids have been elucidated on the basis of spectra analysis as 6‐demethyl‐9‐methoxy‐1,2‐(methylenedioxy)aporphin‐10‐ol (=6,7,7a,8‐tetrahydro‐10‐methoxy‐5H‐benzo[g]‐1,3‐benzodioxolo[6,5,4‐de]quinolin‐11‐ol; 1 ) and 1,10,11‐trimethoxyaporphin‐2‐ol (=5,6,6a,7‐tetrahydro‐1,10,11‐trimethoxy‐6‐methyl‐4H‐dibenzo[de,g]quinolin‐2‐ol; 2 ).     

New C19－Diterpenoid Alkaloids from the Roots of Delphinium Giraldii

Three new C19-diterpenoid alkaloids, giraldines A (1), B (3) and C (4), were isolated from the roots of Delphinium giraldii Diels, together with three known C19-diterpenoid alkaloids, dihydrogadesine (5), tatsiensine (6) and siwanine A (7), as well as their structures were elucidated by chemical evidence and spectral analyses, including IR, MS, 1D NMR and 2D NMR.     

Steroidal Alkaloids from the Roots and Rhizomes of Vertrum nigrum L.

Two new steroidal alkaloids, neoverapatuline ( 1 ) and (1β,3α,5β)‐1,3‐dihydroxyjervanin‐12‐en‐11‐one ( 2 ), together with the four known compounds, veratramine ( 3 ), rubijervine ( 4 ), veratrosine ( 5 ), and veratroylzygadenine ( 6 ), were isolated from the roots and rhizomes of Veratrum nigrum L. Their structures were established through combined analyses of physicochemical properties and spectroscopic evidence. All compounds 1 – 6 were tested for their cytotoxicities in vitro against the human glioma cell line SF188.     

Three New Alkaloids from the Leaves of Uncaria rhynchophylla

Three new alkaloids, 2′‐O‐β‐D ‐glucopyranosyl‐11‐hydroxyvincoside lactam ( 1 ), 22‐O‐demethyl‐22‐O‐β‐D ‐glucopyranosylisocorynoxeine ( 2 ), and (4S)‐corynoxeine N‐oxide ( 3 ) were isolated from the leaves of Uncaria rhynchophylla, together with four known tetracyclic oxindole or indole alkaloids, isocorynoxeine N‐oxide ( 4 ), rhynchophylline N‐oxide ( 5 ), isorhynchophylline N‐oxide ( 6 ), and dihydrocorynantheine ( 7 ), and an indole alkaloid glycoside, strictosidine ( 8 ). The structures of 1 – 3 were elucidated by spectroscopic methods including UV, IR, ESI‐TOF‐MS, 1D‐ and 2D‐NMR, as well as CD experiments. The activity assay showed that 8 (IC₅₀=8.3 μM ) exhibited potent inhibitory activity on lipopolysaccharide(LPS)‐induced nitrogen monoxide (NO) release in N9 microglia cells. However, only weak inhibitory activities were observed for 1 – 7 (IC₅₀>100 μM for 1 – 6 or >30 μM for 7 ).     

New Indole Alkaloids from Kopsia. Alkaloid Variation in Kopsia singapurensis

Five new indole alkaloids, viz., kopsiloscine G ( 2 ), kopsidarine ( 4 ), kopsimaline F ( 6 ), kopsidine C N‐oxide ( 7 ), and aspidophylline B ( 9 ), in addition to 17 other known alkaloids, were obtained from the leaf and stem‐bark extract of the Malaysian Kopsia singapurensis. The structures were determined by using NMR and MS analysis. The results are compared with the alkaloidal composition of another sample of K. singapurensis, collected from the same location but at a different time of the year, as well as with other samples of K. singapurensis collected from different locations.     

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 ).     

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.     

pH‐Zone‐refining counter‐current chromatography for two new lipo‐alkaloids separated from refined alkaline extraction of Kusnezoff monkshood root

An efficient and refined method for the separation of six aconitine‐type alkaloids from the alkaline prepared “Kusnezoff monkshood root” was established. It is the first study that two new lipo‐alkaloids were successfully isolated from refined sample by pH‐zone‐refining counter‐current chromatography rather than synthetic method. It was of interest that a great deal of lipo‐alkaloids was produced in crude extract from the alkalization of “Kusnezoff monkshood root.” A refined sample method was proposed to enrich two types of alkaloids by liquid–liquid extraction, i.e. lipo‐alkaloids and monoester‐diterpenoid alkaloids. The pH‐zone‐refining counter‐current chromatography was performed with an optimized two‐phase solvent system composed of n‐hexane‐ethyl acetate–methanol–water (3:5:4:5, v/v), where upper organic phase was added to 3 mmol/L triethylamine as a retainer and lower aqueous mobile phase was added to 3 mmol/L hydrochloric acid as an eluter. As a result, six aconitum alkaloids, including two lipo‐alkaloids (8‐lino‐14‐benzoylaconine, 8‐pal‐14‐benzoylaconine), three monoester‐diterpenoid alkaloids (14‐benzoylmesaconine, 14‐benzoylaconine, beyzoyldeoxyaconine), and one aconine alkaloid (neoline) were acquired from the plant at the same time. The anti‐inflammatory activities of the two new lipo‐alkaloids were compared to the six alkaloids in vitro, in cyclo‐oxygen‐ase‐2 inhibition assays. The separation mechanism of six alkaloids by pH‐zone‐refining counter‐current chromatography was illustrated.